01 CR250 cutting throttle slide

[VAL]

Originally Posted by junteschan1

VAL,
25 on the pilot.....scary for me...but you say she runs good....I just have to try this...spark plug tip color...chocolate brown/tan I hope...
Thanks to you too. If it were not for you & YZshallme, I have no way of finding out these results from actual tests on the same bike.Appreciate it

The plug is coffee brown on the electrode after running down the river at full throttle for about 30 seconds in fifth, hit clutch and kill switch at the same time. Pull plug.

[YZhallsme]

Finally got a little riding in, here's the update:
Trail stuff @ 8,000', 80*and dry.
JD Blue#2,380main,25pilot,S4 nozzle,air screw 2 3/4 - 3 1/4 out.
This wasn't what I'd hoped for, stutters from closed to 1/4 throttle, then it just rips, but may be too much? Son says it smokes, also notice alot more spooge with this set up. Stock tank runs out of gas at 55 miles.

Next day same trails, elev. and temps.
Back to JD red#3,reduce main to 370,25pilot,S4 nozzle,air screw 2 1/4 - 2 3/4 out.
This is better, still some stutter but clears up a little earlier @ 1/8 throttle, runs great from there. Still spooges but is much less. Don't have a mileage test with this set up yet, a previuos test with red#3 and a richer main and pilot produced 61 miles. I'm assuming this will go a tad further.

A few laps at a local track, @ 5,500', +80* and dry.
Seems to run about the same at this lower elevation, possibly a little less stutter?? I did pull the plug today, it's dry and looks to be brownish/tan in color. I still feel it's a little rich off idle (stutter). I now have a 22.5 pilot and a small washer that might work to shim the red needle a half clip. I'm inclined to try the pilot first! What do you guys think, pilot, shim or ??

[VAL]

Some times you can balance the lower end of the spectrum with the Air Screw and the throttle slide stop. Find a lean idle and then screw in or out on the throttle slide adjuster until you reach the desired idle. Mine has been running great since the JD kit.

[junteschan1]

Originally Posted by VAL

Some times you can balance the lower end of the spectrum with the Air Screw and the throttle slide stop. Find a lean idle and then screw in or out on the throttle slide adjuster until you reach the desired idle. Mine has been running great since the JD kit.

VAL & YZhallsme,
Just installed the s-4 nozzle & I immediately noticed exhaust note just sounded crisper & mean.......will test drive when free and give further feedback.
Again, thanks for your kind notes....

[YZhallsme]

Originally Posted by junteschan1

VAL & YZhallsme,
Just installed the s-4 nozzle & I immediately noticed exhaust note just sounded crisper & mean.......will test drive when free and give further feedback.
Again, thanks for your kind notes....

junteschan- Please do, I'm interested in hearing your results. Once I find the best set up with this JD stuff, I may try some different needle/nozzle combo's.

Val- Thanks for your advice, I have seen improvements with air and idle screw adjustments in the past.

[junteschan1]

Originally Posted by YZhallsme

junteschan- Please do, I'm interested in hearing your results. Once I find the best set up with this JD stuff, I may try some different needle/nozzle combo's.

Val- Thanks for your advice, I have seen improvements with air and idle screw adjustments in the past.

YZhallsme & VAL,
As I mentioned earlier, just installed the S-4 nozzle and what a difference.
Didn't feel this engine scream with such a much better response & less exhaust oil mess. Didn't ride long enough though as I still needed to complete some chores. My last spark plug read a month or so was a wet, dark chocolate brownish and this time was getting wet,light chocolate brownish...looks like the right direction so I may need to tinker w air screw a bit more as you mentioned.
My main jet was a 400;pilot 30; needle on 3rd;a/s at 2/1/2; 32 : 1 ratio;
91 octane -mobil 1 synthetic mix; temp was about 82-85F. Jet Needle was Honda OE 6BEH173.....for the record...thanks again.

[YZhallsme]

Update - Installed the 22.5 pilot, adjusted airscrew for best/fastest idle @ 1 3/4 out. Went for short ride of 26 miles. Still has a tad bit of stutter up to 1/8 throttle. Airscrew adjustments in 1/8 turn increments up to 2 1/8 out did nothing to help with stutter and seemed to produce less power. Airscrew adjustments inward down to 1 1/4 brought back the power but still sputters. One thing to note, during all this I discovered that the engine rpm increases slightly when the bike is taken off the side stand and stood straight up? Also during the ride I stopped to help a friend with a flat, leaned the bike against a tree, after the flat repair I find fuel running out the overflow, this wasn't that much of a lean either!!! Back at home I can't get fuel to run out of the overflow untill it's leaned over @ 45* (that seems normal). I'm pulling the carb today to check the float height and needle/seat. I'm certain I set the float originally to 15mm as per the manual but will check. If it checks out I'm considering lowering the level slightly. What do you guys think? Have you tried different float levels?

