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2001 cr250 jetting help

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Hi guys I have a sick 2001 cr250 that I love and just got broken in and it is at 1.3 hours so this is my first two stroke and I have a couple questions on jetting and carb settings

*My bike smokes quite a bit when warning up does that mean rich jetting?

*I find it hard to set the idle so that I can use the choke for a cold start and let it idle for a bit but when I take the choke off it should idle very low and die in seconds without small blips of the throttle I just don't see how people do it it starts great first kick and let it run with the choke and during warm up the idle starts to raise so I take the choke of and the idle falls and dies I the try and start it with the choke of and it might hicup a bit but it just seems like the idle is just way way low

My jetting is at 420, 32.5 and 3rd clip

S7 NOZZLE

Mix is 32:1

Boyseen Reeds

Temperature is around 75

Sea level 611 feet above

Thanks guys just needin a bit of two stroke help

Thanks Ben

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Oh and today I took her out and I noticed a couple things

After warm up thier is barely any smoke coming from the exhaust

When the bike is warm and idle is set to normal (low 1200 rpm) the bike peak air screw us out around 4 turns

That could me I'm lean on my pilot right?

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There are many people that have your bike and replace the TMX with a PWK to get away from the very issues you describe. I would highly recommend you look into doing the PWK swap.

 

With that said, if you still want to keep the TMX contact Shrubitup on this web site as it appears to me that he is very knowledgeable on that carb and can probably give you some guidance on your jetting.

 

If you were running a PWK I could give you a great base-line to start at.

 

I think if your air screw is 4 turns out, it means that you are actually RICH on the pilot jet and you are trying to add more air to lean it out. You add air when you back the air screw out. You may try dropping down on the pilot at least one more size and then re-adjust your air screw to see how many turns it is out then.

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There are many people that have your bike and replace the TMX with a PWK to get away from the very issues you describe. I would highly recommend you look into doing the PWK swap.

 

With that said, if you still want to keep the TMX contact Shrubitup on this web site as it appears to me that he is very knowledgeable on that carb and can probably give you some guidance on your jetting.

 

If you were running a PWK I could give you a great base-line to start at.

 

I think if your air screw is 4 turns out, it means that you are actually RICH on the pilot jet and you are trying to add more air to lean it out. You add air when you back the air screw out. You may try dropping down on the pilot at least one more size and then re-adjust your air screw to see how many turns it is out then.

 

Thank you vey much for replying I think i might go to a PWK the only thing is i didnt really want to put anymore money into this bike :p and i belive your right sorry i forgot that it controlled the air not the fuel sweet hey do you have a estimate on how much a used PWK would cost ? 

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I got a used PWK off a 2000 Honda CR250 for $125. I then threw a rebuild kit into it ($29) and it has been running better than I could have ever expected..

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I got a used PWK off a 2000 Honda CR250 for $125. I then threw a rebuild kit into it ($29) and it has been running better than I could have ever expected..

sweet i think i might go that way soon but for now do you think i should change to a 30 pilot jet? from 32.5 and do you htink i should go down in main? 

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Leave your main alone for now, just drop down to a 30 pilot and then set the air screw, then check to see that you are between 2-3 turns out on the air screw. Don't risk running your bike too lean and seizing the motor, if in doubt, crank the air screw in to richen it up.

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Man guys i just got my bike back together (I was in Vegas last weekend for the Supercross finals so i didnt have time to work on the bike) anyway I started it up let it warm up to operating temperature and then rode around in first slowly to make sure it was warm after that i started to open her up and it would be good till about 3/5 throttle then it would jsut let off no power this would happen in first right when you would begin to ring out the power band. Now I tried to shift right when the bog would start into second and nothin it would just leave all power. all i did was move the pilot from 32.5 to 30 could it be temperature? Something? please help im really frustrated thanks guys

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I'm not an expert here, but I did fool around with the TMX a little before going to a PWK. What you're describing sounds like a lean bog, but I know I experienced some real blubbery problems due to being overly rich. I know it can be hard to tell if you don't have more experience like some of the guys here. If I had to guess, the way you describe your rich pilot circuit, high idle adjustment and slow warm up procedure, I think you're loading the bike up and aren't getting it fully cleaned out. I say that because I had done the exact same thing last summer and thought something was wrong with my bike/jetting. You've leaned out the pilot, now adjust the air screw and idle accordingly, drop the main at least one size (only because I can assure you it's fat) and don't warm it up so lightly. Jeff Slaven says in one of his videos that he basically warms his bikes up by riding them around, starting lightly then progressing with throttle application. Idling the bike on warm up just loads it up, which is what I think you're dealing with. Just my opinion from similar experience.

