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2004 RM250 goes flat high rpm


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Aloha guys .. I am having some trouble with my 2004 RM250. The mid range is better now after making some adjustments but the power falls flat very quickly and I am having to short shift this bike. My friend who is alot older than me and has had many dirtbikes took it for a ride and says it runs like shit compared to how a bike like this should run.

 

The bike foued a plug (BR8EG) when I was running 30:1 Maxima Castor 927 with a 168 main jet (172 stock) and a 48 slow jet (50 stock). The needle was on the 3rd clip down from the top (4th down is stock). The bike also smoked too much. My friend and I went down to a motorcycle dealearship downtown that sells dirtbikes and talked to one of the guys down there that has raced dirtbikes a lot when he was younger. I told him everything I have described above including that I am riding the bike at 2500+ ft above sea level. He told us that the 30:1 ratio in the manual is for racing and doing all the maintanence at the intervals described. We were already thinking of getting a smaller main jet (#165) and he said that would be a step in the right direction. He told us to check the reeds and the powervalve to see if the reeds are cracked or if the powervalve is stuck. He also recommended that we go to a 50:1 ratio for the fuel because I am not racing this bike and am more of a recreational rider and I wont be going wide open throttle all the time. Being new to two strokes I was suprised he recommended this ratio because all over the internet i've been reading 32:1 or  40:1 is the way to go and I have very rarely seen 50:1 recommended. I will admit I am a little bit worried about running this ratio but this guy knows a hell of a lot more than I do.

 

So we got a 165 main jet went home and swapped it out the 168 and mixed up some gas at 50:1. We took off the slilencer and removed some clogged oil soaked packing and took off the power valve cover to see if it was moving when we started up the bike and reved it. The power valve did open and appeared to be working fine even though it did look very dirty. (probablly should have cleaned it). The bike still ran like shit in the high rpm range. So we got in the carb again and put the needle on the 1st clip (top)(leanest setting). This did seem to improve the mid range quite a bit but we are still not getting the results we are looking for getting the bike to run like it should. The air filter is a new and freshly oiled TWIN AIR.

 

If you guys could give this a read and offer some words of wisdom  I'd greatly appreciate it !

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Aloha guys .. I am having some trouble with my 2004 RM250. The mid range is better now after making some adjustments but the power falls flat very quickly and I am having to short shift this bike. My friend who is alot older than me and has had many dirtbikes took it for a ride and says it runs like shit compared to how a bike like this should run.

 

The bike foued a plug (BR8EG) when I was running 30:1 Maxima Castor 927 with a 168 main jet (172 stock) and a 48 slow jet (50 stock). The needle was on the 3rd clip down from the top (4th down is stock). The bike also smoked too much. My friend and I went down to a motorcycle dealearship downtown that sells dirtbikes and talked to one of the guys down there that has raced dirtbikes a lot when he was younger. I told him everything I have described above including that I am riding the bike at 2500+ ft above sea level. He told us that the 30:1 ratio in the manual is for racing and doing all the maintanence at the intervals described. We were already thinking of getting a smaller main jet (#165) and he said that would be a step in the right direction. He told us to check the reeds and the powervalve to see if the reeds are cracked or if the powervalve is stuck. He also recommended that we go to a 50:1 ratio for the fuel because I am not racing this bike and am more of a recreational rider and I wont be going wide open throttle all the time. Being new to two strokes I was suprised he recommended this ratio because all over the internet i've been reading 32:1 or  40:1 is the way to go and I have very rarely seen 50:1 recommended. I will admit I am a little bit worried about running this ratio but this guy knows a hell of a lot more than I do.

 

So we got a 165 main jet went home and swapped it out the 168 and mixed up some gas at 50:1. We took off the slilencer and removed some clogged oil soaked packing and took off the power valve cover to see if it was moving when we started up the bike and reved it. The power valve did open and appeared to be working fine even though it did look very dirty. (probablly should have cleaned it). The bike still ran like shit in the high rpm range. So we got in the carb again and put the needle on the 1st clip (top)(leanest setting). This did seem to improve the mid range quite a bit but we are still not getting the results we are looking for getting the bike to run like it should. The air filter is a new and freshly oiled TWIN AIR.

 

If you guys could give this a read and offer some words of wisdom  I'd greatly appreciate it !

Lots of possibilities. Have you tested the stator? If it's weak it will cut out on the upper rpm. I'm sure I missed it but have you tested compression ratio? Are the reeds cracked, or not opening all the way? Spark plug cap, etc..

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