96 xr600r wont start after rebuild

The story so far.I bought an xr600 about 2 months ago , was running fine , easy to start but very smokey , pulled it down had it rebored to 2nd O/S reassembled with new gaskets . While motor was out I stripped the frame and blasted and painted it . Reassembled it all making sure all bits that needed to be earthed were , Tried kick starting it ,nothing , took carby off and cleaned it , still nothing , checked timing , it was ok , tried towing it , it would fire about every second or third compression stroke with the occasional very short burst of running . Since then I have rechecked timing again , rechecked earthing and wiring conections , disabled auto decompressor , replaced resistor in plug cap (with a nail) disconected kill switch all with the same result , I should say that right from the start it has had a regular somewhat weak spark and when I pulled the plug out it had fuel residue on it . I'm out of ideas . HELP :banghead:

Did you check how much compression you now have?  Maybe a valve isn't closing(got damaged/installed in wrong hole?) or the piston rings installed wrong??? Did you check the original squish and then recheck with the new one to verify correct piston?


Spark + fuel/air+ compression=fun,   you have 2

Edited by jjktmrider

Check the wires coming off the stator that feed the CDI, while kicking the engine over you should get around 50VAC.  If less than 50VAC I would suspect a bad stator.



Did you reset your valve lashes?

Also if you took out your resistor and it didn't fix any thing make sure u replace the resistor alot of guys replace the resistor with a suitable piece of copper but Honda put the resistors in the caps for a reason

I had the same issue, but not sure it was caused by the same problem.  For me it was the carb being set too lean.  Ensure the fuel screw is put together correctly and out about 2 turns to start.

Is that collar for the pulse generator on the crank on backwards?

I'm thinking it is your spark plug. Try putting the resistor back in

It ran fine before the rebuild so the issue is from the work done, should'nt be a parts failure. Either the engine isn't grounded good or not assembled correctly/damaged when installing ect...

Edited by jjktmrider

Thanks for the suggestions , I have redone the valve clearances , put the resistor back , pulled carby off and checked mixture screw and put back together 2 turns out  ,stator seems fine (48 vac) . Get nothing at all when kicking over , short bursts when towing , I'm thinking electrical , will go over the wiring on the weekend . cheers

48v ac to my understandings I quite low and should be above 50vac and u should check the stator for ohms resistance as well I'm not sure what that exact year should be but something like 280ohms would be good and anything around 300 or above could be bad but don't quote me on that number someone correct me if I'm wrong

When you say you "disabled the auto decompressor" how did you do that??..As far as I'm aware the only way to do that is to remove the mechanism from the Cam..Is that what you did??..If not are you certain you got the little rod and spring back in the head that controls the working of that auto decomp device..??




Parts 8 and 9 in the above..If they were missing from the install maybe the bike will fire every so often under a tow..Dunno about that as I've never tried towing one if those bits were missing..What I do know is if they were missing you can kick it as long as you like,,it won't start..been there done that.


Then again seeing as we don't even know what year XR we are talking about I may be barking up the later models tree..Carby is mentioned so maybe single carb?? :jawdrop:...Whoops 96 in the title so yeah single carb.. :banghead:

Edited by Horri

It ran fine before the rebuild so the issue is from the work done, should'nt be a parts failure. Either the engine isn't grounded good or not assembled correctly/damaged when installing ect...

I am a newbie as well but with a 1983 Xl600r. I did a rebuild as too and I was two teath off the timing. I swore that I did ir correctly, jumped up and down thinking I was dead on with the timing, that I double checked it over and over and over, while the motor was in the bike. Out of frustration I removed the motor from the frame, removed the valve cover so I could have a good look at the two marks on the upper cam sprocket. I was off by two teath and it acted just the way yours side. It would random fire but never put more than two pops together. 

I disabled the decomp by putting a piece of key steel in the slot auto decompressor , that meant pressing the sprocket hub off . Anyhoo I pulled the rocker cover off again today to check that the pin and spring were in there , they were in there but I noticed the pin was stuck down , I pulled the cam out freed the pin put it back together and it started first kick . Yeehaa . Thanks everyone for the help . :-D

When I rebuilt mine it probably took 100 kicks to get it to start but I never had a problem after that. If you have fuel on your plug then obviously you're getting fuel where it needs to go. I suspect the spark is low or possibly too rich? My bike doesn't like to start if I give it any throttle at all while kicking. It cranks right up though at idle throttle. Make sure you have the factory size jets and your idle mixture screw is 2 turns out. You'll probably be a little lean but it's better than flooding that hog man. To me air isn't a huge issue unless the filter is totally mucked up, you know you have fuel. Sounds like an ignition/spark issue, or you're flooding the bike pretty quick.

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