Window piston?

CARider said:
Ignore the pins, they won't catch on either side, just look at the window. Window faces intake.
Click to expand...
The pins WILL fail on the exhaust side, it has happened to me as well as other here in the forums.

Why not just replace the piston for the poor guy with the windows as well as the ring pins being on the correct side, the intake...I do not think that is alot to ask.
 
DAMIEN1307 said:
The pins WILL fail on the exhaust side, it has happened to me as well as other here in the forums.

Why not just replace the piston for the poor guy with the windows as well as the ring pins being on the correct side, the intake...I do not think that is alot to ask.
Click to expand...
The pins will not fail. There are 2 factories currently making the 47mm pistons in China. One is exclusive to Runwell, and the other sells to Yangzhou Flying Horse, Yangzhou Woodpecker, and the piston is $2 cheaper per piston but the quality is worse.

The quality difference is significant. Our pistons will not fall apart like yours did.

I already sent the customer a free extra piston machined the other way so that he can decide for himself.

Logging off.
 
One reason most manufacturers put the pins on the intake side. As the piston heats up on the exhaust side, the side that gets the hottest first, the aluminum expansion rate being 34% higher than steel means that there is a period of time where those pins can get loose which can lead to a failure or damage. Has nothing to do with ring snags, but the properties of the materials.

Yes, eventually the pins will also expand as they get hot, but since aluminum is a better thermal conductor and expands at a higher rate - basically more and more quickly - even if those pins are a tight press fit they can still get loose enough to vibrate out over time.

So, while it may "work" it isn't advised.

If I were the user, I would throw the first one in the trash and use the replacement. Material science being my reason.

Signing out.
 
As some of you may already know, this problem has been amicably resolved between James and CMB at this time, You will see this in the CMB dealer review section of the forum linked below.

motoredbikes.com

USA - California Motorbikes Reviews

Website: https://www.californiamotorbikes.com/ Products: 2 Stroke and 4 Stroke Engines, Complete Motorized Bicycles, Spare Parts for Motorized Bicycles Forum Username: Zane-CaliforniaMotorbikes Ebay Shop: https://www.ebay.com/str/californiamotorbikesstore Ebay Account...
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CARider said:
There is nothing wrong with the piston I sent and it will run properly with great performance with the window facing the intake the way it is currently machined. The rings WILL NOT CATCH the ports. Our pistons are made in a different factory from other factories. I ordered James a window piston machined the other way around free of charge so that he can compare and see for himself!

James, if you engine is not starting, it's not the piston, it's something else. Please email me in our current chain of emails and we will troubleshoot and get it running for you for sure!
Click to expand...
He is correct I installed it and runs great and runs fast as shot. Couldn't be happier w California motor bikes. Customer service is great too! My only question is where is the instructions for this jackshaft
 

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