Pistons Out, Pictures and a couple of questions

Hi guys

Below is a picture of my pistons that I took out this afternoon. Number 2 is very tarnished and Number 3 (the one with low compression) does have a lot of caked on crud on the top of it.



What would you guys recomend to clean them up with? I was thinking of carb cleaner with scotchbright and finish off with metal polish???

Also, while taking out the gudgeons, I realised my fingers were not going to be up to the job, the picture below shows 11mm, 1/4" drive socket on an extention, it worked a treat!

 

Straight Mr Clean, the stuff used to clean the kitchen floor with. Drop the pistons in a container and let them soak overnight, wash them off in the morning. Might need a bit of scrubbing with a scotchbright.
A motor rebuild shop told me this a few years ago when I was rebuilding my sons Honda Civic! I couldn't believe it until I tried it! They came out like new!

 

I'm betting you simply had some rings that were stuck in the ring grooves due to carbon build up.

I've freed em up before with some success.

Run the engine untill it's full operating temp.
Get a can of berrymans chemtool, start spraying it into the offending cylinders carb while running it about 3-4K until you choke it down and it stalls.
Let the engine set overnight, next am go try to start and see where the compression goes after it warms up.

This may need to be repeated for each cylinder.

CON: 4 days

 

IF yr talking about cleaning the cyls/ valves in a Running engine.. Then I suggest water: Using a litre bottle, attach it to the carb vacuum fitting with windshield washer type tubing (to limit the actual flow) then run the engine at approx 3k untill the bottle is empty.
Works 'As Advertised" but then so does ATF OR Diesel fuel.
BUT the water is a LOT more neighbour Friendly
Regarding your pistons: scrupulously remove All traces of carbon from the ring lands.
That amount of crap on yr piston tops means you need head work.. Likely Valve seals but prolly guides as well (they are bronze hyd. and wear quickly).

 

That one Piston with the Oil Trail down the side of the Skirt says Ring Problem or Cylinder Problem. You were both Burning Oil and Using Oil on that hole.

That #-3 ... Without a lot of Oil Burning residue in evidence seems to indicate you had a Valve Problem on that hole.

Level the head with the Combustion Chambers Up ... and fill the Combustion Chambers with Gas and watch for a leak. If the Combustion Chambers stay full to the line you fill them ... the Valves are OK.

If there is Leak-by and the Gas seeps out between the Valves and Seats ... you have to Reface and Lap-in those NON Gas-tight Valves.

As already mentioned, the Rings need to come off the Pistons and the Channels where the Rings fit need to be Surgically scraped clean right down to the bare surface.

The Carbon needs to be removed from where ever it has accumulated.
The Piston Crowns and Cut-outs.
The Outside Diameter ... all over.
The Combustion Chamber surface on the Head.
On the Faces of the Valves and Valve Stems.

You can Polish the Piston Crowns and Combustion Chambers to lessen the possibility of build-up happening again.

The Valve Stems are easily cleaned of the baked-on residue with a wire brush of a rotating wire wheel.

 

Thanks guys, need a couple more tips please. What do you advocate for cleaning the ring grooves? I have heard in the past using one of the old rings and scraping it around but I don't want to damage the piston with scratches and a I certainly don't want to make the groove any bigger, or are the pistons not that fragile? (I always thought the metal was a soft aly).

As for measuring, do I need to take it to a bike shop to get the pistons and cylinders measured to find out what size rings to put in? My local Yam dealer told me that they don't possess any tools any more to do that kind of thing on old engines, cos all the stuff they sell now is "plug n play"!

Cheers
Lea

 

Nuts.

The tool necessary for determining the New Ring Size is a Feeler Gauges or an Inside Micrometer.
BOTH belong in a Technicians Tool Box.

How many miles the bike went and how well it was oiled will have a lot to say about the new rings.

As for Cleaning the Groove ... Nothing works better than a piece of old ring.
The ring will follow the groove nice and has a squared-off edge for "Getting into the angles."

I noticed you have the Wrist Pin "C"-Clips saved.
Under Normal circumstances they are NEVER reused.

 

I've been through this process and although fiddly and potentially messy it's well worth it in the end.

Cleaning out the grooves can be done with one of the rings that you've removed. Careful not to scrape too hard and damage the lands. I finished off the cleaning with some very fine wet & dry paper inside the grooves and eventually all over the piston - very fine paper - don't want to affect tolerance etc., just get a nice clean shine on them.

Also, inside the grooves will be some small oil holes - I used a small old drill bit by hand (could have been around 3mm or less from memory) to open them up and clean them. All those little holes on my pistons inside the grooves were completely blocked so had a nice afternoon carefully cleaning them.

all in all I reckon I spent the better part of a day cleaning the pistons, grooves and lands, polishing them up real nice, and then re-inserting the piston pins and with some frustration the wire circlips (new of course). With new rings the pistons looked pristine by the time I got them back in the engine.

Compared to the black sooty mess they were when I took them out.

And what a difference apart from anything else the new rings made. Now I hardly use any oil whereas before I had to take a litre bottle with me for a Sunday ride!

KH

 

Oil Control Holes on the groove of the Oil Control Ring,
Yes.
They have to be nice and open and clean for there not to be a problem with the Piston not wiping the oil back into the crankcase.

 

I guess I'm lucky, I have a tool called a ring grove cleaner.

It wasnt too expensive when I bought it but that was 20 yrs ago.

Inside micromiter to check cylinder and a set of feeler guages to check the gap while the ring is inside the cylinder

Get yer book it has the specs in it.