2001 First Test by Dirt Rider Mag.

Looks like the stumble is gone with the 2001's.

I don't like the durability aspect of the Ti-Valves, and considering that most of us had to work extra hard to get the stumble out of our 2000's - I'm sticking with my 2000 model.

Thanks Yamaha, for helping us guys out with the expensive carb mods and belly-ing up to the bar. When I belly up my next 5G's for a trail bike (by January in fact, to ride with my three sons, it'll not be a TTR - it WILL be an XR. And to think Yamaha's are all I have ever owned.



I agree with you. I'm not real sure about the durability on the new titanium valves either. The test ride on the '01 says they worked out the "stumble" from the '00 but I haven't had any problems with a stumble on my '00. So I think I'm gonna stick to my '00 426 too. There just isn't any major changes to the new line-up.

Sorry if this is a stupid question but can you explain "stumble"

Monster - I don't have to describe stumble - you already did - on your previous topic.

The '00's have a varying degree of stumble, cut-out, stall, hiccup, kill, cough - call it what ever you like - all these terms can be used interchangably.

The problem root cause is the accellerator pump delivering too much fuel too fast throught the throttle body - this is actually a flooding condition. To correct this you are going to need to experiment with jetting until you find the combination your bike likes. Make sure you have your bike broke in before you start adjusting the carb. Once it is broke in, take off the carb bowl and the accellerator cover and empty them to be sure everything is clean there.

Most guys have at least minimized their bike's condition by opening the fuel screw in small increments, until symptoms subside.

This did not work on my bike however. I believe I had one of the bikes with the worst cases of the stumble. I ended up putting on a P38 accellerator cover and going up one size on the pilot jet. My problem is cured.

You will need to go back and start reading all the topic in this forum - anything related to carb jetting, stalling, etc. You will begin to see a common theme throughout these topics. When you have questions - come back and post your findings - everyone on the site is helpful.

Good luck.


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