03 Rm250 couple questions

Ok guys here's what's going on. Had factory pipe on it, it got beat to poo installed fmf fatty. Jetting with stock pipe as follows 2nd clip stock needle, 172 main 42 pilot a/s 1.5 out power jet stock at 50. No spooge mixing 110vp and castrol 927 at 40:1. But did smoke a bit. After the pipe change I ran an enduro race and always pull the plug after the races to inspect them. Plug was dark running fat. No biggie ordered a 45&48 power jet, new float needle. So jumped into it today fresh silencer packing, good compression, fatty pipe, reeds are good, no air leaks. Installed 170 main and dropped the power jet to 45 to test adjusted a/s to 1.5 where it felt best and kept the 42 pilot everything else the same. Warmed the bike up new plug and rode it around lugging it on the slow circuits bikes smoking all the time and feels like its running a bit warm. The bike runs a lot better though feels "tighter" more responsive but has spooge collecting around the tip on the stock silencer. Gonna play with it more tomorrow just wonderin if anyone else had the same experiences and had any info. I've heard a lot of guys plug the power jet with a machine screw and jet it like an older carb. I'd rather keep it all in tact thanks in advance

No need to replace or plug the power jet, it's generally good stock. The key to jetting a 03 is the #7 slide, it comes with a 6.5 stock. I personally prefer the W needle as well. I'd say you're in the right ballpark with your settings. If it runs well a little spooge wouldn't bother me.

What's the full number on the needle you're speaking of. Ill get parts coming and the slide aswell. It runs good now just smokin a bit. It's just strange going from a 50 power to a 45 and spooging more than it did. All I can figure is its finally getting hot enough to burn the crap out now. Before it was running much fatter. Just gonna take time I recon thanks for the advice

There is the N8RW and N2CW needle. Difference is the CW is a half clip richer (shorter)

I run the N8RW on the second clip in the summer and N2CW on the second in the winter. This is for riding at 500-  2000ft, different elevations obviously changes.

If you're not as fussy as me and need 1/2 clip intervals just pick one.

Get your #7 slide from JD Jetting, less than half the price of OEM. Unless you know a machine shop that will cut yours down, even cheaper.

I've gotten to play some more with it today the silencer packing although new is gonna need replaced. I also have a 40 pilot on hand and a 165 main I'm going to order a 168 aswell as the #7 slide and a couple new needles. I'm really just surprised that this new pipe has made this big of difference in the jetting I know the 03's are tricky creatures I'm riding at about 600feet giver take. I ran a couple chop tests on 2 new plugs today and the carbon ring is a little dark and bit off the base of the porcelain. Checked the reeds again for good measure and found a bit oily. Re cleaned the carb and swapped back in the 50 power jet as to not run a lean condition. I'll get some parts on order have a race comin up sat. So crunch time. I'm just curious why it wasn't spooging with the 172 main. And is with a 170 unless its finally building the needed heat to burn the crap out now.? also checked float level and it was right on at 6.5mm as per the book only other thing I changed was the float needle. I'll getter whipped I greatly appreciate all you guy's help, it can get frustrating. I just need her to hold up for 3 more races then she'll get all the off season attention she deserves.

Did you remove your airscrew and give that passage a good cleaning? An over oiled or too freshly oiled airfilter can easily plug this passage with oil making it run rich. You did say the reeds were oily.....

Aftermarket pipes typically need leaner jetting, so this could also be why you are seeing some spooge now.

I would put in that 40 pilot and see if that cleans her up some.

My 03 I run a different head with 13:1 compression, Gnarly pipe,and  Vforce 3 reeds. I run it on Avgas and 25:1 oil ratio. So take my settings with a grain of salt but I typically find the 03 needs the lower circuits leaned out but you can still run a pretty fat main.

My settings


40 pilot

Airscrew 1.5-2.5 turns out

#7 slide

N8RW or N2ZW 2nd clip

168-172 main 

Yes sir, cleaned all passages inside and out the plastic idle screw on this thing leaves little to be desired lol. I'm gonna swap in the 40 pilot first an like you said one thing at a time. I figured running 110 VP in it it'd be the other way by needing more fuel. Ill keep ya posted thanks again!!

well update. i bought 6 plugs new packing, new pilot, and a new main. cleaned out silencer installed new packing and proceeded to tune. installed a used plug to warm the bike. loosened air boots flipped carb sidewards and pulled main jet installed 168 from a 170. took the bike for a ride. seemed to smoke a bit less. pulled the plug that had only been used for a chop test and looked at it... still dark. flipped carb again and installed a 40 pilot from a 42 rode it around a bit the bike seemed to have a little more in the seat dyno. no detination i could hear but it had always had a little lower note that the average 2T. took the bike down the road and installed a new plug gapped right. chop test. 5th gear pinned for a few seconds shut it down coasted to the garage pulled the plug. the tip by the electote on the porcalin was a tanish light brown. and the carbon ring was a few mm's down from the base of the porceilin and still a bit dark to me. im still getting a little spooge  the silencer but not like it was. and from this whole jetting episode ive found my brand new fmf fatty pipe has a pin hole in it!!!!!!! what a crock of pooo. id say thats about as close as its going to get for now bike lugs like a tractor down low now, i can almost stall the bike and cram it and start grabbing gears. tribalbc thanks for the advice and suggestions. someone to bounce ideas off of. ive got a 165 main i can swap in and picked up a 38 pilot but the bike runs a lot better now. if you have done these chop tests before.... how do you move the carbon ring further toward the tip of the plug(base of the porceilin) keep leaning it out? i would say this is pobably as close as i will get as you stated before it takes a little more air in there with that number 7 slide to help lean things out.

current settings


40 pilot

stock needle 2nd clip

50 power jet

float height at 6.5mm

6.5 slide.

Edited by Onesolidbarr

Good to hear you're getting it worked out. When jetted/tuned right these 03's can tractor/ roll through anything and are pretty much unstalable.

I jet mainly by seat of the pants and sound. I do plug checks more after running a bit rather than the classic plug chop. Once I have it seat of the pants/ sounding good I will check the plug after a few rides. I check the main by the base ring on the bottom of the threads. Color change all around the ring good, carbon buildup rich, less than full circle color change lean. I also look at the electrode for no more than 1/4 of the tip clean and signs of detonation. I've had my bike long enough now though that I know what to jet beforehand for temps and elevation, lots of settings recorded.

Once you get the #7 slide and the W (leaner) needle I think you'll find she runs real smooth and seamlessly through the range.

What have you done with your suspension? I race Hare Scrambles, little Enduro and practise MX with mine. The shock I found the only mod I really needed was a FC HSC spring, never had to play with valving though if I was heavier I could see it needing some more rebound. I revalved my forks and to work in the woods they sucked at MX. Then I happened upon a pair of 02 forks. Golden out of the box.

I as well race harescrambles and air it out a little on the mx tracks like once every blue moon. I had pro action suspension set mine up for woods, went with heavier springs as I'm 186lbs and they say for a 250 they're set up for 150-160lb riders. They changed the seals and revalved it all and I honestly couldn't be happier with it. This is te first bike I've had done.. I've changed seal heads and rebuilt forks before but trial and error style. All springs have been changed I'm running a 5.0 in the back and not sure with out lookin at the bike what all my clicks are. I played with them a little and the bike deflects great, rides a straight line and the rear tire follows. Best thing I could and would suggest is having someone video tape you in short sections if the woods to see how the bike is reacting to your style of riding if you still

Have issues with it or want to fine tune. I did however drop my front forks 6mm in the front and that really helped it with turning and feeling more controlled in the woods on tight sections.

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