Identifying what motor I have

[Paul Crungus]

I have what I think is a 66 or 88cc motor that I need to replace the piston for. My micrometer's battery died so the measurements are not exactly accurate but the total height of the piston is about 50mm. The width of the gap on the sides is about 23mm. The number on top is #3. What kind of motor is this and where can I find a new piston?

 

[Gordy]

Measure the diameter of the piston

 

[Gordy]

How come you need a new piston?

 

[Chainlube]

L44 battery. You need the wrist pin diameter and the piston diameter.

 

[robe]

There are high hole and low hole pistons as well. Referring to the distance from the crown to the center of the wrist pin.
You can have the correct diameter of both the wrist pin and the piston but still not be correct.
How to find the correct one in relation to what you have is hard to tell because this critical measurement is usually not shown in the description of the replacement pistons. Like these.

Amazon.ca

Amazon.ca

 

[Paul Crungus]

There are high hole and low hole pistons as well. Referring to the distance from the crown to the center of the wrist pin.
You can have the correct diameter of both the wrist pin and the piston but still not be correct.
How to find the correct one in relation to what you have is hard to tell because this critical measurement is usually not shown in the description of the replacement pistons. Like these.

Amazon.ca

Amazon.ca

I have a type B high hole piston motor. I ordered a set with the head and intake together off amazon for now. Heres another question off topic but related to the motor, before it had been giving me issues of only running with full throttle going down hill and it would die the second I went uphill. I recall reading somewhere it was a bad crank shaft seal since I noticed a bit more oil than normal coming out the exhaust side, but like I said I do not remember for sure.

 

[robe]

I'm not sure but it would seem to be running too lean. Once a load is applied there is not enough fuel. Look at the plug.
Maybe others will chime in with more ideas.
You can spray carb cleaner at the seals and listen for a change in RPM.

 

[Paul Crungus]

I went ahead and replaced the seals anyways with some red RTV since I had the seals laying around. Once I get the piston on then Ill just be waiting for a new magneto to come in.
I tried just about everything tuning wise when I was last messing with this guy but Im hoping the new top end and new seals with fix that.
Have you tried using a gasket sealer or something along those lines with a gasket for the top end? I want to try it since on both my motors the bottom rubber gasket that goes under the head has always somehow fallen off.

 

[DAMIEN1307]

want to try it since on both my motors the bottom rubber gasket that goes under the head has always somehow fallen off.

Really??? A "rubber gasket" as a head gasket on a 66/80cc 2 stroke China Girl???
All of mine had either an aluminum gasket or a copper gasket for the head gasket, but never a rubber gasket under the head.

 

[Paul Crungus]

Really??? A "rubber gasket" as a head gasket on a 66/80cc 2 stroke China Girl???
All of mine had either an aluminum gasket or a copper gasket for the head gasket, but never a rubber gasket under the head.

its whatever came in the set of gaskets. dont know if its rubber but its flexible.
1 is flexible other is metal. pretty sure every china girl has the "rubber" gasket under the head seeing as it fits perfectly