How to Build a Competitive Kart Racing Engine (Stock Appearing)

welcome to make something with me david patrido today we're going to take this harbor freight engine and turn it into a go-kart racing engine for the stock appearing class if you're just looking to soup up a motor for a yard cart or a mini bike check out the new ghost motor from harbor freight that motor does not apply to the cutting class that i race in today we are building a racing engine for competition in the adult stock appearing class i build all my own engines and have had some success recently in the past year i've won three races three second places and i finished second points for the 2021 season in the league that i run in harbor freight sells two versions of the 212 motor this one is the 69730 non-hemi sometimes they have the non-hemiand sometimes they have the hemi end i can tell this is a non-hemi by the part number and the valve cover i prefer the non-hemi version because there are less clearance issues some builders prefer the hemi version all the parts that i'll be using today are made for the non-hemi version the 69730 mostly what i need from here is the block the crankshaft the head the side cover and the pull start a lot of this other stuff we're going to get rid of some of it you can actually sell on ebay and get some of your money back i don't need the gas tank the muffler the air filter or the carburetor i buy modified carburetors so somebody else will get some good use out of that like i said you can sell some of those things on ebay the stock flywheel can be a little tricky to remove so i'm going to stick a crowbar underneath there you don't want to crack the block you got to be really careful this is only made for 3 600 rpms and it's cast iron we're going to get this up to around 8 000 rpms and this is very dangerous it will eventually develop hairline cracks and when they explode they are actually very deadly we'll talk about flywheels more in a little bit but i'm going to put this billet aluminum one on there later it's okay to use power tools to take the motor apart but i never ever use power tools to put it back together this is the crankshaft and this is the cam we're going to use the stock crankshaft and we're going to replace the cam that just pulls right out we are not going to use that somebody else might be able to use that and modify it i need to take the crankshaft off so i can remove the governor but before i can take the crankshaft off i have to take the connecting right off which are these two bolts right here here we go so this is the stock crankshaft we have to use the stock stroke in our rules so i'm going to reuse this crankshaft it does have this gear on here that's for the governor and i don't need that so this is just friction fit on there as we're removing the governor there's going to be this tiny little washer that usually gets stuck up in there and you want to make sure that gets removed because you don't want that flying around in there and now we need to remove the oil sensor when you are racing the oil is going to get sloshed around the oil sensor is going to kick on and it's going to cut off your engine not something you want in the middle of a race because we took out the oil sensor and the governor we have three holes that we need to tap and plug for this front run i'm just going to take a bolt and a nut and a washer put that through there and on the other side i'm also going to use some gasket sealer around there and some thread lock to make sure that never comes off [Music] we are done disassembling everything so now i'm going to take some brake cleaner and clean this out really good this is the stock connecting rod that connects the piston to the crankshaft the connecting rod takes more abuse than any other part in the engine it's a very violent movement when it reaches its peak and then is yanked back down and then when it reaches the bottom it is yanked back up this is not made for 8 000 rpms so we replace it with a billet aluminum connecting rod there's no performance gain with the bill aluminum it's just this is not going to break on you at 8000 rpm this is the stock piston there's nothing wrong with it except it's dished so i'm going to replace it with a flat top piston and we're going to get a little bit more compression because the measurements of this piston is slightly different than the stock piston this connecting rod is slightly longer than the stock there's a link to everything that i'm using down below before we can connect this to the crankshaft we have to make sure that our clearances are fine for the crankshaft so if the clearances are too tight the metal is going to expand and get hot while the engine is running it's going to seize up on you and it's no good here's the thing i have never come across a crankshaft that has a bad tolerance but they are made in a factory someplace far away their standards are very low so apparently every once in a while you come across a crankshaft that is not perfect all i'm doing right now is checking to see if our clearances are to spec using some plastic gauge so i put that little red piece of plastic in there and i torqued that down to the specs and i'm not going into detail because everything is in the instructions for this connecting rod you can see that piece of plastic it kind of disintegrated but it's spread out and we're actually going to measure that spread we are just under zero zero three so we are perfect for our clearance so now we do have to make sure that we get that plastic off before we install the crankshaft the connecting rod and the piston you can see down the cylinder here there's some cross hatching and that cross hatching is on purpose to hold oil while the piston is moving up and down i'm going to do a very light hone job on there just to make sure it is holding oil at 8 000 rpm