Another Jetting Question

2 replies to this topic
  • bihaga

Posted August 19, 2006 - 02:55 PM



I have a question about jetting my bike. I am new to this and wonder if someone experienced can give me a few ideas.

Temp is 17 degrees celcius. Humidity 77%. I am 70-200m above sea level.
My bike is a stock 2001 WR426F - only mod is that I´ve removed the airfilter box cover. I´ve not touched the carb settings so its stock european setup.

My problem is that when I run at 1/3throttle the bike runs uneven. When I release the trottle after hard acceleration it backfires. If I release the trottle slowly there is less or no backfire. When I removed the cover for the airbox there is more backfiring but less uneven run on 1/3 throttle.

I´ve mounted a Trailtech Vapor to the bike and it says that watertemp is around 61 degrees celcius while riding on the street.
All answeres will be appreciated.

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  • Alley Cat

Posted August 19, 2006 - 05:39 PM


It seems you are lean on the needle. Try raising the needle (go richer) and you should see an improvement.

You may even see some improvement going to a larger mainjet too. Try a 168 or 170.

  • bihaga

Posted August 20, 2006 - 04:20 AM


Thanks. I´ll try this asap. I´ve also ordered a JD Jet kit, hope this will improve things.


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