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03 RM 250 Jetting Advice


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I bought a 2003 RM 250 a couple of weeks ago. The bike is super clean & totally stock, with about 5 hours ride time on it. The original owner looped it out doing a wheelie and hurt his knee and put it away, never wanting anything to do with it again. Aside from a small dent in the pipe, torn throttle grip on the end & a few small scuffs on the right number plate, it looks & feels brand new--like you just rolled it off the showroom floor. I really like the bike!!

I've only ridden it once or twice so far for just a few mins but I've noticed it's jetted really rich. It smokes and spooges quite a bit. It feels rich on the bottom and has a stumble/stutter just past 1/8th throttle before hitting the mid range then it cleans out and pulls hard to the top end. I've read the forums front to back researching what others have said and realize that the 03 is tough to jet. I'm going to attempt it anyway ๐Ÿ˜

I guess my question is this: I can go one of 2 routes. Which one would those with experience with the 03 recommend? Buy a JD jetting kit and tinker with that to get it right or Just purchase the jets separately to get a baseline setting? I guess what I'm asking is: Will the JD needles get me close enough to where I can save money by not having to purchase the 7.0 slide or would I be better off to start with the Pro Circuit recommended jetting to get a baseline? I realize I will have to fine tune either way I go and I really don't mind a little spooge. I just wanna get the stumble cleaned up and reduce the spooge. I'd rather be a little rich in the summer and not have to re-jet for cooler weather.

Stock jetting:

Main:175

Pilot:48

Needle: N8RH 3rd clip

Air screw: 1 1/2 turns out

PowerJet: 50

Slide: 6.5

PC Recommended:

Main:165

Pilot:45

Needle: N8RH 2nd clip

Air Screw: 1 1/2 turns out

PowerJet: 48

Slide: 7.0

My riding mostly occurs at temps ranging from 60 - 90 degrees and elevations between 2200-3000ft. Any advice on what would be the best route to start off with would be greatly appreciated! Thanks!

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I had some other issues to but here is what I am running and I am pretty close.

45 pilot

Air screw was adjusted at approx 1500-2000 rpm for better throttle response

Stock needle in # 1 position

7.0 slide

165 main

stock power jet

My jetting is set for 85-95 degrees, 3000+ elevation, and a tad humid

California desert jetting

I had some reed issues and power valve adjustment issues too along with jetting. I fixed the other issues and slowly came to these specs by runnin it up and down my street a billion times till I felt I was as close as possible. Man my neighbors were pissed:p:p. Oh well, thats what they get for boomin their stereos late at night while driving up and down the street:foul:.

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Thanks for the responses......that's kinda the route I was thinking of going with at first. Buying the following jets: Mains: 168 & 165, Pilot:45 & 42, PowerJet: 48 & just using the stock needle to begin with. Then I looked at how much money I was going to be putting in those jets alone plus buying the 7.0 slide($53 from JD Jetting is the cheapest I've seen) and I started thinking that I may had better ask a few guys here for some advice/experiences with the JD jetting kit. I'm wondering if the custom needles in the kit are good enough to keep me from having to buy the slide? If so that would actually be the cheapest route.

Again thanks guys for taking the time to respond. ๐Ÿ˜

Edited by 05Jacknutt
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Thanks for the responses......that's kinda the route I was thinking of going with at first. Buying the following jets: Mains: 168 & 165, Pilot:45 & 42, PowerJet: 48 & just using the stock needle to begin with. Then I looked at how much money I was going to be putting in those jets alone plus buying the 7.0 slide($53 from JD Jetting is the cheapest I've seen) and I started thinking that I may had better ask a few guys here for some advice/experiences with the JD jetting kit. I'm wondering if the custom needles in the kit are good enough to keep me from having to buy the slide? If so that would actually be the cheapest route.

Again thanks guys for taking the time to respond. ๐Ÿ˜

I tried different needles with no success on my 03. The 7.0 slide and recomended starting point I gave you seems to be the best starting point towards the fine tuning, you can go further if you desire since mine isnt perfect, but it deffinetely is close and got rid of 90% of the wierd running behavior below 1/8th throttle which is where I playride most( rock gardens, forest singletrack, ect..) I have not raced this bike yet, but racing desert I wont notice it probably at all. I also hope as the weather cools down and gets cold for winter that my jetting will adjust and run perfect:thinking:

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I tried different needles with no success on my 03. The 7.0 slide and recomended starting point I gave you seems to be the best starting point towards the fine tuning, you can go further if you desire since mine isnt perfect, but it deffinetely is close and got rid of 90% of the wierd running behavior below 1/8th throttle which is where I playride most( rock gardens, forest singletrack, ect..) I have not raced this bike yet, but racing desert I wont notice it probably at all. I also hope as the weather cools down and gets cold for winter that my jetting will adjust and run perfect

Okay I'll go with your suggested settings and order a few extra jets just in case i need to take it farther. I'll report back when I get them in the bike and have had a chance to fool with it. I appreciate the responses!