so i've got this tool right here everything will be linked down below i'm just going to dip this into some oil and then give it a little hone job this piston did not come with the rings installed so i had to put them on there myself this little tool right here this piston ring installer makes that process a lot easier and a lot safer so you don't bend them in any particular way now you can buy specialty rings that are oversized and then you can gap them yourself because there's a little there's a little gap there and that gap is on purpose that gap allows it to spring out and make contact with the cylinder wall if that gap is too big you get blow-by and you're going to lose horsepower if that gap is too small you're going to get some binding and that's just going to cause you all kinds of issues so i'm just using the stock rings for this but no there's a whole world of piston ring knowledge that you can research for yourself on the piston there's a little arrow that arrow is always going to point down and then on the connecting rod there are two dots on each piece and those dots need to face each other and then when you put them in here you should be able to see the dots if you can't see the dots you have it in backwards i am going to put a little bit of assembly lube on here some people like using assembly lube and some people don't the reason people don't is they don't want this thicker oil to fling in the crankcase and some people just use regular oil depends on who you talk to this goes in here like this that goes in there like that and then this little clip is going to snap into place you need a little a little screwdriver i like using an ice pick for this and it makes a nice little clicking sound when it gets in there and i got to do the same with the other side there are a couple different types of ring compressors there's the spring loaded kind that will work with various size pistons i hate them they drive me absolutely bonkers they're hard to use i only work with one size cylinder and so i have this piston ring compressor that is made for this size cylinder it is tapered so i can put a little bit of oil in there and as i drop that in there it will compress the rings on there and allow it to drop into the block gonna oil up the inside of the cylinder i got my gaps where i want them to be on opposite sides there and i would drop this into the ring compressor this is the toughest part of the whole build right here is getting this assembled sometimes it helps to have a buddy just hold that in place some of us don't have friends we got the connecting rod onto the crankshaft it's time to put on this part of the connecting rod with the oil scoop this is hard to show on camera but you want to torque it down to spec so a torque wrench is a necessary must-have tool when doing this because we changed pistons we had to get a slightly longer connecting rod and we got that piston just below that surface right there if we used the same length that piston would have been set back just a little bit and we would have lost some compression next thing we need to do is upgrade the cam this is where a lot of your performance is going to come from there are dozens of cam choices i can't help you pick the right one one i'm not qualified and two it's so personal to your needs and the type of track and the motor that you are building so you have to do some research i know talking to other racers in my area and i know from past experience that the small tracks that i run on this is the cam that i need and that i've had success with the cam has these lobes on here and these lobes are shaped and sized to give you duration and lift duration and lift is going to determine how far your valves move up and down and the more they move up the more airflow that you can get into there the more combustion the more power the more torque this is a very aggressive cam as far as the lobes are shaped but doesn't have a super high lift i'm going to increase lift using another technique using ratio rockers this cam has a dot on here and then the crankshaft has a dot on here i want to align those two dots and it just fits in there i am going to put a little bit of assembly lube on here i'm using the stock lifters and i do want a little bit of oil on them so they go back in there these lifters will connect with the push rods the push rods will connect with the rockers and the rockers will move the valves up and down then the cam can go in here lining up the dots i've purchased an extra side cover and have cut it down on the bandsaw so i can throw it on here it will center the crankshaft and let me know if we have any clearance issues so i've got that bolted down and now i can start turning this nothing is knocking but a lot of times the lobe of the camshaft will connect with the crankshaft right there and you have to take a dremel and file that down a little bit so they don't connect even with some heat expansion and some crankshaft flex we should be good but just in case i am going to file that down so there is one more spot that i think we're fine but i want to point out and that is where the connecting rod comes up and it gets really close to the block up here i do think that i am fine but i'm going to take a marker and i'm going to mark that and i'm going to do a little bit of clearancing on the block just to make sure what happens is there's internal harmonics within the engine and things start to flex and things heat up and they start to expand and so you want to make sure when things get hot and things are flexing things are not bumping into each other because that could be disastrous unfortunately we got to take everything back out take a dremel to those two areas and put everything back together that's just the nature of engine building we got that all back together the tolerances are where they should be