Motorcycle Top End Rebuild for 4-Stroke (Part 2 of 2)

Motorcycle Top End Rebuild for 4-Stroke (Part 2 of 2)


This is part two of our KTM 4-stroke top-end piston and ring replacement. In our last video, during disassembly, we discovered we needed a new sleeve, and we sent it off to L.A. Sleeve. They were able to get it back to us good as new. We’re going to install a
Wiseco piston, and the first thing we’re gonna do is
check our ring end gap. Throw a little oil in there, and then you install the ring and push it down with the piston so it’s down a bit into the cylinder. And then on this particular machine, it should measure 13 thousandths. This measurement is critical because as your engine heats up and your rings heat up, you want to make sure there’s room for them to expand so they don’t ruin the cylinder. Now we’re moving on to the oil scraper rings. And this is a spring separator. You want to make sure that the end doesn’t overlap on that. The smaller thin rings actually sit on top up the ring expander. It hold them out. This is where most of the mistakes are made when installing rings on 4-strokes, so take care to make sure it looks very similar to this. Now we’re moving on to the upper ring. It goes on fairly simple. On our circlips, you want to make sure that you install these by twisting and compressing, not by bending. I like to seat the one side. Make sure it clips in there solid. You’re going to oil up the piston again. Get our pin started. Set it on the rod and push it the rest of the way through. I use a paper towel to make sure I don’t
drop the ring down in the motor. And once again, we’re putting this in by rotating it instead of bending it and compressing it. Here I’ve got… putting the base gasket on. And once again, the cylinder goes on. Take your time. Feed you cam chain, your cam guides up through. Now we’re just resting the cylinder under its own weight on the piston. I’m using my fingers to actually compress the rings. Very carefully push them through the tapered edge in the cylinder. Take your time with this step. Now we’ve got the piston in. We’re sliding our cam chains. Tighten them up. Here’s our head that we’ve had Faction MX recondition. They cut the valve seat and bead blasted it so looks good as new. We’ve also replaced our valves, and please refer to our valve replacement video for those instructions. Now we’ve just put our two locating dowels in, and we’re going to set our head gasket on top of the cylinder. Notice the piston is at top dead center, and it’s going to make it a lot easier
to find top dead center on the crank here in a minute. Now we’re setting the head on, pulling our cam chain through. Line it up, and then our head bolts with washers. We’re going to tighten those down. And for this motor, it’s 30-35 foot-pounds. Always refer to your service manual for these important specifications. There’s the three bolts that go in from the underside that need to be reinstalled. And now we’re going to find top dead center on the crank. So you remove this Alan bolt, the lockdown bolt. Remove the copper washer off of it, and reinstall the bolt. The bolt has a tapered edge on it, so it makes finding the notch in the crank little easier. And what I’m doing is I’m just rotating the engine back and forth and actually feeling for the notch. Once you get it to top dead center, we can move on to the cam. We’re lubing up the lobes, and we’re setting the cam in with the lobes, generally down for right now. There’s a collar on the end by the water pump that needs to go into a groove. These alignment marks need to be horizontal with the top of the head. We’re putting our cam chain on, taking our wires that we’ve had holding it, putting them out. We’re using our new master link that we got from KTM. We’re putting it on. And we’re going to use our chain riveting tool to swage the ends of the cam chain. We’ve also put paper towels back in, so, once again, we don’t drop anything down on the bottom. This tool makes it pretty slick, makes it so it’s a secure master link. Now we’re going to ready the valve cover. Put a little silicone, a little sealant on there — carefully — you don’t want to get too much. You want to make sure it’s evenly coated on both sides, both surfaces. We’re going to slide the valve cover on. Pull up the lifters a little bit. Make sure there’s no binding. It should all sit flush. You’re going to install the bolts. They are at… eight foot-pounds is what this machine calls for. Now we’re on to the cam chain adjuster. We’ve removed the bolt and the spring so we can reset the adjuster. We’ll mount it on the cylinder and tighten it down. Then we’ll give the adjuster a little head start, release it, and then we’ll put the spring and the
tension bolt in. This holds your cam chain tight. It’s automatic. Now we’re on to the water pump cover. And as you can see, we’re using a new gasket from our Tusk top-end gasket kit. Put those on… once again, about eight foot-pounds. Now we’re going to adjust our valves. We’re going back off our justers. And on this model, it’s calling for between four and five thousandths. So we need our feeler gauge. And you want to just slide it underneath, just so there’s slight resistance. And you have your screwdriver actually on your tappet, and hold it in place while you tighten it with a wrench. Move to the other side. And put your tappet cover back on. Now that our valves are adjusted, we can release the lockdown bolt by putting our washer back in. Now we’re reinstalling our oil supply line. Make sure and get the copper washer underneath… and on top. Tighten those both down. Put our ignition cover back on. Tighten it down. Connect it. We’re going to install our carburetor. Make sure it engages in both the intake boots. Tighten them down. Here, we’re reassembling our decompression lever, checking our play in the cable. We don’t want it too tight. Here, we’re tightening our spark plug, putting our cap on. Now we’re putting our throttle cables on, feeding them through the cam. We’re checking our cable play… tightening everything down. Put the cover on it… crankcase breather hose… shifter… head pipe and our shock… silencer… radiators and our radiator hoses. Slide the tank and seat on. We’re adding fluids here. We need to make sure to remove this air purge bolt. This allows both radiators to fill up evenly. Tighten the bolt back down Add the engine oil. And you’re ready to go ride. Make sure and refer to your service manual for proper break-in procedures.

