Honda CRF450R Top End Rebuild | Part 2

this is part two of our top-end rebuild for our CRF 450 R we've already replaced our piston and rings so if you haven't gotten that far make sure you watch part 1 of this but in this video we'll start with cleaning and inspecting the cylinder head so to work on this just to make everything easy what I'm going to do I'm actually going to take this intake boot off I'll remove both clamps from that and then we'll pull this rubber piece off and the reason why we're doing that is because we don't want to get any solvent on this rubber boot so the first thing easiest way to check these the condition of these valves is to do a solvent test so we'll put some solvent down in this intake port and check to see if we have any leaking that'll tell us if we have any problems with the sealing surface on our valves and for us we're just going to fill these ports with some contact cleaner so what you'll do you'll fill this intake port with a little bit of solvent up past where this valve actually seats and then you'll wait a few minutes and check for any leaks coming out if you have leaks any solvent coming out that indicates a problem with that sealing area and if it is leaking we do have a cylinder head repair video you can watch or if you're not comfortable with doing that kind of thing you can take it to your local mechanic or meet machine shop and have them repair to the cylinder head then we'll go ahead and do the same thing on these exhaust valves we've let our sit for a few minutes and our valves actually appear to be sealing quite well so we'll go ahead dump that out so the next thing we'll need to do we'll clean this gasket surface again and just looking pretty good so we'll just finish it up with some maroon scotch-brite and again you don't want to get aggressive with the cylinder head don't use any air tools or anything like that because you want to make sure this surface is completely flat so we'll wipe that down with a rag some contact cleaner so the other thing it's a good idea to get all this carbon out of the combustion chamber so to do that you can let some of your solvent soaked on this we're just using contact cleaner and we'll use a little bit of scotch brite and you can use a wider brush but be really careful you don't want to be damaging this sealing surface at all so anytime you're doing that just be really cautious okay so you can see you know this helped out quite a bit and it might take a little bit of patience but you can go around and you can get this thing cleaned up pretty well this took a little bit of effort but it cleaned up pretty well overall we have quite a bit of carbon steel on these exhaust valves and it's just baked on there so since the exhaust valves are stainless steel we can actually take those out and we'll use a wire wheel on them but the intake valves the stock valves are actually titanium any time you're dealing with titanium valves you want to be really careful with what you're doing so the next thing you'll need to do I like to measure for warpage before I take anything out and that way I kind of have an idea if I need to get the head machined or anything like that so we'll go ahead and we'll get a feeler gauge that's the size of our service limit and again we'll get our straightedge and check for any warpage the easiest way that I've found to hold our cylinder head is actually use a punch and we'll tighten it down in our vise now we're using soft jaws but it has this nice cutout that holds round objects and it'll work really good but if you don't have that it might be a good idea to put the regular jaws in place just to make sure it holds this solid and then what we can do just one of the holes that our studs go through we'll slide the head down on top of that and so we do have one of these studs that it has an oil passageway that goes through there and make it a point not to use that hole just so we don't damage anything in there so the reason we're gonna take these valves out of the cylinder head is because we're actually going to put the new valve stem seals in place that came in our kit it's really important to do this just because we don't want to go through this whole top end and then have these valve stem seals leak and some oil into our combustion chamber and then have to do everything again so we'll go ahead and take these off and to do that we're going to use a valve spring compressor so to use this to just pick the right size adapter for the top that fits the top of these valve spring retainers and we'll just do one at a time so our valve head it has those indents on them and basically this rounded part is going to go in the indent so it centers it on the valve and make our rough adjustment with this bottom adjuster get this thing pretty close and then we'll screw this top part in and we're just going to screw it down enough to where we can get these keepers out with our valve keepers out of the way we can now remove this top retainer on the bottom we have our spring seat but you can't take that off until you remove the valve guide seal so basically we can remove this valve now but to do that we will move this out a little bit and then I'm going to route grab the head of the valve and rock it back and forth and just feel for excessive play in there and if there's a lot of play then we'll need to measure everything and see what we need to replace and then we'll do the same thing on the remaining valves and we'll go ahead and remove these valve guide seals and just be careful when you're replacing them I'm just taking some pliers