01 cr250 jetting.........again

[mole1]

hi
i'm trying to get my 01 cr250 to run crisply for off road riding but seem to be having difficulty . i'm currently running fmf jetting ( 400main , 30pilot , stock needle 2nd position , stock slide , air screw 2 turns ) fuel at 32:1 and ride at sea level at 70-80deg f . my problem is that it loads up and burbles on the bottom and spits spooge from the silencer . what can i do to get it to run more crisply and can i run 40:1 safely to eliminate some spooge ? thanks

 

[Buzz Bomb]

There are 2 solutions that seem to make this bike run well. One is having the slide filed down about 1 mm, and the second solution is getting an S-7 nozzle (needle jet is another name for this part, it's the piece that the needle goes into when the slide closes). Both seem to lean the bike out sufficiently. Going to 40:1 won't make you lose the spooge, it might even get worse. Try using a 27.5 pilot or even a 25. You have to rev this bike like any 2 stroke to keep it from loading up. Jetting alone doesn't make it run perfect.

 

[Dirtvet]

What is a s-7 nozzle again? Is it the needle? My 01 250 either spooges/loads up at low rpm trail riding with near-identical jetting (except 390 main and 95 degrees, sea level, high humidity) or runs too lean with the clip in the top position. Can find the happy middle ground. I'm thinking of selling it because of this problem and getting a 4 stroke.

 

[Buzz Bomb]

S-7 nozzle is the piece that the needle goes into. It is also what the main jet screws into. The S-7 nozzle has a smaller opening than the stock S-9. If you are having major spooge problems, you might want to consider filing the slide as well, or having Eric Gorr or a professional like him do it.

 

[dale williams]

I have one of those 01 CR250Rs and it started out just as you describe. I ended up using a 15 pilot jet, S-8 needle jet, 76H1 needle on the second clip and a 410 main. It idles very clean and has very good slow trail response and has a real hit at mid range, I might have to raise the needle one notch or go to a 420 main. I find that my jetting is so different from others that I've concluded that Mikuni does not have very tight tolerance control on their carburetors. Don't worry about what the manual says is as far as you should go to clean it up. Keep going until you get there, it really can be made to run without blubbering, I run mine hours on trails with little opportunity to open it up and it does well. I still have a little spooge running Belray powervalve oil so I'm going to try Maxima synthetic blend. The other thing I do is run an Auto Light 404 spark plug. This plug has a heat range of about an NGK BR6 but I have yet to foul or burn or erode one.

 

[parkerCR]

Does the V-force reed cage help with any of these problems for the '01 CR250? I have an s-7 nozzle and was curious if this mod does anything more to clean up the jetting.

Thanks

 

[premeir]

I have an 01 with all the mentioned problems, I just got a V-Force, and S-7 nozzle so I'll post back at the weekend when I get it back together. I run a 30 pilot, 400 main, and needle two leaner than stock, I forgot the number right now, it's much better than stock I'm just counting down till I can get my new 03!

 

[dale williams]

I put carbon teck light reeds in and I couldn't tell that it did anything for the jetting. It did give it a little better low end response.

 

[Marcad]

I can't see how some of you guys get away with running your 01 CRs that lean on top. I never found it to be rich on top and even went with a bigger main jet.

I tried the different needles, positions and pilots. Curently I'm running a 430 main, S-7 nozzle, stock needle in the 3rd clip, 30 pilot and the air screw somewhere between 1.5 to 1.75 turns. It still will pop on some days on pump gas. It usually have to blow it out when I first start it but it's ok after that. Curious to see what the slide mod will do but I'm about to sell the bike and go back to green. I also installed the V-Force cage. Seemed to effect the mid range hit more than anything else. Felt like it came on a bit sooner. You could feel a difference right away.