and i'm going to put on a new gasket and put back on the side cover now if your rules allow you can get a billet side cover and what this does is it stiffens up the whole block and that is going to increase the lifespan of your motor also means you can build up some more compression and your motor can handle it our rules do not allow us to use a billet side cover that's the inside of the block that's just an overview of what i am doing there's so much more you can do you can actually advance or the timing in the cam which is going to move your power band i think i mentioned the piston rings you can get low tension rings and you can set the gap to your needs so a lot a lot more details that you can get into to just get a tiny little bit more horsepower like i mentioned before the cast iron flywheel no good you got to get rid of that so i have this billet aluminum one here this is tapered and then the inside of the flywheel is tapered so the very first thing i need to do is remove this key and then lap that to this crankshaft to keep the crankshaft from turning i have this little handy tool right here which fits on there you throw a little key on there and then i can turn it put that in there and that locks the crankshaft down so it doesn't spin all right so we're going to remove the ignition coil because it's getting in the way and we've got some valve grinding compound on the inside there you can remove that we'll take some brake cleaner and clean that off because you don't want that anywhere in there and then we can connect the flywheel there are a few different options when it comes to your flywheel this is the light flywheel there's also the ultra light flywheel that doesn't have the fins on there i'm gonna have one motor with the ultra lights and one with the light that way i have a choice the ultra light is going to be really handy on really small tracks that's going to allow for a greater acceleration but that ultra light flywheel is not good for bigger tracks because you might have some good acceleration but it's also going to deaccelerate very fast too instead of keeping your momentum through the turns you got a lot of research to do if you're all new to this but for this particular motor we're going to go with the light flywheel now your ignition coil is going to go right here there's a magnet on sticking to it right now there's a magnet on here and the position of this when it's mounted onto the crankshaft determines the timing for your motor if you throw this key on the crankshaft and throw this on there you're going to have 32 degrees of timing timing is a whole subject that we're not going to get into but you could advance or your timing and move that power band around for your particular needs how do you set the timing if you don't have a timing wheel and a gun and everything so this is a normal key and this is a key with eight degrees of advanced timing so if i put this onto the crankshaft the flywheel is going to butt up against that little cutout on there and i can get eight degrees of timing i have other keys one for 10 degrees one for two degrees one for 12 degrees and one for four degrees if you have a timing wheel and a timing light and you know how to set the timing you don't even need the keys especially if you've lapped this correctly once you get this on there they should mate perfectly and if you torque this down to proper specs you don't need the keys at all so it's up to you i'm going to put a key in there and i'm going to put this on at 32 degrees our leg allows gasoline or alcohol so if you are running alcohol you have to advance your timing more because alcohol burns and combusts at a different temperature it gets complicated i'm sticking with gasoline it's just easier i'm sticking with gasoline our lake doesn't allow electric starters but sometimes i am at races that do allow electric starters and that just saves my shoulder and my neck from pole starting so i'm going to put this high torque nut on there and replace the one that came with it getting this torque correct is a little hard so it's just easier for me to go on the floor that one is definitely hard and you have to have that stop on there now that we got the flywheel on there we can put our ignition coil back on and that has to be a certain minimum distance from the flywheel so i have my feeler gauges here now when you get your flywheel it's going to come with these specs so i'm not going to announce them just read the directions a lot of this is just reading the directions not not that hard so that that magnet is just going to make that stick on there like so screw that back in pull off my feeler gauges that is the block next we are going to work on the head this could be a full eight part video series just on this alone but we're gonna simplify it so the very first thing i'm going to do is take off all the parts that's on here right now if you need to remove the carburetor studs the way to do that is to take two nuts tighten those together and then i can use that to back those out of there you're going to notice that one carburetor stud is longer than the other you're going to want to replace the shorter one with a longer one because of the air filter and the intake that we're going to use and if you need to remove the exhaust studs same thing you'll put two nuts on there tighten them together and then you can back them out so we're going to put a bigger valve on the intake and so i need to remove the valve seat that's there and put in a new valve seat so we can throw on a bigger intake valve the bigger the valve the more flow that we can go through there you have to match your valve size to the carburetor that you're using we have to use a stock appearing carburetor we don't want to go too big because you're going to lose volumetric efficiency there's a lot of science involved so we're