nobody can deny that the 45mm w/ accel pump is pretty much the ultimate all around carb for stock bored motors with high comp and cams, its extremely powerful and the violent arm jerking response gained from the pump itself is an absolute joy. but alas, the stiff spring provided by RW necesary for using the pump is so hard on the thumb that it makes twisties a must.

Well, some guys have played with manipulating springs make it easier on the thumb, and I like the pump so much I decided that I'm not gonna live without it any longer so I did too. I decided that if I can't get the spring tension down enough to use the thumb, I'll just bite the bullet and go twist. Turns out all I had to do is twist on the LIGHT spring to make it a little tighter to overcome the pump spring, and it works beautifully. The heavy spring from RW is way tighter than it has to be, and making the LIGHT spring a little tighter overcomes the pump just fine with little to no effect on the thumb tension.

There were posts on this in the past, but I never payed much attention to them because I didn't have this carb at the time, but I'm telling you that there are several of us now that use the pump with the thumb with no Hulk effects on the throttle hand. Its so wonderful to have the pump, I played with it all day and I just don't see why i went so long without exploring this option. All I have to hope for is for the spring's integrity to hold since I manipulated it, but I really didn't have to twist much to make it a little tighter so I think it'll last just fine. If it doesn't I'll go twist for sure, cause this pump rocks. but for now, looks like the thumb will last! Everybody who is not running the pump - I strongly encourage you to do the same thing - twist the light spring to make it tighter and fire up that baby, you won't regret it! Then we can lay the thoughts of the TM45 being a twist-only carb to bed.

 

do you recomend accelorator pump activation for big bore drag racing? i do not run a pump on my 45mm, but i am curious to know if it would improve high RPM launches or top end gain, thanks

 

COOL! Great info. One question, how can i tell what spring i have? I bought my TM45 used(with the accel activated), but i dunno what spring i have. Also, what nozzel are you running for the accel pump? How can i identify which i have? I know it squirts a TON of fuel when its activated(i'm running a short rod to deactivated it right now)!

 

So your saying you enabled the pump without any difference in thumb tension....

If so, where can I get the control rod (I think that's all I need to enable the pump)?? Used or new, whatever.

If it really makes that much of a difference with the pump on, I want it.

I don't know what you mean by "twisting" the LIGHT spring...

I WANT A PUMP!

 

damn, i forgot to add this to my last post.

Here is what my carb looks like : CARB.

Yea, the throttle ***'y is on the left and on top unlike the new ones, but the rest is the same.

Thanks

 

Annihilator - i don't know how much difference in drags yet, haven't dragged with it yet. I would guees it'll help the holeshot a little, I wind up to 5K before I dump the clutch, then its hammer down all the way, and that first initail squirt off the line may help throw me a nose ahead outa the hole.

I don't know which nozzle is in mine right now, whatever comes stock, the 60 I think. there's also a 50 and 70. not sure how to tell, I'd guess its stamped on the side somewhere, not sure how to remove yet either, haven't done had to do that. I would guess you remove the bowl and take a good look - might just screw out, or even just pull out from the inside?..?...It does squirt alot, and I've read where guys had to go to the leanest nozzle, but my porting and cams seem to like the nozzle I have, but after I play more and get a better chance to really ride the trails, I may decide different.

If your throttle tension really pisses your thumb off and sucks to ride for more than like an hour, its the hard spring, if its an easy pull that'll let you ride all day its the soft spring. if your carb slide fully returns like it should when you let off the lever, and the pump is operational, somebody must've already done what I did to the soft spring.

Tyrespinner - call RWR, get the Mikuni tuning manual from them for this carb and it also has a diagram of parts in the back of it, or maybe Elliot at RWR can fax the page to you?.... You can pull your carb apart, compare to the diagram and know exactly what parts you may be missing and then call up Elliot at RWR and order it all. I always get good fast service.
As far as twisting the spring - I mean put one end in a vice gently, clamp the other end with needle nose vise grips, and "unwind" it a bit so that when you re-install it it pushes harder against the throttle return. Just make the spring be tight enough to close the throttle under the tension of the pump spring, but no tighter than needed so that the thumb doesn't get pissed off. Yeah there's a little more on the thumb, but its insignificant, nowhere near the tension of that tight spring we've all complained about.

 

Thanks Hightower for info, i will test this also for my 763cc with and without accelorator pump on the dyno and i will get back to ya..... im a firm believer in the TM 45mm, I would like to see dyno run with the 45mm against the duall carbs, and of course they would be dialed in to the utmost.........

 

Mario don't waste your time with that stupid pump! It won't help one bit. All it does is help consume your fuel that much faster and then you have to start changing nozzles for altitude. trust me on this one I spent three solid weeks on it and I didn't see any noticeble differences. All I got was a Migraine headache from it. If you like to Ftz with your jetting all the time then the accelaerator pump is the way to go.

 

off the topic of the TM45 but I got my stock carb tuned perfect and I did the slide spring cutting deal today and if is way better!!! This thing revs really quick now!!! anyway, would I gain anything switching to a TM 42 or 45?? Remeber I got my stock carb tuned perfect, is it worth messing with? I don't think so but if someone else has a better opinion????

 

you set the travel limits of the pump yourself - you tell it when to start pumping and when to stop pumping, at what point of throttle travel. you can set it up to use as little or as much fuel as you want. these pumps are used on many carbs with no ill effects on fuel economy, all 400ex's have them from the factory, the quicksilver carbs use them, they have their purpose on the trails for sure, but not necesarilly something for drags.
FYI - set all you jetting correctly before you ever screw with the pump, do not change jetting to accomidate the pump, that would be a mistake.