playing with the new Carb Tune II

[nhmaf]

So, I bought a Carb Tune II/Pro from our friends across the pond, for working on
the airhead and my Kawasaki Concours, and whatever other multi-carb/throttle body injector
engined vehicles I can acquire.   I liked the design of the carb tune, no worries about
nasty fluids to spill, and it seemed capable of good accuracy.  I decided to give it a try out
on the R65 this evening, as I was SURE that both cylinders weren't running equally, even though
the bike starts up well,  warms up as well or better than an 80's bike, and is giving 48 - 50 MPG (US, not imperial).

First I checked the valve clearances, which I had recorded as having set at .005" and .008"
about 500 miles ago.  Using different feeler gauges, I found that they were actually more
like .005" and .010" on both sides.  I found my original feeler gauges, and since they didn't
have the bend in them like the second set had, I could see where the difference in measurement
could have arisen from the angle of insertion.  Well, they did sound slightly more tappy lately, but at least this should help
keep the exhaust valves cooler.   I checked the cable free play, and found the left carb throttle cable
had much more than the recommended amount, while the right was spot on.  Adjusted the cable,
started up the bike, warmed it up, took a short spin, then back into the garage, turned off, pulled the
vacuum hoses and hooked up the carb tune.   From checking the sparkplugs initially, it was apparent
that the right cylinder was running about right to perhaps just a little bit lean, while the left was running
a bit rich, though the IDLE speed was good and pretty smooth.   The carb tune has to be inverted and
run upside down to work well with R-series bikes, as the vacuum pressure levels are relatively low
compared to other bikes.   This changes the scale, but the critical thing is to get the readings to be similar.

Adjusting the mixture and idle screws now have both sides quite close, but still not exactly the same at idle.
Running the bike at higher RPMs, like 3000-4000 produces much greater disparity between the 2 cylinders, so
while it is running better and more smoothly now, especially just above idle, I think that it will be time to take
the carbs apart this winter and clean or rebuild them.   The bike seems to run pretty well and pulls about like a 650
should up to around 65 mph (haven't taken it back onto the larger highways yet to try faster speeds) but I think
something else isn't quite right which is causing one side to work harder than the other (and thus cause more
engine vibration) at larger throttle openings.

I am wondering if I should just plan to buy the full rebuild kits from Bing, or try the basic 'disassemble and clean up'
approach first.   Though I've taken the bowls off to clean/inspect for crud buildup in the bottoms of the carbs, the carbs
haven't been taken apart since I bought the bike (and I am wondering when the last time, if ever, this was done).
Anyone with carb rebuild experiences to share on R65s, please do !!!
 

[Bob_Roller]

How many miles are on the bike ? When I ordered the rebuild kit for my '81 R65, I was told that the needle jet should be replaced every 25,000 miles, other than that, I would replace all of the rubber parts , and the floats and float needle valve. You're still getting great mileage compared to what I was getting after 80,000 miles on the original metal parts. The kit that I ordered, and this is without floats, as I installed the alcohol resistant kit about 10 years ago, was $118 from the Bing Agency. This included all the remove-able jets and bleeds, plus all of the o-rings, seals and diaphragms. I would suggest ordering the manual that the Bing Agency has on the carbs, it's worth the $10.

[nhmaf]

Hi Bob,

Already have the Bing manual - picked it up at the BMWMOA rally this summer and I agree, it is $10 well spent !
The bike has about 16,500 miles on it now, and as far as I know, the carbs are completely original from 1982..

[Bob_Roller]

With 16,500 miles, I would change the rubber parts, gaskets and the floats, and this would include the much feared throttle shaft o-rings. A good soaking in carb cleaner, or lacquer thinner will clean the carbs up nicely.

[Ed Miller]

Did you adjust your throttle cables to balance the carbs at 3,000 rpms?  

[nhmaf]

Aha, no I did not (probably a combination of medication and stuffed-up head leading to
a greater than normal level of forgetfulness) !!