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Piston Wear

PostPosted: Tue Nov 09, 2021 7:56 pm
by Lisastec
Is this piston wear normal? The marks are on both sides.
Thanks for any help!

Re: Piston Wear

PostPosted: Tue Nov 09, 2021 8:04 pm
by Mutt
Ive seen a hundred like that

Re: Piston Wear

PostPosted: Sat Nov 13, 2021 9:48 am
by Lisastec
So how bad is it? There are marks on both sides.

Re: Piston Wear

PostPosted: Sat Nov 13, 2021 10:05 am
by Mutt
Most likely the air cleaner wasnt doing it's job. Dirt in the air fuel mixture coming up thru the transfer ports and getting on teh cylinder walls with the piston going up and down works like sand paper.

Re: Piston Wear

PostPosted: Sat Nov 13, 2021 5:34 pm
by Lisastec
Thanks!

Re: Piston Wear

PostPosted: Sat Nov 13, 2021 8:26 pm
by 250_Sprint
So your question is probably, ‘Is this usable?’
I am from camp, WILL THIS FUNCTION AS IS, FOR MY PURPOSE? Or does it need replacement?
With the cylinder and piston cleaned up, and a new set of rings, will compression be within specification?
Is the piston pin within specification?
It all may clean up and be within spec. with time and new rings as the only investment.
Of course, if your intended use requires more than a set of rings, then service the cylinder, new piston, new rings, new piston pin bearing and compression should be factory fresh.

I stumbled upon a 1947 engine in a 1951 frame motorcycle for a fair price. I did get the engine to run several times even though the generator bearing on the crank had considerable play.
I have cleaned the cases, replaced all bearings and gaskets and it was not difficult. I took my time. I took measurements before taking apart, bagged and tagged and didn’t lose a part, or have left-over parts.
She is a hard starter but runs and responds. I am going to revisit timing.

So what you have may suit your needs. It may just need cleaning and rings.

Re: Piston Wear

PostPosted: Sun Nov 28, 2021 3:45 pm
by Lisastec
Thanks for your info! The reason we took it apart was that it would start and not stay running or start when hot. All carburetor adjustments didn't help, compression was inconsistent, checked all the other easy fixes with no improvement. I have a new piston, rings and gasket that will be my winter project.
How much side to side motion should the connecting rod have?
Thanks for your advice!

Re: Piston Wear

PostPosted: Sun Nov 28, 2021 4:44 pm
by Mutt
1/16" each side is maximum. Your seals are shot, probably the original 60 year old seals. I have all engine rebuild supplies in stock if ya cant find them