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Old 06-24-2013, 11:15 AM   #1
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Default Need Help Diagnosing - No Compression on Pull Starter for DRX

Caveat: New to Nitro motors. Any guidance would be much appreciated.

Problem: I have a Kyosho DRX that I picked up used recently. Worked fine but when I went to start it yesterday there was almost no compression on the piston when I pulled the pull starter cord. It would pull freely for the most part with no resistance. After pulling it a few more times, I would get a few "blurbs" toward the end of the cord pull and managed to get it to turn over and start but it was really difficult.

I've read that this is either a bad one way bearing or the motor is flooded. Some questions....
1. How do you diagnose one or the other?
2. If the former, is this pretty common for nitro motors.
3. If later, what's the proper way to fix.
4. Any other things this could be?
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Old 06-24-2013, 12:38 PM   #2
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Quote:
Originally Posted by soulstice View Post
Caveat: New to Nitro motors. Any guidance would be much appreciated.

Problem: I have a Kyosho DRX that I picked up used recently. Worked fine but when I went to start it yesterday there was almost no compression on the piston when I pulled the pull starter cord. It would pull freely for the most part with no resistance. After pulling it a few more times, I would get a few "blurbs" toward the end of the cord pull and managed to get it to turn over and start but it was really difficult.

I've read that this is either a bad one way bearing or the motor is flooded. Some questions....
1. How do you diagnose one or the other?
2. If the former, is this pretty common for nitro motors.
3. If later, what's the proper way to fix.
4. Any other things this could be?
1) Based on your description it sounds like a one way bearing. If the bearing were working properly the engine should turn over throughout the entire pull. If when you are pulling on the cord it turns the motor over inconsistently
(meaning one pull it turns over, another it doesn't turn motor over) Then your one way is most likely going bad.

2) Its relatively common. I worked at a hobbytown for 5 years and saw some cars never need a one way replaced and others took a new one from the package and two runs later it went bad. It has happened to me in the past once or twice.

If the motor is turning over on each pull regardless of compression it is something other than the one way bearing.
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Old 06-24-2013, 03:00 PM   #3
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Originally Posted by JJBinks View Post
1) Based on your description it sounds like a one way bearing. If the bearing were working properly the engine should turn over throughout the entire pull. If when you are pulling on the cord it turns the motor over inconsistently
(meaning one pull it turns over, another it doesn't turn motor over) Then your one way is most likely going bad.

2) Its relatively common. I worked at a hobbytown for 5 years and saw some cars never need a one way replaced and others took a new one from the package and two runs later it went bad. It has happened to me in the past once or twice.

If the motor is turning over on each pull regardless of compression it is something other than the one way bearing.

Thank you, that was very helpful!
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