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Old 09-22-2013, 07:07 PM
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Default Fine tuning

     

I've got a 2000 CR250R that I've posted several times about. I was finally able to take it to the track a few weeks ago and get a better feel for it. When I pulled the plug this week, I found it to be pretty black (coffee-like). I know this indicates a rich condition, which most of my posts have been about. My first question is: I've gone leaner on the main jet (172), up one clip on the needle (2nd), should I consider going leaner on the idle jet? It's currently at a stock 48. I don't think I ever made it past 1/2 throttle at the track, which is why I'm suspecting the idle jet may be a bit rich. It also starts on the 1st or second kick every time.
I also discovered a crack in the center of a dent on the pipe. I put a little high temp silicone and it held up, but I'll probably be looking for a pipe soon. Any recommendations? How will a new pipe affect the jetting? Can I expect to go leaner or richer after the switch?
Thanks
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Old 09-22-2013, 07:22 PM
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Default ?????

What furlix are you using?

Paw Paw
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Old 09-22-2013, 08:55 PM
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Furlix? I'm not sure what that is... I googled it and didn't get anything I could make sense of either.
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Old 09-22-2013, 10:17 PM
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Default Fuel mix

My old hands get away from me at times, sorry....
I was asking what fuel mix you are using?

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Old 09-23-2013, 09:51 AM
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No prob. I thought it might be some unfamiliar lingo XD. I'm running Lucas Oil semi-synthetic mix at 32:1.
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Old 09-23-2013, 02:03 PM
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You have a Kiehin Air Striker in the bike right?

I'm running a 45

If you don't get on it, you will always have a darker plug. If you are riding at half throttle and pull the plug and it's light tan, then when you get on it, like in the a wash or some dry lake bed then you are going to be too lean.

Please do yourself a favor and do a real Plug chop to see where your top end jetting is.
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Old 09-23-2013, 02:27 PM
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I appreciate the input, but there are not lake beds... or hills... or anything where I could "open it up" down here in South Texas. I'm a novice rider trying to make the bike run well at the local track where I have a total of 15 laps experience ( 3 sets of 5 laps before my legs, back, and shoulders gave out). I thought the point of having two jets was for the bike to run well at low rpm (idle jet) and at high rpm (main jet). That is why I am wondering about the idle jet. If I never made it onto the main jet, that should not be affecting my plug, should it?
It's got whatever is the stock Keihin carb with a 172 main jet, stock needle, 48 idle jet, stock exhaust with a few dents and dings and new packing
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Old 09-23-2013, 03:49 PM
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This is one of the best reads on jetting I have ever read...
Spankeys Jetting Guide - Info 2 Stroke riders must have
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Old 09-24-2013, 09:29 AM
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theres some pretty good info on that jetting guide
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Old 09-24-2013, 12:54 PM
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The Pilot Circuit, Tuning from Idle to Throttle -You can use the air screw to help determine if your pilot jet is appropriately sized. Take your bike for a short ride letting the engine come up to normal operating temperature. With the engine stopped, transmission in neutral and the bike on its stand turn the air screw clockwise until it just seats, gentle now it’s delicate and you don’t need to torque it down just gently seat it. Now turn the air screw a quarter of a turn out so the engine will fire and start it. Slowly turn the air screw counter clockwise ( out ) until the point where the engine just reaches the maximum obtainable rpm and continuing to turn the air screw beyond this point wont increase the engine speed (rpms) any further. I find it’s easier to hear the rpm increasing if you set the idle at its lowest possible position without the engine stalling. You’ll want to repeat this procedure a couple times until you’re confident that you’ve found the right spot and that the result is reproducible. When you’re comfortable count the number of turns ( 360 revolutions ) you’ve backed the air screw out to reach this point. The normal operating range is between 1 and 1.5 turns out so if you find the ideal setting is less that 0.75 turns out consider installing the next richer pilot jet (larger number ). If you find the ideal setting is more than 2 turns out consider installing the next leaner pilot jet ( smaller number ).

Last edited by VAL; 09-24-2013 at 01:06 PM.
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