Carbon build up on piston top

[SanTanfan]

Hello I had a 66cc 2 stroke with various upgrades, the thing runs like a champ. However I was doing maintenance and I saw some ashy grey build up on the top of the piston. It's already broken in, oil ratio 24:1. Not sure what to make of it.

 

[Gordy]

What oil are you using? A low ash or ash free fully synthetic oil will help keep buildup down.

 

[SanTanfan]

Been using lucas

 

[Gordy]

Been using lucas

Ok. It likely isn't an issue with the oil then. What does the burn on your spark plug look like?

 

[SanTanfan]

 

[Gordy]

Your burn looks alright. Are you using the Chinese spark plug that came with the kit? If so those things are junk and could be an an issue. Upgrading it to an NGK BR6HS would help.

With a 66/80 cg engine you don't need to run 24 to one. You could go to a 32 to one. That might help with a hotter burn.

 

[SanTanfan]

There was a lot of oil/ black sludge on the top of the head coming out of spark plug hole and on the bottom of the head.. spark plug does get loose sometimes I can't tighten it like it needs

 

[SanTanfan]

Upgraded plugs from NGK, may try a thinner oil ratio.. any got a good way to clean this without taking it apart

 

[Gordy]

Upgraded plugs from NGK, may try a thinner oil ratio.. any got a good way to clean this without taking it apart

Get the piston to tdc, and use either a brass brush, or some fine steel wool. Afterwards use some compressed air to get any from around the piston cleaned up, and that should do. You can also use it in the head.

 

[SanTanfan]

Right on. Thx Gordy..