01 cr250 JD jetting

Hey guys,

 I have a low hour 01 cr250 that I just picked up (less then 30 hours on bike) and everything original. Only thing changed so far is a set of protapers and a pro circuit spark arrestor. It has the stock jetting (420 main) (35 pilot). I just purchased the jd kit ( I have done alot of jetting and just figured this would save time since I have enough work already lol)

 

But I am curious between this and just saying to heck with it and going with the airstriker carb instead. Jd said if the jetting did not work out that I could send it back and go to the airstriker. What are your guys thoughts about the TMX with the jet kit? was there a marked improvement?  The bike starts and runs great and idles nice but loads up often. I am looking to gain some crispness and to not have to be wrapping it out all the time just to keep it cleaned up.

 

Also going to be adding reeds and a pipe soon also.

 

 

My experience with the jd kit was with an 06 250 but it shouldn't be much different for yours. Between having your jetting completely dialed in coupled with their needles the bike ran fantastic. I think their needles work very well. The problem I had was that the mikuni carb was so sensitive to temp, humidity, and altitude changes that keeping everything dialed in was a bit of a chore. I don't have a problem swapping jets every weekend before going riding, but the irritating part was having to do it throughout the day on the ride. That is why I switched the pwk and it is nice knowing I can just fire the bike up and go for a ride pretty much all summer long and just do a basic airscrew adjustment that day. I will say that with the jd needle and the mikuni carb spot on I think the bike had more power than with the pwk, but it was a bit of a hassle. The more I learn about jetting and the more I mess with the carb is kind of a two way street. If I didn't know how great the bike could run and get addicted to that then I may not really ever notice the difference if that makes sense.

Makes perfect sense to me. I dont mind jetting for different seasons but I dont know about during a ride. My riding will be more during the fall and spring, summers are usually so busy that theres not alot of time to get on the bike.

 

Did you find that the recommended jetting from jd was pretty spot on?

 

Im figuring it will be for me since I live pretty much 2 hours away from jd and at sea level

Edited by izcain

The jd kit was already installed on the bike when I bought it so I never saw their recommendations. If you know how to jet a bike and are picky about it then the pwk carb will probably be something you will want to consider. I may have exaggerated swapping a bunch of brass every ride, but I have had to change needle clips and pilot jets on a few occasions with the mikuni if it was cold in the morning and then got hot in the afternoon. Now my buddy would probably never notice the difference or really care about it, but like I said once you see how good it can be then you get used to that.

Ok so after the usps losing the first jet kit I called and they sent out another right away (JD Customer service is TOP NOTCH!) I installed the 32.5 pilot and 400 main jet as per JD instructions and started with their "White" needle in the middle clip position. It got to late to do anything tonight but hopefully tomorrow I will get the bike out and fire it up and see how it does.

 

If their needles are anything like their customer service I am sure I will be happy with the purchase.

 

Curt: what elevation were you and what needle were you running? Just curious.

 

Thanks for the input so far.

 

Just thought I would give an update that with the starting points above I went for a short ride today and it was awesome. The bike has a ton of snap and clean all around. Well worth the money to me at least.

 

Could be though that it has something to do with the bike only having less then 30 hours on it from new. Since when I called JD up the first question he asked is how much time does the carb have on it.

Edited by izcain

The '01 was really rich off idle from the factory. Once its sorted out you won't have to fiddle much with the jetting. I wound up changing the needle and nozzle on the '01 to get it leaned out enough, and yeh - the motor rocks once the carb is straightened out. Since JD cuts custom needles, I'm sure he's accomplishing the same thing with just the needle. The '01 is one sweet motor. Once I got the jetting dialed, I switched mix ratios in the winter instead of messing with jets. I jetted for 32:1 in the summer and ran 40:1 in the winter, had the effect of enriching all the circuits without me having to do any jetting.

Im just wondering how much changing will have to be done once I put on a better pipe and some vforce reeds.

Those are minor mods, and probably won't require much. Are you running pump gas ?

No running vp 110. I do alot of drag racing so I always have that on hand. :cool:  Also the fuel in my area is not the greatest so I just run that. I know its not really doing anything for extra power though. Im not one of those guys that think they are picking up a ton of power from it lol.

Edited by izcain

Once your jetted , I doubt you'll have to change a thing.

I run race gas in all my bikes, just because its one less tuning variable. Everyone thinks I'm nuts, but my bikes always run right !

Edited by oldfrt613

Yea it seems to keep that part constant. The good smell is just a nice by-product lol

I got a air striker that is awesomeee from them but not sure how to jet their carb for winter. Mine has the blue needle installed 3rd clip im at 500ft above sea level. I got a fmf gnarly with a fmf turbine core 2 I believe

I got a air striker that is awesomeee from them but not sure how to jet their carb for winter. Mine has the blue needle installed 3rd clip im at 500ft above sea level. I got a fmf gnarly with a fmf turbine core 2 I believe

 

Depending on how much colder than your normal conditions, I would just drop the clip to #4, if it is really cold, also raise your main jet one step richer.

People seem to get really different results with the JD on the 01. I installed mine as directed and I was instantly rewarded with about the best running smoker I have ever owned. I could putt around with my son on his xr 50, and race hare scrambles with nothing more than a little tinkering with the fuel screw. Others report no improvement with the JD, and end up swapping carbs.

People seem to get really different results with the JD on the 01. I installed mine as directed and I was instantly rewarded with about the best running smoker I have ever owned. I could putt around with my son on his xr 50, and race hare scrambles with nothing more than a little tinkering with the fuel screw. Others report no improvement with the JD, and end up swapping carbs.

Setting mine up like as directed made it WAYYYY better but after tinkering with it a little bit it is even better still.

 

I was going to swap carbs but now I think I will just put the money in other areas now. I do know that one of the first questions the people at jd asked was how much time does the tmx carb have on it. If it is a well worn carb then people tend to have much more mixed reviews then if it is a carb with lower hours on it.

I jetted for 32:1 in the summer and ran 40:1 in the winter, had the effect of enriching all the circuits without me having to do any jetting.

This would be the opposite of how it works.

This would be the opposite of how it works.

 

No, he is exactly right.  40:1 in the winter is more fuel in the combustion, 32:1 is less fuel in the combustion chamber.

And you are wrong as well.

Adding oil richens the fuel/oil mixture, but reduces the amount of gasoline mixing with air. 

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