Carb settings...

Now I’ve stopped my T140 from running a total loss oiling system ( ) I can actually see the fuel related plug colour for the first time!

The motor is stock, but bored to +.060”, 8.6:1 pistons, and a tightened up squish band (0.034-0.036”). It runs straight through Commando style peashooters.

The carbs are brand new mk11 and have been working fine, well, they did after I set them up according to John Healey‘s pre EPA recommendations, which includes 106 needle jet, needle in the middle, 200 mains. I have fitted #3 slides in place of the #3.5s though.

The bike seems lean, so, as a first stab, I tried 220 mains and it was noticeably better in the higher rev range. I just wondered, before I start down the road of marking the twistgrip and trail and error testing, what settings are other guys running ?

T140D with parallel port head, two Mk2' s ,.032 squish, 8.6 Triumph OEM pistons, intake cam timed to 100 degrees lobe center, stock 2 into one pipes with a aftermarket straight through muffler. Total timing at 35 degrees..210 main jets with the Euro jetting. Cotton gauze air fllters
Top end and midrange was fine...but always had an annoying off idle stumble that different slides , pilot jet air filters on or off didn't fix...
32mm Mikuni TM flatslides are far better but it requires some tuning...

Hillbilly Bike said:

T140D with parallel port head, two Mk2' s ,.032 squish, 8.6 Triumph OEM pistons, intake cam timed to 100 degrees lobe center, stock 2 into one pipes with a aftermarket straight through muffler. Total timing at 35 degrees..210 main jets with the Euro jetting. Cotton gauze air fllters
Top end and midrange was fine...but always had an annoying off idle stumble that different slides , pilot jet air filters on or off didn't fix...
32mm Mikuni TM flatslides are far better but it requires some tuning...

Click to expand...

Thanks Hillbilly,

35 degrees ign advance eh? Is that possible due to the tightened squish dya think?

Did the Mikuni TMs solve the stumble? I was told by an old boy years ago that the fix was to open up the plug gap! I did it at the time and it seemed to work, but ‘twas a while ago...

Yes the squish.. opening the plug gap can help fire a lean stumble..A wider plug gap will tend to shorten spark duration however.The TM's did eliminate the problem and arguably function better overall.
John Healy the long time Triumph dealer and race tuner claims the Mk2's are very sensitive to the evaporation rates of modern fuels..I believe this is a part throttle issue...
The Mk2 isn't a bad carburetor because I had a problem. I suppose you will have to keep trying different jets

Ok, ain’t pretending I got it perfect, but it feels very good. Ended up richer than stock Euro settInge by:

#3 slide instead of #3.5

Needle one notch richer

210 mains instead of 200.