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1985 XR600R Wont stay running once warmed up

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Ok so I have a 1985 XR600R that I have been working on the last few weeks. I took it out riding last weekend (it was pretty cold but I adjusted fuel mixture accordingly beforehand). Full disclosure I have not had this bike long and I do not really know much of it yet. The issue it is having is once it has warmed up it does not want to stay running. I have not checked spark once warm yet but that does not seem to be the problem because it still backfires when kicking. Starting when cold is very easy and the auto compression system seems very well set up. I suspected the valves may be too tight and become tighter once it has warmed up. I plan to check valve clearances this week to cross that out. I do have a fully functioning but uglier parts bike that I can pull electrical components from to see if that is the issue as well. Any insight on this issue would be greatly appreciated. You guys have helped me a lot in the past and I hope you can help me again with this bike!

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Check / replace your stator - faulty stators have a tendency of not working when hot

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15 hours ago, S.O.A.N.Z said:

Check / replace your stator - faulty stators have a tendency of not working when hot

Most likely culprit. Probably not going to find a OEM one. I replaced the one on my 84 XR500R with one from these guys a while back and have had no problems with it. This is the one for your bike though.

 http://www.regulatorrectifier.com/catalog/1985-2000-honda-xr600r-xr-600-stator 

Stewart

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Have you checked compression or leakdown when the bike is cold vs when the bike is warm?  If not, you might want to.  Sometimes a cracked head or bad head gasket won't be bad enough until it gets warm. 

Also, we would appreciate more details on the conditions under which it is dying.  Does it die at idle, but run okay if you are cruising while it is warm?  Does it idle for a little bit, and then die?  

Next time it dies, I want you to turn the fuel petcock off.  Lean the bike over on its side until it stops draining fuel out of the carb hose.  Lean it back upright, turn the kill switch off, and kick it full throttle 6 times really fast with the decomp lever activated.  Then, turn on the fuel for no more than 1 second.  Turn it back off.  Kick the bike 6 times with full throttle and decomp.  Then turn the ignition back on and give it the TDC kick.  Does it start up after that?  Thats what I do with my bike for hot-starts.  I turn the fuel back on at the exact moment I get done with the kick.  Its a float issue I think. but that works for me on my dual carb bike. 

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Ok here is whats up. I swapped the CDI, Coil, Voltage regulator for new ones and applied dialelectric grease to all connectors. I also adjusted the exhaust valve lash because it was just a bit too tight. The bike now starts and runs as it should however it has now developed another issue. It is idling normal after starting then upgrading throttle with no input as if the choke was put on. It does this whether it is cold or has been running 20 minutes. The fuel screw is approx 1.5-2 turns out and I have played with the idle screw to see if I could get it to stop. It is now rideable but it does not idle correctly. It isn't pulsing rpm just upgrading rpm and staying there. If I rev it a bit it does go back to normal idle for a few seconds but then upgrades itself again. Could I possibly have a small air leak in the intake boot? Could one of the jets be partially clogged and when it idles it is leaning itself out? 

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Ok here is whats up. I swapped the CDI, Coil, Voltage regulator for new ones and applied dialelectric grease to all connectors. I also adjusted the exhaust valve lash because it was just a bit too tight. The bike now starts and runs as it should however it has now developed another issue. It is idling normal after starting then upgrading throttle with no input as if the choke was put on. It does this whether it is cold or has been running 20 minutes. The fuel screw is approx 1.5-2 turns out and I have played with the idle screw to see if I could get it to stop. It is now rideable but it does not idle correctly. It isn't pulsing rpm just upgrading rpm and staying there. If I rev it a bit it does go back to normal idle for a few seconds but then upgrades itself again. Could I possibly have a small air leak in the intake boot? Could one of the jets be partially clogged and when it idles it is leaning itself out? 

Yes, air leak or obstruction in pilot circuit would be my guess.

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I plan to pull and clean the carbs tomorrow. I will also pull the after carb air boot off and inspect it. Is there a trick to pulling the dual carbs off? I hated doing it on the 87. I ended up cracking the side of the before carb intake boot. 

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I plan to pull and clean the carbs tomorrow. I will also pull the after carb air boot off and inspect it. Is there a trick to pulling the dual carbs off? I hated doing it on the 87. I ended up cracking the side of the before carb intake boot. 

Start by leaving the carbs in and just pulling the left bowl and pilot jet. Hold it up to light and look through the main hole down the center and the tiny holes in the sides for obstruction. Now run a fine wire or torch tip cleaner through all holes, blow it out and look again, you may see that you have found the problem.

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