only going to replace the intake with a slightly bigger valve this is just a fancy dremel most people will use a dremel i like this because it's foot powered i can also reverse it if i need to finally cut all the way through there that's going to pop out this is the tool that i'm going to use to pocket out the space for the bigger valve seat this stem here is 5.5 millimeters currently the valve guides in here are five millimeters which means the stock valves are five millimeters but the valves that i want to put in there they're stainless steel they're upgraded they're a little bit stronger they have 5.5 millimeter stems so i need to bore this out to 5.5 millimeters so i'm going to drill close to that size and then i'm going to use this reamer to get it to the exact size this is a very specific tool just for this job because this is a non-hemi head the valves move straight up and down so if you have a drill press this is probably the way to go but i'm just going to use my hand drill here and drill that out now i'm going to switch to my reamer add some oil and ream that to the correct size another alternative to drilling that out is replacing them with bronze valve guides now once you put them in there you still have to remit with the reamer to the exact size and then do a little cross hatching with this tool right here to replace the valve guides it takes this special tool which fits into the valve the current valve guide and then you can take a hammer and knock that out it is just an interference fit in there so it's all just held in by friction never ever reverse the drill when using a reamer even when pulling it out this is made to an exact size and you round that over so now that we have that reamed out from five millimeters to 5.5 millimeters we can go back to cutting the pocket these carbide blades are adjustable so they can be moved out to cut bigger and smaller pockets my new bigger valve seat that has been sitting in the freezer overnight right now it is on ice i am going to take a heat gun and heat this up so the aluminum will expand the valve seats will shrink and we'll get a nice interference fit in there i made this little tool on the lathe so i can use that to pound that in there so i got that heated up i got the valve seat cooled down so now that we have the valve seat in there we need to do a three angle valve job and what that is going to do is cut an angle on the inside of that valve seat to match our valve the valve seat has a couple of purposes the biggest one is to seal off the chamber so you get the best combustion possible and another one is it removes some of the excess heat from the valve into the head this takes a very special tool i have this kit here which does the three angle valve job the angle needs to be precise and you want a certain amount of contact between the valve seat and the valve lots of videos on youtube on doing a three angle valve job it's the same for a car as it is for a go-kart so you can go look those up if you need a little bit more information this is just done by hand no drill this time we got that first angle we'll put in the second angle into the tool tighten that down now that we got that all done we need to match the inside to the sides of the valve seat right now like i can catch my fingernail below there so now that port matches the size of our new valve see it's a little rough but we're going to smooth that out in a little bit we're going to do a little bit of porting and when i say porting all i'm doing is rounding over the edges porting is where you can gain a lot of that upper end high rpm horsepower it's not something i really need on the small tracks that i run also porting is where you can easily ruin the flow of your engine this is really it really should be left up to the professionals somebody who has a flow bench somebody who has a dyno and they can measure numbers or so just somebody who has experience all i'm going to do is round over the edges on the intake and the outtake imagine if you blew smoke into here would that smoke hit that corner and cause turbulence and roll over onto itself or would that smoke flow through easily like a nice stream of water right now there's going to be a lot of turbulence because the stock head has some very sharp edges in there so i'm just going to round them over i am not going to do any reshaping of the port size just rounding over the edges and then on the outtake we want as smooth as possible you can get up to a mirror finish if you want on the intake we want smooth but not as smooth as the exhaust we want it it should be smooth to the touch but it's okay to have a little bit of scratches in there to help atomize that fuel air mixture before it gets into the combustion chamber [Music] now that the porting is done really i'm just rounding over the edges i'm going to polish the chamber this is just going to help with the fuel air moving in and out and this is just a little dremel polishing tool on the end of my spindle i got all those corners rounded over and then that polish as good as i'm going to get it for now next thing we can do to increase compression is to mill this down now typically you would do this on a mill with a fly cutter that would remove all of this material right here i don't have a mill and a fly cutter so i'm going to show you how to do it with a belt sander that belt sander is pretty darn aggressive doesn't leave a super smooth finish plus it's not perfectly flat so i have a piece of plate glass here that i'm going to glue on some sandpaper you don't want this to be a mirror finish but you do want it flat and smooth next thing i need to do is use some valve grinding compound on the valves to mate them to the seats these are brand new valves and this will allow me to see how good of a job i did with the three angle valve job this is like a liquid sandpaper