Honda CRF450R Top End Rebuild | Part 1

what's up guys this is Charles with Rocky Mountain atv/mc and today I'm going to show you how to rebuild the top end on your CRF 450 arm it's important to keep up on your bikes maintenance and service intervals and that way you get the best performance out of the bike and hopefully that will help you avoid any costly repairs down the road now that's why we're rebuilding the top end on this roached out 2005 CRF 450 AR and it's actually part of our Roadster racing series where we take a bike that's completely worn out rebuild everything and then we're going to go race it so be sure to check that out and even though we're working on a no.5 this procedure will be similar for CRF 450 ours from o to 208 and even some of the X models so make sure you refer to your service manual for any steps that are specific to your bike to do this job we'll need some basic hand tools rags some safety glasses we have a bunch of different precision measuring instruments and we also have a valve spring compressor for parts we're using the rent traffic kit that comes with the common parts that are replaced on the top end as well as crank shaft seals gaskets and a few other goodies we need since we're rebuilding the bottom end as well the bottom and rebuild for this engine will be in a separate video on our channel so if you need help with that be sure to check it out we also have a tusk oil change kit since we want to make sure we have fresh oil in this thing for our new parts if you're just doing the top end we have a lot of different options for parts on our website including piston kits valve kits big bore kits and performance camshafts now that we've covered all that we can get started the first thing you need to do is start with a clean bike now we've already removed our engine out of the machine but this process can be done with the engine still in the bike so to gain access to the top-end you'll need to remove a few things including your seat gas tank radiators exhaust and upper engine mount throughout the process pay attention to anything that doesn't quite look right take some notes so you can give it more attention later on now that we have access to the top and what we need to do is remove this spark plug so what we're going to do there's actually a hole on the side of the cylinder head and we can blow through that hole and it'll blow out any dirt that's built up around in there so it doesn't drop in so I'll take our air hose blow out any dirt the next thing we'll do we'll take our spark plug socket and we'll loosen this thing up after that we'll take these three ten millimeter bolts from our valve cover off then we can pull the cover off the next thing we need to do is put our engine at top dead center compression stroke so to do this what we need to do we've got a couple timing covers on both sides of the engine and on the left side we'll remove this six millimeter allen key timing cover we'll set that aside move over to the other side of the engine we'll take our ten millimeter allen key and loosen this up so to get this thing on top dead center what you need to do this actually is an 8 millimeter allen key right here and from this side of the engine will always want to crank it over clockwise so basically what we're looking for there's a dot on this gear down here but we can be 360 degrees off so what we need to do we'll line a dot on this side and then also on our stator cover we'll line up a line with the cover coming from the flywheel then we also need to make sure that our camshaft gear has both lines lined up with the two dots on the cam holder the next thing we'll do is measure our valve clearance and that way we know if we need different valve shims in here as we reassemble so we'll start with the intake and write those measurements down now that we've got our valve lash measured we need to loosen up this bolt that's in the center of our campaign tensioner because we'll need to use that access that later and this is the best time to loosen it up so after that we're actually going to remove the tensioner and that way you won't have to get that special tool to pull that thing back you want to back these off evenly so something is clearly wrong with ours we've got a bunch of slack in our chain already and I'm guessing this tensioner is broken so normally this thing would be out and you need a special tool in this backside to crank it back in or you can use a small flat blade screwdriver to do that so with the chain loosened up what we need to do is remove this cam sprocket to do that we actually have a cam gear holder from motion Pro and we'll just put that in place with both of those loose we'll remove our gear holder so when you do this just be careful with these bolts you don't want to drop them down into the bottom end and we'll go ahead and slide this gear off and I just like to rest the chain right there for now now we can remove the cam holder so to do that we loosen up these four bolts on top in a crisscross pattern and then once they're all loose we'll back them out all the way so when you take these bolts out you'll notice you actually have two different lengths so these longer ones go in the front but we'll just lay them out in order so we don't mix anything out and we can rock this cam holder loose and when you pull it up you're gonna have two buckets on the bottom and I like to put my finger just under the back and keep those buckets in place and then I'll turn it upside down because sometimes these shims can stick to these buckets so ours didn't this time but it's just something to look for and then when you take these shims out lay them out in order because if you're not changing anything with these valves you should be able to put them back in their original positions on reassembly so to pull these out what's easy for me I just like to use a magnet so now I'm gonna move this rag out of our way we've got this coolant elbow right here on the front I'm just gonna loosen that bolt up because we are gonna replace the o-ring on this this is something you don't have to replace the o-ring every time but could be a