I dont know guys? I put the clip one postion up and changed the main to a 410 and it was really good. The plug looked great too. It was about 55 deg out today. Warmup was not bad seemed like it wanted to load up a little. I rode single track with some open sections. I was pretty surprised at how the main and clip cleaned the power delivery up. Im glad i didnt put the 400 in that would have been too lean. Now my questioin is I am at sea level which most of you are too. How come I changed the main and a clip and I seem good? Whats up with that. I perpusly tryed to let the bike loadup out on the trail today but it didnt. I knew it felt good and i was just surprised, thought i was going to have to put the 420 in. Rumple how come you say i wouldnt have to change the main, I thought changing the pilot was just for starting and low end. I do agree a different pilot will prob help some more in setup. What does the needle and nozzle do when you change it exactly. Im pretty carborator stupid but i can tell what a bike is doing and when the jetting isnt right.
01 cr250 jetting.........again
- Thread starter mole1
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Rumpelstiltskin
Member
- Mar 29, 2001
- 84
- 0
Of course you'll need to adjust the main jet for your conditions. Its just that the rich problem area for this bike was at around 1/4 throttle. Some would lean the main jet with the aim of cleaning up the 1/4 throttle bog spot when it's the pilot, needle and nozzel jet that needs to be adjusted.
When I broke the bike in on the first ride, my impression of the jetting was that it was the midrange that had the bog spot. I was surprised at this. Rumpel, so what do you think? Bottom end is lacking i guess but the mid and top seem good although it was slippery so i was riding her a gear tall and when i did open it up, i wasnt wide open or anything. But overall the motor seemed like it was running pretty good. I just spent a year on a ktm rfs so im new again to 2 stroke power. This is a dumb question but can i obtain the same clean jetting as someone else in my area through a different combo setup. My friend who rides A250 with me has a 01 also and he is currently running- 30 pilot,420 main,s-4 nj, air screw 1.5out, with some type of kawi part 16017-1427 ( i think this is the needle hes running) clip is in 3rd position. Soooo how does his setup compare to mine as far as on paper looking at the specs. thank guys hope you can help me
Rumpelstiltskin
Member
- Mar 29, 2001
- 84
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Can you have the same clean response as someone else with a different combo, I don't see why not. Variations abound between everyone but the general consenses is the 30 pilot and S-7 nozzle. Getting these will be your best starting point then you can fine tune the needle and main settings from there to whatever works and feels best for you. Personally I feel the stock needle and main setting is pretty much on the money once you the pilot and nozzle jet is changed so you shouldn't have to stray far for those.
- Thread starter
- #31
okay , from your response it looks like i should try a s-7 nozzle , does anyone know the correct yamaha part # ? i checked partsfish under yz125 but can't seem to locate the part . also , should i be able to use this nozzle with my current fmf jetting specs or should i increase the main and change the needle clip setting ? and should the s-7 help stop the engine from loading up on trailing throttle situations like down hills . thanks for the help.
Hey Mole, the Yamaha part # for the S-7 nozzle is 3TC14141-S7-00. The S-7 nozzle is from a 1998 YZ 125. Yes, you will be able to use this nozzle with your FMF jetting specs. and it should help your bike from loading up when in low throttle situations.
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Rumpelstiltskin
Member
- Mar 29, 2001
- 84
- 0
The S-7 nozzle I believe was from a '99 YZ 125.....I think. What the part number is I couldn't tell you but you should be able to have one ordered from any authorized Yamaha dealer. Along with the 30 pilot and S-7 if your around sea level and the temp is around 60 try the H2-74 second clip and the 430 main. I'll use the 420 in warmer temps. After fiddling forever this worked to be the best for me. Ultimately you'll have to figure out what works best for you but you can at least try this or the other settings on this forum and hopefully it will get you close to being happy.
:yeehaw:
I just finished jetting my 01 CR250 today, and let me tell you, this bike rips!!!!!!! I have a hard time keeping the front wheel on the ground!!!!!! Throttle response is very crisp now. I live on the East coast at sea level and I run 93 octane with Honda HP2 premixed at 32:1.
It was about 50 degrees outside today.
These are the jetting specs that I run:
420 main
30 pilot
air screw 1.5 turns out
S-7 nozzle (needle jet)
stock slide (throttle valve)
6BEH2-75 needle, 2nd position from the top
I did a plug test, and the insulator was mostly light brown in color. There was some black areas also, but it was not oily by any means. The first 3 threads of the plug were black also, so I don't think I went too lean. There was a little spooge coming out of the silencer, but not even enough to drip onto the swingarm or rear brake caliper.
I do think I'll have to go 1 size larger on the main, and adjust the clip position when it gets colder outside.
My bike is stock except for a FMF Power Core 2 silencer.
For me, the new needle and nozzle made a dramatic difference, but ultimately you have to find out what works best for you.
I just finished jetting my 01 CR250 today, and let me tell you, this bike rips!!!!!!! I have a hard time keeping the front wheel on the ground!!!!!! Throttle response is very crisp now. I live on the East coast at sea level and I run 93 octane with Honda HP2 premixed at 32:1.
It was about 50 degrees outside today.
