Honing Cylinder

Iceberg wrote:I have heard several thoughts on the matter.

I have a #4 cylinder that was running awesome and now it is too tight for a piston. It will allow the piston to go up and down however the friction is too high. I have tried several pistons and they all run the same in the cylinder so I believe the friction is only in the cylinder. Since it is an original #4 and was majorly kicking but before. I would like to salvage it if at all possible.

What is a way to nicely hone a cylinder that is too tight by a fraction of a thousandth or something like this one.

Scotch bright with thinner? Steel wool? Other secret remedy?

Thanks for the expert advice in advance.

Iceberg

Iceman: never, ever use that kind of abrasive stuff on the inside of you engines. It is way too abrasive and may permanently score the cylinder walls-piston walls.
   I agree that it probably is just dried castor oil build up, crud, and if you disassemble the top half, soak in old fuel, a little, not submerged. Then run an old rag thru the cylinder and add a little fuel to the rag at the ends as you twist-pull it back and forth thru the cylinder you will see a brown substance, crud, show on each end of the rag. Same with the piston except I use an old tooth brush. And don’t forget the ball joint inside the piston. It gets crude up as well and can cause the piston rod to be sticky in 1 direction.

P.s. how is your all star bipe coming. Soon I can send you the patterns, all but the ribs are easy. I spent so much time on the rib patterns and they were off. Still trying to get the wing stiffeners in.

Hope that helps. Happydad      

Can only second to Aspeed and Happydad..I apply some nail polish remover (acetone) to a cotton ear swab and move it around the cylinder wall until all brownish crude is gone. Resort to the varnish remover brush only as a last option, and if apply, only do the spiral motions but never axial, that would open ways to the blow-by and destroy compression.

When I have this issue, I have a piece of tubing that fits inside the skirt of the piston. I wrap masking tape as needed around the tubing to obtain a tight fit into the skirt. Clean the cylinder free of oil and crud. I insert the piston upside down into the cylinder. I use Brasso or even Happich Simichrome as a lapping compound. I only use a little and begin to move the piston up and down in a screw like fashion. Don't just move it up or down as it travels but turn it while doing so. Spend a bit of time at the bottom of the cylinder. This keeps the drag low.I then place the piston into the cylinder the correct way and do the same but don't bring the piston up to top dead. Keep it lower in the bore by at least a 1/8". Then clean everything well in hot soapy water and dry it well. The piston should stick in the cylinder at TDC and fall out when you tap it.

Going through checking piston/cyl fit to build a motor and I found one piston that won't go half way in any of my cylinders.

Is that a .051 piston?

Can it or should it be honed to fit a .049 cyl.

An 051 piston would not go into a 049 cylinder at all. I would suspect that this piston may have been set for its ball socket clearance and may have been forced into a mushroom shape on its top..a typical symptom of this is when the piston is stuck half way towards the TDC.

Just my 2 cents...

All the .051 pistons have an identifying groove.

Another common problem with a piston sticking half way is a burr on the exhaust port(s). It can usually be seen under a magnifying glass and carefully scraped away with a sharp exacto type blade.

Ron

The #4 cylinder I have is still tight in the center. I have looked for burs and tried cleaning. What could still make it tight? I have tried multiple different Pistons that are not buldged.

Thanks
Ice

I think that cylinder is tapered, so piston don't move.

I understand the piston sticks in all his cylinders so I think it is the piston and not the cylinders that is out if roundness or damaged in another way..

Iceberg wrote:The #4 cylinder I have is still tight in the center.

What do you mean by "in the center"? Just above the exhaust port?
Does it go easier higher up in the cylinder, or easier from the top?

Reread post one from OP...tis typical Castor Varnish....ran fine kicked butt...now drags..too high friction...castor varnish

I use Hoppes #9 or Balistol and a 45 caliber revolver bronze cylinder brush and de varnish the cylinder, hot soapy water, lite after run oil

find and book mark Paul Gibeaults(sp?) excellent reed valve mouse motor set up instructions

But Andras, a mushroom shaped piston can go into cylinder? I have no info about this, you know better than me.

