for those of you that are interested. recently purchased a used TM48, HR intake and a RWR cdi from ebay. these items went on a 2000 DS650 with impressive results. the tm is a much crisper carb than the stocker but it took a little to get there. the carb had no accel. pump as delivered and had a HUGE bog in it. after ordering the necessary rod, spring, etc. for the pump i installed it in factory config. Most of the bog was gone and the bike ran awesome, however that little bog began to eat at me. i havent heard of anyone doing this next step, an probably for good reason haha. i removed the pump cam and modded it. i took the pump spring completely off the throttle shaft and ran a tension pin directly through the cam and throttle shaft. Mikuni recommends the pump quit pumping at 3/4 throttle and this set up doesnt do that. with this set up i was able to toy with the return spring to get the throttle tension i wanted also. so far the bike seems to run great, anyone else done this yet?

 

I'm interested in this mod. I run a TM45 and have that little bog as well. I also have a buddy that runs the TM48. Can you post some pics of what you've done? I'd love to see it and possibly do that mod on mine. Thanks.

 

My TM45 has no bog, and I only run the pump from about 1/8 to 1/2 throttle....

I run a 30 Pilot

Direct mount filter.

96 needle on 2nd on the 2nd notch from the top.

and a 145 main at sea level...

 

I ran almost the exact same setup as TheStir until my recent 730 build. The trick with the TM45/48 really is getting the AP set up right. I bought the RWR throttle return spring to ease the throttle tension, then bought a lightweight stainless spring from a local hardware store that was roughly the same diameter as the AP pump spring. I just cut some pieces of the spring and built my own AP spring. My AP is set to pump immediately off idle and cuts off at no more than 1/4 throttle. My throttle tension is similar to the stock carb and I can jab my throttle off idle or at any position for that matter with no stumble/bog. No need to modify the AP cam as it is fully adjustable for start/stop position...

It's very easy to over fuel via the accelerator pump and create an annoying bog. Even with my new 730 motor which included Web 110 cams and ported intake - this setup works perfectly.

Note the two pictures attached with my current AP setup...