If you have the money go two sizes up and two sizes down from what you have now on both jets.
RM250 rm250 starting issues
- Thread starter bobkyle2
- Start date
Definately get the all three of the main jets that you listed. I would also get a 165 and 160 main for when it gets to be near summer time. The warmer it is out side the leaner you will have to run your carb. For the pilot jet 60 55 and 52. At least this way you can have a range to play with. Once the engine is up to operating temp it will tell you what it wants. Dont forget about your reeds too. When you get around to looking at them take them off reed block and lay them out on a smooth flat surface. They should not have any curve to them. The should not have any chips, knicks, cracks or fraying. If it doesnt look right it probably isnt. Just for good measure Id replace them anyway, because you dont really have much history with this bike.
Now that your on the right track for jetting Im going to give you some more info about how the engine should respond. Install the largest main jet you have first, the largest pilot jet you have, and set the jet needle clip in the middle position.
Do this first portion on the stand, with the engine warmed up. Your going to be checking the pilot jet. Engine warm and running snap the throttle open and quickly release it. You dont have to open it all the way up though. Say maybe to half throttle. The response your looking for is a quick smooth rpm change and then back to a steady idle. When RPMs come down if the engine hangs at a high idle for just a little bit before going back to a normal idle your pilot jet is likely too lean. But you may be able to fix that by adjusting your air scew. Try turning it in about an 1/8th of a turn clock wise. This will richen it up. Keep doing this untill you cant make the hanging idle go away and not be more than a 3/4 turn from all the way tight on the air scew. You need to richen your pilot jet one size. Once you have installed the richer pilot jet, turn your air screw back out to where it was set at (not more than 2 full turns). Try it again. If you snap the throttle open and it returns smoothly to an idle your pilot jetting is correct. Now ride it. First gear only accerate up to not more than half throttle. If it blubbers during acceleration lean it down one size, and try again. Keep doing this untill it responds correctly.
Now onto the jett needle. This is how I do it, others may say different. If you havent adjusted your jet needle the clip should be set in the middle groove this is the stock factory setting. Now warm the bike up take it out for a straight line run up through say 3rd gear to about 1/2 to 3/4 throttle. If the engine gives you smooth power but feels flat your lean. If the engine blubbers (kind studddering and as you continue to give it more power clears out, your rich. So if its too lean you need to go to the next groove down with the clip. If its too rich go to the next groove up with the clip. Make your adjustments as necessary. Keep doing this untill it responds correctly
Now on to the main. Same as step too. Engine warm. Take the bike out run it up through the gears to wide open. If it starts to blubber at near or above 3/4 throttle and doesnt go away your really rich. If it starts to blubber and clears up your just a little rich. Remember only richen or lean your pilot jet, jet needle, and main jet one size up or down untill it responds correctly.
This process is a little time consuming. I can do it in a couple of hours if the carb is really out of whack. Also bear in mind that you will do this again as the weather changes. Come summer time your bike will start to run rich. Simple just lean it out one size at a time till you give the engine what it wants. And same in the fall or winter. But come winter you need to be proactive about richening. Running a little to rich is ok. Running a little to lean isnt good. Too lean will just cost you more money.
Now dont waste your time doing any of this untill you have verified that you have good compression. If you dont have good compression its likely you need a new topend. Once youve replaced your top end (about $150 including the gasket kit) then you need to tune your carb. I like to break my new top ends in with the with the carb jetted rich. Its my opinion that you need the extra fuel to help with internal cooling and the extra oil to help with the friction during the break in process. Now when I say extra oil this doesnt mean run more oil in your pre mix. 32:1 is all you need. Extra fuel means there will be extra oil included.
I know it sounds like Im preaching
and yes I probably am. But it is my desire that you have success in this process. I was out of the loop for nearly 20 years before I got back into dirt bikes and I need help on this very same subject. I got most of my help for guys on a different web site that are now members here. I feel its my duty to help you like they helped me. Why you ask. Because Im a DIRT BIKE ADDICT!
Now that your on the right track for jetting Im going to give you some more info about how the engine should respond. Install the largest main jet you have first, the largest pilot jet you have, and set the jet needle clip in the middle position.
Do this first portion on the stand, with the engine warmed up. Your going to be checking the pilot jet. Engine warm and running snap the throttle open and quickly release it. You dont have to open it all the way up though. Say maybe to half throttle. The response your looking for is a quick smooth rpm change and then back to a steady idle. When RPMs come down if the engine hangs at a high idle for just a little bit before going back to a normal idle your pilot jet is likely too lean. But you may be able to fix that by adjusting your air scew. Try turning it in about an 1/8th of a turn clock wise. This will richen it up. Keep doing this untill you cant make the hanging idle go away and not be more than a 3/4 turn from all the way tight on the air scew. You need to richen your pilot jet one size. Once you have installed the richer pilot jet, turn your air screw back out to where it was set at (not more than 2 full turns). Try it again. If you snap the throttle open and it returns smoothly to an idle your pilot jetting is correct. Now ride it. First gear only accerate up to not more than half throttle. If it blubbers during acceleration lean it down one size, and try again. Keep doing this untill it responds correctly.