Edited by JDubya381

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Try letting it warm up a little longer before you ride it, or hammer on it. You should be feeling the top of your radiators and when they get to the point that they are almost too hot to touch, then you are warmed up.

 

Most any 2 stroke will do what you are describing if you have not let it warm up adequately before you hammer on it.  If you dropped to the 30 pilot, you may want to try screwing the air screw all the way in lightly seating it. Then turn it out 1.75 turns. Now start it up, let it idle until radiators are warm/hot to the touch, then lightly ride it for the first 5 minutes and DO NOT HAMMER ON IT during that first 5 minutes. After the 5 minutes you can give it a little more throttle.

 

Reply back and tell us how it runs.

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Try letting it warm up a little longer before you ride it, or hammer on it. You should be feeling the top of your radiators and when they get to the point that they are almost too hot to touch, then you are warmed up.

 

Most any 2 stroke will do what you are describing if you have not let it warm up adequately before you hammer on it.  If you dropped to the 30 pilot, you may want to try screwing the air screw all the way in lightly seating it. Then turn it out 1.75 turns. Now start it up, let it idle until radiators are warm/hot to the touch, then lightly ride it for the first 5 minutes and DO NOT HAMMER ON IT during that first 5 minutes. After the 5 minutes you can give it a little more throttle.

 

Reply back and tell us how it runs.

Thanks for the quick reply it is pouring out today so i will wait to try her out till tomorrow that makes good sense man i hope it works I did touch the radiators (i have heard about that before) and they were hot enough that you could only hold your hand thier for a half second or so I did mess with the air screw a bit and ussing the tach on my hour meter i saw that the peak rpm would be when the air scew is screwed in around 1 turn 

 

I will keep you guys posted thank you for the help 

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After warming it up just ride it. If the radiators and cylinder/head are hot to the touch it is ready for whatever you can do. I also think you are not getting it "cleaned out" after idling so long. Ride the dadgum thing!

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After warming it up just ride it. If the radiators and cylinder/head are hot to the touch it is ready for whatever you can do. I also think you are not getting it "cleaned out" after idling so long. Ride the dadgum thing!

That's what I was getting it, I was doing that last year. I wasn't cleaning it out because I was trying to baby it. Nope.

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Oh and today I took her out and I noticed a couple things

After warm up thier is barely any smoke coming from the exhaust

When the bike is warm and idle is set to normal (low 1200 rpm) the bike peak air screw us out around 4 turns

That could me I'm lean on my pilot right?

Have a TMX Mikuni on my 01'. The most i turn the air screw out is 2 turns. I keep my air screw around 1.5 to 1.75 turns out.

My jetting is 32.5 pilot, s-8 needle jet, 410 main, stock needle on 2nd position.

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Well guys I tried to clear it out it out worked better but didn't fox it during acceleration it would seem to get better but when I would truth around (going up and down a straight) it would bog I found that what I ran the head out of the carb the bike ran a lot better at the very last bit of fuel the idle went up it seemed alot more responsive also it seems to be smoking a lot and even going through the gears on a straight I couldn't get the bike hot I could leave my hand on the radiator for seconds no problem

Thanks for the help guys

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Gentlemen, what we have here is a failure to communicate!!! :thinking:

Ha sorry man i wrote that early after havein fun at my birthday :p what im trying to say is it cleared up a bit but i couldnt get the bike hot thier was a lot of smoke comming out of the pipe and when I was draining the carb and it was almost out of gas the bike started to run great the rpm went way up like i had the idle set way to high and the throttle felt a lot more responsive 

 

also when going up and down a straight just trying to figure this bike up the bike would bog when i was turing at the end of the straight then after a couple seconds it seemed to clear up and run down the straight OK 

 

sorry about that last post thanks guys 

Edited by Benfro89

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Jetting and 2strokes can be frustrating at times. In this case I strongly suggest enlisting an experienced 2stroke rider to help. No sense causing some damage while you are learning. I think you are very close but just need a little help. Good luck. 

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Jetting and 2strokes can be frustrating at times. In this case I strongly suggest enlisting an experienced 2stroke rider to help. No sense causing some damage while you are learning. I think you are very close but just need a little help. Good luck. 

Thank you for the help you did give :)

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