and gently pulling up but you definitely want to make sure you don't damage anything there the next thing we need to do is inspect these valve guides and basically we'll just clean them up a little bit on the inside and you can get a flashlight and look down in there and if you see any carbon buildup you'll need to run a valve guide reamer through there but ours are looking pretty good so what we'll do we'll actually use a small hole bore gauge and we'll set it to the service limit and try to insert it into each of these valve guides and if it's out the maximum service limit and can't go in then we know the valve guides okay so we're well within spec on these so we'll go ahead and check our valve stems so what we need to do now we need to check our springs and we'll measure the free link so we'll take our caliper minimum length for the intake is thirty nine point seven and we're above that so this one's alright that one's alright then for exhaust the minimum length is forty two point two this one is 4306 you've got this other one at forty 307 making sure that the stem on our valves are clean we'll need to measure that in a couple different places so we record those and we'll compare those measurements to spec so at this point we need to do a few measurements on the valve and determine where the valve is actually resting on this seat so to do that we want to clean up this cylinder head a little bit first the intakes not too bad but this exhaust has a ton of carbon right here and to do that you don't want to damage these valve seats at all but what you can do is spray a little solvent or contact cleaner on there and kind of let it soak in and then we'll use a little bit of scotch brite on there and we won't get too crazy with it but we want to clean all those chunks and everything away so it might take a little patience but you can see some really not that bad to clean these up we'll probably hit it one or two more times get it a little better and then we should be good and another thing while you're here it's a good idea if you can take a little time and get some of that carbon out of these exhaust ports now that we've cleaned some of the carbon from the cylinder head what we'll do we'll clean it up with some contact cleaner and that way we can check the area where the valve sits against the valve seat now that we have the head clean we'll go ahead and clean up some of these other valve train components now that we have everything cleaned up a little bit we need to check this surface where the valve face meets the valve seat so to do that the easiest way if you have some Prussian blue or machinist die you can put it on the seat right here and you'll put the matching valve into the valve guide and all you'll do is tap it down a few times and then you're going to check the contact pattern on the valve itself but if you don't have Prussian blue something that almost everybody has is a Sharpie so on ours we have a three angle valve cut and basically what we're going to do this middle one where the valve actually seats on and we'll do that there's three different cuts on this valve seat and basically the middle cut is where this valve actually seals so we're going to check that and to do that we'll put this valve in place and you don't want to turn it all the way around you will just rock it a little bit so we can get a good idea of the pattern and if you have Prussian blue what you can actually do is do the same thing as we did with the Sharpie but you'll go straight down and it'll leave an impression of where your contact pattern is as you can see we have a pretty good contact pattern most of the way around the valve except for right here and even though this did pass the leak test these seats have a little bit of pitting to them so we're going to go ahead and just clean those up if you find any problems with the valve valve seat or even these valve guides you want to make sure you take the cylinder head to a reputable machine shop and have it repaired we went ahead and got our valve seats machined and anytime you do this it's a good idea you really want to clean this cylinder head up really well so we did the same thing we did with the cylinder and use some warm soapy water we even used one of these pipe brushes down in these valve guides to help clean them out and then kind of rinse it off with some clean water and use a little bit of contact cleaner to clean up anything else so if you had your valve seats machine definitely you'll want to do that but if you didn't at least go through and use some contact cleaner it on everything and get it cleaned up really well so as far as these parts we went ahead and got a new head gasket we did have two springs that were kind of Scopus and when we put them next to the square they just were really out of shape so we got new exhaust springs and then obviously we got the new keepers all the way around and keep in mind the keepers on this bike the exhaust keepers are going to be smaller than the intake keepers and same with the valve stem seals you're going to have one seal that's different than the other so you'll have two exhausts and two intake so pay attention to that when you're reassembling everything another thing I want to point out on the cylinder head is you actually have an oil passageway right here that comes up from that cylinder stud and you'll always want to make sure that that passage is clear and definitely spray some contact cleaner through it the next thing we need to do is install our spring seats before we put the stem seals on so to do that I always like to put