80 head, 81 head, valve train compatability

[yamahaluke]

I have an 80 head and an 81 head, I need to make one working head out of the two. I have and 81 xs 1100 special. I have a very large hole burnt through the #3 exhaust valve. I do not have the the cam caps for the 80 head (the guy on ebay that sold me the head swears the caps stay with the cam and by the time my machinist said he was wrong, the PO sold the cam and cam caps). I noticed the 80 valves are smaller and am wondering can they be used in my 81 head or can my 81 cam caps somehow be machined to fit the 80 head?

[cywelchjr]

Then you got rooked in more ways than one, cause 80 and 81 valves are the same. If the valves are smaller they are 79 or earlier valves, and you can't switch them. AFAIK the heads on the 80 and 81 are exactly the same, same part number and all. Geezer on here has a deal for brand new SS valves for both the early and late heads, but I'm not sure if he has any left over from the last order of them or not, and I'm not sure when he will be doing another run of them. He has them custom made through a company that makes stuff like that.

[petejw]

as cy already stated,
if the valves are smaller then its from an earlier
model engine.


while ur waiting on getting another valve
u might also want to establish why the valve burnt in
the first place so it wont go happening again when
the valve is replaced.

a couple of things that can cause this
worn valve guides - can prevent the valve from seating properly,
overheating the enging,
lean running mixture,
pre-ignition and detonation.

i burnt one of mine after a cpl of thousand k's
after i lapped the valves, the thickness of the valve was
to thin, heres a pic of that valve.



minimum thickness should be 1mm.

while u have the head off, pour fuel into the ports and
check the valves for seapage.

hope this helps u.

[DGXSER]

Yep, from the factory the 80 and 81 heads would be identical. Exhaust valves on all should be identical no matter what year, but the intakes valves got a little bigger on the 80-81 models. If your head has smaller valves, it may well be a 79 engine instead of an 80. Check the VIN on the engine itself.

As to the cam caps, since they do not have bearings in them, I'd be very leary of mixing and matching them with worn in cams and heads. You can switch the valves easy enough, but if possible I'd keep the cams and the caps on the head they were with originally. Now, if that causes you problems and makes something not work, well, then I would take my chances and mix and match to get one working. Just not my first choice.

[bikerphil]

+1, keep the caps with the head it goes to if possible. You can buy late model (80-82) valves from these guys for about $20 if need be....

http://www.crc2onlinecatalog.com/Index_Main_Frame.htm

[yamahaluke]

You sir, are amazing, for the next twenty four hours you are my hero! I can get the one valve I need and get my bike back together again. Thank you!

[DGXSER]

I would suggest that if your pulling the head off, and the engine has enough wear to have that valve issue, you probably want to replace the cam chain while your in there. And perhaps valve seals, and lap the valves. Funny how the "might-as-wells" add up.

[bikerphil]

I can get the one valve I need and get my bike back together again. Thank you!

Yep, just make sure there is no damage to the seat area on the head. You can check for leaks as follows.

After installing the new valve, place the head on the workbench upside down with the spark plugs in, making sure it is level. Pour gasoline up to the top of each combustion chamber. Wait 15 minutes and see if any of the levels have gone down. If not, there are no leaks and you can install the head with a new head gasket. Do not apply any sealer. HTH, good luck!

Edit: It's a good idea to scrape off any excess carbon, but be careful not to gouge the aluminum while doing. New valve seals would be a good idea also.

[petejw]

"After installing the new valve, place the head on the workbench upside down with the spark plugs in, making sure it is level. Pour gasoline up to the top of each combustion chamber. Wait 15 minutes and see if any of the levels have gone down. If not, there are no leaks and you can install the head with a new head gasket. Do not apply any sealer. HTH, good luck!"

works either way,
i just find it easier if u pour fuel straight into the ports (head tilted on the side)
ull notice straight away if fuel is seaping/leaking between the valve and seat
from the combustion chamber.

he'l also need to lap any new valve thats put in.

[bikerphil]

he'l also need to lap any new valve thats put in.

Yep, that's probably a good idea. When I replaced my bent exhaust valve a few years back, I didn't lap it. I must've got lucky, it runs just fine.

[Ken Talbot]

i just find it easier if u pour fuel straight into the ports (head tilted on the side)
ull notice straight away if fuel is seeping/leaking between the valve and seat
from the combustion chamber.

You would probably want to do this somewhere outside rather than inside your basement or workshop...

[WMarshy]

If you end up mix-matching the caps you could always get some plastigauge and check your clearances. IDK what the spec is but you would be able to compare each one and pick the most reasonable one if you have a few to choose from... I would expect them all to be pretty close...

[skids]

The cams are different between the later and earlier xs11s also I think... Personally, I wouldnt buy a head without the cams attached.

[petejw]

hi skids,
the cams themselves are interchangable between
different model heads,
the cam caps and the head are milled together
and shouldnt be interchanged,
ive heard of others that have used different caps on different heads
with out any problems but its not reccomended.

[natemoen]

Now this is a bit far out there and most likely not worth it (until parts get more scarce) BUT would it be possible to have the head and caps milled down and then insert a bearing in there in place of just the factory surface?