Engine Trouble Big end conrod bearing failure.

[tinochids]

I run a China girl 66cc engine sometimes referred to as an 80cc. At the moment, I have substituted the bearing with a bronze bush. It runs pretty fine, but I can feel the friction in the engine and it is increased as compared to bearing. I use a mixing ratio of 1:25 hoping that it would improve performance of the bearing from the the 1:30 I was using before. The downside of 1:25 is reduced engine power and more smoke.

 

[tinochids]

I don't think I've heard of this issue before now. What engines are you running? Are you using proper lubrication/oil mix? Have any of you other guys run into this problem?

I use a mixing ratio of 1:25. My country only sells blend fuel which is 20% ethanol and 80% petrol. I don't know if this has any effect too. At the moment I've put a bronze bush in place of the bearing and it's holding much better. The last bearing did less than 30km.

 

[Wyvern]

I use a mixing ratio of 1:25. My country only sells blend fuel which is 20% ethanol and 80% petrol. I don't know if this has any effect too. At the moment I've put a bronze bush in place of the bearing and it's holding much better. The last bearing did less than 30km.

Ethanol is nasty stuff, it washes cylinder walls of oil more than gasoline, it soaks up water like a sponge and it has zero lubricity.

It also will kill mixed fuel in the matter of days or weeks, so mix what you need, not big batches.

There are ways to separate fuel from the ethanol, but it's pretty nasty.

 

[Chainlube]

Ethanol is nasty stuff, it washes cylinder walls of oil more than gasoline, it soaks up water like a sponge and it has zero lubricity.

It also will kill mixed fuel in the matter of days or weeks, so mix what you need, not big batches.

There are ways to separate fuel from the ethanol, but it's pretty nasty.

This is what I always say.