[VAL]

If the float height is correct and the floats actually float,(Check and see if they are cracked and actually float in gasoline) the only other thing it could be is something not allowing your float valve to seat. Either some contaminant in the fuel or a bad valve or seat. Do you have a filter in the fuel line?

[YZhallsme]

Originally Posted by VAL

If the float height is correct and the floats actually float,(Check and see if they are cracked and actually float in gasoline) the only other thing it could be is something not allowing your float valve to seat. Either some contaminant in the fuel or a bad valve or seat. Do you have a filter in the fuel line?

VAL- No inline filter, the float was at 15mm, I didn't see any sign of debris anywhere in the carb. The needle and seat were installed new about the time this thread started, I checked both and they look good, didn't see anything wrong with the floats either, they float in water anyhow? I lowered the level 1mm but it's not all back together yet. Now I'm wondering if it's possible for fuel to flow around the outside of the seat, past the o-ring? Maybe I damaged the new o-ring during the seat install???

[VAL]

Originally Posted by YZhallsme

VAL- No inline filter, the float was at 15mm, I didn't see any sign of debris anywhere in the carb. The needle and seat were installed new about the time this thread started, I checked both and they look good, didn't see anything wrong with the floats either, they float in water anyhow? I lowered the level 1mm but it's not all back together yet. Now I'm wondering if it's possible for fuel to flow around the outside of the seat, past the o-ring? Maybe I damaged the new o-ring during the seat install???

I don't know too many float valves that can hold the fuel back for long periods of inactivity, that's why its always practiced to turn off the fuel when you shut down the bike. As far as the change in idle speed, that is probably because of the angle the floats are at when listing to one side when on the side stand. I bet it goes back down after a few seconds once the floats get equalized. Mine does the same thing. A fuel filter is a great investment, especially if you aren't running your fuel through any other filters when filling the bike. I just emptied a 5 gallon jug that had my fuel supply for the last season, you know, straight from the pump, and man was it full of junk. Not dirt but things that looked like very small globs of semi solidified plastic. I am changing my fuel filter soon.

[YZhallsme]

VAL- A filter is good insurance, used them in the past, heck I bet I'd find a new one in the parts box if I bothered to look. The o-ring was fine so I decided to go 1mm lower with the fuel level just to see what happens. In regards to nirvana, I feel I'm running out of options here, I'll try the clip shim next but after that the only thing left might be to come full circle with this thread and cut the slide!!!

[chud]

Sorry to butt in guys, but I found your info. very helpful. I have an 04CR125 w/ JD kit. So far I have only tried the blue needle on the 2nd. The midrange power is phenomenal, revs strong from 1/4-wot, but my bike has a lean buwahh bog at 0-1/4. Hopefully I can fix the bog w/ air screw adjustments.

Thanks again, your dialogue will help me further fine tune my tmx.

[VAL]

Originally Posted by YZhallsme

VAL- A filter is good insurance, used them in the past, heck I bet I'd find a new one in the parts box if I bothered to look. The o-ring was fine so I decided to go 1mm lower with the fuel level just to see what happens. In regards to nirvana, I feel I'm running out of options here, I'll try the clip shim next but after that the only thing left might be to come full circle with this thread and cut the slide!!!

Man you are so close. Dont mess with the needle if shes running good mid to top end. You should be able to balance between the pilot, air screw and idle screw. Also remember that these are two strokes, not known for their stellar bottom end. I was able to get a little more grunt with an 11oz flywheel weight. It smoothed out the choppy off idle response.

[VAL]

Originally Posted by chud

Sorry to butt in guys, but I found your info. very helpful. I have an 04CR125 w/ JD kit. So far I have only tried the blue needle on the 2nd. The midrange power is phenomenal, revs strong from 1/4-wot, but my bike has a lean buwahh bog at 0-1/4. Hopefully I can fix the bog w/ air screw adjustments.

Thanks again, your dialogue will help me further fine tune my tmx.

If she is lean at the bottom, you should be getting surgy power, if she buwahh, sounds like shes a little rich. Also 125s are never going to have a tractor bottom end. Just not their nature.
With the bike in nuetral, slowly roll the throttle from idle to 1/4. See if it surges or you get your buwahh. Surge = lean buwahh= rich

[chud]

Thanks, I'll try that.

[jcorbat]

I had been riding a tuned '95 CR250R with an older Mikuni and getting 50+ miles on the 2 gal tank. Then I picked up a basically stock '01 CR250R and never gave it a thought. I went out for a ride on a 35 mile loop and ran out after 25 miles. I was hella pissed off! I've never run out of gas...ever! I had to walk at least 4 miles before coming up on a guy on a quad. I found out that riding boots are not made for walking! Massive bloody blisters on both heels are no fun!

