Cylinder clearance question

[Millsy240]

I just purchased some cylinders and they are reading 65.55 or 2.581". The pistons that came with them are measuring 65.38 or 2.574" the pistons (wiseco) seem to be worn, are these useable? I realize that I need a .003" clearance. If not should I order 65.50 pistons or are they going to measure under 65.50? The cylinders are honed and are measuring 65.55 all the way through.

 

Any help would be appreciated.

 

Thanks in advance.

[gregrob]

I would install the pistons in the cylinder and measure the piston to bore clearance. Like you said it should be .003

 

I bet it's way off though... if thats what your pistons actually measure

[Millsy240]

I would install the pistons in the cylinder and measure the piston to bore clearance. Like you said it should be .003

 

I bet it's way off though... if thats what your pistons actually measure

 

Thanks for the reply, I will definately try putting the pistons in the cylinders and try to measure. Are there any special feeler guages for doing this.

 

Thanks again.

[Guest utleybanshee]

I would install the pistons in the cylinder and measure the piston to bore clearance. Like you said it should be .003

 

I bet it's way off though... if thats what your pistons actually measure

 

how do you go about measuring that..?

[Millsy240]

Bump

[NN2]

Nothing special. Just a small basic feeler guage. Similar in concept to a spark plug gapper measuring tool thing-a-ma-bob

Edited January 30, 2009 by NN2

[blowit]

I just purchased some cylinders and they are reading 65.55 or 2.581". The pistons that came with them are measuring 65.38 or 2.574" the pistons (wiseco) seem to be worn, are these useable? I realize that I need a .003" clearance. If not should I order 65.50 pistons or are they going to measure under 65.50? The cylinders are honed and are measuring 65.55 all the way through.

 

Any help would be appreciated.

 

Thanks in advance.

 

 

The big question is how did you arrive at your measurements? If you used a caliper, ignore your results. Bore gage and mic is the minimum acceptable method. Your clearance shows .007" with your measurements. I would inspect the bore carefully for damage, taper, and eccentricity. If all that checks out, you may be able to get 65.50mm pistons and pull it back into tolerance. Banshee motors do not stay at .003 clearance very long anyway when "swellcos" are installed.

 

 

by the way, using a feeler to check clearance is NOT a very accurate way of doing things. If you do not have the tools, have someone do it so you know where you are at.

 

Brandon

Edited January 30, 2009 by blowit

[Millsy240]

The big question is how did you arrive at your measurements? If you used a caliper, ignore your results. Bore gage and mic is the minimum acceptable method. Your clearance shows .007" with your measurements. I would inspect the bore carefully for damage, taper, and eccentricity. If all that checks out, you may be able to get 65.50mm pistons and pull it back into tolerance. Banshee motors do not stay at .003 clearance very long anyway when "swellcos" are installed.

 

 

by the way, using a feeler to check clearance is NOT a very accurate way of doing things. If you do not have the tools, have someone do it so you know where you are at.

 

Brandon

 

I had my neighbor (machinist) measure the bore, with his mic and some telescoping guages. The bore measures 2.581" all the way through, I made sure he checked it at the 6 different spots. No scratched, freshly honed. So what you are saying is don't bother with the pistons I received with the cylinders?

 

Thanks for your advice.

[blowit]

I had my neighbor (machinist) measure the bore, with his mic and some telescoping guages. The bore measures 2.581" all the way through, I made sure he checked it at the 6 different spots. No scratched, freshly honed. So what you are saying is don't bother with the pistons I received with the cylinders?

 

Thanks for your advice.

 

 

 

What do the pistons look like? Once the ribs are worn off the piston, they tend to degrade faster due to loss of oil retention. I would inspect them closely but probably would just replace them. .007 is on the high side but I have seen worse. I have seen .015 running. Your call.

 

 

 

Brandon