650/X-2 Possible 750 Electronic Problem

[jetman624]

At or near full throttle I am getting what feels like the ski is miss firing. It feels fine out of the hole, but as soon as the RPM's start to get above 3.5-4 I am getting what feels like a miss fire. The timing of the symptom and frequency is so precise I have to believe it is something electrical. I have checked the Ohms and cranking volts from the exciter coil-- they check out. And I checked the Ohms from the main and secondary leads on my coil and they checked out-- I got nearly the same readings from brand new OEM Kawi coil. Any ideas on what other electrical or other component may be causing this?

On a side note this problem use to go away after a few minutes of riding. I seem to remember a few blips of the throttle and the problem would go away after a minute or so.

 

[Kawikazi]

pull your stator off and look there. Every time I have those similar probs it's always behind the cover. Usually water, corrosion, dirt or frags from bendix stuck to the magnets.

 

[jetman624]

Stator is clean as a whistle...

 

[Kawikazi]

wow! I think that's the cleanest stator I have ever seen!. Imo I don't think it's your electrics then. I would look next at carb tuning on high end. Fuel filters clean? What's your plugs look like after WOT run? What mods do you have?

 

[jetman624]

Is it possible that a coil could ohm out ok and still be bad? It is 18 years old...

The thing is, it used to only do this when it was cold. After a minute or so the problem used to go away. And the timing is so precise and so consistent I can see how it could be fuel related. It seems if it was fuel related there would be greater fluctuations in RPM. It just gets to a certain point and you can here that it isn't running smooth. It doesn't lunge or bog, you can just hear it and feel it in the ski that a cylinder is dropping out as it fails to get up to top speed. Fuel filters are new this season with 4-5 tanks through them. I haven't checked the plugs after a WOT run so I will try to do that next time.

It is a stock 750 small pin with the exception of a timing advance, dual SXR carbs and a coffman pipe.

 

[kevbo]

Pull off the spark plug boots and trim back the wires until you expose the metal core, gently pull on the center wire to make sure it isnt broken. Screw the caps back on and gap your plugs to .022-.025". Solid core wires will eventually break or the insulation will stretch leaving a gap at the boot. Its the most common cause for misfire.

 

[jetman624]

The wires are brand new this season from and installed by JSS. I had this problem before he did the wires, but like I previously said, it used to go away after a minute or so.

 

[Kawikazi]

if you get a chance do a compression check and see if you don't have a low cylinder

 

[jetman624]

I have been meaning to and will do that for good measure, but my thought was that if it was a low cylinder I would have stronger negative symptoms on the bottom end of the power band vs. just the missing towards the top end.

What do you think?