740 carb 24mm bore CFM

[IBAJIM]

No offense to anyone that has put the 740m carb on their bike, since I really appreciate info. from all of you that has spent the hours working out the bugs on your particular build.

I'm trying to add to the discussion by pointing out what the experts who built the carb have to say about selecting the correct size carb and calibration. The info. in the Weber tuning section is specific recommendations for folks adapting the carb to other engines/applications.

Here is the latest gem that I found today. After adjusting the jet sizes ( idle jet, main jet & air correction jet ), it says :

" With the carburettor calibrated whilst the car is staionary, the car should now be road tested to find out if any further adjustments are necessary.
............, take the carburettor through the progression stage to full throttle stage in each gear, noting the engine performance. If the engine appears to lack performance generally, but the mixture calibration seems correct ( my emphasis ), the choke size ( venturri ) may need to be reduced 1 mm or 2 mm . "

Interesting , but concerning ! That's not much of a change in venturii size to made a significant difference.

 

[joedrum]

well ...i can tell you ..ive had both the dft carbs on my bike ...and it dose seem to me that the 2mm bigger airflow of the 24-25 carb acts different ... to the point that on my bike it seems the 24 choke works a bit better ..i must also say the the 22-22 carb actually ran well ...and i am not sure if it much more than just different ....my gut feeling is it has more torque :BigGrin:

 

[IBAJIM]

Joe:

I would like to try a 22/22 carb - didn't know they came in that size. What did it come on and where did you get yours ?? Thanks.

 

[joedrum]

the 22-22 carb is the 32-32 ... witch is basiclly the throttle plate bore spec....it is also the carb known as the tom carb that can be bought new at a extremely good price....as far as i know i am the only one using the carb like you have ... my opinion is both carbs are in the tuning range as good size with this carb being kind of of the max and maybe too much on stock motors ... hard to say ....i will say the 32-32 or tom carb fits better without a doutb ....my bike is extremely modded in its 1200 powerplant ..even more so than i thought it would be ... and even at that ive extremely modded this carb i have thats like yours to work ....more so than anyone has the 32-32 carb ....

 

[IBAJIM]

Ya, I would think your 1200 motor can use a slightly larger carb than a 1100.
I'll check out Tom's website ( again ). I found it in my searches.