[cldryder]

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Bike acted strangely. Rode it about 15 miles hiway; it was fully warmed up. Stopped for a light and it was staying at 3000 rpm with no throttle. checkled the choke and it revved even more when I put the choke on. Had to wait about 5 minutes at the light and the engine got noticably hot, about mid scale on the temp gauge vs. normal just barely into the "normal" range. Engine also smelled hot.

Turned the engine off for about 30 seconds. Problem came back and then suddenly went away as mysteriously as it came.

fast idle and hot engine sounds like stuck timimg.. agree? Suggestions?

ps. bike also runs poorly below 3000 rpm but I was assuming it needed carb work I'd do this winter.

 

[Tonys96]

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I think I'd look at a stuck vacuum piston.

You can remove the shelter and airfilter and look down into the carburetors. I'm willing to bet you have one or both vacuum pistons stuck.

You can either try one of the "Snake oil" treatments in the gas, or spray a little carb cleaner and WD-40 on the piston to free it up. Don't try to rotate them as you'll tear the diaphragm.

 

[cldryder]

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Tony. thx for suggestion; I'll try it. Are you going to the bike swap meet next weekend at the MN state fairgrounds?

 

[exavid]

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I'd check the carbs first but there's a good chance you were on the right track about timing. The older outboard motors had a throttle setup that advanced the timing mechanically while opening the carb throttle plate. I had one come disconnected once so the advance worked but the throttle plate didn't open and it acted a bit like your bike. It was too lean with the advancement speeding up the rpms and it would develop more power with the choke on. In that case it was a matter of hooking up a link rod which came off. I know the bike's mostly electronic, but the symptom is similar.

 

[Tonys96]

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cldryder wrote:

Tony.... Are you going to the bike swap meet next weekend at the MN state fairgrounds?

What is the date ???

I'm really thinking about a day trip to "The Davis Rally" in New Hampton, IA this weekend, so far thinking Sunday.

My son is in town this month, on leave from the Air Force, to get married on the 16th, so I have to choose which functions to attend.

But...I am off work for 10 more days, if you want someone to look at the possibilities with you PM me and I'll get you my address, I'm about 2 hours south of you. We could check the vacuum piston thing in about an hour, maybe ride some of the Mississippi river road afterwards.

 

[BenMC]

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I had this problem a couple years back. The revs would stay up and take ages to drop. It was the plastic sliders in the carbs were sticking. Spraying release oil on them fixed it for a while, but eventually the problem started again and the carbs had to be rebuilt.

 

[Skooter]

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Carbs with flat laying sliders often give grief because the plastic slider becomes a victim of its own weightand rubs and wears away on the ally carb body.