90HP 2 Stroke Exhaust Port scaling

[steven.swiatek]

Rebuilding my 2 stroke again after I just rebuilt it. Looks like it wasnt cleaned properly, but can't say for sure if that is what this is. Anyone have any idea what this scaling is?

 

[jimmbo]

Carbon, along with some dirt, other incombustables
What Oil are you using?
You aren't using one of those Ball Hones are you?

 

[steven.swiatek]

Carbon, along with some dirt, other incombustables
What Oil are you using?
You aren't using one of those Ball Hones are you?

I was using lucas semi-senthetic 2 stroke oil.
No I had the boring and honing done at a machine shop, but now since I have to do it over again I am going to do the honing myself, but not with a ball hone.

 

[steven.swiatek]

I was using lucas semi-senthetic 2 stroke oil.
No I had the boring and honing done at a machine shop, but now since I have to do it over again I am going to do the honing myself, but not with a ball hone.

I will say though, I used a ton of grease when I was putting the motor back together. Do you think soo much grease could have been the culprit?

 

[jimmbo]

Grease? The only place a grease would be needed is hold loose Needle and Roller Bearing in place. And only use an Assembly Grease that gas can wash away easily. Otherwise, TCW_3 is all you need when assembling the engine.

Make sure the Ring Gap is large enough. Find the Narrowest part of the Cylinder and check it there. 2 strokes wear in a Complicated Pattern, and attention needs to be paid when Honing

 

[steven.swiatek]

Grease? The only place a grease would be needed is hold loose Needle and Roller Bearing in place. And only use an Assembly Grease that gas can wash away easily. Otherwise, TCW_3 is all you need when assembling the engine.

Yes sir thats what I mean. I used a ton of it to get the needle bearings to stick.

 

[jimmbo]

You don't need a ton, just a Bead of it laid on the bearing/bearing cap will hold them. And it has to be a grease that Gasoline will wash away.

 

[Chris1956]

You need to determine and mitigate the cause of the piston scoring. It could be overheating or lean mixture, so clean the carbs and replace the impeller and thermostat. I presume Lucas is TCW-III rated?

Do you premix the fuel?

 

[steven.swiatek]

You need to determine and mitigate the cause of the piston scoring. It could be overheating or lean mixture, so clean the carbs and replace the impeller and thermostat. I presume Lucas is TCW-III rated?

Do you premix the fuel?

I premixed it for this. I have heard I should have done double oil, but the guy who did my machine work (in his 80s been doing this for a long time) said not to use double oil. I am going to clean the carbs. I also had ordered a new water pump kit because mine was getting warm at low rpms so that'll be installed too.

 

[Chris1956]

Check/replace thermostat as well. Use TCW-III rated oil.

The piston skirt is the first to run out of lubrication, out of all the motor parts. That is, if you run the motor without oil, the first parts to be damaged are the piston skirts/cylinder walls. The bearings will survive longer. Therefore, double oil is probably a good idea on bored cylinder repairs, for break-in.