R60/5: carb replacement & higher compression

[StephenB]

Hello all,

I am building that 600cc engine from the block up and I don't have Bing carbs. They are very expensive and difficult to come by in good condition. Has enybody FIRST HAND experience with replacing the stock 26mm Bings (1/26/xxx) on the R60/5 with say, 26mm or 28mm Keihins or Mikunis? There would be the added benefit of better throttle response, no?

Can I also increase compression by half a point or so by using a thinner base gasket? The engine will have an electronic ignition which should overcome its tendency to pink under load. Or is the pinking bad enough as it is with the stock 9.2 compression?

Thanks in advance.

Stephen

[guy]

My brother had Mikuni carburetor on his 1974. He had no problems over the last 20 years I am aware of.
Guy

[Garnet]

I'm not sure you will get a half point of compresion unless you eleminate the base gasket, which should be OK with a fine layer of silicone.

Haveing owned a couple of R60/5s I can say it is pretty tough to get rid of the pinking. I was only sucsesful with 94 octane gas. I think you would need high output coils along with the electronic ignition to make a big differance.

I blame the problem on the 296? cam that was used. The sooner the exhaust valve closes the higher the effective compresion ratio, most notably at low RPMs. If I still owned one I would try a 308 cam from a 750. Anyone out there ever tried that?

28 VCM Mikunis are what Rocky Point used to sell for R60s. Edit: make that 26 VCMs

[Garnet]

Mikuni Carbs on Ebay:
http://stores.ebay.com/Niche-Cycle-Supp ... 34.c0.m322

Note that they have LH AND RH 32s.

[kutter]

Hello StephenB
I have found this listing for jetting Mikuni carbs
to suit BMWs.
No listing for R60's however only R75, R100
I currently have a set of Mikuni VM32's in the
mail from the US to adapt to my R80.

I had them jetted as per the R75 however they are
both left adjust as they did not have a pair.
A little bit awkward but still workable.

http://braigasen.com/Mikuni_jetting_cha ... stroke.htm