> Kurt Simione wrote:
> -------------------------------------------------------
> Note: when I initially pulled the cylinder, I had to use a puller to get
> the cylinder off the piston. Again I didn't see any damage, but wouldn't
> this point to a stuck piston, not tranny?
Did you inspect the rings? Maybe the rings are seized to the piston.
> Moped Lar wrote:
> -------------------------------------
> Did you inspect the rings? ...
A lot easier to replace some rings then to replace an entire piston. Do a ring job and hone it and see what happens.
> Kelikaku קוטין wrote:
> -------------------------------------------------------
> > Moped Lar wrote:
>
> > -------------------------------------
>
> > Did you inspect the rings? ...
>
> A lot easier to replace some rings then to replace an entire piston. Do
> a ring job and hone it and see what happens.
Can get a whole used top end for super cheap. I'm sure someone would almost give you one. Everyone replaces them with big bores.
All that^ is great advice ... IF it's needed .
We need pics before any of that^ could be accurate .
Will do. It's going to be a few days to a week to get some pics but I will get them.
Thanks for all the help, everyone.
> P D wrote:
> -------------------------------------------------------
> All that^ is great advice ... IF it's needed .
>
> We need pics before any of that^ could be accurate .
Damn, so you've soft seized the bike like 30 times and it's still running? That's pretty impressive
If that's what's going on, then yes. :/
So it's been a looong time since I followed up on this. Or, more accurately, since I've worked on the moped. :)
I'm in the same spot, where it will run, and then seize. With some work, I can get it unseized and it will run again.
I've decided I'm going to put a 70cc kit in. Will replace the head, the cylinder, the piston, carb etc.
My only question is on the crankshaft. I have the Piston off now and I'm just wondering how much play should be in the crankshaft. In other words, with the Piston removed, how much back and forth wiggle should there be in the arm? I would say they is very minimal play now, but there is definitely a little. Should there be 100% no play?
Side to side a little play is normal (required even).
Turn the crank to differnt positions (tdc, bdc, 90* from either) and hold the flywheel so the crank cant move from that spot while trying to wiggle the connecting rod in and out. This is to see if there is excessive wear on the big end bearing. You should feel NO movement in and out.
Same for small end, but they tend to wear slower because they don’t spin, just rock back n forth.
How about some pictures of the piston and cylinder for those who read through this whole thread.
A few pics.
I probably should've cleaned the parts before taking pics - I hope it gives you an idea of the condition.
Yeah no, you shouldn’t have cleaned them. That turrbl turrbl mess is very clear evidence that the piston rings are not holding back what they should. Combustion products are burned onto everything and lubrication isn’t working.
You need to replace that. If a piston can fit in the cylinder with a layer of varnish on it and the cylinder, once those deposits are gone, it will be loose.
You could try cleaning it and putting new rings on there, but… I mean… why not just put something fresh on it?
Thanks for the input. My plan is to replace with a 70cc kit before Spring.
Not a high torque it’s an #1 open port aluminum cylinder that is seizing,
If you can’t keep a 1 hp cylinder from seizing you may have a hard time keeping a 70cc kit from seizing
Read up on timing, jetting and tuning
https://www.mopedarmy.com/wiki/Puch_timing
https://www.mopedarmy.com/wiki/Category:Performance_Tuning
You could have wrong # piston in your cylinder, too high of timing, wrong jet and or wrong air box restriction
> Probably Fred wrote:
> -------------------------------------------------------
> Not a high torque it’s an #1 open port aluminum cylinder that is
> seizing,
>
> If you can’t keep a 1 hp cylinder from seizing you may have a hard time
> keeping a 70cc kit from seizing
>
> Read up on timing, jetting and tuning
>
> https://www.mopedarmy.com/wiki/Puch_timing
>
> https://www.mopedarmy.com/wiki/Category:Performance_Tuning
>
> You could have wrong # piston in your cylinder, too high of timing,
> wrong jet and or wrong air box restriction
Fred -
The air box is missing the tube that goes into the frame so that restriction is gone. I have jetted richer to compensate. The plug is a dark brown - rich if anything. I verified the timing myself. It's slightly advanced.
The bike only has 400 miles on it so I'm guessing piston is stock, but I can't prove it.
That piston and rings and cyl are fine.
