Im just here to say hi to jerrod.
Just to find out its only 250
...not bigred350X
I think 89 stuff was only the same a few years tho &OG's right ...wc or redo are good choices
Didn't read the whole 13-year-old post but... no, no Silencers, will not cause that. usually it's an air leak or sticking carburetor slide.
I'd verify slides are returning to idle and if so, do a leak down test.
If you're building compression, you're sucking in air. If none of the above, you sure you're jets are correct, Float hight correct, floats dropping, filters not over oiled
Dont remember doing that b4 but... mark where the chain rides ( to make sure when rollers in place it'll be inline).
& install it till it lines up. I'd think it'd bottom out? Is there an inner lip that'll stop it from going on to far ( and or can it even go on to far b4 hitting arm?) If you dont have a seal installer, use a large socket or see how tight it is, might be able to use roller, as an install tool...or a flat drift??
Timing plate is separate part
I'd start with 110
Oe used, is usually ok, do you need to do it now...no just suspect stator if you have issues, some dont have problems, some dont last long...time will tell