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FCR Tuning Woes

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Hello all,

I'm having a bit of trouble getting my 97 XR600R to run with the FCR. This last summer I had it dialed in pretty well (or so I thought) except for a hanging idle that would come and go. I tuned the idle per the FCR website but after finding the optimum A/F screw position I did have to speed up the idle a bit (turn it clockwise) to get the XR to start on the first kick more consistently. The choke was working correctly and the hot start knob was also working correctly. I thought maybe that was a good indicator the carb was dialed in? Fast forward to today and it's about thirty degrees cooler and I can't even get this thing to try and start. I understand that it's colder (air is more dense) than when I tuned the carb but does it really make that much of a difference? I decided to hit it with some starting fluid and I got it to run on the choke for maybe a minute before it just died. Kick for another 20 minutes or so and still every time it would start it would only run for a few seconds and then just die. I could raise the RPMs by twisting the throttle but when I tried to let it idle it just dies. I am almost certain my problem has to be the idle circuit but I am not sure how to start this process now that the bike wont even start or idle.

 

Carb info

Main- 160

NCVT needle third slot from top

Pilot- 45

Starter Jet- 72? Should be stock for a 2006 KX450F

Leak Jet- 35

A/F screw 2 1/2 turns out. I can slow the idle by turning it in (leaning it out) but I cant slow the idle by turning it out (making it richer). Doesn't that indicate a lean pilot?

Bike info

I am assuming the engine internals are stock.

I think it has a full e-series exhaust but I will have to post a picture to confirm the header is White Bros.

K&N Air filter cleaned and oiled before winter storage.

2006 KX450F 40mm Carb with 3D printed adapter for air boot.

Premium gas with sta-bil that's about 6 months old.

 

Any help is greatly appreciated.

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Try turning your idle screw up some,,in colder weather it`s normal to have to adjust the idle screw up more until at least it`s fully warmed up..could be 20 minute or more depending on how cold it`s out..

 

B

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3 hours ago, brianhare said:

Try turning your idle screw up some,,in colder weather it`s normal to have to adjust the idle screw up more until at least it`s fully warmed up..could be 20 minute or more depending on how cold it`s out..

 

B

Thanks for the reply. I did try this while I was out there earlier. I also experimented with turning out the A/F screw. Eventually I returned them to where I had them set originally. Today was about 45 degrees and I tuned these circuits when it was about 80 outside.

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Drain the "preserved' varnish out of it and try again. Modern gas holds up about as well as a loaf of bread. Would you eat six month bread? :)

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Yup, it's normal to turn up the idle speed during warmup.  And these engines do take quite a while to fully reach running temperature.

Also, you may want to readjust the idle mixture screw for the colder temps.  Remember to adjust only when the engine is fully warm.

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Quick update. I think I'll try a richer pilot. I can't bog the engine no matter how many turns out the fuel screw is. I rode my drz400 with the same preserved varnish last time i posted and it absolutely ripped. Hasnt been started since fall either. I've never had problems with fuel going bad over the winter if I've used Sta-Bil. YMMV

 

 

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