Here's a few pics I've snapped of the bike. The dent in the pipe is visible and the number plate background got scuffed up in the original owners crash. I don't think it was rode much, those are the original tires. That'll change!! I'll throw in a pic of it and My '05 RMZ 450 together too. I get this thing jetted and I'll be a happy camper!

2003RM250-07-15-2010003.jpg

2003RM250-07-15-2010001.jpg

2003RM250-07-15-2010008.jpg

2003RM250-07-15-2010010.jpg

2003RM250-07-15-2010006.jpg

2003RM2502005RM-Z450003.jpg

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Bike still looks great! Good buy.

I jetted my 07 according to PC and it is pretty good. The only thing that I could not find (I tried numerous Suzuki dealers) was different power jets. There is no Suzuki part# for different power jets so not sure where PC gets other sizes.

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Bike still looks great! Good buy.

I jetted my 07 according to PC and it is pretty good. The only thing that I could not find (I tried numerous Suzuki dealers) was different power jets. There is no Suzuki part# for different power jets so not sure where PC gets other sizes.

For the 03 the numbers are:

SKU: 09492-45039

JET, POWER (45) OPT

SKU: 09492-48015

JET, POWER (48) OPT

SKU: 09492-50025

JET, POWER (50) OPT

They should fit on the 07 aswell?

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A common mistake everyone makes with race bikes (especially true with the RM's) is that they are race bikes and need to be jetted on a regular basis, sometimes daily. I have found that I can go up or down several mains in one day based on humidity, heat indexes and fuel quality. Sometimes its as easy as adjusting the airscrew as well.

with that said here's a link that will teach you how to jet. Don't worry, once you get the hang of it you'll be adjusting your jetting based on how the air feels to ya and doing major changes during the season change. Good luck!

https://thumpertalk.com/forum/showthread.php?t=412662

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That guy didn't wear boots !!!! Awesome find.....looks really good.

All rm's will get that "dent" in the pipe , does not hurt it one bit performance wise.

My bike ( 03 & 05 ) worked fine with just slow jet and main jet changes ( at sea level ).

The slide change , jd jetting kit , were not needed in my case.

later.

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Put on a 45 or 42 slow jet......168/165/162 main jet...needle clip...probably just move it one more notch leaner.

I had an 03 and ran a 42sj for the duration I had it ( 04-09 ) and no issues, at all.

I run that jetting on My 04,,It always seems that the stock jetting is always to rich,,,it takes a little time, but, it's worth it.........Dr.D..

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Okay I'll go with your suggested settings and order a few extra jets just in case i need to take it farther. I'll report back when I get them in the bike and have had a chance to fool with it. I appreciate the responses!

Here's a few pics I've snapped of the bike. The dent in the pipe is visible and the number plate background got scuffed up in the original owners crash. I don't think it was rode much, those are the original tires. That'll change!! I'll throw in a pic of it and My '05 RMZ 450 together too. I get this thing jetted and I'll be a happy camper!

2003RM250-07-15-2010003.jpg

2003RM250-07-15-2010001.jpg

2003RM250-07-15-2010008.jpg

2003RM250-07-15-2010010.jpg

2003RM250-07-15-2010006.jpg

2003RM2502005RM-Z450003.jpg

Great find! That bike is brand new! Other than the dent and a scratch, oh well big deal. Great purchase. I wish I had a few like that to choose from when I got my 03.

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Yeah I think I got a great deal on the bike. It's just a plain ol' stocker I know, but the pics can't really do the bike justice as far as how "fresh outta the crate NEW" it looks and feels. I was floored when I saw it....I just couldn't believe it! The guy ran less than 2 tanks of gas or less through it since he bought it new in September of '03. Sounds like he crashed shortly after its maiden voyage. Said he'd never had it out in the woods, just in the field behind his house and on the road riding a wheelie when he wrecked it. It screwed his knee up pretty bad & He just put it away, not wanting anything to do with it after that. If it had been me I woulda sold it if I was gonna store it for that long.

