Topic: 400F Stumble at 4-5k RPM

[jakec]

Yes I am on a 400F with everything 110% stock, which helps a lot. The only thing that's not stock is I have a dyna ignition.

I do have a stock petcock that has the integrated screen on it, yes.

[jakec]

It's funny that I posted this yesterday as I barely made it home from work before posting. Taking off the bike was running really badly and I reached down to see pipe #3 was cooler than the other. I had to get home so I just powered through until it eventually started to seem even worse. I put it on reserve even though I had plenty of gas, and that actually made it act normal for a few minutes, but it eventually got bad again.

Well I got home and emptied the tank and removed and disassembled the petcock ,and the sock over the reserve tube was a little dirty with rust particles, but nothing that should have stopped the flow. There was nothing on the inside of the petcock. I also checked the #3 spark plug and it looked perfect. I guess now I will clean the petcock and reinstall it, and consider taking the carbs off and looking at #3 (HATE taking off these carbs lol).

[jakec]

Well I dove into the #3 carb and not a sign of any problem. The only thing I noticed was it looks like the float valve seat O ring was a bit pinched. All the jets were clear, as well as the main jet emulsion tube (so annoying to get it out)! Just like everything on these carbs.. anyways. The only other thing I noticed was a small amount of varnish at the bottom of the tank. I'm not running a filter. But there was nothing in the petcock and nothing in the bowls, either.

I suppose I'll just blow the passages out thoroughly and hope for the best. No other ideas right now.