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Mikuni RS38s leaking fuel

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They're only leaking when the bike is off. I already swapped out the stock petcock with a Pingel as the stock one wasn't sealing very well anymore and the tank would empty itself over night. Took it out for the first ride last night and it is also slow to return to idle at times, more so if pointing up hill and less so if pointing down hill at a stop. The Pingel helps, but they're still emptying the fuel lines and leaving the garage smelling of gas. Float needle valves? I also suspect I need to adjust the floats too.

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I remembered that I have a second set of RS38s sitting on another project at home. Taking the bike camping this weekend, but I might try swapping the carbs and jets next week. Then see about ordering the replacement needles.


Does anyone happen to know what size needle valves are needed for RS38s? I saw 3 different sizes listed online. Cheers.

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12 hours ago, Upshotknothole said:

Unfortunately I'm in the states. I've been on this site for over a decade at this point with different usernames on the different forums. Never really been a fan of say what now!?.com, too many damned purists that get all bent out of shape if you strip the plastics and swap the parts around.

In that case try Sudco - they should be able to assist. Only seems to be one part / assembly across the range.

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Yeah, also going to pull the other set of carbs off my project bike and see how the needle valves look on them. Might just swap the jets over and try them, they're nicer looking as well. I also discovered that I'd left one of the intake clamps on carb #4 completely loose, that could explain part of the high idle. There's also a bit of weeping around the spacer for the pingel, so next week I'm going to pull that off and get a bung welded in too.

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