Hawk Died On Me. HUH???

[Sport Rider]

on the way home from work today the hawk just suddenly quit running. no indication of problems prior to the event. I was running it hard, full out at 7500 RPM. I recall noticing that I was at 59 MPH at 7500 RPM with a 17/50 sprocket set (in case anyone is interested).

the motor quit and even though in gear coasted to a stop. Once stopped, I tried starting it. it would sputter a short bit but die. after a few tried, what I discovered is that it would run at idle, but I could not rev it up without choking it. could have been fuel starvation.

Called the girlfriend who brought my truck and trailer to me. loaded the bike up. tried starting it again, just for fun. idled fine, but could not rev it up. Drove home, which was only a 5 mile ride.

Once at home, I decided to try starting it again. Started right up and revved up like nothing had ever happened. WTF???!!!

I have not done anything to it at this point besides pull it into the garage for the night. Anyone have any troubleshooting ideas or tips that might help deduce what was going on??????

I initially thought that perhaps something had vibrated loose in the carb, perhaps the main jet or something. pilot was working as it would idle for minutes without any indication of problems. lift the slide just a bit and she'd choke and die. I thought perhaps the float had stuck or something. wrapped on the carb and tried starting it again. no luck. I also disconnected the fuel to see if it was flowing. it was. I also popped the cap off the tank to be sure there was no vapor lock. I'm going to pull the carb, cause I want to swap some jets anyway.

[pistolclass]

Check for obstruction in the fuel line\tank\filter.

[mq1991]

Would a bad CDI cause this? Or maybe a connection came loose?

I would check the carb stuff first though.

[jaymalmat]

I had the same symptoms as you describe where it would be fine one minute and then just die. Wait about an hour an ran like it never happened. I figured my Hawk just didnt like going to work bc it usually happened in the morning on the way there. After continuous WTF moments, it turned out it was my ignition coil. Visually it looked all good but the connection just wasnt up to par.

[pete]

Heat....
7500rpm & carbs at the back with very little air flow..
is there a heat riser block between the head & carb?
heat riser block.... bit of nylon/plastic to stop heat traveling
back to the carb.....

PS... if it has a rubber flange a heat riser is not needed...

[Wolftrax]

Fuel line? I had a KLR that did the exact same thing. It had a very cheap fuel line and when it got hot it would collapse and crimp at the bend. Replace it with a better quality line and never had problem again.

[Sport Rider]

Originally Posted by jeffrey

Maybe the carb vaperlocked. Just an idea if you still have the cat in the pipe.

I unscrewed the top of the carb where the throttle cable pulls the slide. did not sense any pressure when I did that and no change in the symptoms after I did. still would only run on idle.

[Sport Rider]

Originally Posted by pistolclass

Check for obstruction in the fuel line\tank\filter.

I considered that. perhaps the massive vibration shook something loose. I removed the gas line at the petcock to confirm there was fuel flow and also removed the gas cap to be sure there was not a vapor lock there.

[Sport Rider]

Originally Posted by pete

Heat....
7500rpm & carbs at the back with very little air flow..
is there a heat riser block between the head & carb?
heat riser block.... bit of nylon/plastic to stop heat traveling
back to the carb.....

PS... if it has a rubber flange a heat riser is not needed...

rubber flange.

[Sport Rider]

Originally Posted by Wolftrax

Fuel line? I had a KLR that did the exact same thing. It had a very cheap fuel line and when it got hot it would collapse and crimp at the bend. Replace it with a better quality line and never had problem again.

I pulled the fuel line at the petcock, but not at the carb. Note to replace it though just in case.

[Sport Rider]

Originally Posted by jaymalmat

I had the same symptoms as you describe where it would be fine one minute and then just die. Wait about an hour an ran like it never happened. I figured my Hawk just didnt like going to work bc it usually happened in the morning on the way there. After continuous WTF moments, it turned out it was my ignition coil. Visually it looked all good but the connection just wasnt up to par.

will check these connections too. I did consider it may be a spark problem, and pulled the plug cap, but nothing further than that. this did not change the symptoms though. seems like it having more time to cool down was the answer. I'm thinking perhaps the fuel line going into the carb. but just a guess.

[Sport Rider]

thanks everyone for your help and replies!

I'll replace the fuel line, check the coil and I'll also be taking the carb apart to check it since I want to rejet anyway.

Work on Thursday, so I'll try running the pee-wad out of it again!

[2LZ]

Sounds like a CDI to me. They get hot, quit, restart when cool. That would be my guess.

[mq1991]

Originally Posted by 2LZ

Sounds like a CDI to me. They get hot, quit, restart when cool. That would be my guess.

Maybe it is breaking down internally, and is shorting out at higher rpm. It will be interesting to hear the solution.

[2LZ]

Originally Posted by mq1991

Maybe it is breaking down internally, and is shorting out at higher rpm. It will be interesting to hear the solution.

That's exactly what happens. I've replaced two on my X-Moto already. Of course, one falling on the hot exhaust pipe when the little rubber mount failed didn't help matters. ;-)
I have a spare at home, just in case. Dirt cheap.