R65 with r80 heads

[mimmo66]

Just wondering how feasible would be to put r80 heads on a r65
Has anyone tried it, my mechanic does not know if it would work or not.
Thank you, Domenico

[nhmaf]

I don't think that it will work well, the R80 head is really designed for a cylinder bore that is 84.8mm in diameter, the R65 cylinder diameter is 82mm.   The R80's valves are bigger by 2mm, but I don't think that will produce much difference, and the R65's pushrods are at a steeper angle (short stroke engine compare to R80/100) so the pushrod angle may not be right for the height of the R80's rockers, etc.   I suppose that anythign can be made to fit, but in my limited experience I don't think that this would be worth the $$ expended to do it properly.  I think if you want more grunt you're better off transplanting and R80 engine rather than just the heads from one.

My $.02, anyway.

[Bob_Roller]

The general consensus about making the R65 a faster bike is, if you want a larger engine, install one, don't try to modify the 650 engine it seems to reduce the life expectancy of the engine .

Also, if you want a faster bike, buy one, this was an entry level bike, and you could put more money into it, than what you would have, if just got a larger displacement bike .

These bikes are 'happiest' when left  pretty much stock, unless you want something to look at rather than ride .

[mimmo66]

The current setup is just fine on the machine, I just wanted to be able to use the 38mm exhaust system of the larger airheads which offer more choices and availability of parts.

[steve hawkins]

I have heard of fitting R80 heads to an r65, but only as part of a far reaching and expensive tuning excercise, including a capacity hike, cam change, and compression hike, twin plugging, etc.  Cheaper to buy an r100 to run along side your R65.  

However what you must remember is that although you might gain 38mm ports, they will still be the same distance apart as an r65, which actually gives you less parts.........well its only the cross-overs on the exhaust that will need to be changed.....And prehaps the mounts.....

You could always try it and let us know.  Real experience is always better than hearsay, especially if the hearsay was gained from the interweb..........

Cheers

Steve Hawkins