should the wrist-pin be off-center in the piston?

Where's my water? /

Old piston on the right, new piston on the left

The new piston is from treatland's simple 50cc party kit

http://www.treatland.tv/puch-50cc-cylinder-kit-hi-head-p/puch-treat-kit-50-hi-hi-party.htm

I tried to get a picture that showed it was slightly off-center. Is this part of its normal design? Just wanna make sure before I throw it all together and have a glorified paperweight

wrist.jpg

Re: should the wrist-pin be off-center in the piston?

Whiskey Tango Foxtrot /

The wrist pin is centered, the skirt cut out is off-set, which is not uncommon on depending on the cylinder.

Re: should the wrist-pin be off-center in the piston?

#CrazyWayne™ rocks. #CrazyWayne /

It's a good thing having it off-center, do a search and read up on it.

(edited)

Re: should the wrist-pin be off-center in the piston?

Yes and no. Yes it can be, no it doesn't HAVE to be. The pin is offset because on the up and down stroke the piston is not pushing evenly and the force is directed partially to the cylinder wall. The pin is offset to even the load and try to reduce the friction from the lateral load. All modern pistons are made this way.

What you DO need to be concerned about is that your pin height is not the same. You need to level the crown of both pistons to each other and be sure that your pin sits even. This means that if you put one end of the pin into the side of each piston side to side to connect them, the top edges are even. If not you stand to make head contact or drastically reduce compression ratio.

Re: should the wrist-pin be off-center in the piston?

Where's my water? /

Well the piston is going into the kit that it came with, so I'm tentatively just hoping it's all kinda made for each other. Reviews on the site mentioned little beyond port timing (only if you really wanted to eke out the best performance from it), and nobody made mention of head contact.

I'm still gonna proceed with caution, though, once it's installed. If there IS some kind of contact, I can potentially grab thicker gasket material or use my original head (which seems to have less compression than the one in the kit.

Re: should the wrist-pin be off-center in the piston?

Where's my water? /

I did try to scour around a little bit on the site before posting because I know I'd attract at least someone's ire ;) I know you guys get all kinds of yahoos here and you're sick of them.

Maybe I needed to look further on the net in general, but I just want this poor bike back up and running.

Re: should the wrist-pin be off-center in the piston?

#CrazyWayne™ rocks. #CrazyWayne /

Go read this link and look at the links in my profile.

Every thing K-Star / DMP piston port.

http://www.mopedarmy.com/wiki/K-Star_70cc_Kit_Compendium

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