My '75 R90S is difficult to start when cold. This condition is new, so I suspect it is a product of something I've done or overlooked.
What I've done: took carbs apart and replaced o-rings and gaskets with kit by Dellorto. Sprayed carb cleaner through orifices and blew with compressed air, reassembled. Replaced cables with new ones form Motobins. Floats are good height per Dellorto spec of 17.5mm. Starter valves slide freely in starter body that is attached to carb. Heads torqued to 25 ft. lbs., valves set at .006" intake and .008" exhaust. New points at .016" and timing set with dynamic light.
I read the Dellorto factory info on the starting circuit. It says if the plugs are wet after attempting to start, the mixture is too rich and starting jet needs to be changed to one with holes higher up on the emulsion tube. I haven't looked into replacing them because before my carb work it started OK with throttle slightly open and no choke.
Once warmed up it starts, idles and runs well. Tried some choke but it will not fire unless the choke is fully "off", throttle is slightly open, then only after cranking awhile, seemingly to clear the rich mixture.
Jets are stock, throttle and choke cables have appropriate slack.
Any hints are appreciated.
What I've done: took carbs apart and replaced o-rings and gaskets with kit by Dellorto. Sprayed carb cleaner through orifices and blew with compressed air, reassembled. Replaced cables with new ones form Motobins. Floats are good height per Dellorto spec of 17.5mm. Starter valves slide freely in starter body that is attached to carb. Heads torqued to 25 ft. lbs., valves set at .006" intake and .008" exhaust. New points at .016" and timing set with dynamic light.
I read the Dellorto factory info on the starting circuit. It says if the plugs are wet after attempting to start, the mixture is too rich and starting jet needs to be changed to one with holes higher up on the emulsion tube. I haven't looked into replacing them because before my carb work it started OK with throttle slightly open and no choke.
Once warmed up it starts, idles and runs well. Tried some choke but it will not fire unless the choke is fully "off", throttle is slightly open, then only after cranking awhile, seemingly to clear the rich mixture.
Jets are stock, throttle and choke cables have appropriate slack.
Any hints are appreciated.