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Really old XT500...help!

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Just picked up two XT500s for cheap and one has to go...

The '79 is a complete basket case that I'll restore/put back together over the cold winter months here in the Land of Lincoln (Illinois).

The '76 started its life as a dual purpose bike but previous owners have pretty much turned it into a dirt only affair. It's missing the battery, lights, kickstand, tack, speedo, etc.

Here's my dilemma...

According to the service manual three wires come from the flywheel magneto: a white wire, yellow wire, and a black wire. The white and yellow wires supply the power for the charging circuit and the lights. The black wire supplies juice for the coil. Since the bike no longer has battery/lights a previous owner clipped those two wires where they come out of a quick disconnect plug. So the only thing hooked up coming out of the magneto is the black wire. But when I hook a continuity tester up to that black wire it's grounding out.

That shouldn't be, should it????

Here's the weird part. The engine is really hard to start (I'm told starting one of these things is an art form under the best of circumstances) and once running pulls strong to about 3,000 rpm but then refuses to go any faster. Like there was a 3,000 rpm governor on the darn thing.

Does this sound like magneto failure?

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Naahh, '79, isn't old.... I had a 1976.

Didn't have to work on it so I can't really help much, butr I have found this website:

http://www.members.shaw.ca/me.walsh/xt500is.htm

Maybe it helps. Good luck with the resto. :lol:

They are really nice bikes. Once you get the hang of starting it, it will fire up in one go. Perfect theft deterrent system if you ask me. :)

Here's a pic of my (ex)

XT.JPG

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Put a timing light on it and see if you are getting advance. I had the street version of this, a '79 SR500, and once I got the starting drill down, one, maybe two kicks each time. Keep after the valve adjustments. I'm guessing you may also have carb problems at the same time. If you put the timing light on it, you should be able to watch the spark advance as the revs climb. If they start cutting out, do yourself a favor and work backwards from the plug: new plug, then plug cap, coil, etc. The magneto coils are available separately, so if one is bad, you can just replace the bad one. Coils can usually be checked with an ohmmeter.

Get a factory manual, the other's don't cover enough.

Speed & Sport www.yamatopdog.com sells factory manual reprints and also has a huge supply of parts for older bikes. That's their claim to fame.

Let us know how this works out.

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You say grounding out but that coil is connected to ground so it has a few ohms of resistance which looks like a ground to a continuity tester. If your having trouble starting it too I would make sure the points are clean and timed correctly. (could replace points and condensor) that should be in a service manual. from there look at carb, compression and all the usual

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you were right about the fact that a continuity tester was a pretty crappy way to check the condition of the magneto coils... after realizing everything was okay in that department i realized that this bike is just kind of finicky in the starting department. You really only get one shot to get these things running, flood it and you might as well just come back in a couple of hours or pull the plug and dry it off.

Now i just need to sell it and concentrate on restoring the '79 xt500 that i got as part of the two bike deal. The '76 is too ratty to be anything but a 'bean field beater' as they call 'em hereabouts...maybe an ice racer or sumpin'.

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