a little coating of oil on everything before I actually put them in place on these valve stem seals I'm just gonna apply a little bit of assembly lube to them before we install them to install these seals since they go on pretty easy we'll just put a little pressure on the sides with our fingers and pop them into place after that we'll apply some assembly lube to this valve stem on our exhaust valve and we'll just keep it on the portion of the stem that's actually going to be used and it'll come up from the bottom and we'll put that valve in place and we'll install the spring on this one it has tighter coils towards the bottom so we'll go ahead and set that there after that we'll install the top spring seat then we'll put the valve spring compressor on with it centered on our valve and we'll tighten it down just enough so we can put the keepers in place we've got this screwdriver magnetized but if yours isn't what you can do you can put a little bit of grease on the end of the screwdriver and it'll help hold the keeper onto the screwdriver will you place it and we'll back off our valve spring compressor and repeat the same steps on the other valves after we have all these keepers in place it's a good idea to take a soft mallet and we'll put it on top of the valve and then we'll take a ball-peen hammer and just tap each one and that just make sure everything's seated correctly so now with this engine back on our table what we'll do is we'll take our magnet and we'll take our cam chain out and then we'll take the second tensioner and put this into place and when you put it in place make sure you hook the bottom of it into its groove after that we'll take our dowel pins slide those down into place and then we'll take our new gasket and since these gaskets or a two-piece design I like to spread them apart and check for any o-rings sometimes they'll get an o-ring from the kit stuck in between there then we'll slide this down into place then we'll take our cylinder head with our valves installed and we'll slide the head down into place after that we'll apply a little bit of oil to the washer and nuts for our cylinder head and install them after that we'll start these two 8 millimeter bolts on the side and we won't tighten them up yet we'll just put them in a few threads to make sure they're aligned and don't forget we have this bottom one on the cylinder that's not tightened up yet either so now we can tighten these cylinder head nuts down and they're going to be tighten to 44 foot-pounds and to do that we're going to go in a crisscross pattern and we'll do it in several different steps to get up to that torque so now we're ready to put the cam and cam holder back onto the cylinder head and all these parts will do we kept them fairly clean we kept them covered under a rag but just in case we're going to clean everything off with a little contact cleaner and then we'll apply some fresh assembly lube and put it back onto the cylinder head and these cam gear or cam sprocket bolts whatever you want to call them you want to make sure these are clean because we'll be applying some blue loctite to them and for the Loctite to set up good we need them to be oil-free same thing with the threads on the cam itself and don't forget to apply some Lube to these bolts they do need some oil on it with our cylinder head bolts tight what we'll do is we can now tighten these side bolts now keep in mind we did have our valve seeds cut so we are going to have to put different shims in but to do this right now what we're gonna do is put the old shims in and then we'll measure where we need to go from there now we'll go ahead and take our magnet and we'll pull the cam chain up I'm just going to weight that chain with a screwdriver for a second so another thing I want to point out is that this cam shaft here we check these lobes when we cleaned everything off and ours actually looks pretty good but if you have any questions on that if it doesn't look very good then you can actually take this out and what you'll do you'll measure these lobes and compare your measurements to the spec in the book so we're going to go ahead turn this over and so we're going to go ahead and put our shim buckets into place we've got them all lubed up already and these when you put these in and out make sure they slide smoothly as I put this on I'm just going to use too much and cover these buckets up and that way they don't fall out on me and we've got our two dowel pins right here on the bottom so we'll go ahead and slide our buckets over the intake valves slide everything into place and make sure we align these dowel pins and then we'll make sure this cam holder is all the way down into place now when you put this on make sure your cam lobes are facing up and towards the back a little bit so now we'll take the screwdriver from our cam chain and I'm actually just going to loop it over the cam shaft right there for now and we'll grab these bolts that we already lubed up and these two shorter ones are going in the back and then we'll install these two front bolts and we'll tighten those in a crisscross pattern to ten foot-pounds okay we so we torque these cam tower bolts down now what we'll do now before we actually time everything up we just want to make sure that our valve lash is correct so we'll go ahead and just make some measurements here and see how much we actually tightened up okay now that we've determined what shims we need we'll actually be taking this cam holder back off so we'll go ahead and loosen those bolts in a crisscross pattern and remove it so we'll