Hello !

As some of you know I have an XT600 3TB and today something quite strange happened.

I changed the air-filter to a new Champion one and immediately after that some problems appeared. It seems the old filter even if I cleaned it thoroughly with compressed air was too dirty in the first place... (my educated guess)

1. My idle speed lowered without messing with any adjustments

2. Engines dies if I snap the throttle wide open at idle speed (standing still)

3. I feel a small power loss around idle and very low speed (maybe I just imagine it ..)

Things I've tried so far:

- enriched the mixture at idle (it fixed a small part of the problems).

- changed the spark-plug to a brand new one

The filter is new hence more air flow can go trough the filter and that would create a leanish mixture but that obvious ?!

My problem with low speed power loss can be solved by raising the needle one notch ? should I try it ?

I sometimes feel the bike accelerating (wide open) and it takes a second for it to really start going. I hear specific sound of the engine and it picks up and start accelerating harder and harder. The clutch is not slipping it's acting like its a little lean then when the main circuit is providing fuel starts to accelerate faster.

I know this carb doesn't have a accelerator pump but should it just die if I snap the throttle wide open and hold it ? A bog would have been nicer but dying is no fun ...

If I don't snap the throttle at idle (with no load) the engine runs pretty good and I have good power all across the rev range.

Was my old airfilter that clogged up that I require rejetting ?! It didn't die with the snap open maneuver before ...

Are you guys experiencing these symptoms ? or I'm again trying to fix a problem that isn't actually a problem ? Should I open the mixture screw more to "fix" the problem or the needle position is the problem ? Also my main jet is old (haven't changed it to the new one that I bought in a carb repair kit). I'm asking these questions because removing carbs take a bit of time.

With all the love and care for this bike even small problems for me are exagerated ... I can't help it

Usually an airfilter change doesn't change jetting or very little . It's possible you were jetted lean all along just the clogged or maybe less efficient air filter allowed it . With a new filter and possibly better flowing it now needs jetting . By the sounds of it you need to raise the needle and go one size bigger with the main . The mixture screw needs to be readjusted for the new jetting and if it ends up roughly 3 to 3-1/2 turns out you'll need to go one size bigger on the pilot as well . Once your jetted better the cutting out at quick throttle should be greatly reduced . Without an accel pump they always do have a bog/hesitation anyways . I really never go from idle to wot anyways so any bog doesn't show up , only crack the throttle 1/2 way , wait till motor starting to rev, then open it up .


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'86 XT600/3TB motor,,, '88 XT600, ,,'92 XT600e,,, '08 Husky TE510,,, '05 DRZ463,,, '95 KLX650 ,,,'96 KLX650

Like always you are offering me great tips thanks man

I did clean the carbs today and used a carb rebuilt kit and changed almost everything and used 48 pilot 135 main 110 secondary and needle for both carbs in middle position ! For the primary it was 1 step higher than middle (leaner) and the bike came alive again.

For the idle mixture adjustment my screw is at 3 turns out from fully seated and I think it's ok. The idle speed screw had to to be turned in a few turns (to increase the idle).

Overall the bike drives and accelerates really nice !

Hot starting is not instant (maybe I'm a little bit rich now) but it starts after 2 turns of the engine sometimes 1 turn.

Cold starting is also great !

If I snap the throttle open from idle the bike revs up nicely and there is no bog or anything similar. Maybe a small (very small) hesitation then it revs up.

Thank you !

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'86 XT600/3TB motor,,, '88 XT600, ,,'92 XT600e,,, '08 Husky TE510,,, '05 DRZ463,,, '95 KLX650 ,,,'96 KLX650