Milling top cases for sleeved barrells?

Gday to all.Was wondering what your thoughts are on whether you can mill top cases out and still use standard size barrells? Will they still seal alright? Reason im asking is that i thought if you wanted to big block the motor in the future you wouldnt have to split the cases to have them milled,just drop on the larger barrells(bottom end has been done with welded crank,back cut gears etc).Any problems with this?Cheers......:huh:

Shouldn't be any problem apart from possible oil leaks from the base gasket if you are unlucky. In which case you will need to do a top end oiling mod (dry block) similar to the one in the thread i have posted.

imy little drag bike i have the cases bored for an 1197 block and i put a stock block back on it when i hurt a piston i have been running the engine for over two season's with no issues at all.

every motor ive ever built has the cases clearanced for 1197 sized sleeves.way back when i would swap out to an 1197 13:1 when i new i wanted to go streetracing on the weekend and sunday afternoon would be swapping a more streetable topend for riding to work during the week.just buy a good base gasket and coppercoat the hell out of it

No problem. This is something people do all the time.

Cool thanks guys.

I have a set of MK11 cases that have been bored for a 1428, but I didn't want to go that big. I was thinking about maybe an 1197. Wonder if I would still be ok with the cases bored out that big or if I would have problems trying to get the base gasket to seal?

i have a set of cases that are bored out to fit a 1393 and i have a set of 1197 barrels on there now and i haven't any leakage problems yet. but i'm ready for it if it happens

mkawasaki23 wrote:

I have a set of MK11 cases that have been bored for a 1428, but I didn't want to go that big. I was thinking about maybe an 1197. Wonder if I would still be ok with the cases bored out that big or if I would have problems trying to get the base gasket to seal?

It will work

Timebomb, did you use a copper gasket? And did you use a base gasket for an 1197 or for a 1393?