good idea just easier to take it off right now and then next thing we need to do is we'll crack 8-millimeter head bolt that's on that cylinder this on the side crack it loose but we'll leave that one in place and then these two on the side of the cylinder head we're actually going to remove all the way so after that what we'll do we've got these four cylinder head mounting nuts and we're just going to loosen them a little bit out of time in a crisscross pattern just so we don't warp anything when we take it apart so why we left this bolt down in the bottom is to help us pull the cylinder head off without pulling the cylinder at the same time and these things sometimes they'll come off easy and sometimes you'll need a little force and if you do need help getting this up you can be really careful sometimes you can use just a little dead blow hammer and kind of tap it but if you do that be very careful with everything you don't want to break anything so ours we were just able to wiggle up and keep in mind you've got a couple dowel pins on this so you don't want to lose those keep track of them and we'll go ahead and lay all this out on our rags so we don't lose anything take our head gasket off and this is something you want to replace every time you do this job you've got a couple dowel pins on this so you don't want to lose those keep track of them now that we have the head gasket off we're going to take this valve guide out and it just pulls up and we'll go ahead and remove this eight millimeter head bolt there's a couple different options to take this cylinder off first we need to break it loose from this gasket if you can break this loose just by kind of moving it with your hands that's the best way to do it if you have to use a dead blow hammer that's fine but just be really careful when you do that and remember you never want to pry a screwdriver a pry bar in between the mating surface where that gasket goes we've placed a rag around our connecting rod to prevent anything falling into the bottom and so to remove the circlip what we need to do I'm just going to use the pick and pry up on the circlip a little bit and pop that out of the place you'll slide that wrist pin out of the way or piston pin whatever you want to call it and you can already see on ours we have actually have a bunch of galling going on right there so that's something we're gonna want to pay attention to we also need to check for up and down play in the connecting rod if there's any play you'll need to replace it so as we pull this cylinder off this base gasket sometimes it can leave some material behind on your case half so we're gonna want to clean any of that off so I'm just going to take a little contact cleaner on the scotch-brite and then we'll go along these surfaces make sure they're clean and smooth and again if you had chunks of material which luckily we don't you'd actually take this scraper and just kind of work along it and then the last part once you get that surface clean we'll take your rag and I like to use a little contact cleaner on the rag and wipe it up okay now moving on to the cylinder what we need to do will remove these dowel pins and just be really careful with them I'm barely barely gonna use any pressure on this and if they don't slide right out and you have to apply a little more pressure you want to put something on the inside diameter of that dowel pin so you don't crush it when you squeeze down on it so again just being really gentle with it so we don't damage anything or more up that surface right there take it out like that move on to this next one so this dowel is pretty tight on ours so what I'm gonna do I'm going to put this we got an 11 millimeter socket right there just gonna put that in place and that way I can apply a little more pressure and help get this out now and I'm not going to be doing anything where it's actually going to damage it and these surfaces here they're still good so after that what we can do we're gonna take this gasket off and I usually try to find a loose spot and that way you can try to pull all of it up as much as possible in one piece so we'll see if we can find a loose spot on this one okay so this back corner actually popped up pretty easy so I'm just going to start there and just start pilling it up and you can see it's leaving stuff behind that's okay we just want as much as possible to keep it in one piece and the reason for that is that it's kind of a pain to scrape through it through the thick spots and when you scrape this gasket material away you don't want to put it at such an angle you're going to be gouging this metal you just want to be real gentle with it just remember the cleaner this is the better it's going to seal so we'll go ahead we'll take this marine scotch brite and do the final cleaning just make sure there's no gouges or any material left behind and with this I'm just using a little bit of contact cleaner the next we'll use this contact cleaner on a rag and go back through and wipe everything up okay now that we have the base gasket surface clean we'll flip this over and we'll clean this head ceiling surface up but we need to do this just keep in mind there's a lot of people that they'll use air tools on this but really this is just soft aluminum and basically it's really easy to damage the surface and air tools really are kind of too aggressive for that so we're just going to do the same thing if there's any material left which on ours is not you scrape it off and then we'll just use a little bit of scotch brite just to clean it up a little more and some contact cleaner so the next thing we need to do is check the cylinder for warpage where it meets the cylinder head and you'll need a machine straightedge to do that and we'll check it in several spots so to do this fastest way is just to get a feeler gauge that is the size of the service limit and we'll just check if that goes in anywhere so as you can see that's really pretty quick ours looks good so we'll go ahead and move on we're gonna clean this cylinder bore out a little bit and I'm just going to use a little contact cleaner and a rag okay