These are the jetting specs that I run:
420 main
30 pilot
air screw 1.5 turns out
S-7 nozzle (needle jet)
stock slide (throttle valve)
6BEH2-75 needle, 2nd position from the top
I did a plug test, and the insulator was mostly light brown in color. There was some black areas also, but it was not oily by any means. The first 3 threads of the plug were black also, so I don't think I went too lean. There was a little spooge coming out of the silencer, but not even enough to drip onto the swingarm or rear brake caliper.
I do think I'll have to go 1 size larger on the main, and adjust the clip position when it gets colder outside.
My bike is stock except for a FMF Power Core 2 silencer.
For me, the new needle and nozzle made a dramatic difference, but ultimately you have to find out what works best for you.
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I do not recommend using a leaner needle than stock when using the S-7 nozzle. I
ran the same jetting spec's as FlyGuy all summer and during my last top end job it
was obvious the motor had been running too lean. I'm not sure which protion of the
jetting curve was too lean, but I suspect there was a small area between 1/2 and 3/4
throttle that was too lean and I have a few deep scratches in my cylinder wall to prove
it. I've rejetted the bike to:
430 main
30 pilot
S-7 Nozzle
H1 - 73 Needle, Middle position
I'm now willing to accept a little spooge. Simple Green is cheaper than a new
cylinder.
ran the same jetting spec's as FlyGuy all summer and during my last top end job it
was obvious the motor had been running too lean. I'm not sure which protion of the
jetting curve was too lean, but I suspect there was a small area between 1/2 and 3/4
throttle that was too lean and I have a few deep scratches in my cylinder wall to prove
it. I've rejetted the bike to:
430 main
30 pilot
S-7 Nozzle
H1 - 73 Needle, Middle position
I'm now willing to accept a little spooge. Simple Green is cheaper than a new
cylinder.
Rumpelstiltskin
Member
- Mar 29, 2001
- 84
- 0
I know when I went leaner on the needle and clip that it definatly caused the main to become leaner also. In back to back comparisons I could definately feel a power loss at 3/4-WO throttle. Going to the H2-74 and running the main a little richer felt alot better for me. It's ok to have some spooge.
dale williams
Member
- Feb 3, 2000
- 69
- 0
I think these carbs are not machined to exacting tolerances and thus everyone will work best with slightly different jetting combinations. On my 01 I'm running a 410 main (the 420 is doggish), an S-8 needle jet, an H1-76 needle in the second clip and a 15 pilot. The bike rips, has a slight mid range hit, and doesn't load up at slow trail speeds. It still produces some spooge, but if I understand oil and 2 strokes only 2% of the oil burns, the rest goes out as oil vapor and oil liquid. The oil liquid ends up in the expansion chamber, the silencer packing and drool on the back end. I'm at sea level to 3000 feet at about 50 degrees F.
steve talley
Sponsoring Member
- Oct 17, 2002
- 94
- 0
Anyone know jet settings on a 99 rm125. running rich with spooge from silencer likes to load up any info would be great !!!
dale williams
Member
- Feb 3, 2000
- 69
- 0
I started with the stock and kept getting smaller until the airscrew had an affect. The 17.5 peeked at about 2.5 turns out and the 15 peeked at about 2 turns out. At altitude I crank the aircrew in .5 turns. Changing to smaller needle jets or larger needle base diameter had no effect on the airscrew. The bike will now idle clean without loading up.
I'm suspicious that there are machining variations from carb to carb so you will have to experiment to find the best combination, but don't be afraid to go small on the pilot jet. Keep going smaller until the airscrew actually has an effect and then one more to place the airscrew in the 1.5 to 2-turn range. A properly jetted low speed circuit will allow the engine to idle at a lower speed and still have good throttle response, so the bike is easier to ride in tight woods.
I'm suspicious that there are machining variations from carb to carb so you will have to experiment to find the best combination, but don't be afraid to go small on the pilot jet. Keep going smaller until the airscrew actually has an effect and then one more to place the airscrew in the 1.5 to 2-turn range. A properly jetted low speed circuit will allow the engine to idle at a lower speed and still have good throttle response, so the bike is easier to ride in tight woods.
Guys explain the S-7 Nozzle
So, I can run this this S-7 with my carb the way it is?
So those that have run the S-7 do you still have the stock jetting and only the S-7 as the mod?
Sorry, all these jetting opinions are getting a tad confusing.
My 01 seems to run ok but it is a tad blubbery and by looking at the plug it is a tad rich but, rather be rich then lean.
I have a 430 MJ not sure about needle or pilot.
It only gets blubbery on hard acceleration which would mean obviously its probably a tad rich on top.
So, this S-7 will help that?
Thanks :cool:
So, I can run this this S-7 with my carb the way it is?
So those that have run the S-7 do you still have the stock jetting and only the S-7 as the mod?
Sorry, all these jetting opinions are getting a tad confusing.
My 01 seems to run ok but it is a tad blubbery and by looking at the plug it is a tad rich but, rather be rich then lean.
I have a 430 MJ not sure about needle or pilot.
It only gets blubbery on hard acceleration which would mean obviously its probably a tad rich on top.
So, this S-7 will help that?
Thanks :cool:
The s-7 nozzle is the ticket, we jetted at higher elevations 5000ft- 8500ft for the tahoe area. We also changed the needle to the 76H1, and ran it on the second from the top. 30 pilot and 400 main. The air screw was 1 3/4 out. This really worked well, the plug was carmel colored, and the bike was crisp through all ranges. We probably could have even gone to a 380 main if we wanted, but It really works well. This is definately the alternative to the carb swap.
