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Steve Wagner

XR100R 1985 no fire

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To check the crank, just look for circular marks on the taper.  There should be zero marks.  Plus you can see damage on the flywheel as it spins around the key.  But, if it's not backfiring, it's probably didn't spin. If it gives you much more of a headache, you can easily swap it for a CDI ignition.  

Edited by socalxr

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On 9/30/2018 at 11:50 PM, Alexxxx said:

What number is stamped on the flywheel?

F130- ??

F130 is stamped on flywheel. Installed a new aftermarket carb on it, and switched spark plug cap to a resister cap and she runs!! Idles ok but at full throttle it wants to stall and backfire and lose power. So some fine tuning to be done there. 

Thanks again to everyone’s help. I’m sure as I get deeper into this project I will have many more questions

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Just wanted to ensure you got the correct flywheel F130-58 for XR100 and not F130-54 for XR80 with different timing marks.

Now that your engine is running, it's important to check ignition timing with a timing/strob light. That is extremely important because even small deviations lead to the above described running symptoms.

When timing is done you may think about the carb and other things.

 

Btw., the engine runs with or without resistor(s) in spark plug or cap. That resistor is only to eliminate distortions in electronic devices at the environment.

There are lots of faulty plugs and caps out there, even new ones.

Edited by Alexxxx

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I think it is 130-58. I do need to fine tune the timing. When I got it going it started clicking under the valve cover. Shut it down and removed the cover to find the cam chain sprocket had loosened. Tightened the sprocket but now I think cam chain is loose. Didn’t have time to investigate further but will have to look at before starting up again

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When the cam chain sprocket loosened it resulted in the woodruff key getting sheared and messed the timing. Got a new key and learned the hard way I need to torque the flywheel nut before I ride the bike, sheared the damn key again. Before it sheared the key it was running well but does feel like the clutch slips. Revs up but power stops making it to the rear wheel. 

Woodruff, clutch, fork seals, steering head bearings and rear shock bearing and she should be good to go.

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