Hi Levent yes I regretfully have 2 or so such pistons that I messed up while setting the balljoint. They go up bout halfway then get stuck

balogh wrote:Hi Levent yes I regretfully have 2 or so such pistons that I messed up while setting the balljoint. They go up bout halfway then get stuck

Is it proper using a hard surface like as metal or a hardwood while resetting piston? Perhaps using a hardwood surface or a rubber sheet on metal surface is better?

fredvon4 wrote:
find and book mark Paul Gibeaults(sp?) excellent reed valve mouse motor set up instructions

Hi Mr. Fred, glad you are back here!

OP, Paul G's mouse motor paper is on your left, click on "instruction sheets" to the left:
<----------------

balogh wrote:An 051 piston would not go into a 049 cylinder at all. I would suspect that this piston may have been set for its ball socket clearance and may have been forced into a mushroom shape on its top..a typical symptom of this is when the piston is stuck half way towards the TDC.

Just my 2 cents...

I agree with Balogh and my solution was to use a super fine grit Emory cloth, the highest number you can find. And CAREFULLY work the last 1/3 or so of the piston side near the head with the Emory cloth rotating the piston as you go. What you should see, if the piston is mushroomed, is slight marks on the portion of the piston top 1/5 or so near the head. The piston usually mushrooms only the very top portion of the piston near the head. Not the piston head. So only work the very top portion near the head. Not the head. I have done this before and IF you take your time and are careful and use very, very fine grit Emory cloth, you can recover the piston. Hurry, use the wrong type of sandpaper or Emory cloth and you will not succeed.

Take your time just like with the cylinder. Take your time looking for burrs inside.

Happydad              

Levent Suberk wrote:

balogh wrote:Hi Levent yes I regretfully have 2 or so such pistons that I messed up while setting the balljoint. They go up bout halfway then get stuck

Is it proper using a hard surface like as metal or a hardwood while resetting piston?

Yes, use a very hard surface like a concrete floor, or the flat end of a large vise.

Happydad            

Iceberg wrote:The #4 cylinder I have is still tight in the center. I have looked for burs and tried cleaning. What could still make it tight? I have tried multiple different Pistons that are not buldged.

Thanks
Ice

So you ruled out it’s not the piston(s) and you think there is no burr. A burr can be ever so slight and make a huge difference. If you are 100% sure you have devarnished the cylinder than I would do what Ken suggested. You will remove any burr too small to see and clean any varnish left behind. Use the original piston though.

Hi Ken/Fred
I will try the brasso system. I have about 30-40 spare pistons I have tried some of them. But it seems they all are similar so I wonder if there is a bur that I can't see. I will look really close and try. Just seems strange that the compression dropped out of the cylinder.

Thanks much!
Darren

Cribbs74 wrote:
So you ruled out it’s not the piston(s) and you think there is no burr. A burr can be ever so slight and make a huge difference. If you are 100% sure you have devarnished the cylinder than I would do what Ken suggested. You will remove any burr too small to see and clean any varnish left behind. Use the original piston though.

It definitely NOT a burr. IT IS THE PISTON. it sticks in ALL of the cylinders that I put it in.

SkyStreak wrote:

Cribbs74 wrote:
So you ruled out it’s not the piston(s) and you think there is no burr. A burr can be ever so slight and make a huge difference. If you are 100% sure you have devarnished the cylinder than I would do what Ken suggested. You will remove any burr too small to see and clean any varnish left behind. Use the original piston though.

It definitely NOT a burr. IT IS THE PISTON. it sticks in ALL of the cylinders that I put it in.

SkyStreak: look at the very top of the piston,  not the head. Use a magnifying glass if you have one. You should see signs of mushrooming. It looks like the piston is bulging, but it could be only .0005inch to cause this problem. Then use my method above. Emory paper, or cloth. You should be able to find it at a car shop. At least you used to be able to. Google it for sources if you don’t have it.

Then CAREFULLY try to knock off the .0005inch edge a little at a time as you rotate the piston.

Happydad

SkyStreak wrote:

Cribbs74 wrote:
So you ruled out it’s not the piston(s) and you think there is no burr. A burr can be ever so slight and make a huge difference. If you are 100% sure you have devarnished the cylinder than I would do what Ken suggested. You will remove any burr too small to see and clean any varnish left behind. Use the original piston though.

It definitely NOT a burr. IT IS THE PISTON. it sticks in ALL of the cylinders that I put it in.

Well, in your case that might be the problem however, I was replying to Iceberg who is the original poster which is why I quoted his post to prevent confusion as to whom I was addressing.

While you both have fitment issues it generally best to post a separate thread so you can get the sole attention you desire.

Ron