Valve clearance issue

[Incubus]

Here's an interesting conumdrum. I installed an XJ head on a XS1100F ('79) engine. I am using the XS cams. The valve clearance for the exhaust on both models is .25-.25. The clearance for the intake valves is different, though. The XJ calls for .11-.15, while the XS is .16-.20. So, which clearance should I go with? The XS, because of the cams, or the XJ, because of the valves?

Opinions are solicited.

Thanks,

Patrick

[trbig]

I think (That usually gets me in trouble) that the lobes are the same HEIGHT on both cams, but the duration is a tad different. I did the same thing on my bike... XJ head on an XS with XS cams.. and shimmed them to the XJ specs. The thinner gap between the cam and the shim means it will open the valve FURTHER than the XS's in the same situation. I have been told that in this case you should shim this XJ head to the XS specs, since the bigger round valves of the XJ may come into contact with the piston. I didn't find this out until after I had already done it. It didn't cause any problems or damage for me, but I wouldn't feel comfortable telling you that it wouldn't hurt YOURS. All I can say is what my situation was... take it for what it's worth. If you are shooting for a touch more HP,(Probably nothing really noticeable in the seat of the pants) you could take a gamble and shim it to XJ. To play it safe, shim it to the XS.

Tod

[mro]

Closer tolerance = better performance.
Should not be a problem.


mro