I appreciate all the advice given so far. I'm new to posting at TT even though I've been hanging around for awhile. I'm definitely not new to dirt bikes though. I'm 35 and I've been riding since I was about 5 years old. I've torn into a few carbs in my time but my re-jetting experience is very limited. Most bikes I've owned seem slightly rich from the factory but so close it wasn't worth fooling with, for me anyways. But this thing definitely has the sputters down low especially at or just past 1/8 throttle. It's bad enough for me to try to tackle and the thoughts of getting a little extra power out of it doesn't hurt either.

I realize I may not need to change the powerjet &/or the slide but to be honest, I hate dealing with my local dealer, so I buy most of my parts online if I can. Plus.... when I get a day to jet this thing I wanna be armed with enough jets to get it running crisp (at least I hope). From what I've read the 7.0 slide helps it the most & is needed in most cases, so I do wanna try that for sure.

Again thank you all for all the helpful advice. I'll let you all know how it goes as soon as I get the jets in and have a day to tinker with it. You guys are my Tech Support.....Sorry it doesn't pay any better!๐Ÿ˜ Thanks Guys!

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Yeah I think I got a great deal on the bike. It's just a plain ol' stocker I know, but the pics can't really do the bike justice as far as how "fresh outta the crate NEW" it looks and feels. I was floored when I saw it....I just couldn't believe it! The guy ran less than 2 tanks of gas or less through it since he bought it new in September of '03. Sounds like he crashed shortly after its maiden voyage. Said he'd never had it out in the woods, just in the field behind his house and on the road riding a wheelie when he wrecked it. It screwed his knee up pretty bad & He just put it away, not wanting anything to do with it after that. If it had been me I woulda sold it if I was gonna store it for that long.

I appreciate all the advice given so far. I'm new to posting at TT even though I've been hanging around for awhile. I'm definitely not new to dirt bikes though. I'm 35 and I've been riding since I was about 5 years old. I've torn into a few carbs in my time but my re-jetting experience is very limited. Most bikes I've owned seem slightly rich from the factory but so close it wasn't worth fooling with, for me anyways. But this thing definitely has the sputters down low especially at or just past 1/8 throttle. It's bad enough for me to try to tackle and the thoughts of getting a little extra power out of it doesn't hurt either.

I realize I may not need to change the powerjet &/or the slide but to be honest, I hate dealing with my local dealer, so I buy most of my parts online if I can. Plus.... when I get a day to jet this thing I wanna be armed with enough jets to get it running crisp (at least I hope). From what I've read the 7.0 slide helps it the most & is needed in most cases, so I do wanna try that for sure.

Again thank you all for all the helpful advice. I'll let you all know how it goes as soon as I get the jets in and have a day to tinker with it. You guys are my Tech Support.....Sorry it doesn't pay any better!๐Ÿ˜ Thanks Guys!

I don't think you need a slide at all. I also don't think you need to spend the coin on the JD kit as well. I have a JD kit that I tried and it worked well once I ironed out the issues but it was nothing big once I sorted out everything. Their needles are like works of art though. You will need to make sure your motor is fresh along with the silencer packing. If you aren't settled on an oil yet use this stuff at 30:1. zookpremix.jpg It's great, Its cheap and it will make your life really easy since it was used in setting the original specs on your bike. Next step is using a high quality pump gas. One of the issues I had here on the east coast is fuel quality. Now I can buy Race gas or Av fuel but ended up using a combo of Silkolene Proboost (1oz per gal) and Marine Stabil/Seafoam with quality pump gas. It ends up being a really good fuel for about $3.50 a gallon instead of $13. Smells just like race gas too! Now here is a jetting prediction chart for your bike. 2004RM250Jetting.jpg

It should get you in the ball park and then you can dial it in using this:

https://thumpertalk.com/forum/showthread.php?t=412662

Good luck

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I don't think you need a slide at all. I also don't think you need to spend the coin on the JD kit as well. I have a JD kit that I tried and it worked well once I ironed out the issues but it was nothing big once I sorted out everything. Their needles are like works of art though. You will need to make sure your motor is fresh along with the silencer packing. If you aren't settled on an oil yet use this stuff at 30:1. zookpremix.jpg It's great, Its cheap and it will make your life really easy since it was used in setting the original specs on your bike. Next step is using a high quality pump gas. One of the issues I had here on the east coast is fuel quality. Now I can buy Race gas or Av fuel but ended up using a combo of Silkolene Proboost (1oz per gal) and Marine Stabil/Seafoam with quality pump gas. It ends up being a really good fuel for about $3.50 a gallon instead of $13. Smells just like race gas too! Now here is a jetting prediction chart for your bike. 2004RM250Jetting.jpg

