Hitchcocks Forum

Dear Bullet tinkerers,

Can anyone help me stop my carb leaking? This is on an iron barrelled 350 from 2001. I can see drips forming on the bottom of the carb, and when I wiggle the bike there are many dribbles that come off. I already took the carb apart once - the float height was wrong and so I adjusted it. Took out the float valve, cleaned it, although it didn't look dirty. Squirted carb cleaner in the various orifices. Put it back together, and it leaks just the same!

have you checked for a punctured float? i had a float that very slightly rubbed against the inside of the float bowl. that stopped it from moving freely. are you using a fuel filter?

thanks for that suggestion. I dipped the float in water and could not see any bubbles. But I will have another look to make sure it's not rubbing on anything.

I realize not everyone has the desire to upgrade from the Mikcarb to a Mikuni, but I sure was impressed with the perceived quality in Mikuni's VM28-49 over the stock unit; I believe its float design to be superior.

Help! I'm still stuck.

The carb still leaks. I just took it apart and replaced the float valve, and now the leak seems worse. I don't know what else to do apart from buy a new carb.

Ton Up Boy - where would I buy a Mikuni?

In my experience, float heights do not change themselves. So if it was wrong and needed to be adjusted, something has gone wrong with either the float or needle valve. I wonder if the tiny sprung pin in the top of the needle valve is stuck in or if the spring has failed.



Floats are usually obvious when punctured so if it were me, I'd be changing out the needle valve assembly which should set you back around £15 (part: 141969). It's a shame the service kits are out of stock for the 350s because re-brassing those carbs with japanese jets makes a world of difference, it was a really good upgrade for them.

Did you replace both parts of the valve? Replacing only half of it isn’t always enough to solve the problem.

Hi Guys------- well, you could try buying a new one ( On E-Bay at £38 approx ) ......... That'll get you back on the road straight away and then you can fiddle with the old one at leisure....My guess is that your present carb is Original Equipment which makes it 17 years old and they don't start off with the best of pedigrees, do they..............????

Daveh - I would have serious doubts that spending "£38 approx."(really?) on eBay is the answer and will "get you back on the road straight away" - or that the need to replace the one part (the float valve assembly)of your 17-year old carb. that's actually giving you problems is a valid reason to condemn the whole carburettor, solely on the basis of its age. This makes altogether too many assumptions - diagnosis by substitution (and at a distance) is an expensive way to treat a problem, in my view.

Allens Performance are the Mikuni main agents in the UK- I recently bought a pre-jetted Mikuni for my 650 Triumph and it was spot on. Top quality too. John L is right- its not worth wasting 38 quid on what is probably Chinese junk.

http://www.allensperformance.co.uk/