Bought xr600r that ate choke plate

Bought a 93 xr600r from a guy that "got it in a trade", that was supposedly running, but happened to have kick lever missing and broken throttle cable. I wanted an xr600r pretty bad and hadn't read about the infamous choke plate problem on these bikes. Just pulled the carb and sure enough, bottom of choke plate is gone. Paid 500 for the bike, now what?

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Edited by j2b50

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Any chance the motor might not be completely destroyed?

Hard to say,,Maybe,,maybe not. No kickstart huh..Go to the lefthand side of the bike and look down towards the bottom sidecover..There's a sort of large slotted looking screw type head in the centre of the cover..Get that out with a large screwdriver or punch if it fails to move or impact driver..Then grab a 17mm socket and put it on the bolt head you see..Try and rotate the motor,,don't force it..The bike will maybe have a bit of compression ,,be aware of that..ie,,if it gets as solid as a rock and won't move don't continue,,something may be jammed so you'd need to get the head off for a proper look in that case..

 

If the motor actually rotates fully that's a good start but not the end..The engine will still need the head off for a proper look at what has occured with that plate..I'd be happy with that bike for 5 hundy but I'm in NZ where bikes are expensive,,be a 1200 dollar possibly more machine as it is here..

Edited by Horri

Always beware of buying used bikes that happen to have certain parts missing that prevent you from hearing it run.  For instance, how often do kick start levers just fall off and get lost?  And why wouldn't the previous owner replace a $15 throttle cable on a supposedly otherwise good bike?

 

You'll need to disassemble the top end of the engine to check for damage.  Luckily most problems can be fixed without tooo much money or effort.

Hard to say,,Maybe,,maybe not. No kickstart huh..Go to the lefthand side of the bike and look down towards the bottom sidecover..There's a sort of large slotted looking screw type head in the centre of the cover..Get that out with a large screwdriver or punch if it fails to move or impact driver..Then grab a 17mm socket and put it on the bolt head you see..Try and rotate the motor,,don't force it..The bike will maybe have a bit of compression ,,be aware of that..ie,,if it gets as solid as a rock and won't move don't continue,,something may be jammed so you'd need to get the head off for a proper look in that case..

 

If the motor actually rotates fully that's a good start but not the end..The engine will still need the head off for a proper look at what has occured with that plate..I'd be happy with that bike for 5 hundy but I'm in NZ where bikes are expensive,,be a 1200 dollar possibly more machine as it is here..

I agree with Horri...However, he forgot to mention you may want to rotate it counter-clockwise.

Had a tappet nut come loose in mine. The bike crunched it up with no problems. Of course the plate probably is a bit larger.

Tappet nut is not going thru combustion chamber,& thus can't bend valves, upon interfering. Although I still wouldn't like either one to happen.

Edited by bork

Exact same thing happened to mine, one day starting and riding fine, next day couldn't start it at all, found choke plate missing and don't remember any strange noises,stripped everything, starting with air filter to see if I was lucky and it had blown back in on a backfire (hadn't heard one though), not there, checked carb inlet manifold, ports, both inlet and exhaust, removed exhaust, not there either, decided it must still be buried in the piston crown so brought a borescope home from work and looked down the plug hole and through the valves ports, before I remove the head, but couldn't see any remains anywhere so decided to take the risk.

Turned the engine over by hand feeling for any unusual resistance, all seemed ok so made new choke plate from 3mm brass plate complete with backfire relief, fitted it to carb and carb back on the bike, two kicks later motor running fine and has done for at least 6 months up to now

Maybe just lucky.

Thanks for all the replies. Bought a kickstart lever and have tried to slowly turn engine, it turns but started feeling resistance, so stopped. Not sure if it was compression or not. Been too busy to take head off to check. That's a little out of my comfort zone, but found a video of xr600r rebuild on YouTube, maybe with that and downloaded service manual I can do it.

There will be a LOT of resistance at compression stroke especially by hand. Pop the spark plug out.

@orjy, could you post some pics of your homemade choke plate? Going to remove the stocker on mine before it gets sucked into the intake.

Exact same thing happened to mine, one day starting and riding fine, next day couldn't start it at all, found choke plate missing and don't remember any strange noises,stripped everything, starting with air filter to see if I was lucky and it had blown back in on a backfire (hadn't heard one though), not there, checked carb inlet manifold, ports, both inlet and exhaust, removed exhaust, not there either, decided it must still be buried in the piston crown so brought a borescope home from work and looked down the plug hole and through the valves ports, before I remove the head, but couldn't see any remains anywhere so decided to take the risk.

Turned the engine over by hand feeling for any unusual resistance, all seemed ok so made new choke plate from 3mm brass plate complete with backfire relief, fitted it to carb and carb back on the bike, two kicks later motor running fine and has done for at least 6 months up to now

Maybe just lucky.

Maybe??? You're hell lucky. I have seen them digest a choke plate a few times without injury but it's rare. Usually you get divits all over the piston crown and combustion chamber in the least and catastrophic failure if you're stars aren't right. Seen holes thru piston, bent or broken valves, cracked sleeves, completed ventilated heads, even bent rods. To swallow one of these and ride away is indeed remarkable.

Didn't take any pictures of the choke plate I made, as it just seemed like another everyday job but I copied the look of the XR's only choke plate, theirs is aluminium though, I just reckoned brass was malleable enough to take the beating it seems to get, coupled with the fact I had a 3" square piece of 1/8" (imperial size) brass in my collection of salvaged off cuts.

 

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Hey Valvesrule'

Not usually lucky, if I fell into a barrel of tits I would come out sucking my thumb!!!

All the same, not even a ding on the piston. 

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