Pop goes the weasel

73bennie

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Nov 1, 2023
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Location
Arizona
So, I bought a 4-stroke motor from bberry last year and its been running great. But the last week or so it has become increasingly difficult to pull start. Used to start right up, maybe 2-3 pulls at most. Then it became, like, 20 pulls.

A little carb cleaner helped, and then I noticed the idle screw was vibrating itself back out. Threw on some teflon tape and that seemed to do the trick.

Today I was cleaning the bike and had taken the air filter off to clean and I took it around the block a couple times without the filter on to see if maybe the air filter was choking it up or something. During that ride, going wide open, on two seperate instances when I let off the throttle completely there were two pops, kinda like the sound of a backfire. So, I walked it back, put the filter back on, and went riding again. No problems, a mile or so into town, got some groceries, came home. No problems.

About a half hour ago I took the bike back out for a short run. Running fine, then I hit a bump, and at that very moment, I heard One loud Pop, and the bike died instantly.

Not only would it not start again, but pulling the rope and trying to get it to turn over sounded very different than usual, kinda "weak". And on a couple pulls, the rope kinda bound up or locked up, flying out of my hand. So, I can pull it, it just sounds different and won't turn over now.

It's dark so I'll look at it tomorrow, but looking for input/insight before I get into it. Thanks in advance
 
Piston to valve contact I would bet a coke on that 1. I'm betting it needed the valve lash adjusted.

Then since valve lash was too tight it had piston to valve contact, & either dropped a valve keeper or broke a rocker arm. Possibly broken timing belt.
 
How difficult would that be to repair? If even possible. I would say Im mechanically inclined, although I don't have any experience actually working on a four-stroke motor,
So I'm not getting confused? Will it pull over with the pull rope or is it locked up?

Next if it does turn over? Is it making any loud noises. Unusual noise I should say.

Thanks.
 
As of now it will not turn over. The rope pulls. There were a couple of times pulling the rope that the rope locked up halfway through the pull, but I would say that it works despite those couple of instances. Does seem like there's no compression though. Just kind of weak sounding and "loose" feeling during the pulls
 
As of now it will not turn over. The rope pulls. There were a couple of times pulling the rope that the rope locked up halfway through the pull, but I would say that it works despite those couple of instances. Does seem like there's no compression though. Just kind of weak sounding and "loose" feeling during the pulls
Ok 2mrow or whenever? Take the valve cover off of the top of the engine & post some close up pics of the rocker arms & valves. We will go from there. Thanks.
 
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