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pump jet -- what's stock and what have you tried

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2004 TC450, runs great everywhere, little to no pop on decel, starts good cold and starts good warm with a little bit of pressure on the throttle, but still have off-idle bog/stall problem.

Initially the bike would barely rev (just wanted to die), adjusted the AP preload to zero and set needled to 2nd clip from top and the bike ran great, but still had off-idle bog/stall when you quickly twist the throttle. Jetting is what came stock with 30 pilot and 175 main.

In experimenting I found that if I applied extra pressure to AP cam to keep the squirt speed more in time with the throttle the bog/stall went away and the bike revs like mad (faster), so I am thinking bingo. I just pulled the pump jet and found it's a 30, which according to the online parts catalog appears to be the smallest size and I am guessing that the normal stock 450 size is a 40 as that size has "(450)" listed next to it.

I only found a few threads with info on the pump jet and no real details.

Can someone confirm the stock TC450 pump jet size?

Also, has anyone tried changing the pump jet size to eliminate off idle/bog stall?

I am hoping this is the cure for me based on my finding with applying more pressure to the AC cam, but have to wait on the new jet (I am going to order the 35 and 40).

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my 510 doesnt have any off idle issues so havent looked into it.

but--let me just say that my Edelbrock had that same bog off idle and it was to rich of a setting on the pumper. backed it down a bit and it stopped bogging...so you are probably on to something-just cant help ya. let us know what ya find. :applause:

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Your bike ran fine for me, I think it is your unorthodox style and lack of clutch control combined with riding over your head all the time. :eek:

Now send that suspension off to Les. :applause:

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Your bike ran fine for me

you only rode it on smooth easy trail, it works great there... but try riding it in the tight stuff where you need to "blip" the throttle for a quick loft of the front-end and it wants to die. and it does it just sitting in neutral.

I've rode other 450s (husky (JR's TC) and non-husky) that don't have this problem, so I know how it should behave and expect nothing less.

I am also modifying the AP cam spring to give a bit more tension to increase the cam timing (quicker squirt).

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Let us know what happens, I've always wondered about the pump jet but just never got there to check it out.

I did get better low/mid end pull with a bigger pilot but hot start got worse so I went back to stock.

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I am still securing some pump jets so haven't tried yet (my dealer, tasky, has a 35 I am going to pick up in the next day or so). however, got this email from Hall's when asking about pump jets:

I recommend sending us the carb to do our modification. Replacing the pump jet is a critical part of our modification, but we do other things like change the needle and modify the whole acc. pump...

I may end up sending in the carb if I can't get it, but the bike runs really good besides the off-idle stall... I changed the pilot to a 32.5 and raised the needle 1 clip and improved the stall condition, I am hoping/thinking the AP jet change will take care of the rest.

I also would like to try the 10F01-50 needle, the bike currently has the "52" needle.

A friend also suggested getting the thicker head gasket that is available, that will drop the compression a bit and help with stall issues (as well as the 05 gasket has larger water ports and helps with cooling). you have to pull the motor to change the head gasket, so I will probably wait on this one.

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