Jetting Spec and Hot start lever acting like throttle


2 replies to this topic
  • Ak Yammy

Posted May 27, 2008 - 12:32 AM

#1

Ok trying to get a handle on my jetting for my 03 wr450. Went to manual for base numbers and it has my main listed as a 150. Cant find anyone in the jetting section with this low of number. Have not had it apart to verify, just a misprint??

Also thought I read somewhere on here that if you activate your hot start lever while riding and it acts like a throttle you have some jetting issues?

Bike runs OK but I do get the occasional startup backfire and the surge at steady throttle.

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  • Frostbite

Posted May 27, 2008 - 03:09 AM

#2

Ok trying to get a handle on my jetting for my 03 wr450. Went to manual for base numbers and it has my main listed as a 150. Cant find anyone in the jetting section with this low of number. Have not had it apart to verify, just a misprint??

Also thought I read somewhere on here that if you activate your hot start lever while riding and it acts like a throttle you have some jetting issues?

Bike runs OK but I do get the occasional startup backfire and the surge at steady throttle.


If your hotstart causes the bike to rev higher or run better as you're riding, you're rich on the bottom end. The hot start lets more air in, leaning the engine at low RPM. My bike is doing this right now and I'm fairly sure that it's a clogged air jet.

A 150 main sounds a bit lean, but the main shouldn't affect your bike at low RPM, and it sounds like you're rich at low RPM.

Remember that you can be rich at low RPM and lean at high RPM, or vice versa. The pilot circuit, needle and clip position and main jet are 3 seperate systems.

  • Ak Yammy

Posted May 27, 2008 - 08:22 PM

#3

Ah ha. Makes sense, I think I went a little rich on the pilot screw tuning out a pop on decel. I think I see a JD Kit in my near future. This bike was bought from a clueless second owner who did who knows what to the carb. Anyone know if the kit has the quick adjust pilot screw, seems like the hot ticket.




 
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