Just for FYI. Exhaust valves take a lot more abuse due to the hot exhaust air passing across it whiles it’s not seated. The intake valve doesn’t get hot air running across it and it is seated which heat sinks heat away from the valve thus lowering it’s temperature. Intake valves also benefit from cool intake air and fuel mixture flowing across it when it’s open. If you seem to have repeated issues with exhaust valves check your fuel air mixture. The more lean the mixture the hotter the exhaust gas temps, the more abuse the exhaust valve takes. Excessive lean is another set of issues. Thanks for the video and good luck!
To my understanding, yes. (I haven't tried) I expect to have to do one of my yfm200's next year. From my research so far my understanding is that I can put the 225 cylinder/piston on my yfm200 and reuse the existing head. I'm not sure if this will affect my jetting at all but, while I can't say 100% I do believe they are interchangeable and the 225 kits are a lot easier to find.
Just a thought for next time. If you place the rocker arm shafts and the cam in the freezer overnight and then heat the head in an oven or with a torch just prior to installation, the shafts and cam should slip right in with minimum effort due to the difference in temps of the metals. (The aluminum head heats up and expands nicely). These jobs can be a little frustrating as you obviously experienced.
Sorry, had timing chain on the brain. I didn’t replace the valve guides. Matter of fact, the kit didn’t come with them. I’ll have to watch for that on the next moto4 head. Do they just ‘pull out’ on these quads and you press new ones in?
Tell me more. I was considering giving it a try on one of my yfm200’s. It looked like it would but I haven’t found any definitive information. You could save me some misfortune.
:). I’m sure I didn’t get far without those. I’ll have to go back and look in the video. I’m sure they are there but I may have skipped it in filming unfortunately.
Exactly, I'm in the middle of doing one of these at the moment. I never removed the rockers at all, I just took the cam out. So much easier.
Use grease to hold keepers
Now that is an awesome idea that I will definitely be using!
Just for FYI. Exhaust valves take a lot more abuse due to the hot exhaust air passing across it whiles it’s not seated. The intake valve doesn’t get hot air running across it and it is seated which heat sinks heat away from the valve thus lowering it’s temperature. Intake valves also benefit from cool intake air and fuel mixture flowing across it when it’s open. If you seem to have repeated issues with exhaust valves check your fuel air mixture. The more lean the mixture the hotter the exhaust gas temps, the more abuse the exhaust valve takes. Excessive lean is another set of issues. Thanks for the video and good luck!
Use a little bit of grease to keep the keepers in place. Not oil.
I figured that out over the years. Man I struggled with these until I figured that out.
What is the difference between the yfm200 motor and the 225 other than displacement? Will the 225 top end fit on my 200?
To my understanding, yes. (I haven't tried) I expect to have to do one of my yfm200's next year. From my research so far my understanding is that I can put the 225 cylinder/piston on my yfm200 and reuse the existing head. I'm not sure if this will affect my jetting at all but, while I can't say 100% I do believe they are interchangeable and the 225 kits are a lot easier to find.
Just a thought for next time. If you place the rocker arm shafts and the cam in the freezer overnight and then heat the head in an oven or with a torch just prior to installation, the shafts and cam should slip right in with minimum effort due to the difference in temps of the metals. (The aluminum head heats up and expands nicely). These jobs can be a little frustrating as you obviously experienced.
Did you change the valve guides ?
Ooh, I can’t recall if I did on this one but I don’t think so. If I replace the timing chain I usually do as the guides usually come with the chain.
Not the timing chain guides , the valve stem guides
Sorry, had timing chain on the brain. I didn’t replace the valve guides. Matter of fact, the kit didn’t come with them. I’ll have to watch for that on the next moto4 head. Do they just ‘pull out’ on these quads and you press new ones in?
Ya did you install the valve seals in?
@VermontLife yeah just pull them out qith a pair of pliers
nice job on the lapping, use the drill for the first 90% finish with the dowel lapper
Does anyone know if the 225 cylinder rebuild kit would work on my yfm 200?? Just bolt on kind of deal like normal installation?
It doesn't..
Tell me more. I was considering giving it a try on one of my yfm200’s. It looked like it would but I haven’t found any definitive information. You could save me some misfortune.
@@VermontLife The gaskets are different 1 is 67mm the other is 70mm so not sure if it will work
Not sure if you know web cams can grind your cam shaft to get a little more power
Great videos though very thorough and helpful!!
I wanted so to reach in and stop you ! Wait ! You didn't install the valve spring and keeper !
:). I’m sure I didn’t get far without those. I’ll have to go back and look in the video. I’m sure they are there but I may have skipped it in filming unfortunately.