So I get my scoot back from the shop yesterday after I had it dyno-tuned and the carb re-jetted. It ran just fine all the way home because it was gray and overcast and pretty cold. This morning, it ran fine, because it was in the high sixties, so it was cool. This afternoon on the way home from work it was in the 80's, no traffic, so I'm cruising at around 70-75 mph and the motor decides to start coughing and sputtering until it finally dies and I coast to a stop on the side of the freeway.

I've got plenty of fuel, so I think it might be an electrical problem, but the lights work and the starter motor works. I let the bike sit for about ten minutes and it starts right back up. A little further down the road, same thing happens: Throttle doesn't respond, the motor starts to cough and sputter, then it dies. I start pushing the bastage home, try starting it again, and it fires right up. I pull into my garage, let the bike idle, and then it coughs, sputters and dies again.

They put in a 200 main jet when they dyno-tuned it yesterday, so I don't know if I'm getting too much fuel in the carb when I'm at /4 throttle. I don't think it's overheating either. Spark plugs are fine, not fouled.

I'm beginning to think the seal between the carb and the intake isn't seated right and as it heats up it might bulge and let a whole bunch of air in the carb choking it out. Plus it was a warm day, the motor is hotter......

 

Sounds like you may have some crud in there barring anything that was done, a 200 jet sounds a bit fat, but shouldn't cause you this problem as your symptoms do not reflect a 200 main jet. Possible problem with your vented gas cap not venting? Next time it does this pop the cap loose and see if it returns to normal running.

 

Thanks for the feedback. My other thought was I had some junk floating around in the that might be causing some interference. But then again, I didn't have that problem in cold weather, only in hot weather which makes me think the seal between the carb and intake isn't seated properly and when it heats up, it lets in too much air and it chokes the motor out.

Well I just started her up to go for a quick ride, and it started up fine, but then it died on me.....tried starting it up again, won't turn over. So I guess that throws me theory out the window.....I'm starting to think there's junk in the carb that needs to get cleaned out....don't have the time to fart around with it right now, though.....

 

Sometimes the ign. pick up will do this from the heat.May not have anything to do with the carb.

 

I tried firing up the bike up and it won't turn over now......so I don't think this has anything to do with heat, just crud in the carb. Unless I'm missing something.

 

Pull the carb bowl off and unscrew the low jet and see if there are any signs of blockage, pay attention to the gas in the bowl if there is any crud in it. Clean things out with some gumout spray and blow it out good with some air and re assemble it. See what you get

 

Thanks brother! I'll give it a shot.

I didn't start having this problem until I got the bike back after having it re-jetted and dyno tuned. I've never re-jetted a carb, but is it possible to leave a little crud or gum up the jet while making this repair?

 

Anytime a carb is opened up and worked on, there always is this posibility.

There's always the possibility that an intake boot seal may have been compromised when they worked on the carb, some mechanics are clumsy when they handle things, check for a leak with wd 40 or carb cleaner by spraying around the seal and see if the idle changes. Take care not to allow the spray to go into the carb while you do this or it will give you a false reading.

 

How much do you want to bet that they "find" some other problem and want to charge me for it? I wouldn't put it past them, especially since they know that I'm new to HD and pretty green?

 

.........How much do you want to bet that they "find" some other problem and want to charge me for it

Geez, I think we are related or something!

Great minds think alike!