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[Jon]

Ive got a TR250 im working on at the shop, its been stored away for about 10 years now so im going through it for the owner. He had sent the carbs out to be rebuilt, bolted them on and brought the car to me. I set the timing and im 90% posotive ive fixed all vaccum leaks but the car still runs lean, if i choke the car by putting my hands over the air box opening it smooths right out and idles real nice. The car drives good just hunts around at idle. I was wondering how to adjust the mixture in the carbs before i buy the tool i put a 1/8 allen into the top and felt around to see if it was adjustable and it doesnt feel like it is??? Any help is appreciated.

[Triumph68]

Jon,  If the carbs are the originals for the TR250 they are not adjustable. 

Cheers,
Roy Smith
VTR TR250 Vehicle Consultant

[Darrell]

Jon,
Not an expert tuner here but the TR250 intake manifold was Triumph's first attemp at emmission control and are known to be prone to leaks so perhaps you are sucking air somewhere causing the lean condition.  You can adjust the needle by taking the piston out and just moving the needle up or down and resetting the set screw.  I have done that.  If all the emmission control stuff is operational it is typical for a TR250 to hunt at idle, mine did that for years until I finally blocked that all off. Still does it a little.  In addition I have found that if the motor has been worked on and the head shaved or the cam profiled like mine has forget the emmission stuff for it will no longer work. Nor do the factory timining settings.  I just set mine where it is "Happy".
Darrell
68 TR250
Been fooling with it for over a decade now. It will not idle for xxxx But it has a nice power band from around 3200 revs to the redline   

[slapz]

I have a brand new Stromberg manual if interested. Contact me at my email. Also have a FACTORY (straight from Britsh Leyland)manual that covers from TR2 thru TR 250 supplement. I also have original sale brochure for TR250. I bought one brand new in '68. Email is homer2105@aol.com

[FullChat]

Jon:

If you are still out there ...

What should have been told to you in the beginning is that the early ZS on the TR250s were without adjustable jets.  Later ZS did get adjustable jets.  You can quickly tell if the jets are adjustable by reaching (and/or looking) at the underside of the carbs.  If you see a threaded "screw" at the bottom they are the later ZS and are adjustable.  No "screw" and you have early ZS; and the jet is not adjustable.  You can then follow the others' advise in the previous threads for adjustment and tuning the early ZSs.

Alternative solutions could be: replace the early ZS with later models(from a TR6 donor, or from ebay-where they appear regularly).  Or replace the ZS completely with Dual Weber DGVs.  Or for added performance triple Weber 40DCOEs or a triple ZS setup from Goodparts.

As noted, if you are still following the thread(doubtful) and would like further info on replacing early ZS  with Weber dual DGVs, I do have some experience with that.  That is the route I took.

At Full Chat, Tom