Seized my 1961 G80CS

green66 · Post by **green66** » Tue May 29, 2012 5:44 am

Hi everyone today I seized my 1961 G80CS on the freeway at 70 mph, after getting home i pulled top end apart , piston was shattered and melted in to tiny bits, cylinder head looks fine, bottom end feels ok, looks like barrel and piston are shot, I do happen to have a very nice 1957 alloy barrel on standard bore with matching factory piston, if anyones knows if this barrel and piston will work with my 1961 head please let me know, also when took the head off I noticed there was no head gasket, is this correct, what type of material is the head gasket if there is one ?, and can someone point in the direction to get some parts for my engine if i need them - piston, head gasket etc. thanks TimEdited by - green66 on 29 May 2012 04:47:09 AM

Don Madden · Post by **Don Madden** » Tue May 29, 2012 5:26 pm

Do you know what piston it was? You cannot mix pre-1960 with later top end parts as the piston, head & other parts are not campatable. The barrel is an exception to the general rule, other than the trimming of the fins to clear external parts. You must make sure of the type of head as I know of several bikes that had the wrong one fitted. We are making new, high quality pistons here in the US for the 1960-up engine. I also live in So. Cal. so not to far away for better exchange of info. Send me a PM for my contact info. I also reccomend you join our fine Owners Club, there is a North American Section active. Cheers, Don.

green66 · Post by **green66** » Tue May 29, 2012 5:40 pm

I am a member of American Club, I have no idea what piston it was there nothing left of it, i have 1961 or later style head ,Edited by - green66 on 29 May 2012 4:45:48 PM

rgregory · Post by **rgregory** » Sat Jun 02, 2012 1:00 am

Better send Don a photo of the head, particularly from above with a clear view of the plug area.

The beauty with a forged piston is that it doesn't hand grenade when holed from detonation.

Cheers,

Rob

Marty · Post by **Marty** » Sun Jun 10, 2012 9:45 am

I'm probably going to get in trouble here !! What Don says is correct if you want the bike to run as the makers intended, but a '57 piston and barrel will run with the later head. I have done so, but it negates the squish of the later head and piston and lowers the compression. So it will still run well, just loses some urge
Marty

Don Madden · Post by **Don Madden** » Sun Jun 10, 2012 11:16 pm

Marty is right but I usually advise people to use correct parts. The late piston in 1956-59 heads will cause collision. Everybody knows how the "Rumor Circle" distorts a message, losing critical info. "Sometimes works if you do it right" comes back: "It works". Cheers, Don.