100 thoughts on “Motorcycle Top End Rebuild for 4-Stroke (Part 2 of 2)

  1. How does it go long term with the resleeve I had mine recoated with nikasil my local KTM dealer mechanic who has 10 + years experience said in no way shape or form should you resleeve these cylinders as the cast iron sleeves cannot disipate the heat like the nikasil coated aluminium, I don't know but I went with his advice and got it recoated as I was just about to do the resleeve any thoughts or experiences you have had with the resleeve would be much appreciated.
    Mike

  2. – I would guess the nikasil is better – that is why the OE's do it. However, I have never had a problem with a sleeve. The one we did in this video is still running strong 3 years later.

  3. hi. you look wery experienced, i have wery similar engine, but i hawe problem with dealers, they dont know which model i hawe, would you bee able to help me? i hawe a picture of hed gasket its wery similar like this one, the hole in gasket for piston is 102 mm, will you be abble to determinate model?
    tnx

  4. you seemed to remove a lot of periferal parts, such as the silencer and rear shock, is there a reason for this? better access or something?

  5. My dumbass friend got a $2000 seized 250 4 stroke and he thinks he will make at least $2500 on it so he thinks he will sell it for $5500 at least and its a 03 moddel

  6. hello! I make you a question, did u put some kind of glue to the cylinder head gaskets and cylinder base? or they didn´t need that? sorry for my english, i don´t speek it very well..

  7. im 13 years old and i want to tackul me crf 250r this winteE is it really that many parts that need to come off cuz i never done it befor? plez reply

  8. how much more is it to buy a top end for a 450f yz compared to a yz125 top end? this is a new cylinder, piston, rings, bearings, but no bottom end work at all I really wanna know cuz i might have to get a 4 stroke, and am worried about the cost on the 4 strokes. Plus how many years or hours would i get on a 450f that i will just baby and trail ride it?

  9. – you can look up pricing on our website. 4-strokes cost a lot more; more moving parts! If you take care of a YZ450 though, it will last a long time. In my oppinion it is the most reliable 450.

  10. ok and how long will a yz450 last me if i do take care of it? I will only ride once or twice a month on the bike and its only trail/woods riding.
    Also how long would my yz125 last compared to the 450? I do the same amount of riding on it as well and always clean hear and maintain everything. I"m VERY OCD on maintaining and cleaning my bike and cars. So last question….Should i stick with my yz125 and learn how to it or trade it for a 450 based on the style/time i will put on the bikes…

  11. Oil Starvation was ultimately the cause. This damaged cylinder was bored and sleeved slightly larger than stock. Most resleeving companies will restore your cylinder back to stock specifications.

  12. Well thank you very much! but no, not at all. Any motor that is maintained regularly and taken care of correctly is going to last you. Obviously all the manufacturers are striving to to improve their design and to be the best and so in my opinion any modern bike is going to be a good quality bike for you . . . it all comes down to maintenance now

  13. Thats an exceptionally well done video actually. Thats pretty much the same technique as me except on the gasgets I mix up some graphite and oil into a paste and apply on 1 side of a gasget, and what that does is make it possible to pull covers and what ever else that has a gasget on it off without ever breaking another gasget and it never leaks either. This is something I learned from an old timer, it works.

  14. Thank you! If everything goes smoothly you can do this in an hour or two depending on experience and how smoothly the job goes.

  15. We have heard excellent things about both bikes and either bike is going to be reliable depending on maintenance. I have heard the WR is a little lighter but i'd say it's personal preference deciding between both of them. I don't see any big advantage to either one

  16. I have and X and you can email me if you like and I can tell you my experience with it. I also have an R and F which I can compare for you. If you're not already, sign up to thumpertalk and send me a private email, tomjv.

  17. hey i have the same bike and did a top end rebuild and put everything together like in the video and it starts and runs really good but theres a ticking noise in the top end. any idea what it might be?

  18. As far as reliability goes, even though I hate to say it, go Honda. Yamaha is probably a faster/lighter bike though.

  19. Replacing the top end on a bike isn't hard so long as you've got the correct tools such as a service manual and some other common hand tools and then you would need a valve spring compressor if you plan on replacing the valves. We are actually working on a YZF Top End Replacement Video right now that would help you out but you are going to need to refer to your service manual mostly for this job.

