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xr 80 wont run

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I have a 1987 xr80 it will start but it has a very rough idle, it will not rev up, when you give it throttle it makes no difference in the idle.

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<p>I have cleaned the carb 3-4 times already and it makes no difference

Edited by mtebear32

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Have you taken out the jets and visually seen light thru them? This may sound silly, is the throttle cable working?

Edited by ickfinger

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With the limited amount of info on the bike in question, I'd suggest starting with a complete tune up, pick up a shop manual if you don't have one, the $20 bucks they cost is well worth it and will save you hours of frustration.

1) check and adjust the valves if needed

2) install a new spark plug [gap is .024~.028]

3) inspect the points and clean, adjust [gap is .012~.016] or replace if worn

4) as Ickfinger suggested, be sure you can clearly see through both the main and pilot jets

  • Like 1

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I am having similar issues with mine although mine runs great i have probs when I dont keep on the gas a bit (it wont idle).

I agree with the previous posts but also check the following b/c you could clean the carb 100 times and still have a crappy ride if these are out of sync:

-Float height, mixture screw @ 1.75 turns out (stock), idle adj screw, needle position

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Good advice from Racer - as might be expected. Being that he's from Manitoba - you're stuff better start and perform first kick - they've only got so much time to ride before the snow returns.

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You can see through the jets, cable throttle works perfect. I have a brand new plug in it, adjusted the valves, how do you adjust the points?

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Good advice from Racer - as might be expected. Being that he's from Manitoba - you're stuff better start and perform first kick - they've only got so much time to ride before the snow returns.

Hahaha! Yes, sadly, here in Manitoba we have two seasons, snow shoveling season and mosquito swatting season :(

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You can see through the jets, cable throttle works perfect. I have a brand new plug in it, adjusted the valves, how do you adjust the points?

Here's what I recommend for anyone having problems getting proper spark with point ignition bikes. There is a more accurate way but this should get you running if you have limited tools.

1)It's always best to remove the flywheel but it is possible to work on the points with it on. Remove the left hand side engine side cover and look through the cut-outs on the flywheel and you'll see the points, you may need to turn the flywheel a bit. Now use a small point file [if you don't have one you can use a small, thin strip of sandpaper folded over so the "sand" part is on the top AND on the bottom] and gently insert it between the point contacts and file them just enough so that both contacts look shiny. [if you're using sandpaper, you'll need to open the points with a small screwdriver, push the sandpaper in between the contacts, and then drag the paper back out with the pressure of the points spring squeezing the sandpaper]This will be easier with the flywheel off, but you can still do it with it on and may take a lot of sanding before they are look nice and shiny.

2)Now you want to clean the contacts. Take a piece of white printer paper and cut 2 or 3, 1/4 inch strips. Now once agin open up the points and slide the thin strip of paper between the contacts, let the pressure of the point spring squeeze the paper, then drag the paper back out. Repeat this 7 or 8 times, tearing off the end of the paper that you just dragged through the dirty contacts, so you have a nice clean strip of paper each time.

3) Set point gap. Gap should be .012~.016

4) Check for spark [make sure you have a new spark plug or know that the one you are using works] If no spark, use the paper again 2 or three times just to make sure they are free of debris.

That should do it. Once again, I strongly recommend getting a manual.

Edited by Racer

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Hmmm.....strange......do you know anything about the history on the bike? Did you buy it not running? Has the head/cylinder ever been apart, perhaps the valve timing is off? Does it pop and backfire when you try using the throttle?

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i bought the bike not running but got it going, then I put new rings in it drove it once for like 100 yards and it died and hasn't ran right since. I have set the valve timing by the marks on the flywheel and the cam chain sprocket

it dot pop and backfire when trying to use the throttle, but sometimes when trying to start it

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it doesn't back fire when trying to use the throttle, it just back fires sometimes when I try starting it

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One thing to try is to have the bike in a darkend area, pull off the left side engine case, start the engine and look through the holes/cutouts on the flywheel, you should see some little sparks between the contacts of the points. If it's REALLY sparking, then you have either a bad condenser or it may have be unplugged, if so, check the wiring under the fuel tank, if all looks good, replace the condenser. If the there is just a tiny bit of spark between the point contacts, all is well. in which case I suspect the issue is with the cam timing, pull out your shop manual and go over the cam timing procedure step by step.

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Have you checked the wire from the rotor to the concenser? I was having intermittatn spark issues and was about to pull my hair out. Ended up finding a break in the wire. Do a continuity test to verify your getting power to the condensor from the rotor.

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