Mikuni TMX Carbs

Does anybody have any experience of setting up a TMX 35mm carb on a '75 250?

Previous owner put it on the bike but not too sure about it. Thinking about changing it for a VM?

Thanks

Colin.

No, but I can tell you that I am very well experienced with TMX and TMXX carbs.

You are better off with a VM carb with original specs or someone who did conversion and got carb close, needle and jetting wise.

With the newer carbs, you almost need A/F ratio meter to get starting point.
Just starting from scratch is going to cost $ and headaches. There are several things you have to figure out to set these carbs up, because they are performance finicky! Thickness of the needle, the slide cut for air mixture, Mikuni uses taper minutes ( which is a pain), then you have to figure where you want the tapers,taper thickness, and taper angles,etc... To adjust powerband. In other words you are shooting in the dark, then try to tune it from there.

VM is going to not be Performmance Finicky, most times they come close and easy to tune from there.

Hope this helps!

TMX is a flat slide and VM is a round slide, this you know
advantage to a flat slide is quicker throttle response
advantage to a round slide is better throttle control
the flat slide was created for motocross, but is way cheaper to build
do the math if you are a manufacturer making many bikes a year
back to subject, depends on what you want to do to it
there are some gurus that have the 3x5 cards with the jetting you are looking for

Thanks guys.

Just had a quick measure up and there doesn't seem to be enough space to fit the VM carb in. I'm short of approx. 15mm.

Can anybody tell me what difference it would make reducing the length of the spigot coming out the reed block? I could get some space back from there.

Cheers.

Colin, Are you looking to race your bike? I had a similar question about the use of a TMX on my bike a few months ago and was reminded that many race organizations do not allow flat slide carbs. AHRMA does not allow it.

What's up with that? I wonder why?

They were not available at the time. Period correct flat slide carbs like the Lectron are legal for '75-up bikes in AHRMA but a modern flat or D slide carb like the TMX or Keihin PWK are not legal because they were not available at the time, nor was there anything like them available at the time. Having said that, the Lectron is a far better carb than a TMX or PWK anyway, and the VM is better in my experience than the TMX.

Yeah, I race in the Scottish Classic Championship. Discretion is used in certain areas and with common sense! Let's just say I'm not the type of rider that will benefit from any extra performance a carb will give me!

I've rebuilt the bike for the season and don't want to run a new motor with a carb that I'm not sure about so I've ordered a VM36 and can make it fit.

Cheers
Col.