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1991 Dr650s NEED HELP! PLEASE

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I have a 1991 DR650s that will not start when hot! I have done everything that I can think of to remedy this situation,I have replaced the fuel cock,fuel lines,carburetor to a Mikuni TM40 ,rebuilt the top end including a valve job,I have excellent strong spark but not sure if it is sparking under compression. It will start when cold using the method of, "key off decompression lever held choke on kick 6 times turn key on choke off top dead center kick and will start every time! But will not start after up to operating temp. Will start after sitting for an hour or so.Any help is very appreciated! 

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you did all that to fix an iffy igniton power coil or pickup? Hilarious. It's not the sparking under compression the issue, it's the heat that can often make all sort of coils placed under engine covers misbehave. You will see good spark when cold which then disappears when engine is warm.

Talk to us before changing half your bike next time.... 😉

 

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well the spark isn't any different looking after up to operating temp,can you explain that?  which made me wonder about not firing under compression! 

Edited by BC12

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if it was some tuned race motor with 14:1 CR i could understand your questioning sp[ark under compression, but the stock 9:1 compression at kickstarting speeds is not killing your spark. you are looking in the wrong place... a bit like with all the other stuff you replaced.

Main thing i meant to say is that: at this point, when you changed so much stuff to get rid of the original warm starting problem, it's harder to understand whats causing it NOW, you just added a lot of new variables. If you didnt change all that sutff it could have been easier to identify the problem. 

My bet is on ignition related issue, cant help you more than that, maybe others will.

good luck

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I have been chasing this conundrum for almost a year,after up to operating temp it will run strong and great until I shut it off but will not start even after putting gas in the cylinder or even eather and it will not even pop until it cools off.it will start and run until I shut it down! when up to operating temp after shutting it down I can kick over 20 plus times  with choke  on and it will not flood the plug,I can pump the throttle ,{accelerator pump carb}multiple times and still not flood the plug  

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I hear you and I repeat, still sounds to me like a weak/iffy CDI power coil or ign pickup.

Hope also that it's a proper TM42 and not some cheap Chinese copy of it, these are known to simply not having some fuel passages drilled 🙂

 

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