Hello and thanks for all the help with my Bultaco

Last time i had a bit of time off i was working on and trying to ride my Bultaco 199A i have a mikuni carb fitted its starts with a few kicks from cold, ticks over nice and pulls smoothly from tick over ..... well that what i think ! the thing is the carb now like to run fuel stright through it if i leave the fuel turned on when its not running. is there any tips for fixing this ?

( i did strip the carb and have a look and all looked ok to me, so pop round to a friends and all looked ok to him to ) so any tips would come in really use full.

My carb seems to have the idle screw and the air screw on the same side which make things easy it looks a bit bigger than the ones i have seen for sale but it is a 26mm.

All the best BR

I would check the float and the float needle with the rubber top if it is attached right and sit proper and thight.

Now in even better English I hope ...

Edited March 22, 201412 yr by pschrauber

Beta`s have always had this problem with the mikuni. Typical fixes were an extreme adjustment of the float, and or the vent tubes. With your long vent tubes, you could be causing this just by pulling a vacuum. Pull off the vent tubes and see what happens. Also check out the Beta forum.

Mikunis in general do it, probably every Mikuni I've ever had has done it, whether an old 70s Mikuni off some Jap road bike (which yours looks like) or a brand new one - regardless of the overflow pipes being long, short or not fitted.

Even if they don't flood when the bike is upright, they generally do if you lay the bike down at sections if you've no side stand, without turning the fuel off. They're a pain in the a***.

The usual checks are as mentioned above, float level, float valve sitting correctly and not obstructed with something which prevents it shutting off fully when the float lifts.

It would pay you to renew the float needle and needle housing - make sure you by a float needle with the rubber tip. You should be able to get them from Allens if yoou can given them any model numbers off the carb - or just email them a picture of the needle and housing. There are many variants of Mikuni.

Hello pschrauber and lineaway

Thanks for the feed back pschrauber I will have a look at the things you have pointed out to me

Thanks for the feed back lineaway will check the Beta forum and try pulling off the vent tubes

BR

I had a blue frame 325 and it did the same and the little valve stop thingy looked fine but when I changed it for a new one all was well.

Hello Woody

Thanks for the feed back always a big help, i will email Allens about the new parts and see what happens. Good to know most mikuni flood like this old 70s one or new one can do the same.

If it keep doing it am i better to refit a Bing like it had when it left the Bultaco factory ?

made me laugh an old 70s mikuni off some old jap road bike, im now wondering which bike it came off

Hello tbone

Thats great news thanks for that

BR

Edited March 22, 201412 yr by bultacorock