 

[premeir]

ParkerCR,

About the V-Force and the 01CR, I'll agree with the other post, it seemed to change the mid hit more than anything. I ran mine on low tension and at the same time went to the S-7 nozzle, I was way lean and on low tension for whatever reason I could not seem to get it straight. Anyway I didn't really notice any difference on high tension, and after all this time I have a bike that runs cleanly on bottom, great mid hit, and revs to the moon. I'd take a little more bottom though, and I now found a problem on pump gas, but I'm sending my cylinder to Eric Gorr for that. Anyway, aside from the reeds I'm running stock slide, 6BEH2-75 needle 3rd clip, 25 pilot, 400 main and S-7 nozzle. I really think the nozzle was the biggest difference

 

[Rumpelstiltskin]

For my 01 Cr250 I cut the slide and tried out every needle and jet combo. Thought it was good till I finally decided to put the S-7 nozzle in. The nozzle is a "must" for those with an 01 CR250, the difference is dramatic. Along with the Boyesen Power valve cover, V-force and about a half mm slide cut I'm running the S7 nozzle, 30 pilot, H2-74 second clip and 420 main. AS 1 1/2- 2 turns out.

 

[James]

Does the 01 and the 02 have the same carb? Also, where are you guys getting these S7 nozzles..dealer or mail order. I have an 02 that is running real rich like your 01s. Mine has a Mikuni and I think they are the same carb.

 

[Buzz Bomb]

It's a Yamaha part from a YZ125. www.powersportspro.com has them in the parts fish section.

 

[Rumpelstiltskin]

I was thinking how incredibly lucky we all are to have this site and to be able to share solutions such as the S-7 nozzle to one another. Who ever would of thought that you'd have to use a YZ125 carb part to make the bike run right.

 

[motometal]

The '02 is a totally different motor, with somewhat different jetting requirements. Folks 'round these parts have been running the s-8 in the '02s and have found that to be ideal. Our dealer now stocks this part.

 

[parkerCR]

Hey everyone,

It sounds like you can lean the 01 CR250 out quite a bit from stock guidelines while still being safe. I am running a 27.5 pilot with S-7 nozzle,
400 main and stock needle and clip position. It sounds like I can go to a 25 pilot. Does the slide cut make much of a difference with the S-7 already in place? Also, do you guys have your V-force set to low tension and was the result better than high tension? My instructions said that reed life would be greatly reduced by setting them to low tension. Maybe this is not true after all. One of the screws on the top of my carb is stripped, does anyone have any ideas on how to loosen it? Sorry for all the questions.
Love to hear your opinions.

Thanks

 

[dale williams]

Parker, if I understand correctly it is the Philips head that is stripped out. To get it out, remove the carb from the bike, of coarse the throttle cable will still be attached, drain the gas from the bowl. Pull all the rubber that you can away from the carb. Using a heat gun or boiling water, warm the top of the carb up until it is difficult to touch but not hotter than 300F. Use an impact driver or a vise grips to remove the screw. Replace it with an allen head screw or a stud and nut. If heat doesn't loosen it try cold. Pack it in ice or even better dry ice. Heat will loosen the bind on the threads cold will relieve the tension on the bolt. This works on the principle that aluminum has about three times the thermal expansion rate that steel does.

 

[parkerCR]

Thanks Dale!

 

[DEANSFASTWAY]

We were using a S7 nozzle and 32 pilot and 420 main WQe also have had problems with the floats not setup correctly. Theyll also run great if you go to the previos years 00 Keihin carb which quite a few of the locals were doing and its not really all that expensive.

 

[parkerCR]

Deansfastway,

I was thinking of getting the 00 keihin for my 01 CR250. Do the other guys you have talked to seem to like the change?

 

[jmart233]

I have an 01 and I had everything changed before I brought it home from the dealer. I can't remember what I have, but it doesn't load up that much at low rpm and runs great mid on up. I just iinstalled the Delta V-Force Reeds and it started running leaner. I had the air screw almost three turns out, but now it runs better at around 2.25 turns out. Great throttle response with the V-Force, it was well worth the money. My bike is mostly set up for dune riding (high reving).

 

[Dan105]

whats a s-4 needle jet equivilant too. How much different is it then a s-7

 

[Dan105]

well im starting off slow on the jetting, tomorrow morning im trying the bike with the clip moved up one position, and a 410 main, and if the 410 is not enough I will put the 400 in and try that. Just want to see how good I can get the jetting before i cut the slide or get the s-7.

 

[Rumpelstiltskin]

You shouldn't have to lean the main jet, it's the pilot, needle and nozzle jet you need to adjust. 410 main would be too lean I think. You could lose the great top end.

 

[FlyGuy20]

The S-4 needle jet (nozzle) is much leaner than the S-7. The 01 CR 250 comes stock with a S-9.