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Discussion Starter · #1 ·
I'm well aware that I'm probably the millionth person to make a post about this on here but I'm at a bit of a loss on what to do馃槀.

About a month ago I bought a 50cc air cooled engine and it ran ok for the first couple days. Then one night I had it running, it slowly died over about 5 seconds and when I tried to start it again the pull start was really stiff for a couple pulls but then it loosened up and i got it running again.

Every time I started it since then the number of pulls it took before the pull start would loosen up increased to the point where now it's impossible to pull every time.

When i remove the spark plug its easy to pull again which to me suggests its got too much compression.

I've read a lot of forum posts about it and so far I've tried:
  • Regapping the coil at the flywheel
  • Making sure piston isn't hitting the spark plug
  • Cleaning out the carb
  • Cleaning the reed valves
  • Cleaning the inside of the head (it was actually really clean anyway but i still thought it was worth a try)
I've heard people mentioning hydrolocking but im not 100% sure how to fix that as this is the first time I've worked on an engine.

I'd be really grateful for any help on this.

Thanks!!
 

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What's your poison? Mine is 40:1
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Hey welcome, there is a possibility that the crank bearings are going bad. Those stock crank bearings are not very good. How did you break in the engine? When you had the head off how were the Rings?
 

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Discussion Starter · #3 ·
Hey welcome, there is a possibility that the crank bearings are going bad. Those stock crank bearings are not very good. How did you break in the engine? When you had the head off how were the Rings?
Thanks for the reply!

All I did was run it with 40:1 with the choke on for about 15 seconds and played with the throttle a bit before it would die. I think the longest i ever had it going for was about 30 or so seconds. I bought the engine 2nd hand so I assumed it was already broken in but as I said im really new to this so I could well be wrong.

The piston rings looked ok to me but I'm gonna try and attach a photo of them so you can have a look aswell. Let me know of you can see it and if you need me to take any more馃憤.

Thanks again!
160911
 

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Looks ok probably just to mutch oil go 40:1 one knee on the bike one oven mitt and one good firm hard pull is the way to do it
 

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What's your poison? Mine is 40:1
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I would probably definitely try a few more times, and if it's been second hand, maybe even pull the carburetor apart make sure it's clean and there are no intake leaks around the gaskets. Some of my second hand engines I was really surprised at how some of them even ran. When I pulled them apart there were some crazy surprises
 

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I would probably definitely try a few more times, and if it's been second hand, maybe even pull the carburetor apart make sure it's clean and there are no intake leaks around the gaskets. Some of my second hand engines I was really surprised at how some of them even ran. When I pulled them apart there were some crazy surprises
I had a two-piece come loose before and after it was still running like that I definitely have questions it had zero compression lol
 

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Did you check the flywheel? Is it correct on the crankshaft and is nothing broken from the starter?
It's also possible that something of the clutch is broken. Or a loss screw of the crankhous.
 
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