That’s varnish. Nbd.
You gotta soak em in parts cleaner to get the gunk off and then it won’t be “stuck” anymore.
It’s sticking from varnish. It’s like fucking glue. I had it in an old solo engine I bought. Once cleaned it ran as you would expect. That’s what’s up
> Totally normal JBOT wrote:
> -------------------------------------------------------
> That piston and rings and cyl are fine.
>
> That’s varnish. Nbd.
>
> You gotta soak em in parts cleaner to get the gunk off and then it won’t
> be “stuck” anymore.
>
> It’s sticking from varnish. It’s like fucking glue. I had it in an old
> solo engine I bought. Once cleaned it ran as you would expect. That’s
> what’s up
I honed the cylinder before my last ride (when it locked up again). I used this: EWK 1 to 2-1/2 Inch 3 Stones Engine Cylinder Hone Tool Adjustable Cylinder Deglazer Piston Honer 220 Grit
https://www.amazon.com/dp/B01BHO9ZDK/
That cylinder was 100% clean and decently crosshatched.
The piston I didn't clean, but I have cleaned it before, when trying to diagnose the seizing. I probably should've cleaned it again before my last test.
What kind of oil are you running?
Do you know how to do the piston “drop test” to see if it’s an acceptable fit?
Also, have you checked your ring gap?
It would not be at all typical to see this kinda buildup in a short time.
The castor oil varnish is glue like JBot said. It melts at high temp and then that’s probably why your sticking.
Maybe the whole case is full of that shit and even if you get a new kit, the crap will melt and flow up there. I’m sorta pulling that out of my ass, but if it was my engine, I’d have it split open and start from clean fresh everything.
If you do get a 70 kit. Do a full rebuild of the engine so you can clean it all out as James mentioned. Then a new needle bearing crank can also be installed.
How could you not clean the piston lol.
Yeah everything needs to be clean like in a space shuttle. That glaze took a long time to make. Then yes do the piston drop test without rings. That varnish is in the ring lands too so it must all be cleaned well. When you say you cleaned it was it shiny and aluminum? That glaze looks old as hell. It should look like new if you cleaned it recently
That image looks bad - but not the worst it could be. Lightly honing, and taking another photo will show if there are any imperfections in the bore. One section in your photo might be dirt or might be a crack/casting error. With only 400 miles on it your components should be fine, not impossible if the piston and rings are damaged but they look good in the photo.
Light honing, and light sanding with a fine grit (#300 or higher) of the piston till you can see clean metal. You need to get that combustion chamber clean, put it back together, then see if the problem duplicates. When you hone it, you don't go crazy, just get the honing tool in there and make several passes, it just needs to look clean inside, being careful not to open up the bore any more than needed. When you hone it you're also wearing out the cylinder. EDIT: with only 400 miles on it you might get away without even honing, just using wet/dry sandpaper that you're using on the piston should also do the trick.
If you have a wire wheel on the bench, that might be enough to clean up your piston, and a drill mounted wire wheel could do the trick for your cylinder. Probably before you start sanding, try using a wire wheel and take some photos. If you can get everything clean and you can see clean metal with a wire wheel it's possible that might be all you need. Start with a wire wheel before you start honing and sanding. Make sure everything is absolutely clean before you put it back together. If you do it take photos with similar views and post them, if you can.
Also, did you check to see if the rings are loose on the cylinder? They should flop around slightly. If they're stuck or too tight, they need to be removed and the slots need to be cleaned out. You may want to do that anyway, and when the rings are out, you should lay them flat and take images of them. They should be of even width all around. If there are thin spots, they're worn out. With only 400 miles on them it's likely that they're almost new.
If you pull the piston/cylinder and put in a 70cc kit, you have an entire project on your hands; changing the carburetion, the exhaust, and other stuff is going to come into play.
Just doing some simple maintenance on a 400 mile engine should be both easier and all that you should have to do, but putting a bigger cylinder in will be a huge project comparatively. I'm just trying to give you some perspective. Comparing hours of work to weeks of work. (edited)
> Kelikaku קוטין wrote:
> -------------------------------------------------------
> That image looks bad - but not the worst it could be. Lightly honing,
> and taking another photo will show if there are any imperfections in the
> bore. One section in your photo might be dirt or might be a
> crack/casting error. With only 400 miles on it your components should be
> fine, not impossible if the piston and rings are damaged but they look
> good in the photo.
