Bore Size

[tindall2006]

Yes, i know the OEM bore size is 85MM. I recently measured my bore size on my cylinder's (at the top, middle and bottom and at diffrent rotations) with my digital calipers and T guages and the cylinders where around 84.78 MM.

I am not new to measureing cylinders like this as i have done it countless times on jet ski and snowmobile engine's. My question is does this measurment sound right? or are my caliper's out of calibration.

 

[interex]

Kind of like my .040 bore keeps showing up as 85.88 - 85.95. Kinda is a little weird to me. I called a few places and they said I can bring the block to them and they can tell me the exact size it is so that's what I'm gonna do.

 

[97 4G63]

Stock bore is 85.5

 

[atlguyinbama]

Stock bore is 85.5

No it is 85mm. 85.5 mm is .020" over.

 

[LocknessMonster]

I would double check the caliper to make sure that it is correct, this is what i do to clean my calipers and micrometers. I take a clean sheet of paper and clamp down on it. With the caliper or micrometer still snug on the paper pull the paper out from it. Do it a couple times to make sure that it comes out clean, then re zero the tool.

 

[1992awdlaser]

Kind of like my .040 bore keeps showing up as 85.88 - 85.95. Kinda is a little weird to me. I called a few places and they said I can bring the block to them and they can tell me the exact size it is so that's what I'm gonna do.

0.040 refers to inches. There's 25.4MM in one inch. So, .04" would be about 1.016MM. Your bore won't be exactly that much bigger than factory due to differences in piston to cylinder wall clearances.

 

[tindall2006]

So... most people agree this is a number i should never get and my caliper's are junk...



I am gonna borrow a nice mac or snap on pair tommorow at work and remeasure

 

[interex]

0.040 refers to inches. There's 25.4MM in one inch. So, .04" would be about 1.016MM. Your bore won't be exactly that much bigger than factory due to differences in piston to cylinder wall clearances.

You really didn't clear anything up. None the less I bought .040 Wiseco pistons so I guess I'll find out if they fit properly when I put them in.

 

[1992awdlaser]

You really didn't clear anything up. None the less I bought .040 Wiseco pistons so I guess I'll find out if they fit properly when I put them in.

Stock bore = 85MM
0.040" over bore = 1.016MM over bore
Added together = 86.016MM bore

Like I said it won't be exact due to different piston/wall clearance with aftermarket pistons than with the stock pistons. I think your readings are pretty close. Since it sounds like the motor isn't together, have the cylinder even been honed? This will make the bore bigger. Get a bore gauge that you know is accurate and take the measurements.

 

[LocknessMonster]

I would set up the gauge with a micrometer. Even the cheap ones come with a checking pin to calibrate them. Try looking for a phase 2 or an spi, they have carbite tips and arent bad for cheap.