  20. Watching this 1) reminds me why I got a 2 stroke and 2) makes me want to watch it again to marvel at your talent. Great video.

  21. Ha Ha Thanks! 2 Strokes are definitely a little easier to work on but 4 strokes aren't bad as long as you've got the correct tools and you get all the steps in the correct order.

  22. Hello friends from Rocky Mountain ATV MC, I'm from Brazil, São Paulo and also motorcycle mechanic'm here, I have a youtube channel (vba bikes), like many of his videos and try to be organized the same as you guys, thank you for the videos and hug here from Brazil.

  23. hi, i've got a question 🙂 how fits this la sleeve for ktm 4 stroke? does it warm too much? can i use this into my cylinder or better is a nicasil ? sorry for my english 🙂

  24. im 15, my dad has alot of knowleage in vehicles… do you think we could manage to rebuild my 2011 crf 250r if neccicary?

  25. I'm sure your dad could manage the rebuild. Anyone with the correct tools, a service manual and some basic knowledge of motors would be able to manage a rebuild. As long as you do everything in the right step you should be fine. We also have these videos for you to follow through the rebuild.

  26. I'm not sure on this bike. You shouldn't have to and it should just about be like any other bike. Remove cylinder head and then slide the cylinder/s up off and you're at the pistons… I would suggest investing in a service manual to complete this job.

  27. If you have a 400 sxc 2000 and try to follow this video you will most likely fail. The main problem is the original oil ring, totally different design. IT IS EXTREMELY SENSITIVE! Very easy to snap.

  28. hi, i opened up my top end and forgot to put it in TDC so when i took the piston out the crank turn a couple of times so now i dont what i should do?
    help this lost lad please!!

  29. Hello,
    I must say thanks for this useful video!
    How much oil do I have to order to my bike? I have a exc 125 2004. I know that the air chamber is 120 mm. Do I need 3 or 4 pieces of 500ml bottle?

  30. That is the first time I have ever seen someone break the timing chain to do a rebuild. I have never done that, and I found it interesting. I haven't watched the first part of your rebuild video, so I will to see why you broke the chain.
    A good video, and will definitely be helpful to those who are new to this type of work.
    Rebuilding the top end is pretty easy, and I have done a few over the years.

  31. Hi. Did every step in your toturial, but my piston stops on the top of the cylinder and will not move after. I can pump the kickstart so the piston moves down and up 1 time and then it stops. What do you think I have done wrong

  32. you say to put the 2 smaller rings on top of the oil scraper ring. do you mean on either side of it. or both on the top side of it?

  33. Hi on the video you say please refer to our video on the valve replacement instructions …I cant seem to find the video , do you have a link to the video please?

  34. Hmm i own a ktm 560 from 2006 and i went to a long rod setup just like the 525.
    Got the oil line, timing chain and rod from a 525 in it so it's the long rod setup.
    I had 0.040" valve to piston clearance so i add to add another 0.025" gasket to it, but now
    my timing chain is to short? It's still a 96 roll chain but a 0.05" to short.. any fixed for this?

    Thank you in advance!
    btw: The reason i went for a long rod setup with cometic spacer gasket is because the 560 is notorious for ovalizing the lower part of the cylinder.

  35. Just installed a new cam, water pump and a few other parts (all ordered from Rocky Mountain of course) on my 2006 KTM 450 SMR. This video along with the previous about the KTM RFS engines were super helpful! Thanks a lot for all the videos you guys put out!

  36. This video has helped me to uninstall my RSF motor on my KTM 450exc. However, installing everything back on up till I had to work the Allen locked down bolt to get it lined up right with the rotor I noticed that I can no longer push down on the kick starter or rotate the rotor. Even when I put the cylinder on top of the piston I also noticed that the piston won't move if I try to push it down. Any tips on what to do next?

  37. Great video. Just seized my BETA 525 a couple days ago. Engine is basically a KTM. This video sure has helped me out. Thanks

  38. Something not mentioned is make sure you back off the coolant bleeder screw on the head until coolant drips out of it after filling with coolant. If not an air pocket will sit in your head and make for overheating.

  39. Just had a 2005 ktm450sx rebuilt for burning oil like a 2-stroke. Get it back from the builder and 4 miles on the bike and I have crazy blow by like a lot and drips about 3in puddle of oil out of the crankcase vent tube so ik think broken compression rings? Builder wont stand by he work began cussing us out over the phone when we informed him about the bike. Thinking about trying it myself this time while watching your videos for guidance.

  40. Does the Crank Lock Bolt for TDC have any play in it (slotted) or does it locate and prevent the crank from moving at all (hole)?

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