I broke the piston, help

James Foster /

Well I was re-tapping the threads on a busted cylinder stud hole, and was getting up to get another tool, but I hit the bike kinda hard when I got up, and in a millisecond the scooter hit a table next to it. Unfortunately, when it hit the table, it also hit the rear brake, which got depressed enough for the engine to kick over. Whack! SNAP! So my piston's Skirt got damaged, and I'm afraid that if I put it back in that it would screw up the port timing, not to mention scratch everything else.

Since it's highly unlikely that it could be somehow repaired, my question is where the heck can you find a replacement piston? I don't care if it's used or not, as long as it isn't damaged. And yes I already looked on google search, but didn't find much. Can somebody help me on this?

Thanks,

JF

Re: I broke the piston, help

JF, it's important you get the right information to the right people.

1. Try posting in buy/sell.

2. Tell us what kind of bike/piston you broke/need.

3. Do the same on the MRA site.

Surely someone out there, who has up kitted there ped/scooter, has a piston lying around for you. I've got a Tomos piston I use for a pencil holder if you need it.

Re: I broke the piston, help

Don Pflueger /

what bike and what engine?

Re: I broke the piston, help

James Foster /
jf OP

Oh sorry, It's a 1980 Honda Express NC50, and I believe it's an A3 engine.

JF

Re: I broke the piston, help

The damage either does or doesn't affect port timing. Take a look and see.

Remove the cylinder and mark it as to piston position at BDC and TDC and push the piston in the cylinder, orient it correctly, move it in and out and see if the damaged part leaves a port open. If just the edge of a skirt was chipped i doubt it will come anywhere near a (stock) port.

Of course i have no idea how big the chip is and i'm assuming it's in the one centimeter range. Round over any sharp edges with a file .. some pistons are deliberately relieved in the skirt area so it doesn't touch the piston walls, reducing friction.

Re: I broke the piston, help

James Foster /
jf OP

The attached pic shows the piston and the pieces that came off. The biggest chip was on the intake side, to the left. Exhaust side wasn't as big, but it put a chip right in the middle. Do you think that most likely I'll have to get a new piston(I was thinking of modifying it slightly to accommodate a puch piston), or might the chips actually help, if smoothed out?

Thanks,

JF

1104980223_picture_28.jpg

Re: I broke the piston, help

See Ya Moped Army /

I'd get a new piston. It'll cost you a lot more if the engine seizes due to additional piston chips breaking off.

Re: I broke the piston, help

James Foster /
jf OP

True, you've got a point there, that's why I really don't feel like putting it back in. I was thinking that maybe I could put a puch piston in it's place, by removing the original upper connecting rod bearing, and putting a puch one in it's place. The two piston's are identical in shape, just the puch one has a bigger gueigon pin hole. It might work, just not sure if I should attempt...

JF

Re: I broke the piston, help

holy cow .. looks like it got caught in a garbage disposal after an angry girlfriend took a hammer to it.. It'll probably still be useful as a paperweight if you don't expect it to hold down too much paper.

Re: I broke the piston, help

My recomendaton is not to put a diffrent piston in. Be patient and a new piston will reveal itself in a week or so

Re: I broke the piston, help

Don Pflueger /

that piston is junk. too much of the skirt is gone. go to www.network54.com. from there search for the expressly mopeds forum. join the forum and ask those guys where pistons can be found. the express is the bike they deal with most.

Re: I broke the piston, help

James Foster /
jf OP

Ok I'll try that first before I modify anything. Thanks guys. :)

JF

Re: I broke the piston, help

Jonas Quimby /

Now would be a good time to look into a cylender/piston kit.

I'd love such an excuse to go for more power!

I need money

James Foster /
jf OP

Yea I know, it is the perfect excuse. ;) If only I had a little more money...

JF

Re: I broke the piston, help

Try your Honda dealer. They might still be making the pistons. Thats where I get all my parts, just the local yamaha/honda dealer.

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