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2004/2005 rmz250 won't rev , just backfires

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Help....I bought a 2004 Rmz250 with no engine, I pieced together an 05 rmz250 engine, this thing fires right up and idles like a champ, revs ok up to 1/4 throttle then anything over that it , SOUNDS LIKE A REV LIMITER KICKS IN, I have checked the : Timing Marks, had the intake cam re-indexed and welded, exhaust cam is good, loads of compression, new spark plug, checked jetting, disassembled entire carb - cleaned - set up rich, tested stator and crank sensor - resistance ok, reset the timing marks a zillion times, cant figure this one out....Any help would be great...Thanks

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i know just the problem! its a suzuki! lol

but seriously, to me it soundsl like a jetting problem but you said you checked that so i dont know

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LMAO, you're telling me!!! I ride a CRF450, Stupid ZUK!!! I've over jetted it , tons of fuel, its like a rev limiter comes on or something??

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On my 2t pocket bike(laugh all you want), it sounds like a rev limiter when the air screw is adjusted too lean.

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I have had the carb completely apart, cleaned beyond clean, and the fuel screw is @ 3 turns out, needle 2nd clip from bottom, 180 main jet- i just cant see there being a fuel problem??

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Not sure about the cdi, I think I may have tracked down the problen, when I measured the resistances in the Stators, the Excter and the Charge coils were bang on, but when I tested the running Voltage output the Charge coil made 25V-32V (spec 16V +) , and the Exciter Coil made 8V (spec 59V +).....POS = ZUKI.....Anybody seen this before????

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So after WAYYYYYY too many hours, I've finally figured it out, the flywheel and stator set up on an 05 engine is totally different than an 04, I switched up the parts and the bike runs like new....Thank you to everyone that had ideas!!!!

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I'm having similar issues with my 04 RMZ250. I thought it was the CDI, so I went ahead and bout a complete electrical set from a parted out 2005 kx250f. I can get the bike started up, but any attempt to turn the throttle and the bike will die. I checked compression (within range), valves and valve clearances (more times than i should say), spark, spark plug gap, carb (even swapped for another carb), air leaks in boots, etc

The bike will also back fire a bit when kicking it over a bunch.

I'm sure you ran through the deck when experiencing your problem, so any guidance is greatly appreciated.

Thanks in advance

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Well I just posted and have figured it out. I also have spent WAYYYY too many hours on this problem.

SOLUTION - ONLY THE 2004 RMZ250/KX250F CDI WORKS FOR 2004 MODELS!!! The 2005-2006 units work with eachother, but 2004 is only 2004.

sighhhh...

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i have a 04 or 05 rmz 250 , cams havent spun , spark is perfect , plenty of gas , timing marks are now at 13 pins between marks , thats were it idles best but dies if u touch the throttle , it looks perfect at 12 pins but cant seem to get the right info ? the pin count changes from web sight to websight on the 04s & 05s , the 07 and up is 13 , been threw everything in carb ? the tdc mark is were its suposed to be ( was hoping it spun a key) with the compression weight held open all i can get with the throttle open is bout 100lbs ??  any ideas ??????????



This post has been promoted to a wiki Edited by 520exc1

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