YS 1.20 tappets stuck-how to fix - RC Groups
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Apr 10, 2013, 07:56 PM
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YS 1.20 tappets stuck-how to fix

Hi everyone, I bought a YS 1.20 and I guess the tappets are stuck. The rest of the engine looks like it got the afterrun oil just fine when it was put up many years ago but as usual nothing got done down there where the cam is and now they are stuck. I tried to fix the exact same problem on an old OS FS .60 that I have and I broke one of the two lugs on the cam cover trying to get it off to get in there and fix this. I don't want to repeat the same thing here on the YS but it still will not come off. Maybe, if you have experience, I don't even need to remove this cover? Let me know the best way to fix this.

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Apr 10, 2013, 08:04 PM
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williame3590's Avatar
Hammer and chisel.....works everytime


ps. HEAT
Apr 10, 2013, 08:10 PM
Registered User
Also, what does that phillips head screw between the cam do?
Apr 10, 2013, 10:20 PM
Hope to get out of life alive
kenh3497's Avatar
Warm the engine with a heat gun or small torch. Just enough to make it "uncomfortable" to hold. Try to slip a #11 blade in the crack between the two parts. If that works then try to twist it apart. The is an o-ring seal on the cover and sometimes the o-ring will glom onto the case. A little light oil may help it release also.
Apr 11, 2013, 08:40 PM
Registered User
Thanks for the tips here people. Heat was a big factor, however, I succeeded in mangling another cam cover and couldn't get the cam out even when I did get it off. BUT I did figure out how to fix this problem which plagues four stroke engines that inevitably get put away wet and this area rusts:

Instead of trying to remove the cam and cam bearings (which are probably fine even though they look like a glob of rust) just take off the head and pushrods and heat the tappets up with a heat gun and penetrating spray. Then use a phillips screwdriver or something and with the engine mounted on a test stand push the tappets down as you turn the engine over. If they won't go down it's either because the lobe is on it or you need to heat it up more. Keep doing this until they are freed then do it some more until you think the valve springs can handle it. Then put the head back on and turn it a bunch more with tons of penetrating lube spray. Eventually they will free up enough to work. Next time you put the engine away remove valve cover and spray lube in there.

It's just too damn hard to get that cam out with the bearing being in a blind spot and no practical way to pull it out. Even if you did, how would you push the tappets out? Then your timing is screwed up, too. They are in there permanently. In reality, the cam lobes and ball bearings are made from hardened steel and probably aren't rusted so much they need to be replaced. They only go half speed anyway.

Try doing this to fix stuck tappets instead of mangling your four strokes like I did. Or you could find someone who knows how to do this.



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