Newbie with b12 carb troubles

[PaulSimmons]

 

1200 mk1 bandit. 4900 miles. hi guys. I've just Ultrasonic cleaned the carbs and then fully rebuilt them wIth Keyster kits. IT now starts on the button just like when I bought it in 2000. But.... It will only run normal on 3 on tick over and low revs. On the other cylinder it pops and fires occasionally. On run down, out riding it pops and bangs. If I giVe it some revs say over 3000rpm  the problem cylinder kicks in.  Full beans and it's fine al the way up to the red line, pulls like a train . As the coils fire two cylinders I am puzzled. Could it be a dodgy hit lead? Or a dodgy Spark plug (already fitted iridium) ?  Or could it be the slow running jet? ( which one is this?) All jets were changed during rebuild. Could it be an air leak? could it be overfueling?

Any ideas very much appreciated, I'm near Gatwick?

Edited July 26, 2020 by Wee Man

[johngsx]

On 7/25/2020 at 6:50 PM, PaulSimmons said:

 

1200 mk1 bandit. 4900 miles. hi guys. I've just Ultrasonic cleaned the carbs and then fully rebuilt them wIth Keyster kits. IT now starts on the button just like when I bought it in 2000. But.... It will only run normal on 3 on tick over and low revs. On the other cylinder it pops and fires occasionally. On run down, out riding it pops and bangs. If I giVe it some revs say over 3000rpm  the problem cylinder kicks in.  Full beans and it's fine al the way up to the red line, pulls like a train . As the coils fire two cylinders I am puzzled. Could it be a dodgy hit lead? Or a dodgy Spark plug (already fitted iridium) ?  Or could it be the slow running jet? ( which one is this?) All jets were changed during rebuild. Could it be an air leak? could it be overfueling?

Any ideas very much appreciated, I'm near Gatwick?

check that you haven't pinched a slide rubber even a pin hole will cause a problem. easy to do as I have done it on mine when I had a b12. 

Edited July 26, 2020 by Wee Man
Cool

[Wee Man]

Welcome to OSS.  Its customary on here to say Hi and post a couple of pics of your bike, it tends to help get a response as we realise you are likely to hang around rather than feck off when you get the answers you are looking for.

Also RTFR. Thanks.

[Oilyspanner]

Welcome to the site. Just 4900 miles ? Probably  a typo. Have you looked at the plugs - a low speed running  problem will show on the plugs, normally sooty. You say you replaced all jets, does this include the needle jets ?

Check your plugs to narrow down the problem, then you can move in the right direction.