so we've just kind of clean this up a little bit for the preliminary inspection and basically we're gonna look where the piston rides and check for any serious scuffing or damage to the cylinder wall basically you can take your glove off and if you run your fingernail across the surface and it catches on anything then you're probably going to need this cylinder replated because it's a nicosia liner now this is a really hard coating but it's super thin so if it gets damaged it does need to be recoded on our cylinder we don't have any real noticeable damage that we can fill with our fingernail so this cylinder is going to be reusable Honda doesn't recommend honing these cylinders out because of the the way this liner is so thin but over the years what I've seen everybody do basically you'll use a hone that's designed for the nikah seal and you'll just get in and get out really quick make a couple passes because you do want the cross-hatching to be in there so the Homeless cylinder we're actually going to use a ball home to do it and when you do it you're definitely going to want to have some oil on the inside of the cylinder and on the hone and flex hone actually does make an oil for that so the other thing you're going to want to have your drill going at a slow speed get in and out really quick with this type of cylinder we're not really trying to take anything off we just want to have some cross hatches in there and we have this clamp in our vise just in some soft jaws and then we also have a rag to help protect it and it's not really clamped down that tight just snug enough to hold it and we don't have anything clamped where our cylinder head is actually going to come in contact with the cylinder so the other thing when you do this you want these cross hatches to be at a 45 degree angle or pretty close to that and we'll go ahead we'll wipe some of this oil out of here and again I'll use a little contact cleaner on our rag then we can reinsert our cross hatch looks good this thing's deglazed and make sure the NICUs seal coating isn't damaged so we're looking pretty good there so now we're ready to put this back on the bench and measure everything out now that we've honed this out it's really important that we clean it out thoroughly and to do that you'll need some hot or warm soapy water and we actually have this ball brush from Flex home made for cleaning these cylinders out and what you'll do you'll stick this in the water and then you'll describe it and then another thing we'll do we've got these holes that are studs run through and we'll run a brush through those as well and we'll go ahead and take our cylinder and rinse it off in some clean water after that we'll go ahead and blow it off make sure it's completely dry before you move on and get some oil on the cylinder liner as soon as possible usually pistons they'll just come in one size but sometimes piston manufacturers they'll offer three different sizes for the same bore and to determine which sides you need you'll use some snap gauge and you'll measure front to back in the top of the cylinder middle and towards the bottom and write all those measurements down and then you'll turn this 90 degrees and then you'll measure top middle and bottom again and then what you'll do we'll go ahead and show you one you'll take this over to the micrometer then we'll write this measurement down and compare it to specs and then you'll compare those three different options to your cylinder and then you want to get the one that best matches the piston to cylinder clearance specification the next thing we could do is measure this old piston to check to see if we can reuse it but the service interval on these dirt bikes is so frequent I can't ever imagine a time that you'd actually take this piston out and reuse it so we'll just set this one aside our Zagat harvess has quite a bit aware and a little bit of scuffing and we're just going to reuse the new piston and to do that we're going to heat our rings out and check the ring end gaps if you don't know what the compression ring is basically on this piston even though we have four individual pieces really we just call it two different rings basically you have the compression ring and these three pieces make up the oil ring so some Pistons you'll have a second ring that's your scraper but on this one the end gap that we need to worry about is this compression ring so we'll go ahead we'll install that into the cylinder and we need to square it up so what we'll do we'll take our piston and we'll just put that square with the top of the cylinder and then we can measure our end gap so the spec on this ring end gap is 0.3 1 to 0.45 millimeters or 12 to 18 thousands of an inch so what we'll do we'll start with the minimum end gap that we need and that slides in nice and easy so we know we're okay usually you won't have to do anything with this Manufacturing is really good nowadays so we'll jump up and check the service limit just to make sure and that one won't go in so we know we're okay if you did have to make this gap bigger if it was tighter than 0.3 one millimeters or 12 thousandths of an inch basically what you do take this out and you can take a file and what you'll do you'll clamp this down into the vise and take the ring and rub it up and down on the file but you want to make sure you're cutting this down squarely and we do actually have a video on that so be sure to check that out if you have any more questions so now what we need to do is put the rings on this piston to do that what we'll do we'll put this oil rail with its opening on this side right here and when you put it on these gaps just need to touch each other make sure if they overlap that is not the right way so they just barely need to see it against each other so those are butted up against each other so these side rails basically will make a why for the gaps so this gaps facing forward it is possible to break them so just be really careful with them when you're working them on so we have a gap here a gap here and then we'll make another gap on this side over here this will be the top side rail and