How about a Del Orto carb questions... anyone up for it?
I have a 74 R90S with what I think are the factory carbs. PHM 38's. (We are trying to tune the bike with the sidecar attached and at 5000' elevation)
The left cylinder is running perfect, right side is a bit rich. Bike has a bit of a studder at any rpm and especially noticeable at under 4k. Just pick any rpm and hold it and the bike gives the feeling of running out of fuel. Ever so slightly though. I would almost bet that if the bike did not have the sidecar attached you would not even feel the hesitation. (grab a handful of throttle from about 3k and a noticeable amount of black smoke from the right exhaust)
The BMW mechanics started by rebuilding them. They then moved on to changing main jet, idle jet, they have even taken the accelerator pumps out. To be honest taking the pumps out helped the problem. (at this point the carbs have different main and idle jet sizes)
The mechanics have also adjusted the valves, done a leak down and compression test, all came out great. The exhaust has been gone through and so has the intake, no leaks at all.
The bike first started out running really rich... you could stall it just by grabbing a handful of throttle. Now once it gets cleared out and you are on it hard the bike rips.
Bottom line.... is it feasible for the slide to wear out? If so, is there anyone that could rebuild it or would I need a new carb? I guess you would have to almost hone the carb housing and use an over sized slide... that sounds like a ton of work.
If you have any ideas please throw them my way. Thanks a bunch. Ryan