It should get you in the ball park and then you can dial it in using this:

https://thumpertalk.com/forum/showthread.php?t=412662

Good luck

Those are 04 specs. I have a freind with an 04 which ran pretty good out of the box. I wondered if I should try running the stock needle from an 04 or the complete specs. I wonder how much different the motor is and whether the oem specs for an 04 would completely eliminate the bla fromthe off idle throttle position. Whatchya think? BTW thanks for the jetting chart, I am gonna print that out and put it in the manual I made.

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I don't think you need a slide at all. I also don't think you need to spend the coin on the JD kit as well. I have a JD kit that I tried and it worked well once I ironed out the issues but it was nothing big once I sorted out everything. Their needles are like works of art though. You will need to make sure your motor is fresh along with the silencer packing. If you aren't settled on an oil yet use this stuff at 30:1. zookpremix.jpg It's great, Its cheap and it will make your life really easy since it was used in setting the original specs on your bike. Next step is using a high quality pump gas. One of the issues I had here on the east coast is fuel quality. Now I can buy Race gas or Av fuel but ended up using a combo of Silkolene Proboost (1oz per gal) and Marine Stabil/Seafoam with quality pump gas. It ends up being a really good fuel for about $3.50 a gallon instead of $13. Smells just like race gas too! Now here is a jetting prediction chart for your bike. 2004RM250Jetting.jpg

It should get you in the ball park and then you can dial it in using this:

https://thumpertalk.com/forum/showthread.php?t=412662

Good luck

Thanks for the advice on the fuel and the links. I really need some of that Marine formula Stabil. I've used regular Stabil a lot in all my small engines but with the amount of crappy ethanol out there this stuff is a must have it sounds like. I myself only buy 93 octane for my bikes from a station that only sells 100% gas but I'm gonna switch over to Marine Stabil after reading about it. Especially since 100% gas is getting harder to find and the fact that you never know if they are selling you ethanol gas and claiming it to be 100% gas. I'll be running Motul 800 2t @ 40:1 with 93 octane.

Also thank you for giving your honest opinions on the JD kit. Your advice makes sense and as a result, I've decided to forget about the 7.0 slide for now since it's so expensive and just try to get it dialed in with simple jetting changes and clip position on the needle. I'll try the slide at a later point if I can't get it close enough with a reasonable amount of tuning.

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Those are 04 specs. I have a freind with an 04 which ran pretty good out of the box. I wondered if I should try running the stock needle from an 04 or the complete specs. I wonder how much different the motor is and whether the oem specs for an 04 would completely eliminate the bla fromthe off idle throttle position. Whatchya think? BTW thanks for the jetting chart, I am gonna print that out and put it in the manual I made.

I wondered the same thing so I've got an 04 needle coming my way to try out. I'm gonna see what I can do with the stock one first, then I'll give the 04 needle a try. If it helps, I'll let you know. ๐Ÿ˜ I should get a chance to fool with the jetting this weekend if I get all the parts I need this week.

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Thanks for the advice on the fuel and the links. I really need some of that Marine formula Stabil. I've used regular Stabil a lot in all my small engines but with the amount of crappy ethanol out there this stuff is a must have it sounds like. I myself only buy 93 octane for my bikes from a station that only sells 100% gas but I'm gonna switch over to Marine Stabil after reading about it. Especially since 100% gas is getting harder to find and the fact that you never know if they are selling you ethanol gas and claiming it to be 100% gas. I'll be running Motul 800 2t @ 40:1 with 93 octane.

Also thank you for giving your honest opinions on the JD kit. Your advice makes sense and as a result, I've decided to forget about the 7.0 slide for now since it's so expensive and just try to get it dialed in with simple jetting changes and clip position on the needle. I'll try the slide at a later point if I can't get it close enough with a reasonable amount of tuning.

You can run the Motul if you want but I wouldn't unless I was running Full throttle MX in the Pro class. It has a high flash point because it was developed for Moto GP racing and tends to spooge alot on dirtbikes. I would find something different to use. If you are gonna be running trails and stuff you can get away with the really cheap stuff (Walmart)at the factory ratio, MX will require slightly better lubrication.

Let us know what kind of riding you'll be doing and maybe we can help you out a little better.

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