Just aquired a fairly nice 1975/76 350 sherpa t (159)that has been sitting for at least 10 years. Tonight I disassembled the stock bing carb and it is worn out. The VM28 Mikuni is cheap and is an excellent replacement from what information I have been able to find. Hard to go wrong with a mikuni. Like to know if anyone has the jetting specs for the VM28 for my bike and any other pros and cons concerning this swap. Thanks in advance,cheers,Jim

Good original looking Bultaco.

Many in the UK fit a Mikuni VM26 in place of the Bing, they work very well giving a smooth pick up but you will also need a different manifold connector tube.

My bike has a VM26 fitted with the following settings,

27.5 pilot some fit 30

125 main or 130

needle jet 182 - 08

jet needle 5DP7

slide 2.0

main air jet 1.6 or 1.75 mine has a 1.6 though a friend runs with the 1.75

 

 

 

Edited January 28, 20179 yr by trialsrfun

http://www.mid-atlantictrials.com/Bultaco.html

Hi triasrfun, I have a 159 sherpa, I had a carb built to your above spec and bike runs spot on,,,, I have a 78 350 too, rebuilt to 340 cc, carb is lean on bottem end with these settings, shall I just richen it up with bigger pilot jet, or does this bike need all different settings, ps is Bob on on power, thanks 

1 hour ago, rev4t said:

Hi triasrfun, I have a 159 sherpa, I had a carb built to your above spec and bike runs spot on,,,, I have a 78 350 too, rebuilt to 340 cc, carb is lean on bottem end with these settings, shall I just richen it up with bigger pilot jet, or does this bike need all different settings, ps is Bob on on power, thanks 

Pleased to learn your bike also runs well with the settings I use on my own Bultaco.

I would initially go up to 30 on the pilot and then maybe lift the needle by one ring if you think it needs it, the settings above should not be a mile out on your 350 they work well on my 199A.

Thanks very much, it also looks like that I might need a stepped rubber to manifold, according to in motion website, so will order one of those, I used the straight one from the 159 to try it,,,, would that make much difference 

You need a carb connector that fits correctly at either end with no air leaks

Edited September 27, 20214 yr by trialsrfun