What does it control? What ones go with the TM33? Also what needles go with the TM33? You guys with the TM33s, what needle and needle jet are you running?

 

Needle jet (some call it emulsion tube) controls the fuel flow into the main circuit (as opposed to idle or starter) together with the needle and main jet.

Needle jet has biggest effect at approximately 1/8 - 1/2 throttle.
First part of the needle is not tapered, and within that range the needle jet is your main "tool" to control the jetting.
At approximately 1/4 - 3/4 the needle taper has big effect and past 3/4 throttle the main jet starts to dominate.

There's only one needle available for the TM33-8012, the 5FP96.
Stock needle jet is P-8 (640 Series), and most people seem to find out that the next one richer, Q-0 actually works best for the KLX.
The richest needle jet is Q-2.

--
Mikko

 

The needle jet is the nozzle tube that the tapered needle (jet needle) loosely slides down through. The area of space between the nozzle and needle is what meters the fuel past it. When the needle is lifted the area gets bigger, or if the nozzle is bigger. each will meter more fuel. At some point in the needle rising through the nozzle this space becomes equal or greater than the size of the main jet hole. At this point the Needle and nozzle circut "hands off the metering to the main jet" So changing needle size and taper, nozzle, or raising or lowering the needle not only makes it richer or leaner at any set throttle setting. It also can change when it hands off to the main.

So a needle that may be dialed in good for mid throttle jetting may hand off too early or late. OR visa versa. Why we change them.

 

I am still messing with my jetting on my TM33. Bill says you have to run with the snorkle in but I just have to see if I can get it without all that restriction. Almost got it right. Currently I've got the P6 needle jet and the 130 main. Not sure what the needle is, was going to change it but there is only one other made and its not readily available. I've got it on the middle position without a spacer. Going to drop it a notch in a few minutes.

 

I see! Thanks for all the info. I've hit a bit of a dead end in my tuning and someone suggested I change the needle and that's when I found the needle jet.

So the P-6 will make it open slower and the Q-0 will make the hole dump wide open a bit faster? Do I have that right?

 

I must be running everything way too fat then. I've got a 140 main and 45 pilot. But I'm using a KDX snorkel, pipe, and Unifilter too. We're at 500 feet here. Out in the Black Hills this last week I dropped the needle one notch because it was dumping in way too much fuel at that altitude and I at least got it to run well enough to ride. Going past Mt. Rushmore on pavement it was a friggin dog but that was pretty high up. If I ran full open it would bog and miss a lot. That's why I'm looking at smoothing out the fuel delivery some. I'll buy a Q-0 and a P-6 and see what works better.

 

Close but not quite. Mainly the P-6 will make it leaner in the range before the needle taper starts. The needle determines more of the timing of transition.
Q-0 makes it richer during the "straight" portion of the needle.

To make it start open up earlier/later you adjust the needle height.

--
Mikko

 

Too big main. Try 125 - 130.
I'd say try to get the WOT pretty much perfect before spending much time changing the needle jet.

--
Mikko

 

What's WOT?

 

Wide Open Throttle.