>
> Light honing, and light sanding with a fine grit (#300 or higher) of the
> piston till you can see clean metal. You need to get that combustion
> chamber clean, put it back together, then see if the problem duplicates.
> When you hone it, you don't go crazy, just get the honing tool in there
> and make several passes, it just needs to look clean inside, being
> careful not to open up the bore any more than needed. When you hone it
> you're also wearing out the cylinder. EDIT: with only 400 miles on it
> you might get away without even honing, just using wet/dry sandpaper
> that you're using on the piston should also do the trick.
>
> If you have a wire wheel on the bench, that might be enough to clean up
> your piston, and a drill mounted wire wheel could do the trick for your
> cylinder. Probably before you start sanding, try using a wire wheel and
> take some photos. If you can get everything clean and you can see clean
> metal with a wire wheel it's possible that might be all you need. Start
> with a wire wheel before you start honing and sanding. Make sure
> everything is absolutely clean before you put it back together. If you
> do it take photos with similar views and post them, if you can.
>
> Also, did you check to see if the rings are loose on the cylinder? They
> should flop around slightly. If they're stuck or too tight, they need to
> be removed and the slots need to be cleaned out. You may want to do that
> anyway, and when the rings are out, you should lay them flat and take
> images of them. They should be of even width all around. If there are
> thin spots, they're worn out. With only 400 miles on them it's likely
> that they're almost new.
>
> If you pull the piston/cylinder and put in a 70cc kit, you have an
> entire project on your hands; changing the carburetion, the exhaust, and
> other stuff is going to come into play.
>
> Just doing some simple maintenance on a 400 mile engine should be both
> easier and all that you should have to do, but putting a bigger cylinder
> in will be a huge project comparatively. I'm just trying to give you
> some perspective. Comparing hours of work to weeks of work.
Ummm...I absolutely would not use a wire wheel on a piston or the bore. The wire wheel is steel and the piston is aluminum. It will chew up that shit so fast. Can you put the piston in the cylinder and push it through with no problem? I have a cylinder here that looks fine but when I push the piston through it gets hung up at a point and gets real tight.
I ended up selling the bike to a forum member who enjoys tinkering with these things. We determined that there was still varnish left in the gas tank after I flushed it once. That varnish was gumming up the carburetor and the cylinder every time I rode it. The varnish would harden when I stopped (as someone mentioned) and lock up the piston.
The new owner plans to properly clean the gas tank and will install a new engine kit for better performance.
Thanks to everyone for all the ideas and assistance!
Thanks for rounding out the thread, so many just leave one hanging.
Agreed. I'm appreciative of the responses I received! :)
Thanks for letting us know the solution, and also thanks to the others who pointed out the cautions regarding the fact about wire wheels being steel and the piston being aluminum. Maybe a brass/copper wheel would be feasible but it looks like the issue was with the fuel tank.
I use a fiber wheel for cleaning most stuff , including aluminum .
It does a pretty good job on rust , too .
I'm the one who grabbed it. Nice bike. Complete. Almost blemish free. Interesting that the side panels are marked luxe hi torque when it's a 1hp with lo torque top end that was factory black. The whole case is covered in varnish, even the crank. The rings were stuck also. May be interesting to try boring out the intake port on the pinhole 1hp cylinder, but i have a cylinder and piston from a 2hp bike i can slap right on there once the tank and case are clean. Straight gas in the tank now and may have to drop the motor to fill the case up with gas and let it soak for a few weeks, so as to not wreck the bearings and seals with brake cleaner. Also soaking the cylinder and piston. It's cold here so Ive got some time. The head of the piston is gauled from previous owner trying to move it with metal on metal, but dome may be salvageable. I don't quite understand why the engine heat wouldn't burn the varnish off the inside of the case and how so much of it was able to get there. Crank moves very freely and smoothly. I think its a legit 400 miler.
The most tenacious gunk I’ve seen on a two stroke is dried castor oil. It doesn’t seem to come off except mechanically or (I think JBot told me this) with heat.
Maybe a really long soak in strong solvent will get it too, but I wasn’t patient enough for that.
Good luck getting it all out and please post if you come up with a “good” way to speed up the process.
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