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Xr100 wont run

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So I recently bought a 2001 Xr100 that supposedly just needed a carb cleaning of course thats not the case. I cleaned the carb and it still wont run. The spark plug was super loose so I checked it and tightened it up. The plug was pretty black. I plan to replace that and try again tomorrow. The bike doesn't seem to have much compression either. I can push the kickstarter down with my hand. The guy that owned the bike drained the oil out and let it sit for a few months too. It didnt have the key ignition on it but he gave me a new one. Maybe I didn't install it right so that could be why it wont start. It doesn't seem to want to start at all. It barely makes a noise when I kick it. Any ideas on what to do to get it running?

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Did you blow compressed air through the pilot jet? Did you make sure you can see through the pilot?

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First thing, make sure you have spark. Remove spark plug from head, insert it back into plug wire boot, lay it on the head and kick. Should be a nice blue spark. Then recheck the carb. Then set the valve clearances. Keep asking questions here. There are a lot of people more then willing to help you out by answering questions.

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Yea I made sure I could see through the pilot jet. It was a little clogged and I had to stick a needle through it. There was a little bit of gun kin the bottom of the carb I couldn't get out because I didn't have any carb cleaner but I thought it looked alright. I'll check for spark next. Thanks for the replies.

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sounds like an ignition problem. especially since you had to replace the ignition switch.

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The bikes not getting any spark. I'm going to try a new plug.

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Yeah pretty much everything is the same. The 100 has the weakest spark in the whole world. So sometimes you can have a spark but can't it because you're in too bright of sun light. That's happen to me at the track a few times.

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i wouldnt say it is weak. mine will blast a spark at least an inch easily. iv got a 2002 cdi ignition.

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The ground is the bolt underneath the gas tank that pins the wire that goes to the kill switch to the frame, right? I'm 99 percent sure I installed the key switch right. Its plugged all the way in.

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Yes of course haha. I tried it in both on and off positions. I had a friend come over and look at the bike and he pulled off the stator/flywheel cover and it was all muddy and dirty behind it. Hes gonna come back over the weekend with his flywheel puller and look at it again.

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Here's some photos of the flywheel cover. It seems there was a rock kicked up at the cover and put a hole in it which allowed dirt and mud to get in there.

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And a pic of the bike

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Also all the electrical connections seem fine

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Edited by DMS 56

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So with a new stator it should run? And not sure about the tires. I'll check later.

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Liberated from factory service manual.. with a little extra info from me

If there is no spark at plug, check all connections

for loose or poor contact before measuring each peak voltage

Disconnect key switch (locate "bullet" connectors at end of switch harness, disconnect bullets (Black / white wire and a green wire)

Disconnect the kill switch (follow harness from switch, disconnect it at "bullet" connector - Black / White wire)

Remove spark plug, Set Spark plug gap 0.6-0.7 mm (0.024-0.028 in) Reinstall it into the plug wire boot, lean it against the head and kick engine over and check for spark.

If no spark...

All voltage readings are AC, with respect to good clean ground on frame.

Spark plug must be installed. Setup your meter leads, set DMM to AC Volts, if available use the Min/Max function to get the best reading (Most Digital Multi Meter screens don't refresh quickly enough to use an 'unsecured' reading reliably) - You MUST disconnect each plug containing the indicated wire prior to taking the reading!!! Do not check readings by back probing the harness!

give the engine a good healthy kick over and record results.

Alternator exciter coil peak voltage 100 V minimum (Measured at Black / Red wire @ CDI: If voltage is less, you may have a break in the harness. Recheck reading at plug coming out of magneto cover. If it's still too low, you've got a dead stator or magneto - possibly someone has hit the magneto with a hammer trying to remove it?). If the reading is acceptable 100V AC or more, continue on.

Ignition pulse generator peak vo ltage 0.7 V minimum (Measured at Blue / Yellow wire @ CDI : - If you're using an auto ranging meter you may have to change the working range of the meter to get an accurate reading here; Again, if the original reading is poor; check Blue / Yellow wirecoming out of the Magneto cover. Also note CRF/XR 80/100's are real chain chuckers. If your bike has recently tossed the chain, there's a good chance the pickup coil is damaged (under magneto cover, small black box at 2 O'clock position with respect to magneto - just look for cracks.)If the reading is acceptable, continue on.

Ignition coil peak voltage 100 V minimum (Measured at Black / Yellow wire @ coil, a low reading indicates bad CDI or damaged harness/plugs) If the reading is acceptable, remove the spark plug cap (hold cable, turn cap to left - may have to give it a final tug to get the boot free of the wire), set your meter for resistance and measure from the Black / Yellow wire at coil to the spark plug wire (jam lead into exposed end of spark plug wire). Reading should be about 5-20 Ohms - This value is from my general experience. It is not law. Generally, read with a good quality DMM {I use a Fluke 187} 5 - 20 Ohms is good. More is bad. Dead short (0.00 Ohms) bad. [/font]

Edited by theraymondguy

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So with a new stator it should run? And not sure about the tires. I'll check later.

I wouldn't bet the farm that the stator is the culprit. See post above, you've got a chunk out of your engine case (between sprocket and flywheel) indicating a possible problem with pickup coil (ignition pulse generator). If that counter shaft (front) drive sprocket gets any sharper you'll be able to shave with it.

Edited by theraymondguy

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