MRA 12 piston

GoldenMotor.com

triride

New Member
Jun 28, 2013
23
0
1
U.K.
Hi Guys,

Anyone know where I can buy a Type "B" piston for a FM 80 con rod, (higher wrist pin location).
It is for a China Girl 80cc engine.
I bought a piston off Ebay and fit it to engine not knowing there where 2 types, this one hits the head on TDC!

Cheers, Pete.
 

YesImLDS

Member
Jun 29, 2013
960
12
18
Columbia, Missouri
Here is a link from a buyer on ebay I have bought two pistons from before and received the right one.

This is more expensive though option and I am sure someone will come along with a cheaper link. I couldn't find much else on ebay with the right piston. I am looking for a guy I bought a type b piston, jug, rings, head/base gasket, retaining clips, and wrist pin from for around $25-30.

Edit: I am pretty sure this is the right piston and comes with rings and other etc for $10

http://www.ebay.com/itm/MOTORIZED-B...ORSE-MOTORS-/271904827879?hash=item3f4eca69e7
 

triride

New Member
Jun 28, 2013
23
0
1
U.K.
Hi YesImLDS,

Thanks very much for the lead on the piston!
I have just purchased a piston and a cylinder to be on the safe side.
Cylinder sleeve was not in the best of conditions with some scratches on it so thought I better change that as well.
Was thinking about changing out the head for a high compression head but did not bother for now as I will see if she fires up ok before I throw anymore money at her!
Will let you know how it goes when i've fit the parts :)

Cheers, Pete.
 

YesImLDS

Member
Jun 29, 2013
960
12
18
Columbia, Missouri
Sounds like you got it figured out. Whenever I get a new piston I always do a new jug as well with new rings so I can get everything broken in to each part. That and the jug's coating sucks anyways so those need fixed often enough.
 

Davezilla

New Member
Mar 15, 2014
2,705
10
0
San Antonio Texas
Sounds like you got it figured out. Whenever I get a new piston I always do a new jug as well with new rings so I can get everything broken in to each part. That and the jug's coating sucks anyways so those need fixed often enough.
I've successfully rehoned these cylinders when the nikasil coating was still in good shape, just gotta use a flex hone with 240 grit aluminum oxide stones and just hone enough to break the glaze and put on the proper cross hatch pattern, it's not worth honing if the plating is messed up or if it's a stock jug, but if the jug has been ported, decked, or had any good amount of time spent on it then a rehone can usually save it. I would imagine one could re hone a jug 2 or 3 times as long as the plating is OK and they only broke the glaze with as few passes as possible to get a nice cross hatch pattern.
I've also honed new jugs to get a better cross hatch pattern and to help smooth the port openings after doing a port job, this also helps seat the rings since most these aren't honed very well to start with. I wouldn't recommend doing this with a 3 stone hone or with anything coarser than 240, and it requires a really good cleanup after the honing is done.