so i can stick that in there i can take this tool here and do one of these numbers you can tell by the sound when it starts to mate i can see on the valve itself exactly where it touched there is an optimum place for that contact on there again there are plenty of videos on youtube that goes into great detail on lapping valves and doing a three angle valve job this is just your overview to get you started last bit of work to do is cut a bigger pocket for the springs the factory springs are like 10 pound springs maybe 11 pound springs we're going to put in bigger 36 pound springs and they have a wider outside diameter i've got the spring pocket cutting tool mounted in my drill this stem fits into the valve guide and allows me to cut the pocket so now that is going to allow a bigger spring you have to cut them deep enough so you don't get coil bind and then if you cut them too deep you're going to lose some spring pressure so there are shims that you can put in there to get the right about of spring height that is a lot of work for the head the first time i did this this actually took me a couple days the more i do it the better i get at it that being said you can buy heads that are already done you can find them on ebay or various racing sites where they already have the bigger valve seat in there they've already got the valve guides drilled for the five and a half millimeter stems you've already got the spring pockets cut already ported and polished so you just got to look around i really enjoy doing all of this myself i like knowing what goes into there and i like being able to say i did that i did this here in my shop and that means a lot to me i've won a couple races with motors that i've built so i know that this works for me we talked about the springs that came with it these are the 10-pound springs not going to be good enough because we changed out for a more aggressive cam we removed the governor and we put on a lighter flywheel we're going to get a lot more rpms with a more aggressive cam and more rpms you need a higher tension spring my cam came with a card that recommended 36 pound springs so that is what i'm putting in here if your springs are too light your valves are not going to close there's not going to be anything for them to push them close especially up at higher rpms if your springs are too heavy you're putting drag on your engine and your engine actually has to work harder and if your springs are too light you're going to get what's called valve float the valves are not closing you're going to it's going to be a very noticeable loss in horsepower in the upper rpms and you can easily hear it if i experience floating valves during a race that means i'm going to have to make some adjustments either higher tension springs or work on my spring height so we're going to start with the 36 pound springs and put them in here this is actually one of the more difficult things to do 10 pound springs you can you can easily squoosh with your fingers to get them in there to get the retainers on 36 pound springs there's there's going to be some curse words said off camera i guarantee it there's some oil on the valve stems i'm going to go ahead and throw them in there i clean all of this out really good to make sure there are no metal shavings anywhere so now we can throw in our springs these valve retainers go on top and then this has to be pushed down below that little nub there on the valve so you can get the keepers underneath that roll up a paper towel and set that underneath there and that's going to keep that valve pushed up i'll just do one at a time throw on the spring throw on the retainer i've got this tool right here that makes this job a little bit easier there we got one in got those heavy springs in there that can be sometimes that can be a little difficult so i threw my spark plug back in here temporarily and i'm just going to fill this with water and what i'm looking for is it leaking down below it'll it'll come right out the exhaust or the intake i'm just going to let that sit for a little bit if nothing comes out we have a really good seal i really don't know how the professionals do this i don't know i don't i'm not sure if this is a common technique somebody showed this to me once and this is how i do it i use the fire ring thicker head gaskets which means i lose a little bit compression because this gasket is so thick you can get thinner gaskets but i personally have not had the best luck with these thin metal head gaskets i've lost i've lost pressure and some seal and once that happens to me once i just don't mess with it again so i like using the thicker fire ring gasket we're going to put these dowel pins back in the head on this particular gasket that i have doesn't fit over the dowel pins so i'm going to take a dremel and just widen those holes just a little bit so that goes on there and you want to torque these down to spec i keep a handy little torque spec sheet hanging up in my trailer these are the rockers that came with it these are stamped and just your standard rockers not made for this application we are going to install these black venom roller rockers these have a true roller tip we're going to put lash caps on the valves and then this will get seated in there if you use this style of rockers you don't need to put the guide plate back in so i don't need that these are one to three ratio rockers that means we are going to get higher lift you can get higher lift two ways one with the cam or one with the rockers so we have an aggressive cam but it doesn't have a super high lift so we're going to increase that with the roller rockers this is one of those things that a real engine builder can throw on a dyno find the right ratio rocker find the right amount of lift and the right amount of duration so what is duration and lift lift is how high