I am tearing into my carb for a cleaning / rebuild and to check my jet sizes. The diaphragm and shaft were crudded up pretty well. It looked like water corrosion to describe it. Just wondering if this is normal. Also, part of the reason I'm tearing into it is it has given me trouble starting when cold a few times. I have renewed the plug twice and with little riding it looks carbon fouled. Now it runs GREAT and doesn't smoke a bit if it is running rich. Could the diaphragm cause any of the cold starting symptoms or flooding and fouling plug maybe ????? Thanks

 

If you use the throttle to start, then it could flood. Try starting by just choke, and no throttle til it catches. That corosion is normal, but there should be a small rubber bellows above the acc pump area, on the shaft, to keep crud out. That may be missing.
Lots of guys use the #40 or #42 pilot jet, to make cold starts easier. The #38 is a bit small, and if it gets any corosion on it, its even smaller.

 

Thanks hondabuster, the small rubber bellows is still there. The corrosion is limited to the diaphragm area just wasn't sure if it was normal. Yah, I gotta change my starting habits.I know I've flooded it twice. The 38 pilot is still there. I may put in a 42 while I'm in there.

 

I'm doing a 400ex carb right now and I'm at the accelrator pump area. I took off the cover and theres 4 holes in the bottom of the cover, no actually 5. Theres a real small one with a brass type fitting and that could be clogged giving you the problems. Make sure that you clean that out if you haven't. Just thought that would help if you still had problems.