overheating

[Toby woodman]

I'm just about to start my third 66cc engine in about two months. I am running 25:1 oil mix with semi-synthetic. both engines I have had have seized (I am a light rider and do not push the engines ridiculously hard) on the second engine I purposely jetted the carb too rich to aid reliability but both have seized. I think temperature is causing this even after running just 5 or 10 minutes and just warming up, the engines seem to loose power and start to make grinding noises. could it just be a bad batch of engines with poor tolerances or is there anything to do to stop them from overheating?

 

[Gordy]

I'm just about to start my third 66cc engine in about two months. I am running 25:1 oil mix with semi-synthetic. both engines I have had have seized (I am a light rider and do not push the engines ridiculously hard) on the second engine I purposely jetted the carb too rich to aid reliability but both have seized. I think temperature is causing this even after running just 5 or 10 minutes and just warming up, the engines seem to loose power and start to make grinding noises. could it just be a bad batch of engines with poor tolerances or is there anything to do to stop them from overheating?

Use a heavier oil mix. Try a 32 or 36 to one ratio

 

[Chainlube]

Use a heavier oil mix. Try a 32 or 36 to one ratio

Already at 25:1 which is already old school 2t territory.
I would look into lean running.
What carb/intake are you running?

 

[Street Ryderz]

Use a heavier oil mix. Try a 32 or 36 to one ratio

If he's using 25:1 then 32:1 or 36:1 is a lighter or less oil mix.

 

[Street Ryderz]

I'm just about to start my third 66cc engine in about two months. I am running 25:1 oil mix with semi-synthetic. both engines I have had have seized (I am a light rider and do not push the engines ridiculously hard) on the second engine I purposely jetted the carb too rich to aid reliability but both have seized. I think temperature is causing this even after running just 5 or 10 minutes and just warming up, the engines seem to loose power and start to make grinding noises. could it just be a bad batch of engines with poor tolerances or is there anything to do to stop them from overheating?

These engines really only last if you take it all apart and clean up the sloppy castings, clean out the metal debris that is usually left in them then break it in properly with a few heat cycles, no prolonged idling, avoid engine braking and use of full throttle.
Once broke in then set it up to where it maintains an idle and allows you to accelerate cleanly but still four strokes at a fixed throttle position and load is low, as you increase throttle from that point it should clean up again until the load of trying to accelerate decreases and four strokes again slightly, this will run much cooler and help to prolong the life of the engine.

 

[mony0_3]

I'm just about to start my third 66cc engine in about two months. I am running 25:1 oil mix with semi-synthetic. both engines I have had have seized (I am a light rider and do not push the engines ridiculously hard) on the second engine I purposely jetted the carb too rich to aid reliability but both have seized. I think temperature is causing this even after running just 5 or 10 minutes and just warming up, the engines seem to loose power and start to make grinding noises. could it just be a bad batch of engines with poor tolerances or is there anything to do to stop them from overheating?

Is it a 1 piece head and cylinder or 2 piece?

 

[ismellnownlatters]

i run leaner then that

 

[Gordy]

Already at 25:1 which is already old school 2t territory.
I would look into lean running.
What carb/intake are you running?

If he's using 25:1 then 32:1 or 36:1 is a lighter or less oil mixmix

My bad, I thought i read 50:1

 

[Toby woodman]

it's a 1 piece head and the spark plug was a brow colour when I took it out. could it be the the piston and cylinder were too tight as they seemed to have a very tight fit

 

[mony0_3]

I bought a couple engines like that and had the same problem. Would over-heat and seize up. Had to let cool and put penetrating oil in cylinder to free piston. They never ran proper and I put a new cylinder on to solve the problem. Also, never had problems with the black ones, only silver engine!