go ahead and stuff this rag right here where the cam chain goes make sure we don't drop anything down in there and then we'll take our new shims and put them into place now one thing when you put these shims in place one side usually has a number on it if you put that down sometimes it's easier to read it when you pull them back apart and that's because the top side is the side that gets all the action like especially on these exhausts it has the rocker arms moving on it back and forth so I'll just go ahead and put the numbers towards the stems and we'll go ahead remove the rag and we'll take this cam tower and reinstall it making sure that we have the dowel pins and the shim buckets in place then reinstall our bolts and torque them to spec and during this process remember to be mindful of the position of the camshaft so we'll go ahead and take this cam chain right here and we'll route this above on top of our cam and then what we need to do before you install the sprocket is we need to double check the timing marks on our engine so so ours actually did move just a hair so we've got that line back up and when you move it you might have to pull up on the cam chain just a little bit to make sure nothing binds so after that what we can do we'll take our cam chain sprocket or gear whichever one you want to call it and we'll put that into place so we actually have these two timing marks again they'll be lining up with these arrows on the cam holder so we'll make sure everything is aligned and we actually look like we might need to move it just a little bit and once you have this cam gear lined basically you'll want to double check your timing marks on the engine and then after you've verified everything we'll go ahead and install these bolts and torque them to spec now keep in mind if your bike is in the frame you'll install one bolt and get it almost snug turn it until the cam gear is 180 degrees you'll Snug that other one up and torque it down then you'll turn the engine back over and tell the original bolt that your installed is there and then torque that one down as well so we'll go ahead and apply some blue loctite to both of our cam sprocket bolts be careful with these you don't want to drop these down into your bottom end and we'll take our cam gear holding tool and we'll torque these bolts down to spec which on this one is 15 foot-pounds the next thing we need to do is install our cam chain tensioner to do that we actually got a new one since our old one is broken and this has this nice little plate in here holding the tensioner all the way back but if you don't have that what you'll need to do if this comes out you can screw this in with a flat blade screwdriver and then what you'll do you'll uncertain us into place you this has to be screwed all the way in while you tighten it so what we'll do now is we will take a couple bolts right here now on this screwdriver you need to make sure you're holding all the tension in the tensioner until after you have both of these bolts tightened down and then what you can do is you'll remove it and your tensioner is going to extend in here and tighten up the chain after that we'll put this bulb back in place with this crush washer so now what we'll do on this right side of the engine we'll turn the engine over twice in the clockwise direction and then we'll line up all our timing marks again and recheck our valve clearance to make sure everything's correct and make sure that the engine turns over freely so all of our timing marks match up and look good so we'll go ahead and double-check our valve clearance on this and keep in mind with these timing plugs we don't have to crank them down very tight if you do you're never going to get it back off just get it a little bit snug and make sure you have a little bit of Lube on that o ring after that we'll go ahead and clean the sealing surface on the bat on our cylinder head and we'll take our valve cover we already have a new gasket on ours but if you don't it's a good idea to inspect that and replace as necessary so we'll go ahead put that into place make sure this ring on the valve cover aligns with your spark plug hole and then we have these three bolts we'll put back in and we'll go ahead and install our new spark plug the next thing we'll do it we'll take our new o-ring put it onto this cooling elbow and we'll slide the elbow all the way into place and install our bolt and tighten it down for us the last step is to install this intake boot and we'll make sure we align these grooves with the cylinder head and that's all there is to rebuilding your top end if you need any parts for your bike like the wrench rabbit kit that we use today they're available on our website and always remember any time you do your top end you'll want to use fresh engine oil and a new oil filter and make sure you have a clean air filter as well if you have any questions leave them down in the comment section below we'll get back to you and if you like this video subscribe to our youtube channel because we have a ton of other helpful videos on there so be sure to check that out and that's all for today thanks for watching you

Channel: Rocky Mountain ATV MC

Views: 128,033

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, crf 450 piston replacement, crf 450 piston ring install, how to rebuild the top end of a dirt bike, wrench rabbit engine rebuild kit, measuring piston ring end gap, honda dirt bike rebuild, 4 stroke top end rebuild, how to rebuild a crf450r engine

Id: EiKuyraNECo

Length: 26min 39sec (1599 seconds)

Published: Tue Jan 21 2020