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83 cr480 won't start/ backfire

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Hey everyone I recently got a 1983 honda cr480 I knew they can be notoriously hard to start. Engine has good compression,very clean carb. (Pilot jet was tiny bit stripped due to apparent prior removal ). I have Changed oil, drained gas&replaced, new spark plug and air filter. It sounds like it wants to fire up most kicks but just backfires every so often. 1 Have kicked it well over 150 times. Any info or ideas would be helpful. I tried the trick,leaning bike over, 2nd gear rock, 3 slow kicks and finding tdc. I have read to check the cdi, woodruff key. The next step would be to have a legit bike mechanic look at it.

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With all due respect, from the info you have given, I would say let a mechanic look at it.  There are several things that could be wrong.

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On second thought, what did you mean by the "pilot jet being a tiny bit stripped"?  Did you mean the slot where you put the screwdriver blade to remove it was chipped off?  If so, what happened to the tiny chip?  If that tiny chip is in the pilot passage, or something else is in there, it could be causing a blockage.  That "strip", one way or another could be a clue to your problem. 

 

If it occasionally backfires, you likely have spark.  Make sure the plug is clean and dry, and you have spark. Turn the engine over several times with the plug out.  That will clear out any raw gas that might be in the cylinder.  Replace the plug. Remove the air cleaner and squirt about 1 seconds worth of spray carb cleaner into the carb intake with the throttle open, so the spray can get into the intake.  See if it will momentarily start.  If it does, you have a problem with fuel flow.  It could possibly be fixed by blowing out the passages with compressed air.  If that doesn't work---call a mechanic.

 

Does this bike have more than 1 carb??  I am a vintage dirt bike rider, and think in terms of 1 carb.  If it has more carbs, that complicates the problem, but the principle is the same.

Edited by Weezer the Geezer

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Thanks for the responses guys, I am sure it is fuel related as well. I just gave the carb to my neighbor who is a real bike mechanic. I have fixed up other bikes but have no shame if i need a lil help with something like this. I bet it's the pilot jet. when I said stripped I meant the bottom of the pilot jet is a flat head but with the jet whole in middle. It looked like the previous owner took it out or back in like an idiot because it was stripped and stuck in there. After I tried to unscrew the pilot jet a couple times I could tell it wasn't budging. unless those are reverse thread for some reason?. Either way I'll have the carb back soon. Only 1 carb 38 mm kiehn

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Hi mate I have a 83 I got a while back and I have the same problem !! It has started once , did you find the problem cheers Eric 

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Thanks for the link at a quick glacé looks really helpful . When I got the bike 3 month ago the owner had to bump start it behind a Ute , got it home found it on last over size and loose as . Now it has a resleaved barrel and a new makuni carby , air filter , she has good spark . I was thinking timing might be out !!  After reading your link it has shed a new light on things , I have been trying to start her the way a lot of people have said ( flood it ).  Any way thanks heaps mate will let you know how I go , cheers Eric down under 👍

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Just went through the broken woodruff key scene.  It almost put me back into therapy until I figured it out.   

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On 12/10/2018 at 2:12 AM, Jimmy Pascol said:

Just went through the broken woodruff key scene.  It almost put me back into therapy until I figured it out.   

Thanks for the reply ! The woodruff key is what holds the fly wheel in place , checked it out and mine moves around in its slot with the fly wheel off . Seems ok but not sure . Would you mind taking me through how it should be , thanks Eric 

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Thanks for the reply ! The woodruff key is what holds the fly wheel in place , checked it out and mine moves around in its slot with the fly wheel off . Seems ok but not sure . Would you mind taking me through how it should be , thanks Eric 

my 480 is 'easy' to start and never backfires when I kick it.

maybe your timing is off a few degrees...maybe that woodruff key is too small and allows a few degrees of rotation before you tighten it down?

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