the rockers open up allowing more air fuel into the head and then the duration is it's kind of like the the ramp speed of how it gets to that point and closes from that point one of the things about using the rockers for lift instead of the cam is the the motion and the geometry that it causes it's almost like when you're in a room with two doors and somebody opens one of the doors and the other door slams shut because that vacuum in the room these rockers kind of create that helping the airflow through the head you can have too much lift if you don't have a carburetor that is supplying enough fuel air mixture into your head one of the reasons why going to an actual engine builder might save you a lot of time and money i am going to put the lash caps on here you got to be careful the last caps can fall where the push rods go so i can drop my push rods in here sometimes you got to play with them a little bit so they catch and fall on the lifters you can tell when they fall on the lifters when you rotate it and they move and then i can start screwing this part back in the piston is going to reach top dead center twice in the four cycles we want it on the compression stroke easiest way to find that put your thumb over the spark plug hole and then rotate the crankshaft and you're gonna feel it push your thumb off that's the compression stroke and so right now it's sucking my thumb in as soon as as soon as it starts to push my thumb off i can then throw in a screwdriver or anything and then just rotate a little bit more and it's until when this gets to the top point you're at top dead center and you're actually going to feel the crankshaft it's going to kind of fall into place when it gets the top dead center there's like there's a little bit of play right there it's like boom i can feel it hit right there this is where you would set your lash so before i set my lash i just want to get this in the ballpark and as you can see when i rotate the crankshaft the rockers go up and down now depending on the type of rockers that you have when you get to top dead center there should be a slight downward angle on the push rod side of your roller rocker this angle isn't super critical it does but what determines that angle couple things if you the your spring pockets your shims within the spring pockets but mostly what people will do is just find the right push rod so you have different push rod lengths off camera i tried a couple different push rod lengths to see if i could get the angle to where i want it arc racing has a whole video just dedicated to push rod length it's it's going to be worth your hour and a half watching that you're going to learn so much so now that i am in the ballpark and i have the right push rod length in there i'm gonna find my top dead centered again it's gonna there's a little bit of water in the valves from that water test yet but it sounds all squishy so all right it's pushing my thumb off and right after it pushes my thumb off it reaches top dead center which is right there i'm going to set my lash according to the specs that came with my cam i'm going to set it cold and then after the engine heats up i will reset it to what it tells me to so depending on the type of cam and your engine you are probably going to have a different lash setting than me from here you want to make sure you don't have any coil bind i'm nowhere close and also you want to make sure your rockers are not bottomed out so i can get a screwdriver underneath here i can lift that up a little bit so i know i'm not bottomed out now that we have the one to three rockers they're pretty big compared to the old rockers and now they also have more lift and so when i put on my valve cover it hits the valve cover you have two options one you can grind away and make clearance for that the option that i like using is this valve cover spacer right here so we'll put that on you'll need to put that means you'll need twice as many gaskets so you put a gasket on there you put the valve cover spacer and then you put another gasket on there this spacer also comes with this pulse fitting on there which means we can use this to our fuel pump to pump fuel into the engine otherwise we would have to drill a hole and then tap that and then put that pulse fitting on here so that spacer does two things another thing that you can do to stiffen up the assembly is use head studs but our league does not allow head studs we have to use bolts to put the head on so if you wanted to stiffen up the whole block you would use a billet side cover and then you would use head studs we can't never assemble the motor with power tools always hand tools get the spark plug in put the carburetor studs back on carburetors a whole nother subject a whole nother 10 part series that i know nothing about we use a stock appearing carb but they're highly modified there's a new there's a new little idle jets a new main jet a new e-tube and then this one is the venturi is board out a little bit i don't do any of this myself because they're relatively cheap you know just a little over a hundred dollars there are plenty of places online that you can buy them i got mine locally but you can get them from nr racing or arc already bored out with the jetting that you may need this is the insulator plate that comes with your carburetor or comes with the motor from harbor freight i have already gone ahead and taken a dremel and worked on that hole that hole should match the whole of your intake because by default there's not a smooth transition so i you want you want the easiest access for that fuel and air to get into your cylinder head so i work on the insulator plate shape it do what i need to do throw on our gasket throw on the insulator plate the modified one then i throw on the next gasket this gets confusing to some people this tiny little hole we