Friend has a 107" (4.125"), recently did upper 100 miles ago, the front head has a leaky valve seal. When he pulls the head, will he need to also pull the cylinder and change the base gasket?

 

If he is careful and secures the cylinder with some 1/2" PVC couplings to the case, he can probably get by. I know he doesn't want to mess with dropping the cylinders back on ringed pistons but that's what I would do in spite of the extra work; his call.

 

So he should replace the head gasket also? Didn't know if Cometic could be used twice.

 

I have reused Cometic MLS head gaskets in situations like this with only 100 miles. The motor hasn't seen operating temperature much at all and Cometic MLS gaskets don't crush. Once again, his call.

 

Going to be pulling my heads in a couple weeks, thought about maybe securing the cyls while I am removing the heads and then using some clippings bolting to down until I get my heads back. I definitely don't want to remove the cyls.

 

If you replaced the base gaskets with good steel or silicon gaskets you will probably be good to go, BUT, if you used cheap paper gaskets that come with cheap gasket kits, I would replace them with steel or silicon gaskets, as base gaskets on evo style engines have been a weak point since day one.

 

Easiest way to seccure the cylinders is to use two 1/2" PVC couplings at opposite corners secured with two head bolts. Be careful removing the heads if they don't come right off; if OEM head gaskets were used, they could be "stuck". If you tap the heads with rubber mallet to loosen, you could also break the cylinder base/o-ring seal. Use a gasket scraper or some other thin tool to "pry" the head loose. This way you are putting downward pressure on the cylinder. Once one head is removed, secure that cylinder to avoid bumping it while removing the other head.

 

There is not base gasket it has a o ring.

 

You can disturb the oring on the base of the cylinder and not have any problems, you don't have to engineer any hold down items. Also I've reused cometic gaskets, I don't reccomend it, but have done it, just spray a little copper coat on it and let it eat !

 

No o-ring fella's. Cases have been bored.
Thanks for the tips all.