How do I identify what cylinder head i have

[GTXS1100]

I have a burnt valve in my engine and i found an extra cylinder head in my shop but Im not sure what motor it came off of. I know that the older heads had bigger valves. I have a motor off of a 78-79 on my bike now and want to keep it the same but I have to do what I have to do to get my bike going. Just wondering if anyone knows off the top of their heads how to tell the difference. Any advice will be greatly appreciated. Thanks

[jetmechmarty]

Bigger valves came on the '80 & '81. FSM has the specs. That and a caliper should get you to the answer.

[GTXS1100]

So would it be better to put an 80-81 head on a 78-79?

[jetmechmarty]

So would it be better to put an 80-81 head on a 78-79?

No, it would not. With the 78/79 cam, I'm not sure the pistons won't hit the valves. Ignition is set up for a different cam profile. Find the correct cylinder head or replace your valve.

[GTXS1100]

I think im just going to swap the motor with a 78 i have.

[GTXS1100]

This is want I was talking about. Does anyone on here watch Andys motorcycle obsesion XS1100 Basket Case? He talks about using an 81 head with big valves and using the 78-79 cams? Anyone have an opinion on this?

https://www.youtube.com/watch?v=Qo4vKG_2aIk

[jetmechmarty]

Andy is pretty much up on this. Where he has gone, you may follow. He's on FB XS1100 Nation.

[3Phase]

So would it be better to put an 80-81 head on a 78-79?

GT, the '80/'81 heads have larger combustion chambers along with the larger valves so the pistons have higher crowns to maintain the compression ratio.

You can use an '80/'81 head with flatter '78/'79 pistons but the compression won't be right and it won't be much fun to ride.

The cams won't make any difference. With the late-model head and early-model pistons, the valves can't even come close to touching the pistons.

Going the other way and using the later pistons with the early head works too but there's almost no room for error with the piston-to-valve clearance.

[GTXS1100]

The heads i have that are good are all small valves. I checked them earlier tonight. I did order the big bore kit from ebay this morning. So the motor thats on my bike will get completely redone someday. For now im planning on swapping out a stock 78 i knew ran a few years ago. Thanks for all the help guys. Ill keep you updated on the bike.

[GTXS1100]

Update on my bike

Heres a short video i shot today on my bike progress. Got the motor all put in and painted and new exhaust. Hope you all like it.

https://youtu.be/loY4VKJHX6k

[Schming]

Lookin' & Sounds Good !!!

Good Job !!!

[GTXS1100]

Anyone know where to find the Schrader valve for the top of the forks on an 80G i think the part number is 3H5-23190-00-00. Mine is broken and makes it hard to get air in it. Ive looked all over ebay and can find the caps but no air valve.

[Schming]

Anyone know where to find the Schrader valve for the top of the forks on an 80G i think the part number is 3H5-23190-00-00. Mine is broken and makes it hard to get air in it. Ive looked all over ebay and can find the caps but no air valve.

I may have an extra one.

I'll check and let ya know asap.

[Schming]

Yep got one.

PM me your address and I'll get it to ya