Piston seizing in the cylinder

GoldenMotor.com

Thomasp

New Member
Dec 15, 2021
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Hello, I am trying to get info on what is making my piston seize in my cylinder. This is a 100cc motor with the head and cylinder all one piece.it was broken in at 16:1 with Lucas semi synthetic. Never a drop of ethenol. Moderate throttle. At some point I learned a little about lean / rich. And I did move the clip on the throttle needle from the second to the richest setting to the second of the leanest notches. It ran great like that. I didn't run it any different than normal. Normal had also only been about 1 1/2 weeks of breaking it in. So I was almost home and the motor locked up. I used wd40 to lube it and the piston came free. It did this once more about a week later and I was able to bump it in reverse and freed it again. Also I had moved the clip to the center of the five notches on the throttle needle. After the first episode. So it has been around a month and around 300 miles and it has suddenly froze again. And again I can get it free of the cylinder pretty easy. But it just locks up again after a short ride. Can anyone tell me what's likely going on and what the fix is.
 

wrench

Well-Known Member
Aug 20, 2019
825
1,187
93
So Cal
Tear down and Inspect your engine For some reason your having a softy seize
Thermal expansion will cause a soft seize
A soft seize is usually caused by the cyl boar being undersized or the piston ring are too big

IDK I would have to look at you engine It could be something else????
 
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Thomasp

New Member
Dec 15, 2021
20
8
3
56
Tear down and Inspect your engine For some reason your having a softy seize
Thermal expansion will cause a soft seize
A soft seize is usually caused by the cyl boar being undersized or the piston ring are too big

IDK I would have to look at you engine It could be something else????
Thanks for the info. I will rear it down tomorrow. Fortunately I messaged the seller on eBay and I got a message back today wanting me to video the year down and if it is not my doing they will replace or refund it. Kind of surprised me. We will see tomorrow.
 
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Thomasp

New Member
Dec 15, 2021
20
8
3
56
Thanks for the info. I will rear it down tomorrow. Fortunately I messaged the seller on eBay and I got a message back today wanting me to video the year down and if it is not my doing they will replace or refund it. Kind of surprised me. We will see tomorrow.
Guess I never learned how to spell "TEAR"
 
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wrench

Well-Known Member
Aug 20, 2019
825
1,187
93
So Cal
Thanks for the info. I will rear it down tomorrow. Fortunately I messaged the seller on eBay and I got a message back today wanting me to video the year down and if it is not my doing they will replace or refund it. Kind of surprised me. We will see tomorrow.
It's good the seller is working with you to resolve this issue.
 

Thomasp

New Member
Dec 15, 2021
20
8
3
56
I took the jug off and all I found was a few scratches and the bottom ring was a bit stuck but not real bad. Although I am not very skilled with this stuff . I would appreciate all the advice I can get. I feel like I can possibly sand this stuff down and it might be ok. ???
 

Venice Motor Bikes

Custom Builder / Dealer/Los Angeles
Mar 20, 2008
7,337
1,981
113
Los Angeles, CA.
Here are my thoughts on this... Running too lean can cause this problem.

Running too much oil (16:1 mix) makes the mixture lean... (more oil makes less room for gas).
I would break it in at 32:1 (& ride it like you stole it)! , because riding at moderate throttle 'can' also cause a lean condition.
Also... riding it fast means that there's lots of air flowing fast over the engine to cool it!!!
Last thing... Don't break it in using synthetic oil!!! It works too well & the rings will never break in properly.
 
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wrench

Well-Known Member
Aug 20, 2019
825
1,187
93
So Cal
I took the jug off and all I found was a few scratches and the bottom ring was a bit stuck but not real bad. Although I am not very skilled with this stuff . I would appreciate all the advice I can get. I feel like I can possibly sand this stuff down and it might be ok. ???
What did the seller say about the Vid pics you sent him?
 

Thomasp

New Member
Dec 15, 2021
20
8
3
56
The spark plugs looks good like caramel is how I described it to my friend. I haven't heard back from the seller about how to get the videos to them yet. The email will only let me send up to 25 megabytes I cut the videos and compressed them and still can't get under 25. I offered to post them on my Facebook where they could easily watch them but haven't heard back yet.