I just bought a tm42 carb off of ebay. What would be a good starting point for jetting? I have a Big gun pipe and rev box and K&N filter w/no lid. It should fit on to the same intake manifold, I hope. If anyone knows any different let me know. I know that the I should use a 50 ap jet and outside of that I need some general help. Thanks

 

Still looking for help? Anybody?

 

To be honest I do not know of anyone using a TM42... Same size as stock. I think the stock carb with the stock carb mods would be very comparable..

But, that does not help you, so here is what I have with my TM45. I run a direct mount filter that uses about a 10 drop on the main over running a snorkel. So if I run a 145 with the direct mount I will run a 155 as a starting point if I put a stock snorkel on.

Here is where I'm at for sea level, thanks to Hightower for helping me get here:

Idle mixture screw: 2 turn from seated, give or take a little.


Pilot: #30.


Needle: #96, 2nd groove from top.


Main Jet: 145


Accel pump nozzle: #50 (Squirting directly on the needle jet. You can turn it by reaching in with needle nose. Set to squirt from just off idle until just under 1/2 throttle.)

With this set up I can run from sea level to 4,500 feet just by changing the main and resetting the idle mixture.

Good luck!!
Scott

 

I am using the 42 because I have a 40 on DR650 bike and like the throttle response and easy tuning of the tm. I got a real deal on eBay for about a quarter the price of the 45. I hate tuning vacuum carbs. Thanks for the info, that will give a starting point.

 

I called RWRacing since they sell a TM42 for the DS. I told them my situation and asked if they would sell a kit with jets needle etc. They were very helpful and are putting together a kit with what I should need. This should get me very close. I'll update later.

 

They are great to deal with. They usually jet for running without the accelerator pump, but since you want the TM for the throttle response you will want to run it.

They will probably give you a 40 or so pilot, this is for no pump, you will probably end up around a 30 if you run the pump.

You can download a TM45 manual here, has real good tuning tips.

 

Thanks for the info. I told them to send me 50 jet for the accel pump so he knows that I plan on using it.