Based on this thread I picked up the JD Kit. Totally amazing! James is a great guy and answered all my questions quickly. I was hesitant at first but the $75 price tag was worth it.

Stock = OEM Needle 2nd-pos, 420 main, 30 pilot, s9 nozzle, airscrew 1-1/2
elev=770ft, temp=75° F
JD = red 3rd-pos, 380 main, 30 pilot, s4 nozzle, airscrew 1-1/2 out
elev=850ft, temp=45~50° F

I went from 12.5 mpg on the first trip and improved to 25 mpg on the second trip. I have to add that the filter was dirty on the first trip but the JD kit was the trick. It is shocking that Honda would use a 420 main when I can smoothly run a 380 in fairly cold weather.

I used my stock 30 pilot because I didn't have anything smaller. At 45~50° F, the 30 pilot worked fine. Maybe if it was 85° F outside, I would have to step to a 27.5 pilot. The JD kit came with a 32.5 pilot and I'm not quite sure why.

[VAL]

Originally Posted by jcorbat

It is shocking that Honda would use a 420 main.

I would think that Honda would want to make sure that as long as you mix the fuel at the prescribed 32:1 there would be no way of the engine seizing. Even if you were fouling plugs every 50 feet. This way, once you start messing with the jets, the blame becomes yours if the engine is damaged.

[YZhallsme]

chud, As far as I'm concerned your not butting in at all, actually I'm glad to see and hear that other's are interested!

Originally Posted by VAL

If she is lean at the bottom, you should be getting surgy power, if she buwahh, sounds like shes a little rich. With the bike in nuetral, slowly roll the throttle from idle to 1/4. See if it surges or you get your buwahh. Surge = lean buwahh= rich

VAL, I'm not sure about this but I might have to respectfully disagree with you on that? It's just my opinion but from my experience so far, a bog or that buwahh sound has been an indication of being lean, while the sputter has been an indication of a rich condition. However I do understand that things can get confusing due to the different terminology we all use to describe our jetting issues. I guess my question then is does surge equate to sputter, and bog to buwahh or am I all messed up here?

[YZhallsme]

Originally Posted by jcorbat

I had been riding a tuned '95 CR250R with an older Mikuni and getting 50+ miles on the 2 gal tank. Then I picked up a basically stock '01 CR250R and never gave it a thought. I went out for a ride on a 35 mile loop and ran out after 25 miles. I was hella pissed off! I've never run out of gas...ever! I had to walk at least 4 miles before coming up on a guy on a quad. I found out that riding boots are not made for walking! Massive bloody blisters on both heels are no fun!

Based on this thread I picked up the JD Kit. Totally amazing! James is a great guy and answered all my questions quickly. I was hesitant at first but the $75 price tag was worth it.

Stock = OEM Needle 2nd-pos, 420 main, 30 pilot, s9 nozzle, airscrew 1-1/2
elev=770ft, temp=75° F
JD = red 3rd-pos, 380 main, 30 pilot, s4 nozzle, airscrew 1-1/2 out
elev=850ft, temp=45~50° F

I went from 12.5 mpg on the first trip and improved to 25 mpg on the second trip. I have to add that the filter was dirty on the first trip but the JD kit was the trick. It is shocking that Honda would use a 420 main when I can smoothly run a 380 in fairly cold weather.

I used my stock 30 pilot because I didn't have anything smaller. At 45~50° F, the 30 pilot worked fine. Maybe if it was 85° F outside, I would have to step to a 27.5 pilot. The JD kit came with a 32.5 pilot and I'm not quite sure why.

I agree with what your saying and also with VAL's assesment that the factory jetting in most cases is rich to some degree. Certainly the altitude around here requires I go leaner than the factory settings for sea level, but I've allways ended up leaner than the manuals recommendations for my altitudes. Fuel mileage is important to me also as I don't care for the larger tanks. I tune for engine performance first and formost but do keep a close eye on mileage, and as you, I've seen some huge increases in mileage from jetting. The best mileage I've seen so far though was with the stock needle in clip 1, 380 main, 30 pilot, 68 miles on the 2 gallon tank. The best I've seen so far with the JD needles has been 62.

[VAL]

Originally Posted by YZhallsme

chud, As far as I'm concerned your not butting in at all, actually I'm glad to see and hear that other's are interested!



VAL, I'm not sure about this but I might have to respectfully disagree with you on that? It's just my opinion but from my experience so far, a bog or that buwahh sound has been an indication of being lean, while the sputter has been an indication of a rich condition. However I do understand that things can get confusing due to the different terminology we all use to describe our jetting issues. I guess my question then is does surge equate to sputter, and bog to buwahh or am I all messed up here?

I have been fortunate enough to have a testing ground where you can hold your throttle position for about as long as you want. If you have a spot , mid range on the throttle, that is lean, the bike will go wa wa wa wa wa wa if you hold it there, if it is rich and I mean rich it will go boooooooooooooh.