Siezed engine after rebuild

[Skattracker2]

I rebuilt my 2pg in my 88 marathon. I actually bought a spare motor that had a like new jug because my block was cracked in my cart. I combined the two engines and put in new rings and piston and the good jug (I had it checked by a engine rebuilder). I ran the cart for 5 hours and no problems. I was running it 50:1 gas mix and my oiler was hooked up, but not sure if working.
I figured might as well remove the oiler since I am mixing and my oiler was leaking. I then mixed the gas 100:1 as suggested with synthetic 2cyl oil. Cart ran great for about 20 min then it just locked up and died. It restarted within 30 sec and did it twice more before I got it home. I had the gas and oil mixed very well before I put it in the cart. I pulled the engine apart and the piston and jug are scored up.
I have a new jug and piston on order and will rebuild it again. I will run 50:1 mix from now on.

It seems 100:1 was to thin for this engine or did something else happen?

[jacannon]

I run all my 2 cycle motors at 40 -1 with no ethanol and high grade 2 cycle oil. They smoke more, but last a long time. The shop that keeps my chain saws running told me this.

[93yellowclubcar]

Run your golf cart at 40:1 much after the break in tank and you'll plug the muffler - quickly.

[BrewCityMusic]

factory spec is 128:1 (one ounce of 2S oil per gallon of gas) - like 93 said, running anything more after the first break-in tank is just a recipe for an expensive muffler replacement (or the pain of BBQ-ing it) ...

Sounds like something else may have happened - When I did my first 2PG rebuild I had the rings upside-down, forced it together and it lasted about an hour, LOL, possibly I'm not the only one who made such a mistake? How easy did the piston slide in? With the rings backwards it's a real tight fit, when they're right it pops right in no problems

[Tinken]

Depends on jetting and how long you sustain high rpm on a two stroke engine. More oil makes the engines last longer, especially at sustained high rpm and produces higher hp. But it sounds to me like that will ruin your silencers. Seems like that would be something to look into. We race motorcycles, at supercross we use 50:1, but for the high speed desert where the engine must sustain high rpm we run 36:1. I know this may be comparing apples to oranges, but engines generally are similar.

[Morgan44]

100 or 128 to 1 should not be your issue. How did it run when it was running? Did it get extremely hot, or smoke or knock? Are you 100% sure the piston and rings were the correct ones for the jug? Was everything bought for an 88 model year?

[racin161]

Just to throw something out Check the ring end gap & the piston clearance to jug even on a new setup. I've had to file fit the rings on 2 different builds and no fitting on 1. Sounds like a ring end gap problem.


LOU

[Skattracker2]

I ordered a piston for an 88. I did not know the rings can only go in one way? I thought you just lined up the pins and it was good.

How do I tell the proper direction. I have a new jug and piston& rings on the way and don't want to do it again.

I also have a new muffler coming as my other one is shot, so I don't want to plug it up but I will run 50:1 for quite a while before I try 100:1 again.

I was running the cart fairly hard when it seized. It was running close to wide open for 10 min, but then it was ran slow for 5 before it seized. This was after about 5 hrs of flawless running.

[Dave Box]

The rings should have a letter stamped on the top edge. Mine said "R" When you disconnected the oil pump did you cap the pipe leading into the elbow behind the carburetor?

Dave

[rib33024]

Welcome to BGW



Did you look at the plug and see what color it was, that will till you alot. And when i bought a new Honda 2 stroke from Honda they said do not break the engine in with synthetic oil, after break in i can use synthetic