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Discussion Starter #1
I have a 02 250CMX. It has a new carbeurator and battery and spark is good. It obviously turns over but doesn't start. When I turn the throttle it will spit and backfire but never actually start. Any ideas on what to check now?
Compression? It seems okay but I haven't did a compression check. I think it's supposed to be at about 149psi.?
 

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Give us a little background on the bike, miles, maintenance practices, recent work, modifications, what have you tried so far, etc.
 

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I work as a national guard diesel mechanic in a fulltime shop usually. I have two bikes gl 1500 goldwing and this little 250. I had a coworker put a new carb on it. It has new fuel. It wasnt firing and i found a wire going to the ICM that wasn't connected well. I also put a new ingition coil on it.
It has had starting fluid sprayed into the air intake so I was told. Thats why i wonder if it might've jumped time. Im not sure how to go about checking it. I think the compression is still good. It will turn over and if I throttle it or choke it it seems to maybe sputter or backfire but not on every revolution.
 

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Is the "new" carb brand new or just cleaned and refurbished? If new, is it a Keihin brand or something else? If refurbished, who cleaned it, and how was it done? The reason I'm asking is that about 99% of the starting and running issues with these bikes is carb related. If the carb was sprayed with canned carb cleaner, that doesn't do a good enough job. Soaking in Berryman's Chem Dip is effective, but it can take several rounds of soaking only the metal parts for at least two days, rinsing well with water, and blowing out all the orifices with high pressure air. An ultrasonic cleaner will get it clean the first time, and if you have access to one at work, I'm wondering if the higher-ups would object to you using it if needed.

A properly operating Rebel doesn't need any throttle at start up. Rebels differ as to how much "choke" (actually a fuel enrichment circuit) they need to start. Mine needs none during the warmer months.

Is the stock air filter system in place? There's a diagram of one here: 2002 Honda CMX250C A AIR CLEANER | Cheap Cycle Parts Ditto for the exhaust: 2002 Honda CMX250C A MUFFLER | Cheap Cycle Parts

Is the choke cable properly attached to the carb? It goes through a black plastic nut that threads into the carb. It's the one with the thumb lever on the left handlebar. Off is pushed away from the rider, On is the opposite.

The folks here are very knowledgeable and should be able to help you get this bike on the road soon.
 

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You can check cam timing by removing the valve cover and checking the marks on the cam sprocket when the pistons are at TDC.
The valve cover is held on by only 2 shoulder bolts on top of the engine and the cover can be removed if you loosen the tank and lift it up at the front. alternatively you can completely remove the tank to get at it easier.
 

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Thanks for the info. Im doing this in my spare time when I can. I shall keep you guys posted on what I get figured out.
 

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If you follow along on this video on valve lash adjustment, you can see the fly-wheel marks to look at and the position of the "pac-man" on the end of the cam shaft, if they don't match like in the video then you have jumped timing.
 

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Discussion Starter #9
So my crankshaft woodruff key that holds the flywheel has sheared off. Now I have to locate a flywheel removal tool.
 

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Thanks for the video Kryton! It led me down the path to find out for sure my flywheel timing was off. The rest (valves and camshaft) seem to be okay.
 

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So my crankshaft woodruff key that holds the flywheel has sheared off. Now I have to locate a flywheel removal tool.
Flywheel jacking bolt is 16mm X 1.5 thread pitch. Snug it into the threads and give the bolt head a sharp rap with a hammer. Flywheel should come loose. If not, repeat.
 

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So my crankshaft woodruff key that holds the flywheel has sheared off. Now I have to locate a flywheel removal tool.
The Rebel flywheel key is somewhat like a ball bearing set in a round hole rather than a woodruff key in a slot which is more typical. I'd be interestd to see a pic of what you find when you remove the flywheel.
You need the bolt style flywheel puller available for less than 10 bucks or so from a number of sources.
 

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Discussion Starter #14
Does anyone have a video or knowledge of the best way to re-install the new key and flywheel? I have never dealt with this kind of key. Maybe it'll come to me once I get the new one.
 

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My question is what is the condition of the flywheel that made a mess like that on the crankshaft? There should be a nice clean slot that that key slides into. If there is any damage at all to the slot I would expect a new key to fail again as well because the flywheel will not be precisely postiioned.
There seems to be damage on the crankshaft all around the key area as might have been caused by fragments grinding in the space
The shaft is tapered and if there is any distortion of the taper, the flywheel female taper may not seat properly on it. When properly seated by tightening the flywheel bolt, the flywheel will be held very tightly in place. If the tapers don't seat there could be problems.

Is there a stump of that broken key remaining in the hole in the crankshaft?
 

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Discussion Starter #16
Yes there was a short stump left. Once the removal bolt got snug the flywheel came off very easy. I think it'll clean up pretty good with some emery cloth. I see what you're saying about it being able to tighten up and grab though. I have never seen such a key contraption. Confused on how to reistall the new one? Slide the flywheel on and then insert the "key" or does the key sit it the slot and then slide on flywheel?
 

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The key has to install in the crankshaft first and then the flywheel slides on over it in exactly the right place. The key must fit tight in the flywheel. Looking at your pics I see the slot in the flywheel is damaged just where it has to hold tight against the key and also there appears to be a lot of damage from spinning the flywheel when the key let go.
You must get that key solidly mounted in the crankshaft. I'm not sure, but I suspect a new one would drive into the hole with an interference fit.
Assuming you can get the key securely mounted OK then I would look at replacing the flywheel because of the damage to the slot and the taper. The repair won't last because the slot is damaged right where it has to hold against the key.
 

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Discussion Starter #18
Thanks! My thoughts exactly and i got the opinion of the cycle repair shop next to my work. I ordered another flywheel. I got it from Ebay for $100.00 Hopefully it is good. I have my fingers crossed for luck.
 

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I could be wrong ...
looking at the pics of the crankshaft taper, I believe it is supposed to have a nice neat round hole for a round peg (key) and in the pics it looks like a wide oval trench, like the side of the cylindrical key well was gouged out?
 

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You're not wrong. That crankshaft is quite badly damaged too.
 
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