Struggling at 70mph

[Firenze]

Thanks again for all the tips , I think I am getting somewhere which confirms your comments! .. I first re set the timing which was a bit advanced, and ordered 2 rebuild kits for the Bing 32's .While waiting I checked float levels in situ going by the book , all good in the garage ,revving freely etc,so went out. After a couple of trouble free miles a short blast to overtake and I had a 400 single . pulled over and adjusted the tab on left hand float to let more fuel in , sorted ! went well with no hesitation up to 75 ,only when I got back did I notice my boot wet and slippy and covered in petrol and with petrol trickling out of carb. So fuel starvation on one hand and too much on the other , definately time for a closer look and a clean out and fit those new bits which arrived today. to be continued .....

[Major Softie]

Well, trading one problem for another isn't exactly a solution, but it IS helpful in diagnosis.

[Firenze]

Been stripping the carbs this morning, and here are the results,....
Left hand carb (the flooding one) Perished diaphram . Now replaced and carb body cleaned out with new o rings and gaskets in place. Also fitted new float needle.
Right hand carb. Cleaned and rebuilt same as the other one . its had a replacement diaphram and float needle at some stage already so was in better shape , but have replaced them again anyway. Only thing I noticed was a missing O ring on the base of a jet . Back on the bike for setting up and it runs ok . I have noticed R/H carb is less sensative than the left one while adjusting pilot air screw but even tick over acheived. Will see how it goes when the opportunity comes around!

[Major Softie]

Yeah, you should always replace diaphragms together, as they don't seem to always be the same thickness and flexibility. This leads me to believe that replacing one can lead to the two carbs react slightly differently - not good for balanced carburation.

[Firenze]

Well ! .. just had the road test and guess what . She pulls like a train from about 60 to 85 (when I wimped out). but the difference was amazing . Less than 60 is about the same though but maybe a bit smoother. Just got popping in the exhaust on the overrun (closed throttle) to sort out now. Air leaks??

[jtoml]

Idle mixture screws - turn each one out an eighth to a quarter of a turn.

jtoml
1973 R75/5 SWB

[Jean]

Go for some new coils too, when you can find some. I got a pair of 6v Bosch Blue from a VW Beetle shop on line...I have now discovered the new High-perf Bosch coils are shorter and fatter, so if you get them, BE SURE YOUR FUEL TANK IS NOT TOUCHING THEM as they will worry a hole in the tank!!
P.S. I wuss-out around 85MPH too!

[Firenze]

I find on an un-faired machine its just too much hard work hanging on at that speed for long ,probably just as well for the health of my license!

[Firenze]

Idle mixture screws - turn each one out an eighth to a quarter of a turn.

jtoml
1973 R75/5 SWB

Thanks ,I will try that tomorrow .

[Jean]

It's now been 2 tomorrows. How's it going?