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sparkyz

Bike died, any suggestions

9 posts in this topic

So I was at the track today and out of nowhere my bike would randomly sputter on decel or occassionally when cracking the throttle. It was about the same as it does before it runs out of gas. It did it maybe once every 2 or 3 laps with some being a mild hiccup and others where the bike would hardly accelerate. Then it stopped for a while. What ended my day was when it finally stalled out getting on the track and would not fire after that.

I am looking for any ideas before I actually get a chance on Monday to dig into it. At first I was thinking carb related cause opening the throttle in the air or landing from jumps semed to do it more often. I had noticed when it first started happening that the wire for the neutral sensor had gotten into the header and melted slightly.

I was able to take a quick look at the bike after riding. I pulled the plug and it looked ok, although I plan on changing it before beginning the trouble shooting. The spark also looked good. We also checked the neutral sensor wire and found it seemed to be ok, just melted the jacket a little. We did get it to start again in the shop but it would not stay running.

I am planning on starting out with the plug, and when that doesn't solve it probably go through the carb (cleaning and check float level). Any other ideas or suggestions?

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If the neutral wire shorts, the rev limit will drop to about 6-7000, as it is in neutral. This would cause a misfire at any speed higher than that.

You might also check for dirt or water in the fuel.

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So I started out with fresh gas and a fresh plug. Then went on to cleaning the carb. It still wouldn't fire and I eneded up noticing the coil doesn't really click onto the plug. I took the boot off and noticed that there isn't really anything in there to contact the spark plug. It looks like it wasn't making good contact and basically deteriorated. I assume that there used to be a piece of spring steel or two in there that contacts the plug? I won't be able to get the coil for a few days but I am hoping thats what it was.

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Well I bought the new coil and after looking at it the old one was definately missing the pieces that contact the plug, problem soved right? No! I only got a short time to work on it, which consisted of putting the coil on and trying to start it. I did get it to fire once and it ran really rough for maybe 5-10 seconds and died. When kicking it, it still feels the same as usual, but it doesn't sound the same in terms of trying to fire (compression sounds fine). I didn't get to check for spark or anything yet but do you think that with the coil jumping a gap to reach the plug for a while it put more strain on another electrical component, causing it to fail. I'm not very familiar with the electrical system on bikes but am familiar with electronics in general (testing and what not). I will look through the manual but I just thought I would see what anyones thoughts were.

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might be a bit oddddd. but hows the cam chain tensioner and maybe one of the cams jumped a tooth?

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so i got a little more time to look at the bike and checked tested the cdi magnetto how it says in the manual. Everything was ok so I went ahead and pulled the valve cover to check cam timing and they were still sitting fine. I also found that I am now getting a strong spark and the plug was very wet. So after putting the valve cover back on I gave it another go and it fired up like normal. It must have been flooded from the other day and checking the spark with the plug out cleared it out. I've only been able to start in the shop, no riding yet but it seems it was the coil connection that had deteriorated. Thanks for the help.

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Well the first chance I got to ride was today on a poker run. The bike still started fine and ran strong like normal. About 45 minutes in it started missing randomly just like it did before until it finally stopped running. I am pretty sure that it has a weak intermittent spark (popped my other plug in the coil on the trail to look). After it dies again I could sometimes get the bike to start but it would run very rough and would definately not move under its own power. So at this point I;m thinking its the CDI. Maybe the condition of the coil put an increased load on it and caused it to go bad? Any other ideas? From what I got from the service manual there ins't any way to test the cdi, just the coil and magneto and pickup?

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So I just wanted to update you on what the actual problem was. It turned out that the harness going to the magneto was somehow damaged near the raciator. The factory loom was still in good shape but when I stripped it off i could see three of the wires were frayed and missing insulation. I guess they would intermittently short to each other causing all the random havoc. The annoying part was that without stripping off the loom I never would have know because they all still tested correctly for resistance. Thanks to those who helped.

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