R80 heads on R65

[GrimReaper]

Hi all,just a toght.is it possible to put a r80 cylinder head on r65.Of course everything else(carbs and pipes)will be changed too.If it possible what are the pros and cones of this action

  tnx

[Barry]

No idea for sure if it's possible but I suspect the pushrod tube location would rule it out. If you look at the two heads they are superficially very similar until you note that the pushrod holes are in slightly different locations. Other differences - the R80 heads were designed for a 84.8mm bore while the R65 is 82mm so the resulting compression ratio would be a bit of a lottery The R80 valves are also 2 mm larger than an R65.

[larstorders]

I found the head gaskets for my 1982 R65 and the mono r80 are identical. So maybe the 80 head will be a good fit. However- there may be issues with pushrod length and compression. Interesting though.
Having just reassembled and fitted myr65 heads after their rebuild I'm not going to bother trying this myself, For a while anyway.

[steve hawkins]

I have heard of a tuner putting R80 heads on an R65, but that was only as part of a larger and more expensive tuning setup.  I.e. new cam and larger bore - i.e it was no longer a 650cc.  The cost of the conversion was more than I was willing to pay, unfortunately.

The details were a closely guarded secret.

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