How To Rebuild the Cylinder Head on a 2018+ Honda CRF250R/RX

[@randy-yo8zi]

Do you have a video for a 2008? Honda CRF250 valve and topend tear down, any help would be appreciated thanks Charles.

[@rmatvmc]

Yeah, that one is a little different. It's got the uni-cam with the bearing that slides to the side. With the chain tensioner released, and the cam cap off (don't drop the half moon retainers in the cap), you'll slide that bearing towards the cam sprocket. That will allow the cam to drop down and you can pull the chain off the sprocket and remove the cam. The 450's of that era had a cam tower and a removable cam sprocket. Even with those differences, I would say use this as a guide kzbin.info/www/bejne/o366faydhdWphLM and just use your manual with it. -Charles

[@aidanvelthuis1267]

Wish this series came a few months ago, just did a top end on mine, not a bad job, I pulled the motor out just for sheer ease. I did however notice quite a bit of carbon buildup, any reasons why that would be, or what can I do to rectify the issue?

[@NickW90]

What type of gas do you use and how many hrs were on your bike?

[@aidanvelthuis1267]

@@NickW90 I run 91 no ethanol, and my bike had 100 hours ish

[@dustin9035]

@@aidanvelthuis1267 unlike regular pump gas, ethanol free fuel does not have many of the additives that regular fuel has like deposit and carbon prevention chemicals. Run 1/4 cup of Chevron techron in your fuel tank. Next top end you will probably have much less carbon.

[@KennedyCastro-uu2sy]

. Boa tarde Aqui do Brasil pegando aulas com voce thank you Mr .. 🤗🤗🤗 . Eu vou regula valvula de uma crf 250 2019

[@NickW90]

Damn Charles i wish i could get you to rebuild my bike lol

[@germane4493]

Is there a hours limit to replace the Valves and conecting Rod? I've just buyed a 2020 with 120 hrs on it. No strange noises from somewhere, but i want to open the Engine to check it. When the Valves are in spec, should i reuse them, or should i go with new Valves because of that hours? Thanks!

[@rmatvmc]

Hey @germane4493 , a lot of that stuff depends on how well the bike was taken care of (oil changes, clean air filter). I would imagine that your valves and connecting rod are probably fine with 120 hours. If you don't have any starting issues, burning oil, or any abnormal/excessive noises you are probably fine to ride it as-is. However, it's never a bad idea to blueprint (teardown and measure, replace worn parts) the engine and freshen it up around 100 hours. If it hasn't had a new piston installed yet, I'd recommend throwing in a new one, then inspect the connecting rod while you are in there and only replace it if there is any up and down play, or if the side clearance is not correct, or if the small end is scored or if you see any other obvious damage. Check the top end video for that info. As far as valves go, once the protective coating is worn through, it's time to replace them. That means usually once you have to adjust them, you'll want to replace them. I'd always do one adjustment, then check the clearance after a ride or two and if they are out of spec. again, then you know it's time. Or if any of the shims are close to the minimum size, I believe minimum is a 1.20mm. Other than that just do the checks in the video. -Charles kzbin.info/www/bejne/bqiUdWaLpbd6eqs

[@germane4493]

@@rmatvmc Hey Charles, first of all thank you for your fast and detailed response 👍🏻. Okay, then i will go for the top-end check from your Video. Is there a standard lengh of the Valves to compare? Couldn't finde it in the video. Conecting Rod vertical play will be checked. Should I go with a new timing chain? Bike was first a Racebike of a better amateur for 100 hrs, after that it was a hobby amateur bike for 20 hrs. History is plausible. The pre owner told me that before he buyed the bike the first owner checked the valve clearance and put a new piston in it. He couldn't tell me more about maintenance jobs. So I will check the valve clearance tomorrow once again. Bike looks in shape so far. Frames are straight, not worn out. Greased achsles and bearings, Bike is starting well, no leaks on Engine and Suspension, no strange noises by listening to the Engine without stethoskop, no worn out bearings except the linkage but not massive by now, after taken off the gastank and plastics probably more one the clean side. Thanks for your help guys, and thanks for your detailed and extreme helpful Videos. Keep it up! Regards from Germany.

[@huntfishnridetv]

How many hours are in this bike

[@thatcoalminer275]

In a different video the Justin said roughly 80 hours