How much damage could I do?

[Incubus]

I am in the process if switching the head out on Succubau, the bitch bike that has never run right.I tried an experiment - using an JX head on a '79m engine. It did not turn out as well as I hoped. Awesome power, crappy low range and ridiculous idling. Nuff said.

Anyway, I had a head on a parts bike. I pulled it yesterday and installed it today. My question. I believe the cam holders are machined to the individual cylinder head. I cannot find the cam holders that came from the '79. I have the cam holders that came off the XJ head. They look like they will fit.

Could I ruin my cam by using these holders instead of the ones that came with the head?

Patrick

[3Phase]

Could I ruin my cam by using these holders instead of the ones that came with the head?

Yes, or the hardened steel camshafts would survive, mostly, but ruin the aluminum cylinder head and bearing caps. Can you keep looking for the original caps or are they really and truly gone?

If the caps/heads were bored closely enough to match you might be able to get away with it if you use a bore gauge/Plastiguage and carefully remove any high spots by hand. If they're offset vertically or horizontally even a little bit you can't (okay, shouldn't) do it.

Check again (and again, and again) to make sure the bores are actually, you know, round and not too loose, but you're really not supposed to do that. If you remove too much material it's done: stick a fork in it and get another cylinder head.

[SFerinTEXAS]

What method did you use to block the YICS ports on that

JX head

?

[crazy steve]

I'll semi-agree with Scott about the advisability of swapping cam caps with this caveat; Yamaha shows these as separately replaceable parts (with only two part numbers; the two thrust caps, and all the rest) for all years except the XJ. So, did they come to their senses because that's a bad idea, or just decide to make more money off the XJ owners by forcing them to buy a complete head instead of a cheaper single part?

But even so, after these parts are worn as an assembly, swapping bits around can cause problems. Like Scott said, check clearances carefully and I'd personally pull the valves so I could turn the cams without a load to check for binding. Anything too tight or out of alignment, it's a no go...

[Incubus]

I plugged the YICS with set screws into the head.

[3Phase]

Steve, all manufacturers sell all of their engine parts as separate parts or as complete assemblies and sub-assemblies, it depends on what you need and how much you want to spend but bare overhead camshaft cylinder head castings and camshaft caps are available separately.

When you buy new parts the machine work that goes along with the purchase and installation is at least implied if not explicitly stated in writing. Just because the parts are shown in a parts diagram and you can buy them, you really can't (okay, shouldn't) skip the machine work and bolt on new camshaft caps and expect the engine to work for much longer than it takes to get out of the driveway.