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im in the process of fixing up my brothers h model ready for mot.
it ran okay when i got it to mine but it had been off the road for a long time and was a bit of a shed so it needed a lot of bits sorting.
I completely cleaned the carbs out as they were disgsting in the float bowls, new bowl seals, cleaned and made sure all jets are unblocked and set float heights etc.

The problem i have is since fitting the carbs again every time i start it it will run for a bit, then fuel will start pissing out the overflow tubes and out of the top brass jet tube #3&4 carb.
when i remove the carbs all the carb rubbers are wet with fuel.

i have gone through the carbs a hundred times and checked everything, the float needles are all good and not worn, i had thought maybe the fuel pump is getting stuck on, feeding too much fuel, i was going to try the once from my race bike as i know its good.

any other ideas would be most welcome, it starting to test my patience now.

i know you will tell me you have replaced them...but it can only be the float seals and the float needles not sealing properly, you can test this by running the fuel pump with the back of the bowls of 3 and 4 removed and at the same time press lightly on the float's to seal the carbs, doing it this way you can see easily if its flooding from #3 or #4 or both, and try and isolate exactly where its coming from.

its common for race bikes to have the fuel pump running continuously so thats unlikely to be the issue, it might be that one of your floats is sticking or damaged - i.e. does one of them have a small hole that you might have overlooked?

banner001 wrote:i know you will tell me you have replaced them...but it can only be the float seals and the float needles not sealing properly, you can test this by running the fuel pump with the back of the bowls of 3 and 4 removed and at the same time press lightly on the float's to seal the carbs, doing it this way you can see easily if its flooding from #3 or #4 or both, and try and isolate exactly where its coming from.

its common for race bikes to have the fuel pump running continuously so thats unlikely to be the issue, it might be that one of your floats is sticking or damaged - i.e. does one of them have a small hole that you might have overlooked?

I'll have another good look, I havent replaced the seals or needles, needle wear is very good and not in need of replacing, the seals did have some crap behind them when I removed the seats so maybe taking them out ended up unsealing them as they are probably the original seals.
I'll replace the seat seals and see where we are at then.

replaced the seat seals, they were non genuine as its all i had to hand but still overflowing.

I would normally buy genuine but its not my bike and trying to get the money for the partd out of my brother is pretty damn hard.
the only other think i will try is swapping round some floats ad needles to see if the issue moves or stops , and putting my L carbs on just to make sure its the carbs that are the issue and nothing else like fuel pump.