boring case?

[cals400ex]

do we need to get the case bored if we are running a ross sleeve to fit 426's-440's?

also, are we suppose to run that rubber o-ring at the base of the sleeve?

[pairanutz]

no you dont need to bore cases for 426 or 440
atleast i didnt have too when we did my 440
i used the rubber o-ring at the bass-my buddy didnt
mickey dunlap told him not too
neither off us has had problems
so i guess ist a judgment call - i would talk to your engine builder or whom ever your getting your big bore kit from

[cals400ex]

i wasn't sure. mickey is the one who said problems commonly come about when you don't bore the case. however, i don't believe all the 426-440 sleeves require it. however, i wasn't sure.

i am not sure on the o-ring either. i believe the stock one is only for a stock-sized sleeve.

[pairanutz]

i used a stock o-ring-it stretches
due you what the reason is to bore the cases
just wondering why bore the cases if it fits

[cals400ex]

Originally posted by pairanutz
i used a stock o-ring-it stretches
due you what the reason is to bore the cases
just wondering why bore the cases if it fits


i am sure there are a couple of reasons. when the metal get hot, it expands. this can actually make the sleeve touch the case. this will put stress on the piston and sleeve along with other parts.

here, check this out. there is some useful info in this whole thread:


http://www.exriders.com/vbb/showthread.php?threadid=83162

[UglyMotha™]

some 440 sleeves to require boring of the cases and the reason is the heat exapansion as you stated the o-ring is not necessary i haven't ran one since i built my motor

[Hondaluva]

I did some light grinding on my cases to make my sleeve fit properly (Advanced sleeve, I think). It fit without the grinding, but when you set it on the dowels it was a tight fit. I just ground a litte bit off the carb side right where the cases meet. Didn't want to get a hot spot at bottom dead center.

I used a stock O-ring.

[dariusld]

I read somewhere, that the reason they bore the cases is because some sleaves aren't tapered down in size. The reason the sleaves crack is because they are thinner towards the bottom, where they go into the case. So some company says they put a stronger sleave to avoid this, but it requires the case to be bored. Correct me if I'm wrong.