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50 Won't Start

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So I have a '06 crf 50 that won't start or run. It was running fine a few months ago and would start first kick every time. Ever since then it has been a pain to start and wouldn't run properly of idle until it gets hot. I checked the timing and it is spot on. Cleaned the carb completely still not running. Checked the spark plug and it is getting a good spark. I don't know what else it could be besides the valves. I am going out to get a feeler gauge sometime this week to check the valves. Does anyone else have any other ideas of what else it could be? And what are the valve specs?

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Good Video to check and set valves:  

 

Good Video to check and set valves:  

+1 on this fix as it is often overlooked, but often the problem.  at the very least, do it and ensure it is spot on before looking at other possible problems

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My son has the CRF70 -- when we bought it (used) the spark arrestor baffle was removed from the muffler -- ours seems to run a lot better since we installed the darn thing!  Seems these small 4-stroke engines seem to run better with a little back pressure - maybe it keeps the exhaust valve in check....... 

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My son has the CRF70 -- when we bought it (used) the spark arrestor baffle was removed from the muffler -- ours seems to run a lot better since we installed the darn thing!  Seems these small 4-stroke engines seem to run better with a little back pressure - maybe it keeps the exhaust valve in check....... 

 

Without a baffle in place the carb will be jetted to lean. If you take out the baffle you will need larger jets

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So just got the feeler gauge and will get started on checking the valves tonight or some time tomorrow most likely.

Edited by JT_A_CRF

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So just got the feeler gauge and will get started on checking the valves tonight or some time tomorrow most likely.

let us know how it goes.  there may be other issues, but starting with valves set correctly will help everything

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After maybe 5 minutes of adjusting the valves, it started first kick and feels like it at least doubled my compression. Thanks Big Red for the help!

And for next time, do I need to drain the oil before doing this??

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