Now onto the jett needle. This is how I do it, others may say different. If you havent adjusted your jet needle the clip should be set in the middle groove this is the stock factory setting. Now warm the bike up take it out for a straight line run up through say 3rd gear to about 1/2 to 3/4 throttle. If the engine gives you smooth power but feels flat your lean. If the engine blubbers (kind studddering and as you continue to give it more power clears out, your rich. So if its too lean you need to go to the next groove down with the clip. If its too rich go to the next groove up with the clip. Make your adjustments as necessary. Keep doing this untill it responds correctly
Now on to the main. Same as step too. Engine warm. Take the bike out run it up through the gears to wide open. If it starts to blubber at near or above 3/4 throttle and doesnt go away your really rich. If it starts to blubber and clears up your just a little rich. Remember only richen or lean your pilot jet, jet needle, and main jet one size up or down untill it responds correctly.
This process is a little time consuming. I can do it in a couple of hours if the carb is really out of whack. Also bear in mind that you will do this again as the weather changes. Come summer time your bike will start to run rich. Simple just lean it out one size at a time till you give the engine what it wants. And same in the fall or winter. But come winter you need to be proactive about richening. Running a little to rich is ok. Running a little to lean isnt good. Too lean will just cost you more money.
Now dont waste your time doing any of this untill you have verified that you have good compression. If you dont have good compression its likely you need a new topend. Once youve replaced your top end (about $150 including the gasket kit) then you need to tune your carb. I like to break my new top ends in with the with the carb jetted rich. Its my opinion that you need the extra fuel to help with internal cooling and the extra oil to help with the friction during the break in process. Now when I say extra oil this doesnt mean run more oil in your pre mix. 32:1 is all you need. Extra fuel means there will be extra oil included.
I know it sounds like Im preaching
and yes I probably am. But it is my desire that you have success in this process. I was out of the loop for nearly 20 years before I got back into dirt bikes and I need help on this very same subject. I got most of my help for guys on a different web site that are now members here. I feel its my duty to help you like they helped me. Why you ask. Because Im a DIRT BIKE ADDICT!
yes i got a new piolet jet...for sure.. i dont remember what size it was now.. it was either a 52 or 55....
i got 2 new main jets.. but there the 2peice type.. and im pretty sure mine has the one peice like you showed me... and yes that one of the left is the 2 peice type..... but im going to take it apart and make sure before i try to order some more...i have the keihn carb....the guy at the zook shop said mine should have the 2 peice.. but i just cant recall....
i got new packing for the silencer.....
i got to check my reeds... and check the throttle needle setting..
i rode the bike today.. it start up pretty easy took me about 20 kicks ..but i do have a messed up leg..
but it didnt run correct so i just brought it back... i ordered a new comp gauge.. i wish i just would have went and picked one up somewhere i really wanna see what kind of reading i have... im pretty sure its fine though
i got 2 new main jets.. but there the 2peice type.. and im pretty sure mine has the one peice like you showed me... and yes that one of the left is the 2 peice type..... but im going to take it apart and make sure before i try to order some more...i have the keihn carb....the guy at the zook shop said mine should have the 2 peice.. but i just cant recall....
i got new packing for the silencer.....
i got to check my reeds... and check the throttle needle setting..
i rode the bike today.. it start up pretty easy took me about 20 kicks ..but i do have a messed up leg..
but it didnt run correct so i just brought it back... i ordered a new comp gauge.. i wish i just would have went and picked one up somewhere i really wanna see what kind of reading i have... im pretty sure its fine though
Uuummmmm thanks I think
. Im just glad Im not a cowboy on a mountain
. I did some snooping around and found this info, for base line jetting.
Ok this guy states he is below 500 ft running this jetting set up on the same year RM as yours but he is also running aftermarket pipe, silencer and reeds. Which will tend to make the bike want to run more rich.
Main-180 RD
Pilot- 52
Needle- R1471NS #2 position, one lean from center
Air Screw- 1 ½ turns out
So this leads me to think that a 190, 185, or 180 maybe a 178 main jet should get you what you need for winter and summer jetting. Im also thinking a 50-55 pilot jet will do you just fine.
. Im just glad Im not a cowboy on a mountain. I did some snooping around and found this info, for base line jetting. Ok this guy states he is below 500 ft running this jetting set up on the same year RM as yours but he is also running aftermarket pipe, silencer and reeds. Which will tend to make the bike want to run more rich.
