Carbon build up on piston tops (not poison tops...)

[nitrosurf]

Some sage advice if you will;

I've taken the head off the motor that decide to spit a valve adjuster lock nut down its cam chain channel (happened a while ago but the use of another bike and work has slowed down me fixing it), and I noticed that the tops of both pistons have a fair amount of carbon on them. Before the adjuster issue the bike was running well, pulled through the revs, no noticeable problems. The carbon is stuck on there good. When the valve rocker stopped doing is job it seemed to knacker the crank case pressure up, as oil showed spewed everywhere at the time. Could the carbon be from trying to burn a load of motor oil, or is it likely to have just built up over time? It's a 2006 bike with minimal mileage on it, using a copy of the ubiquitous Honda 125 twin motor. I'm assuming it's on its original pistons, but it is quicker than its supposed to be on standard gearing so maybe not.
Should I worry about it? I don't really want to tear the motor down any further if it's healthy, I've got the bits replaced and a new gasket set and was just going to put it back together. It'll get ridden for a bit after a point job then it's going to put money back into the kitty that my DAS is coming out of!

Cheers in advance.

[Suntan Sid]

IMO, you'd be very lucky to strip down a motor and find pistons without some carbon build up on the tops.
The usual culprits are oil burning, running to rich, incomplete combustion, wrong spark plug, crap modern fuel.

If you've got the motor apart you might as well clean them, they can be cleaned in situ, just blank off all the oil and water ways before you start!
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"Everybody needs money, that's why they call it money!"

[nitrosurf]

You have a point, I've been looking at ways to clean it out safely. Glad it's 'normal'. I've read about old vehicles suffering with a lot of build up, was just a bit surprised to see it on my reasonably well maintained machine. I guess carbon is inevitable when you're blowing up fuel in a confined space!

Thanks for the reply.

[Laamapalmu]

A good way to get rid of the carbon in pistons is to use Oven/Grill cleaner. Comes right off after you let it sit for and hour. I don't know if it will kill the fairies and imagination coatings the piston has.

[stinkwheel]

You can scrape carbon off a piston crown with an old screwdriver. Put it up to TDC, blank off any other holes the bits of carbon could go down then scrape away.

Blow the excess away with compressed air.

A 2p coin is good for removing coke from inside the cylinder head.

I have some experience in this. Mmm carbon. This is from burning oil. Lots of oil.

https://i48.photobucket.com/albums/f216/stinkwheel/enfield%20head%20231010/DSCN0992.jpg
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[bikenut]

good old royal oilfields, arent they just great.
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nuts about bikes

[stinkwheel]

[MCN]

Caustic Soda will dissolve carbon so if you can paint the item with it then the carbon will wash/wipe off after a bit of time to soak. 24hrs will work.
Repeat as required.

Nitromors may work or Oven Cleaner.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[smegballs]

[MCN]