Strange Symptoms (Road Toad)

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tedwhite - 08/28/06 at 12:49pm

We have been trying to figure this out now for about two weeks and have gotten nowhere.
I started it one day and it over-revved (without twisting the throttle grip) so I shut it off and put it in the garage. It sat for a month as I was busy working.
Two weeks ago I took it to a garage whose owner is a motorcycle enthusiast/mechanic.
We determined the battery was dead. Installed a new battery. Attached a volt meter to the battery wires and got a normal reading for a 6 volt battery.
Started the engine and it immediately over-revved AND the voltage meter showed a jump from 6 volts to 20 volts.
I removed the carburetor slide and made sure it was installed properly.
We decided the possibly the voltage regulator was no longer operating, so I ordered a new one from Strictly Hodaka and we installed that. It made no difference. Same symptoms.
We'd appreciate anyone's thoughts on this.
Thanks,
Ted, AZ

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thrownchain - 08/28/06 at 1:02pm

OK , over revving has zero to do with the voltage reg.
Although with a reading of 20 volts it was bad. Check to make sure the slide is bottoming out in the carb body. If it is the bike should start and stay at an idle, if not it'll start and rev up. Also make sure the slide moves up and down easily, and the cable works smoothly.

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Bullfrog - 08/28/06 at 1:22pm

Thrownchain gave you good information . . . but I'll add some detail:
1. Something mechanical is probably causing your over revving. Something is probably preventing the carb slide from bottoming. You've already said you checked to be sure the slide is installed correctly. Here are two ways to be really sure about that. (I ALWAYS use one or the other of these methods to check when the slide has been out.) A - Remove the rubber air cleaner "boot" and look/feel that the slide is traveling all the way to the bottom and to feel that the slide cut-away is facing the air cleaner. B - Engine OFF, open the throttle with the twist grip then release it completely, feel and listen for the slide bottoming in the carb.
2. Check that the throttle cable isn't way out of adjustment. It could be holding the slide from bottoming. Check that the cable isn't kinked or otherwise damaged such that it prevents the slide from freely bottoming (see"A" & "B" above).
3. It is quite possible that you have an air leak (probably somewhere near the carb - intake manifold cracked, bolts loose, oil injection banjo bolt missing, cracked intake manifold gaskets) which is causing the over revving. If so, the air leak must be found and repaired.
The high voltage reading suggests the voltage regulator is either disconnected or "toasted". Note that as the engine revs higher, the magneto lighting coils will produce higher voltages - which is why there is a voltage regulator in the circuit. A good battery (ie, not dead/damaged) helps absorb a considerable amount of the excess electrical energy. The high voltage readings are to be expected when there is no battery and the voltage regulator is "shot". There is no way the high voltage readings can cause the over revving .
Ed

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tedwhite - 08/28/06 at 2:33pm

Thanks, thrownchain and Ed, for all the useful information.
I'll go down to the garage this PM and start checking out all these possibilities, especially air leaks and determining whether or not the slide is sticking or not seating properly.
Still not sure about the voltage problem. Perhaps the VR isn't grounded? Or there's a short somewhere else?
Ted

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thrownchain - 08/28/06 at 6:43pm

I was going to mention lean mixture from an air leak, but figured we'd attack one thing at a time. The best way to check the slide movement is to actually take the carb off the manifold and watch the slide go up and down. With the idle screw out all the way [ not the air screw] the slide should cover all of the passage thru the carb , if not adjust the cable down until it does. If it won't you may have the wrong cable. Also like bullfrog said check the cable for any kinks that may hold up cable movement. Any sign of a kink and the cable should be replaced.

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tedwhite - 09/11/06 at 11:28pm

Boy, am I dumb.
Took it to Tim Zierman, an old two stroke guy from Minnesota who moved to Sierra Vista, AZ. It took him ten minutes.
He started it up and again it revved way up and then died. He figured it either had air leaks OR WAS RUNNING OUT OF GAS.
How could that be? The tank was 3/4 full. He disconnected the gas line and opened the petcock (the new ones leak, so I installed a second, brass, open/close valve in the line, plus a filter). No gas came out. Rather, one drop every minute. The one drop per minute was enough to eventually fill the carb bowl, so it would start up and then run out.
So he transferred the gas line to the right petcock - which I had never used - and the bike fired instantly and ran normally.
Conclusion: Rust in the tank had completely coated the little tower screen attached to the top of the petcock on the left side. However, the right side was clear as I had never used it.
So I can either buy the plastic tank from Paul or buy the two solution coating kit.
Which would you choose if it were your bike?
Ted

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gregg_floren - 09/12/06 at 12:36am

Ted,
Before I'd coat a tank with anything, I'd try de-rusting the tank with electrolysis.
It's easy and it will clear up all but the worst cases of rust. There is an article about how to do it in the files section.
It doesn't require anything that you can't find around the house and about $5 worth of hardware.
Gregg

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Bullfrog - 09/12/06 at 12:54am

...or - take a look in there. How bad is the rust? You may get by just fine by pouring in 100 count box of 1/4" X 20 hex nuts and shaking them around to "grind off" the loose rust. Clean the tank well, install an inline fuel filter, fuel up and go. (Oh yeah, don't forget to remove the 100 hex nuts.)
Ed

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