Forgive me if this has been covered but I am new to this forum and might have missed it. Anyways, I have a Ebay 80cc/66cc Chinese 2-stroke with less than 20 miles on it. The first day out it ran great, typical drivetrain noise. The second day out, it did ok and then started making a high pitched whine at almost any RPM. I started up a hill, trying to get the bike home, when I lost power and it felt like the clutch was engaged. After I limped the 6 miles back to the house, I took it apart to find the small bevel gear stripped 3/4 of the way up. I also noticed it was not seated completely against the crankshaft. So now I have a new gear installed and it continues to wonder on the crankshaft. The gear fits very tight and seems like the screw stays tight. Has anyone seen this before and is there a fix for it? Any help would be greatly appreciated.
Stripped Small Bevel Gear - NEED HELP!!!!
- Thread starter musicman8302000
- Start date
Wandering....did you install the woodruff key? All else fails, RED lock tite will or should hold it in place (after application let dry). much better then a new crankshaft. BUT if you ever need to remove it for any reason, you will need to apply heat.
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The key was installed when this happened. I have not tried loctite but that sounds like it would help. I have also thought about replacing the screw with a bolt to try and tighten down a little more.
Buy a screwdriver with a square shank and use a cresent wrench on it when tightening the screw head on the small gear. Apply lots of pressure against the head as you tighten and make sure the screwdriver fits the slot in the head. If it's too small it will just slip out and not give you the necessary torque.
Tom
Tom
music
sand file grind the flat part of the crank so when you tighten the screw it fits tighter
welcome to the wonderfull china quality control
also watch the flower nut on the clutch I had one strip out before I even got the motor to start
sand file grind the flat part of the crank so when you tighten the screw it fits tighter
welcome to the wonderfull china quality control
also watch the flower nut on the clutch I had one strip out before I even got the motor to start
Hey Musicman, Al is right about the key. The only way for the gear to spin free is if the key is missing or sheared. Also sometimes when installing the gear the key will get pushed up behind the gear. I've done that a few times. Take the gear back off, Check that the key is still in place and not sheared and that the key slot in the crankshaft is not fubar'd. Then you just have to make sure the key stays in place while installing the gear.
fatdaddy.
fatdaddy.
Super glue the key in place on the shaft, let dry and install the gear. This is especially handy when installing the magnet.
Wandering? sounds like you have a lot of play in the crank, side to side. Will not hurt anything but proves how sloppy these engines are made. Did you need the puller to get the gear off? And if you put the gear on without the woodruff key does it seat better, if so the key is too tall, or too wide. Also I use sticky grease on the gears or you don't go too far. Have fun, Dave
In cases like this, what the OP posted, that is the only time I'd use RED lock tite on anything attached to the crankshaft or clutch shaft. I use it on all my studs, and when dry, unless I use heat...it's there for duration. I've tried to pull a stud without heating, and it was a no go. Was afraid I was going to do damage. If the gear fits tight on a shaft (we're not talking about crankshaft lateral play), then replace the key and tighten. If I had lateral play in a crankshaft, I'd try some washers (shims) on the external before I opened the case. Just a thought.
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Forgot to mention, There are AT LEAST two sizes for the key. That means there are at least two sizes for the key slot in the gear and the crank. The slot in the crank, the slot in the gear and the key itself all have to be the same size. I run into this problem almost every time I try to change the bevel gear. Sorry I didn't let you know sooner. I've custom made my own key at times (very carefully with a very small file) to get around this problem. If the slot in your gear is too small it will just push the key behind the gear and you'll NEVER get it right. If it's too big it will allow play in the gear and shear the key every time. I know, I've been through this, (and through this,) time after time. You can try ordering a gear from another company and HOPE it's the right size slot. I just gave up and custom make my own keys now. Only if the slot in the gear is too small you can try fileing it to size. GOOD LUCK, it only takes patience.
fatdaddy.
fatdaddy.
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I have a engine (free for experimenting with) that the sprocket is wielded.
Bro, are ya really tryin to figure out chinese enginering? Good luck with that.
fatdaddy.
Batch of inferior stock, heck, it might not have been tempered, or tempered enough...who knows? Only thing I can figure out.
How are the teeth on the flywheel gear?
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Did someone say sake?they need to start paying better wages and not giving out the sake before work
Well, perhaps AFTER work.