If the cylinder had .010 clearance in one spot and .003 in another you would need to bore for sure that's a HUGE difference, something is very wrong, each engines manual has a spec that tells you whats allowed for taper and out of round.

The first cylinder measured the dirty way was off the 583 ROTAX the last part where it was actually measured with the proper tools was off a Pilot.

Here is a perfect example as to why I started this thread.

Here is the cylinder ludedude sold afastcar through his http://p-o-ps.com/pops/portal.php web site and ebay account, BUYER BEWARE of this guy below is why, the cylinder is on its last bore, he knew this he installed the LAST OVER BORE Wiseco piston into this cylinder and DIDNT TELL ANYBODY IN THE AUCTION.


All Ludedude of http://p-o-ps.com/pops/portal.php had to do is this simple test if he did NOT have the proper measuring tools.

In the pictures I have TWO .005 feeler gauges one on each side of the piston between the piston and cylinder wall.

IF the piston to cylinder clearance was CLOSE to being right those would be .0025 feeler gauges NOT .005

Piston to cylinder clearance is defined as the DIFFERENCE between the SMALLEST INSIDE DIAMETER found in the cylinder and the LARGEST OUTSIDE DIAMETER found on the piston.

You would think even if Ludedude of http://p-o-ps.com/pops/portal.php was DUMB AS A ROCK he would consult one of his "Tech Advisor - Guru's" and they would help the guy out.

IMO the .010 clearance was intentional Ludedude of http://p-o-ps.com/pops/portal.php had been SCHOOLED on piston to cylinder clearance and Wiseco pistons the first few weeks he joined my message board. IE he knew he was selling JUNK to someone on ebay when he listed it.

BUYER BEWARE of this MUTT!!!! Here is his ebay account http://myworld.ebay.com/ebaymotors/www- ... allel-net/
consider this thread a "FEEDBACK"

.005 on the exhaust side.

.005 on the intake side.


in case you cant add .005 PLUS .005 = .010

I hope everybody understand this and will perform this SIMPLE FAST test on their cylinder BEFORE they assemble their Engine.

IF you don't feel comfortable measuring your own parts PLEASE feel FREE to send them to me I will do it for you for FREE you just pay shipping both ways.

Hoser,

When I have measured piston to cylinder clearances I get a reading of the piston at the largest point with the mic write it down and then use my dial bore gague to get the largest reading of the cylinder and subtract piston OD from cylinder ID. But it appears that your are setting up your dial bore gague to give you a differential reading. Is that what you are doing? I may be a little slow on understanding that step. Can you walk me through that part? What exactly are you setting as zero for the dial bore gague? Is it the largest outside diameter of the piston?

Very cool that you took pics of the process.

Hoser,

Also how much differece do you see in measurements between the telescope gauge and the dial bore? It seems to me that the telescope gauge withthe larger diameter flat ends would not be as accurate as the dial bore gauge in measuring the arc of the cylinder. Do you know what I mean?

You can do it either way long as you find the DIFFERENCE between the smallest cylinder bore size and the largest size found on the piston.

I measured the piston and found the largest part, then I locked the dial so it cant turn and put it in the vise then I set the dial bore gauge to 0 when I insert it into the bore and it reads .0035 on the dial that means I have .0035 piston to cylinder clearance, follow me? I am just letting the tools do the math for me, were both doing the same thing.

I am glad you asked, you have to be real careful when using the telescope gauge also called a 'snap gauge' by some.

The ends are not flat they are arced or have a radius, you angle the telescope gauge in the bore so it will be longer than the bore is wide then tighten the lock a little as you move the telescope gauge to be square with the bore it will shorten, this is where you need to be careful and work slow, it requires a touch to get it right, you allow the telescope gauge to shorten by bringing it closer to square then you stop and move it back to where its longer and not touching the bore on one end then gently move one end left to right to find or feel for the center of the bore then try moving it again to be square with the bore (making it shorter) you keep doing this until it will glide through the hole, the key is to keep sweeping left to right so your finding the longest part of the circle then you measure the length, I usually check it 3 times with the telescope gauge, sometimes I find it off when compared to the dial bore gauge but usually its only .005 or less.

The dial bore gauge has a 3 point of contact that helps you find the longest point of the bore so all you have to do is rock it back and forth to find the longest point the other way, follow me?

I sometimes have a hard time with my descriptions....

Got it.

No your descriptions are good. I just really wanted to understand a different way of doing the same thing. I like your way with the dial bore. It's now going to be my way.

On the telescope gauge. I didn't know they were arced, but I think I will stick with the dial bore gauge. That is what I always saw the Engine builders for the IMSA and Indy car teams use when I was on the crew.

Thanks