Morning all, I've recently had my carbies ultrasonically cleaned and serviced by a very well known company in Sydney who race and do a lot of R&D on our little 400's.

I'm now having an issue with fuel not getting to cylinder no. 2. Petrol is in the carbie bowl, however it doesn't seem to be going any further. With the bike running on 3 cylinders, when I've sprayed carbie cleaner down the throat of carbie no. 2 the engine comes to life.

I've stripped and cleaned the jets several times, removed the float valve to make sure it's clean, etc, but can't fix the issue. Should I spray compressed air through every orifice, or is there something else I can try?

I had a set of carbs stripped and ultrasonically cleaned still had issues after stripped the problem carb and left the jets in acetone for 15mns solved the problem .at a guess the acetone is a bit more aggresive at removing varnish and blockages than the ultrasonic process alone.

Thanks for the reply, and I'll give the acetone soak a try. Did you just soak the pilot jet, main jet and needle jet holder (the 3 jets within the float bowl), or did you take it further?

Yes but keep it away from plastic or rubber parts it's nasty stuff.

Finally got around to installing the carbies and I'm still not getting any fuel into cylinder no. 2. I'm really all out of ideas at the moment.

Would compressed air through all the orifices help, or more likely to do more harm?

Did you hold them up to a light and look through the jets (main and idle) to make sure they are visibly not obstructed?

Yeah, both the main and idle jets were inspected, I could see straight through them.

I gave it another run this arvo and revved it much harder, up to about 12,000rpm, something I don't normally like to do without any load, and it seemed to rev fine. So I'm thinking it may just be in the lower revs where I have the problem.

I'm taking the bike to a dyno this Sunday with a bunch of other 400 mates I race with so I'll see how it runs and let you guys know... fingers crossed

Lots of carby cleaner sprayed into the jet passages and check that it flows out easy from the various passages. A "good" carby would be a guide as to the correct flow rate and the various exit points.

have you synched your carbs ?

I disassembled the 2 front carbies to see if I could spot any differences between them but everything looked to be the same. While I had it apart I sprayed a good dose of carbie cleaner through every orifice.

I sync'd my carbies just after I re-built the engine, but I might check them again just to make sure it's all good. Thanks for the suggestion.