do my internals look normal?
 

Hi guys I just took my alpha s852 apart and I was looking at the internals and the sides of my piston and the conrod are a light gold and the top of the piston is black and so is the underside of the head button and on the crankshaft There are a couple of brown spots (not sure if rust) but i just wondered if it was normal.

Thanks

Post up the pics and let us see.

Here's a pic I'll add some more.

I'm having a little trouble adding the pictures from my phone so I'll have to add more when I get home, thanks

The gold colour is nothing to worry about, It is actually a good sign as a goldish brown colour means your tune is good you actually want that same colour on your plug also good way to check your tune by looking at the colour of your piston head and plug, Now if it starts turning black means it's running too lean :) hope this gives you the info your after.

REALLY doubt rust....when was the last time that you ran the engine..?? most fuels have a residual that inhibits rust/corrosion..

rust
 

It looks like normal carbon oil stuff on the piston, a little bit dark though. I would clean it off. as for rust hell yeah cranks can rust. I see it all the time on all kinds of engines with different fuels too. Usually it's the rear bearing races and the crank that rust, not much else. I always use plenty of oil when not running them.

Agree with post above. Surface rust is pretty common on uncoated cranks and the bearing races, since they're obviously steel and stationary parts. Not really going to see rust on an aluminum crankcase, piston/rod, button, or brass sleeve.

Looks ok to me. It's just the castor from the fuel coating the internals and that's good! The black on the top of the piston is where the castor burns but doesn't always mean your running too lean. Clean it up with some silver polish or even motor spray sometimes gets it off but don't clean around the side of the piston as the coating helps form the seal around the piston against the sleeve.

Hi thanks guys , it's the first time I've ever taken one apart and I hadn't ever seen that colour and yeah the head button and top of piston are dark brown but completely smooth and no pits at all , but just a quick thing seeing as I'm rebuilding the engine I've got new bearings but do they need oiling before they are used ?

Thanks

Don't clean the sides of the piston, just a light wipe with methanol to remove any gum.

Heres my regular maintenance list for engines:

Pull down, Engine
Clean out all heat sink fins with a toothbrush to maintain best cooling.
Flush bearings of castor gum with good quality brake cleaner
Using plastics only clean out bearing grooves on crank and check conrod oil hole for crank pin
Carefully polish off the top of piston without going near the edges and polish head button, again careful not to touch the edges.
Polish and remove rust/oxides from crank, do not use petrol or harmful solvent on the crank in case you react with silicon in crank (if applicable)
If liner top is scratched or damaged, I place 2000 wet and dry on FLAT GLASS and use an old liner with after run oil to rub up the wet and dry so the brass acts like a lubricant and use oil to gently polish out any scratches in a figure of 8, do the same for backplate if needed.
Hand lube the entire engine without overdoing it
Use clean cotton, nothing abrasive and enjoy the experience.
It doesnt have to be shiny, just clean of oxide and residue that might harm combustion.


Sure there'll be many people that will argue against my method as being over the top or harmful, but I take special care where it's due to maintain compression, like never touching the inside of liner, edges of pistons, button and piston sides. The carbon on the piston sides would have worn away if it was tight.

PS: You piston looks fine, just a little cleanup as I noticed your fingers!!

+1, if people havent seen a rusty crank, not sure what they have been looking at or perhaps live in a dry climate, if in London, you'll have rust!

Ok so how does this sound once I get the bearings out and before I rebuild everything , I use meths on a cotton bud to clean the inside of the case , lightly on the side of the piston and around the ports on the liner the motor spray on the top of the piston and on the the Head button but leave the edges well alone , as I'm rebuilding bits can I use ARO as lube and as for the bearings, do they need to be oiled before use ? Or will they have oil already on ? ,

Thanks for the help

Yeah it's pretty normal and considering it's been sitting for over a year I'm not surprised good thing I always use ARO.

cheers

Won't brake cleaner into the bearings attack the plastic ball cages?

PS: There's nothing better to clean an engine's outer parts than an ultrasound cleaner. :)

I don't think the ball cage is plastic. I always thought it was a composite material due to the high operating temperature.

Your right about those ultrasonic cleaners. They are very handy!