want it on the left side the reason some people think it goes on the right side is there's a little hole here in the carburetor but nope we want it top left so that goes on there this goes on there this goes on there like that and then next goes the air filter adapter and then that gets bolted on this air filter right here is a high flow air filter you don't want to use the stock one this one's going to allow a lot more air into the engine the more air the more fuel you can get into the cylinder the better we got the carburetor we got the intake on there next thing i want to do is install a top plate this goes on top of the motor where we can put our fuel pump and our throttle assembly there's a few different versions of this the version that i like the one i feel is the easiest to use is this triangular weird shaped one this is made for the hemi version this is a non-hemi and so i need to make a slight modification and bend this little guy down so i can mount it on here on top of this we'll go a fuel pump i have this other top plate that i robbed from another cart and i'm just going to go ahead and use this i've already got the fuel pump mounted on there it's just screwed on there and i'm gonna bend this down and attach it to this that mounts on there like that the throttle from the cart is going to go right here at this point you should know what you're doing this first line here this is the pulse there's a little p on the fuel filter and that goes to the valve cover all this is doing is creating a vacuum to the fuel pump so the line in can pull from the gas tank and then this will go to the carburetor there's no gasoline anywhere around here so i will use a lighter to heat up the fuel line so i can get it around the carburetor some people will put a fuel filter here i may or may not do that later and then we start adding some ties make sure everything is air tight you don't want to suck any extra air so now we're going to put oil in there and do the break-in there are a lot of theories on breaking in an engine the way i do it is probably going to be different than the way somebody else does it one of those theories is a hard full out break in fill it up with oil take it on the track and run it as hard as you can that's going to help those parts mate together i don't have the luxury of running at a track so i'm just going to throw this on my cart throw it on a stand and just run it for a good 15-20 minutes it has to be higher than idle these engines lubricate the parts with splash and so at idle you're not going to get a lot of splash there's the dip on the connecting rod that goes into the oil and flings it around the engine so after i put some oil in here i'm also going to hold the engine upside down and tip it left and right just to make sure oil gets everywhere it needs to go for that initial pull starts and speaking of pull start i pulled the pole start off and i'm going to use an electric starter today because it's just going to be easier another thing you can do is add a little bit of zinc to your oil for the break-in period it's just going to add even more lubricant to your engine i don't run this at the races i only use this for the initial break-in period once we break it in then we're going to dump the oil out and it's going to look very glittery as all those parts are mating up actually the next couple of oil changes i might see some some glitter in there throw on your exhaust look to see what your rules allow and don't allow but this has a loop on there to create a little bit of back pressure to help with the flow inside the head throw on the chain guard [Music] we got a good break-in period so now we're gonna pull out all the oil i'm gonna take it all apart and i'm going to inspect everything make sure everything looks good i'm gonna check the cylinder walls to see if there's any scratches in there see if i need to make any adjustments to the piston rings make sure the cam is doing what it's supposed to do might have to work on the jutting for the carb a little bit but uh we're we're almost there gotta take it off the cart and just tear it all apart put it all back together again it's a lot of work but it's worth it down in the description i'll link all the tools that i use as well as all the parts that i used on my motor the principles of building this four stroke one cylinder engine is the same as this eight cylinder engine here this is just a smaller version of that you've got intake compression combustion exhaust suck squeeze bang blow suck squeeze bang blow suck squeeze bang blow except here you just got eight cylinders so i'm going to rebuild this one next i'm not claiming to be an expert engine builder and i'm not claiming that all of this information is 100 correct racing is a very competitive sport and some of the things that i've learned from other engine builders were told to me in secret and i believe i have not revealed that information here you will almost always get a better performing engine from an experienced engine builder with knowledge in your class and someone who has a dyno and a flow bench again check down in the description for a bunch of resources including the league and the rules that i race under and if you're curious no i won't build you an engine i only build them for myself i will try and answer as many questions as i can down in the comments and i'm hoping some experienced engine builders will also chime in with corrections and answer questions as well thank you for watching and good luck

Channel: Something About Making

Views: 2,024,652

Keywords: kart engine build, go kart, gokart, stock appearing, how to build a racing engine, predator 212, harbor freight, non-hemi, hemi, kart racing, gokart racing, dirt oval, dirt oval kart racing, engine building

Id: RKOK5drBSQo

Length: 43min 34sec (2614 seconds)

Published: Tue May 03 2022