WR 400 need some info please

Hello, i am new here.

First off, i just wanted to say that I read all the faq's and searched and did not find the answer i need.

I just bought a wr 400.

The bike came with no airbox lid and a procircuit aftermarket slip-on.

Now, it does not like to start, stalls easily when cold, and when warm will idle for a while then eventually die.

Next, while crusing at 1/2 throttle it hunts and stumbles (TPS)?

When going from mid throttle to WOT quickly it will just bog out and die unless I roll on slowly.

Now, I know all about how to rebuild and rejet carbs, but not this perticular unit.... can anyone give me any hints/tips on what to look for to fix my issues? thanks

Pull the carb off and gas it. Time the accelerator pump squirt. Is is squirting a lot of gas slowly. You can put a small collar around the accelerator pump rod. Called the taffy Mod. Some times there is no squirt and you need to replace diaphram in the pump housing or clean the AC squirt passage.

"Taffy Mod". This mod consists of a collar and set screw that limits the push of the AP rod into the AP. Thus limiting the internal pressure build up and allowing less gas to be pressured into the nozzle - resulting in a shorter squirt. In essence, it accomplishes the same thing that the FCR equipped Yamaha and Hondas do with the leak jet.

Then just try different jet - needle - airscrew combos. It took me 2 months to get mine right. If you have an after market pipe check the manufacture jetting specs.

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