Hi there I own a Bultaco Sherpa T 250 M49 and I have fitted a new dellorto PHBH 26 BS and I am wondering if anyone has a known and tested jetting specs for this bike I have tried to contact various company's but with no success. I would like to know which of the following

1. Atomizer

2. Needle

3. Pilot jet

4. Main jet

I know each bike is different and will require a tune specific to the bike but a good base jetting will be great to know as a starting point

Maybe start by getting the jetting specs from a modern 250 and using that as a starting point.

I have a dellorto on my 340, when I next work on it I'll note the jetting and let you know. It should be close enough

Hi,

I've done a couple, a M199a and a M158 both with PHBL26BS, I drew information from several other threads on trials central, PeterB being very helpful, I can't claim any credit, I copied the specs and made the adapters. I can't say it will be exact straight out of the box for your bike but it should be very close. The PHBL is sensitive to float height, my M199a bogged just off idle, I messed about quite a bit with pilot jetting until Peter put me straight, I lowered the float level slightly and reverted to the jetting here and all was good. Runs perfect every time.

270K needle jet (emulsion tube)

60 slide

36 pilot

95/100 main (250/325)

D36 needle (D34 is supposed to be better with the 325 but it ran so nicely on the D36 I never got around to fitting it)

The only other 'watch out' which must be common, is that the fuel filter that is part of the feed to the carb blocks very easily if the bike stands, you get the dreaded unleaded gel like substance and find the bike will not rev, just dies on wide throttle openings. Pop the connection off wipe the filter, put it back and all is good unless it's 6 months until you next ride....

Hope it helps

Hi twinshock325

Thanks for your replie

I think I seen these specs on an old post but the PHBH and the PHBL carby run diffrent emulsion tube and needles PHBH run an X needle and PHBL run a D type needle I am unsure what the diffrence between the two carbys are but the are small differences between them. Is it possible two cross reference the emulsion tubes and needles to the other styles. I could start buying needles and emulsion tubes until I get the right one. I have an idea on tuning needles but emulsion tube are a diffrent story I can not find any info on selecting the right one. Dose any one know how to select an emulsion tube.

Thanks Matt l

Have you asked

http://www.dellorto.co.uk/ ?

Matt, apologies I should have read the question properly! I have no experience with the phbl type, worth a search on "todo trial" forum good Spanish site, the phbh mod is more common there due to regulations I think. Even if you can' t understand Spanish, specs you may get enough info. Worth a quick look I think.

These are the jets on the PHBH 28BS that I have on my 340 and it runs very clean.

Pilot 40

Main 98

Needle tube AV264

Needle X2

Slide 4.5

The early 250 and 325 bikes which used a 627 27mm Amal shared the same jetting, so although mine is a 28mm and on a 340, it won't be too far off for the 250 and a good starting point.

Hi there

Thanks for the replie I have ordered the bits for the carb

Plus a few extra jets around that range I will let you know how it performes once the parts arrive

Thanks

Matt l