Forum bmwbike.com

After new springs installed on spark advance and also new condenser , the point gap set , new plug wires and cap, carb needles set in the third hole from the top . my 68 r50 still does'nt want to take any throttle . And I notice the right side header pipe glows in the dark , the left side not at all ??? . Vech Told me to check the spark advance for fireing out of time one side in relation to the other which would indicate a faulty spark advance cam if I understood him correctly?? thanks for any help

Have you tried balancing the carbs using a synchronizer?

For a quick emergency check on the carb synchronization, pull off one spark plug cap, then the other, while the motor is at idle and again when the motor is held at a higher rpm.

On the high rpm test, if the motor runs faster on one cylinder than on the other, that cylinder is doing more work. See if that correlates to the glowing header.

Wasting sparks like this is probably not the best thing for the system, so you should order a set of tuning pegs for $5 from Ed Korn's Cycle Werks (email me if you need address info). They allow you run the motor with the caps standing off the plugs on bare metal rods. You can then use a long screwdriver to short out one side then the other.

Frank,
If you can start it, it idles, but you give it gas and it sputters or dies, your mixture is too lean in
the needle jet/jet needle circuit. Mine was like that after a carb rebuild. I had installed incorrect
needle jets. Did you replace yours? It might be a good idea, but generally the mixture gets
richer with wear (the needle wears thinner and the jet opens up). You should check the mounting
flanges on the carbs as they can warp allowing air to leak in and leaning out the mixture. Take
off the carbs and hold the flanges up to each other. If you can see daylight, they need to be milled
flat. The Bing Agency in Kansas does this. They also have a carb tuning and trouble-shooting
manual which goes over all this in detail.
Tom

Its very possible that your carbs are not supplying fuel at the same rate. A plugged idle jet or main jet or both in the glowing side is possible, resulting in a lean condition and causing that cylinder to run very hot. Misadjustment of the idle air jet is also possible, the hot cylinder may have too much air mixed into the idle stream, either from dirt or being set wrong. I suggest a thourough cleaning and checking of all passages, as well as tuning and balancing the carbs. Bing Intl. in Kansas has all the poop you need. Call them at 316-862-5808.