Piston Skirt

[allen]

Have 50cc motor with score maks on piston skirt in line with ring gap,both sides of skirt to suit top and bot ring gaps, No scoring or damge to cylinder,vertical scoring slightly worse on skirt to suit bot ring gap,The engine appeared to lose sme compression,otherwise all mechaicals bearings etc in top working order... Any help would be welcome, Thanking you, Allen

 

[Frankenstein]

 

[crassius]

if cylinder walls are good, I can only guess a too rich condition may have deposited carbon there - maybe fresh rings would help, or maybe a carb adjust might help, or maybe motor is just getting old and slow near its end of life

these are disposable motors

 

[allen]

if cylinder walls are good, I can only guess a too rich condition may have deposited carbon there - maybe fresh rings would help, or maybe a carb adjust might help, or maybe motor is just getting old and slow near its end of life

these are disposable motors

Thanks for the input and yes it had been running rich,Rightly so about,disposable,Here in AU a new motor complete with carb about 74$ US Way to go I think,thanks again for advise... Stay Safe...Allen

 

[Randall]

if cylinder walls are good, I can only guess a too rich condition may have deposited carbon there - maybe fresh rings would help, or maybe a carb adjust might help, or maybe motor is just getting old and slow near its end of life

these are disposable motors

these are disposable motors ---

 

[Frankenstein]

these are disposable motors ---

Well compared to the other engines in the various vehicles you see the price point would put them in the "disposable" category. If they weren't I don't think we'd have this collective bin of random happy time engine parts. Heads, cylinders, crank cases and cranks in a jumbled heap in a recycling bin filled to the brim. Tool boxes with random almost assembled happy times. There's a big tarp with cylinders and cranks tied to it to weigh it down.

Very disposable

 

[Randall]

Well compared to the other engines in the various vehicles you see the price point would put them in the "disposable" category. If they weren't I don't think we'd have this collective bin of random happy time engine parts. Heads, cylinders, crank cases and cranks in a jumbled heap in a recycling bin filled to the brim. Tool boxes with random almost assembled happy times. There's a big tarp with cylinders and cranks tied to it to weigh it down.

Very disposable

Well I wish this wasn't the case, but oh well.

 

[Frankenstein]

Well I wish this wasn't the case, but oh well.

It doesn't have to be, you can get highly upgraded bearings, get cylinders and pistons coated in stuff like nikasil to make them last even longer, go extra heavy on the oil and have plenty spare clean plugs on hand.

Certainly with the proper modification you could make one of these last a very very long time. Most death is caused by really unbalanced engines and having something break up such as a wrist pin bearing or a ring, which can end up demolishing the entire motor really. Nikasil would stand up to the ring breaking apparently, and has on even bigger machines than these. Well balanced crank will save the bearings a good amount of life.

Everything wears down, luckily enough the parts for these engines are cheap.

 

[Randall]

It doesn't have to be, you can get highly upgraded bearings, get cylinders and pistons coated in stuff like nikasil to make them last even longer, go extra heavy on the oil and have plenty spare clean plugs on hand.

Certainly with the proper modification you could make one of these last a very very long time. Most death is caused by really unbalanced engines and having something break up such as a wrist pin bearing or a ring, which can end up demolishing the entire motor really. Nikasil would stand up to the ring breaking apparently, and has on even bigger machines than these. Well balanced crank will save the bearings a good amount of life.

Everything wears down, luckily enough the parts for these engines are cheap.

Yeah okay thanks for the info.