Main-180 RD
Pilot- 52
Needle- R1471NS #2 position, one lean from center
Air Screw- 1 ½ turns out
So this leads me to think that a 190, 185, or 180 maybe a 178 main jet should get you what you need for winter and summer jetting. Im also thinking a 50-55 pilot jet will do you just fine.
Explaining how to repack via text is kinda tough. So I went to a reliable source. www.RockyMountainatv.com. I buy alot of stuff from these guys. And they have some good instructional videos. Here is the one on how to pack your silencer.
http://www.rockymountainatvmc.com/videos.do?videoId=108
Or try this one from FMF
http://www.fmfracing.com/RiderSupport/RepackingInstructions
http://www.rockymountainatvmc.com/videos.do?videoId=108
Or try this one from FMF
http://www.fmfracing.com/RiderSupport/RepackingInstructions
im ready to burn it lol.... i got some pictures to load up... the main jets wont work... its got a 172 main jet....
it had a 48 slow jet in it.... i just put a 52in it... i need to order a 55... and some main jets... i figured out how to repack it... the new packing came with instructions...and a guy at the zuki shop told me a little bit... all the zuki shops are junk around here... main jet is a one piece... the main jets they gave me are very small..ahhh this bike is killing me..............i rode it before i started working on it... and it killed the plug...about a half mile down the road... this time is was a black burnt... not really oily.... but just black burnt... but i think my oil had settled to the bottom......... i really need to get some different oil... i forgot all about that...at the zuki shop
it had a 48 slow jet in it.... i just put a 52in it... i need to order a 55... and some main jets... i figured out how to repack it... the new packing came with instructions...and a guy at the zuki shop told me a little bit... all the zuki shops are junk around here... main jet is a one piece... the main jets they gave me are very small..ahhh this bike is killing me..............i rode it before i started working on it... and it killed the plug...about a half mile down the road... this time is was a black burnt... not really oily.... but just black burnt... but i think my oil had settled to the bottom......... i really need to get some different oil... i forgot all about that...at the zuki shop
Well youve got a good start with the new reeds. That will help. You definately want the hex head main jets.
Here is a link to a very reliable online parts place. I use them almost exclusively. Here is the link to the jets for you bike
http://www.rockymountainatvmc.com/vehicleSelectProd.do?prevVehicleType=2&prevMake=7&prevModel=&keyword=&vehicleTypeId=2&make=7&model=211&year=&navTitle=Intake%2FFuel&navType=type&webCatId=16&webTypeId=454&prodFamilyId=24374&stockId=&listingId=&uri=%2FproductDetail.do
But for your jets at the price they are asking for I would start at the biggest jets they offer which is like a 205 and order the next 10 smallest. $22 dollars Then on the pilot jets I would order the # 70 thru the #55 since you already have a 52. That will be another 22 dollars. So $44 bucks plus $7 to ship just a shade over $50. But then you'll have or should have enough jets to cover you through for all the jetting needs winter through summer.
Plus you should order some more plugs use the NGK plug numbers I listed for you. I would go with the BP7ES. They are only a couple of bucks a piece and work very well. Get like 5 or six of them the help you through your jetting process. I use them in my 92 RM.
Also here are a couple of other places that I use to find stuff for my bike.
www.OEMcycle.com
www.cheapcycleparts.com
These places carry alot of older bike stuff.
This is kinda fun. I love spending other peoples money.
Here is a link to a very reliable online parts place. I use them almost exclusively. Here is the link to the jets for you bike
http://www.rockymountainatvmc.com/vehicleSelectProd.do?prevVehicleType=2&prevMake=7&prevModel=&keyword=&vehicleTypeId=2&make=7&model=211&year=&navTitle=Intake%2FFuel&navType=type&webCatId=16&webTypeId=454&prodFamilyId=24374&stockId=&listingId=&uri=%2FproductDetail.do
But for your jets at the price they are asking for I would start at the biggest jets they offer which is like a 205 and order the next 10 smallest. $22 dollars Then on the pilot jets I would order the # 70 thru the #55 since you already have a 52. That will be another 22 dollars. So $44 bucks plus $7 to ship just a shade over $50. But then you'll have or should have enough jets to cover you through for all the jetting needs winter through summer.
Plus you should order some more plugs use the NGK plug numbers I listed for you. I would go with the BP7ES. They are only a couple of bucks a piece and work very well. Get like 5 or six of them the help you through your jetting process. I use them in my 92 RM.
Also here are a couple of other places that I use to find stuff for my bike.
www.OEMcycle.com
www.cheapcycleparts.com
These places carry alot of older bike stuff.
This is kinda fun. I love spending other peoples money.
.... wow...i feel like a bag of buttholes...its pouring rain... and i cant work on the bike its freezing out there