then this compression ring this is really important so we have the marking right here on top and on the bottom there's no marking so this marking faces the cylinder head so it faces up so the other thing this compression ring that needs to fit in between where these two exhaust valves go and how you know these are the exhaust valves intake valves are bigger the exhausts are smaller but we also have that arrow that faces the exhaust so basically you can line this top ring with the are making facing up and with the gap in line with that arrow the next thing we need to do is oil everything up for assembly so we just took some oil from our oil bottle and put it in this cap you can use an oil can to whatever you've got and we'll take this and put a bunch of oil on our piston and these rings basically you want to thoroughly coat everything for start-up and before we install this what we'll do it's easier to put the circlips in with the piston out so we'll go ahead we'll install one circlip into this piston and that way with this actually sitting on the rod we only have to install one more clip and when you install these they either need to face down or straight up one of the two the theory is that if they're on the side as the piston goes up and down that force can compress the circlip and it can come out of place so just something not to really mess around with just have the opening up or down I'll start with this circlip facing down and then basically I'll use my thumb to kind of help hold it in place while I work it in and then so I've got it worked in three-quarters of the way and then basically I just have a small screwdriver and we're going to try to expand it as little as possible just kind of use that as a ramp to help snap that into place and then I'm just going to make sure it's seated all the way and the last check I like to do I'll just rotate this pin inside of its groove until that gap is completely centered straight this is going to face the top of the piston on ours okay so the next thing we'll put a little oil where our wrist pin goes both sides then I'll put a little oil on the wrist pin itself we'll set that aside for now and something that I like to do when I'm putting these pistons on put the cylinder and the orientation it goes and line this piston up with it so this is our exhaust side so we'll align that mark up with it and then I'm gonna flip this over and I like to install the piston while it's still on the bench it's just to me it's a lot easier than having to fight a lot of moving parts that way you can really see what's going on with the piston rings and basically I'm just compressing the rings with my fingers you can see as these rings go on basically if I'm not pressing these down they're sticking out quite a ways right here so just make sure you're pressing them in all the way and that they don't catch when they go into place so everything's moving pretty smooth on ours now that we've got our rings in place and make sure that it went and smooth basically what we'll do we'll pull the piston up just enough to where we can get this wrist pin in place and then we'll install it just through this first boss in the piston and we'll go ahead and install these dowel pins into the case hat after we've installed these dowel pins basically what we'll do we'll take our base gasket make sure you're using a brand new one and we'll slide this into place so with the base gasket in place take a little Lube and we'll boil up this connecting rod small end then we'll take our cylinder and we'll gently set this down into place and make sure you've got this cam chain guide where it's supposed to go and then we'll take this connecting rod and slide it into place where it's supposed to go in between that piston and then we'll just slide the wrist pin in place and that holds everything where it should be so basically that's why I like to put the piston in the cylinder before we install it on to the case house it's just a lot easier going together with it and you can do this with the engine still in the frame as well so don't forget we still have this rag in the bottom so we're good to go on putting this last circlip into place make sure the end gap is either facing up or down again we can use a small screwdriver as a ramp to help get that clip into place and like I mentioned before if you're really prying on that thing you could actually bend that circlip so you want to make sure you're just barely using any force and really just using the screwdriver as a ramp to help push it in place now that we've made sure our Sur clips are securely in the grooves what we'll do is remove the rag that we have stuffed down here and we'll take the cylinder and slide it down into place and everything up with these dowel pins we've got sticking up here then we'll go ahead and wipe off any excess oil on the crown of the piston then we'll take our six millimeter bolt with the eight millimeter head and we'll loosely install that back down into the crank case but we don't want to tighten it down until our cylinder head bolts are tightened now we'll go ahead we're going to move this engine back out of the way and we'll be working on our cylinder head and that concludes part one of our top and rebuild series in part two we'll show you how to clean and inspect the cylinder head and get everything buttoned up if you need any parts for your machine check out our website we have a ton of different options on there 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Channel: Rocky Mountain ATV MC

Views: 236,714

Rating: 4.8967137 out of 5

Keywords: Rocky Mountain ATV/MC, rmatv, rmatvmc, atv/mc, atvmc, motocross, rockymountainatv, dirt bike, motorcycle, off road, offroad, honda crf450r engine rebuild, honda crf450r top end rebuild, crf450r top end rebuild kit, crf 450 engine rebuild, dirt bike engine rebuild, honing a cylinder, roached 2 racing, honda crf 450 piston change, how to rebuild the top end of a dirt bike, wrench rabbit engine rebuild kit, how to rebuild a crf450r engine, 4 stroke top end rebuild

Id: mMWLygPpvNQ

Length: 26min 36sec (1596 seconds)

Published: Tue Jan 21 2020