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Replacement cylinder head advice needed

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barber1303

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I've had a significant setback in the restoration process for my '85 Vmax. I am in the process of rebuilding the engine (2nd gear fix) and I paid a friend with a powder coating business to strip the paint from the engine parts. Most came out well, but for unknown reasons (I have my suspicions), the front cylinder head and the oil pan got heavily pitted as they sat in the paint stripper tank. I'm not so worried about the pan as it will not be too noticeable once painted and put into service under the bike. The head, on the other hand is a complete loss. The combustion sealing surface is very rough and the cam journal surfaces are also rough. For a replacement, I'm assuming I'll need to find a head with the cam journal caps included as they are a matched pair. Will I also need to be concerned about getting the matching cams, or can I just use the cams I have?

Thanks in advance for your help.

Chris
 

Fire-medic

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I'm not a machinist, but I assume your clearances can easily be checked with plastigauge. Use the factory specs. You can find the manual here under the VMOA part of the website. I don't think you need the cam caps or the cams from the same head, if the clearance is within spec, that's it. The head in its current state could be saved, but shop time is expensive, it's cheaper to source a good used head.
 
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MaxMidnight

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On this (rare) occasion I have to disagree with Mr Fire-medic.

I would assume that the head and cam caps are line bored during the manufacturing process and ensures alignment in the vertical and horizontal plane. They are, therefore, matched.
As you will have noticed each cap is numbered so it can go back into its matching half on the head.

On that basis I would go for a head that comes with the matching caps.
 

Fire-medic

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On this (rare) occasion I have to disagree with Mr Fire-medic.

I would assume that the head and cam caps are line bored during the manufacturing process and ensures alignment in the vertical and horizontal plane. They are, therefore, matched.
As you will have noticed each cap is numbered so it can go back into its matching half on the head.

On that basis I would go for a head that comes with the matching caps.
Yes, without a doubt, keeping the cam caps on the head with-which it came is the safe thing to-do. However, I suspect that the machining done by Yamaha in the factory is precise enough that you should be able to get the clearances from using other cam caps, which is why I said, "measure the clearances," and if your clearance is within-spec, there should be no problem.

I know it's a long-time ago, and not a near 100BHP/liter engine like we have, but here's a story about the engineering put into American cars and trucks. And, it happened in The Old Country, England.

To demonstrate the advances in engineering, manufacturing, and interchangeable parts that American auto manufacturers had been able to achieve, three Cadillacs in the pre-WW I era (1908) were driven to famous Brooklands racetrack. They were totally-disassembled. Their parts were commingled. After that, a team of mechanics re-assembled the three cars, with no regard for 'car A parts being used for re-assembly of car A.' Upon completion, they all started and ran perfectly. This was a clever way to demonstrate the precision of American automobile manufacturing, and the success of interchangeable parts in a production line. Read this article, a fascinating story.
https://www.autonews.com/article/19...-parts-put-america-and-cadillac-on-a-pedestal
 

barber1303

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Thanks for the advice guys. I'll find a head that includes the caps, but won't worry about finding matching cams. I'll check clearances while I'm checking the rest (conrods, mains, etc.)
 
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