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Discussion Starter #1
hey neil, does the stock cdi have a rev limiter? I do not want to sound stupid but I had the opportunity to test my motor limit when I rode it at max throttle in a dry lake bed in the mojave desert. it sounds like the engine is bogging or cutting off at extended max throttle at 6th gear and I end up constantly pulling the plug ..... but the jetting seem spot on from the light brown color. Could it be a mismatched port/pipe combo. Im running ct 350 mx port, cr250 rad valve, trx5 centermount pipe. any input appreciated. thanks.
 

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its most likely an electrical problem. typically if your jetting is spot on but you still have some cutting at full throttle its a sign of a weak spark. whats your plug gapped at? try .018 if you havent already. also when you say you checked your plug after each run, did you kill the bike WFO, and then stop and check the plug? or did you idle down from WFO and then drive over to your trailer and check the plug? because if you did the latter you really just checked your plug at idle. i also assume compression has been checked and is good?
 

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You know I've heard it asked before about a limiter in the CDI but I dont think it has one, I'm not 100% sure though. I would think its fuel related like blackers saying.

Realy though, 250Rs dont like real high rpms like banshees. Ol 250Rs are happy around midrange rpms where they perform their best, it can screem but just think what that piston is going through.
Neil
 

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Discussion Starter #4
I do have the spark gapped at .018 and cutout the ignition at WFO in 6th. If its electrical, then what do I do to correct this problem. Do I change the CDI, stator, or coil or all? All this time I thought it could be the limits of my port job since I had the same problem a while back until I changed pipes. But I only notice this at very high rpms. Could it also be as reed problem? Thanks for all your input at this point.
 

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it would not be a reed problem, you would notice a reed problem at idle or low rpms's. it could be a pipe problem. it could be a fuel problem, but it may be an ignition timing problem as well?????
 

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you could check all your electrical connections and make sure they are corrosion free, and snug fitting. it could be your just falling out of your power band at the high RPM's and you dont quite have enough to pull 6th gear WOT
 

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Discussion Starter #7
I am geared 14/38 with 18 inch rear tires so does that sound correct? Also, are the CDI's of all years interchangeable together with the stator and the coil? Lastly, is the timing adjustable, and if it is, then how can it be adjusted? Thanks for your patience.
 

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I am geared 14/38 with 18 inch rear tires so does that sound correct? Also, are the CDI's of all years interchangeable together with the stator and the coil? Lastly, is the timing adjustable, and if it is, then how can it be adjusted? Thanks for your patience.
14/38 & 18s is good.
No, the CDIs are different as well as the wiring harness & flywheel.
On a stock bearing carrier the timming cant be adjusted but if you buy an aftermarket carrier, those have adjustments.
Neil
 

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my 86 r almost had the same kinda problem down the road it didn't wanna scream the jetting seemed ok but then i noticed that the guy i bought it from had like a 39mm roundslide off some older bike when i got the right carb on it it made a big diference my bike only has 13/39 gears and now i wanna try gearing it for more top end like 14/38 or 13/38 or 14/ 39 whatever my eng will pull alright
 

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Discussion Starter #10
How can one tell what year cdi ones got since my quads fully aftermarket and the wiring harness is all hacked up? Is it just a plug/connector difference ?
 

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Most all y ears look the same but theres just a little difference.

Best I can remember, the plug in on the CDI boxes are the same all years but the harness had different connectors. Old 85/86 CDI boxes inside were different than 87 & up, something about the timming.
85/86 flywheels were different than 87 & up, timming was set different, weight of the flywheel was more & the center mounting hub was smaller on the old models.
Dont remember anything about the stators or the pickup modules.

One thing I do know for sure, 100% sure, when you bite the bullet money wise & go ahead & get the CR250R ignition change over, god knows, you have eleminated one of the biggest never ending headakes of anything or part that came stock on a TRX250R engine.
I realy beleave that who ever designed the ignition system for the TRX250R must have been a spy from some other bike company & sent there to sabotage the Honda bike :eek: , might not be, but you start having ignition problems it will make you think about it.
Neil
 
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