Took head off Grubee G5 -- should I clean this carbon & how

[digital_life]

I was loosing power yesterday so today I took the head apart and was a little disappointed at what I saw.

First thing I noticed was a carbon buildup on the head, It is not solid but it has carbon and oily feel to it and seems like I can use sandpaper to get it off but not sure if there is a better way to do it.
I do have another head from an older Grubee that looks exactly the same except for the spark plug hole which a has a bigger area around the inside than the one on the motor now, Should I just switch heads and be done with it. (pictures near end of post)

I also noticed burning or carbon buildup on the piston, Should I clean this up or just leave it as is or is it an indication of the piston rings needing replaced -- I'm on disability and have very little money left over after paying for rent and food so buying new rings will probably take quite a while.

I also noticed what looks like scratches on the cylinder walls, I can see them but cannot feel them with my finger. (pictures at end of post)

What would you guy's do if you had very little money with a new (2017) Grubee and a few older (maybe 2010 ~ 2015) Grubee motors kickin around.

This is the head, The new grungy lookin one is a 2017 Grubee and on the right

This is the cylinder like I said it looks scratched but I can not feel them.

 

[Karl Snarl]

running pretty hot there, i'd make it a bit richer. I'd clean it off with some seafoam and brake cleaner. Then jet a little richer. Looks like your rings didn't seat right. I'd do a quick rehone and change the piston and rings, and the bearing.

With me , I use the largest mass head I can. More cooling power.

 

[digital_life]

running pretty hot there, i'd make it a bit richer. I'd clean it off with some seafoam and brake cleaner. Then jet a little richer. Looks like your rings didn't seat right. I'd do a quick rehone and change the piston and rings, and the bearing.

With me , I use the largest mass head I can. More cooling power.

I don't have any jets so the only way to make it richer would be to move the clip on the needle down one, It came with the clip in that position but I moved it up one because it was not running that good and went threw a liter of gas in about 30 km right now I think I get around 40 km.
I will think about trying it there again

 

[Karl Snarl]

gas mileage means nothing if it's killing the engine. You want a little 4 stroking here and there, lets ya know you're tuned in. When you are romping it and flying along, a little extra fuel cools the engine( also helps keep the cylinder clean). I run a bike with nitropropane, imagine how much fuel I go through. lol, a lot.

 

[Chainlube]

Wrap a clean rag around the connecting rod before you clean the piston. Looks like good seal on the head gasket, do you have a new one?
The cylinder is fine, I can still see some cross hatch at the top. Looks like a nickelodeon cylinder, so honing will just destroy it.

 

[Wrench]

I just take the piston off the conrod before I clean it . That's much easier for me

 

[Street Ryderz]

That's a shame, China sucks! You're cylinder is fine from what we can see of it, the piston how ever is not. the rings did not seat in very well so a new piston and rings may seat in yet for very little cost,https://www.gasbike.net/collections/spare-parts/products/piston-set-80cc-66cc.
The head on the left is a bit better choice imo for what you have there to work with, I'd consider decking the cylinder as you can see in the pics there's a pretty big gap between where the rings stop and top of cylinder. That is an easy diy fix which will gain a bit of power and efficiency (gas mileage) at little to no cost. proper break in again and you should be good for awhile.

 

[JerryAssburger]

What 2-stroke oil are you running? And at what ratio?

In my "Even Dumber Than I Am Now" days, I premixed regular motor oil for my poor little Yamaha 100 Enduro, and it looked as if someone was cleaning and gutting fish inside the cylinder. HORRIFIC. (It was like scraping burger stuff off of the grill after a cookout!) Switching to decent 2-stroke lube helped. Please don't think I'm insinuating that you are doing the same thing, but some two-stroke oils run a LOT cleaner than others, I've noticed. Maybe experiment?

Also, you'd be shocked at how good soaking oily parts in a strong mixture of Dawn and some scotch-brite scrubbing will do for that kind of build-up.

 

[Frogslayer]

Oil is pretty good these days and must meet specs laid out in a standard. Even the cheapest wally world 2 stroke oil will be just fine.

 

[Greg58]

When I was about 14 I worked at a VW shop, a friend of the owner left his 250 Bultaco there for the owners son and I to ride. I clearly remember filling a 6-1/2 oz. coke bottle with 30w Castrol and mixing a gallon of fuel, it smoked like crazy and sounded funny, when we mixed with good oil it was a lot better. Sorry if this is off topic but good oil helps.