Boring over .080 , questions

[dustin lafeir]

I just got a 2002 blaster but the top ends blown up and the cylinder wall has some gouges and scratches . I found a wiesco piston that's 68mm ( 2 mm bigger than stock ) . My dad can bore it over he said but doesn't know if to bore the cylinder 2 68mm or a hair bigger so it's not to tight and there's room for the piston rings to open up . Where should we bore the cylinder too ??

 

[Awk08]

no need to go .080 over if .020 will clean up the gouges.
only go as far as needed, any further is just wasting bores and adds zero performance.

this will help a little, but dads got some homework to do........

 

[tbrooks]

No offense, but if he has the proper equipment and know-how to do a bore that you wouldn't be asking this question. Some things are better left to the pros, and half of them can't even get it right! So I'd be finding a good local shop or shipping it off. Its a small price to pay for piece of mind

 

[jbuckster07]

No offense, but if he has the proper equipment and know-how to do a bore that you wouldn't be asking this question. Some things are better left to the pros, and half of them can't even get it right! So I'd be finding a good local shop or shipping it off. Its a small price to pay for piece of mind

I concure... had a "buddy" bore a cylinder once for cheap, wasted a bore and a piston on it. Took it a REAL shop and was perfect!

 

[OntarioBlaster]

I dont agree or disagree. But boring a cylinder is as easy as it sounds.
Its more difficult to port a cylinder by hand via dremel tool or die grinder from kens video than to bore.

Its all equipment and basic knowledge, if you have a bore gauge, boring bar, mill and have the clearance info given by the piston manufacturer then you should be set.

If you own a proper milling machine then you should have the knowledge to complete the job, if your dad is planning on mcgyvering something up and boring on a radial arm drill, stop right there.

My local shop would charge me $60 canadian to bore a cylinder.

 

[dustin lafeir]

I just got a 2002 blaster but the top ends blown up and the cylinder wall has some gouges and scratches . I found a wiesco piston that's 68mm ( 2 mm bigger than stock ) . My dad can bore it over he said but doesn't know if to bore the cylinder 2 68mm or a hair bigger so it's not to tight and there's room for the piston rings to open up . Where should we bore the cylinder too ??

 

[tbrooks]

My local shop would charge me $60 canadian to bore a cylinder.

Exactly. Bore, hone and chamfer the ports for about the same US$ and know its right. Do not try to bore the cylinder using a hone!

 

[dustin lafeir]

I dont agree or disagree. But boring a cylinder is as easy as it sounds.
Its more difficult to port a cylinder by hand via dremel tool or die grinder from kens video than to bore.

Its all equipment and basic knowledge, if you have a bore gauge, boring bar, mill and have the clearance info given by the piston manufacturer then you should be set.

If you own a proper milling machine then you should have the knowledge to complete the job, if your dad is planning on mcgyvering something up and boring on a radial arm drill, stop right there.

My local shop would charge me $60 canadian to bore a cylinder.

He's been a machinist for 19 years , he's gonna use a mill with a boring head and micro bore . The marks in the cylinder are only .002 - .003 deep . He wants to know if he could just smoothe the cylinder with a hone ?

 

[dustin lafeir]

He's been a machinist for 19 years , he's gonna use a mill with a boring head and micro bore . The marks in the cylinder are only .002 - .003 deep . He wants to know if he could just smoothe the cylinder with a hone ?

I dont agree or disagree. But boring a cylinder is as easy as it sounds.
Its more difficult to port a cylinder by hand via dremel tool or die grinder from kens video than to bore.

Its all equipment and basic knowledge, if you have a bore gauge, boring bar, mill and have the clearance info given by the piston manufacturer then you should be set.

If you own a proper milling machine then you should have the knowledge to complete the job, if your dad is planning on mcgyvering something up and boring on a radial arm drill, stop right there.

My local shop would charge me $60 canadian to bore a cylinder.

 

[OntarioBlaster]

It does depend on piston manufacturer, cast pistons recommend a tighter cylinder to piston clearance than forged. Say oem vs wiseco.
Pick your piston get the clearance spec. If your going 0.010" over bore 0.007" and hone the remaining 0.003". This will smooth peaks and valleys from tool marks.

 

[OntarioBlaster]

Here is a link for pro x piston clearance info.

https://www.google.com/url?sa=t&sou...IQFjAA&usg=AFQjCNEH_74VFEM53extmgMJrO_vSML3TQ

Looks like cast you shoot for 0.0025" clearance on our cc engines.
Wiseco should have something for forged piston info.

 

[dustin lafeir]

Here is a link for pro x piston clearance info.

https://www.google.com/url?sa=t&source=web&rct=j&ei=PJr-U-XnIbHZigK88IBA&url=http://www.pro-x.com/media/downloads/Piston%20Kit%20Instructions.pdf&cd=1&ved=0CCIQFjAA&usg=AFQjCNEH_74VFEM53extmgMJrO_vSML3TQ

Looks like cast you shoot for 0.0025" clearance on our cc engines.
Wiseco should have something for forged piston info.

We could try that , how about using a jig grinder ? He said it would be more precise.

 

[speedyslyder]

i would say,what was the measurment you got of the current cylinder bore,and or what sized piston came out of it?
those pics show little cuz of the lighting but it is just a pic

then you may have this problem

 

[Bluesman]

The ports should already be chamfered so you should never have to rechamfer a cylinder unless you are resleeving.

When cylinders sleeves are made they are chamfered the full depth or thickness of the sleeve, making rebores simple. Remove 0.010" and cross hatch.

WOW! Who told you that? Have you ever seen inside a Blaster cylinder?

 

[OntarioBlaster]

We could try that , how about using a jig grinder ? He said it would be more precise.

Its not needed 0.0025" is a wide open tolerance to a machinist. Grinding would take longer. He could bore and hone that cylinder in like 8 minutes minus setup. The setup takes the most time.

 

[Bluesman]

Lucky? Yeah, lucky if it stays together. Somebody didn't have a clue what they were doing.

 

[OntarioBlaster]

Lucky? Yeah, lucky if it stays together. Somebody didn't have a clue what they were doing.

Its a factory untouched cylinder. How deep do you figure they chamfer the ports from the factory? Depth of chamfer would have nothing to do with the motor staying together, its to ease the interuption of the ring clipping the port.

Please enlighten me. Maybe I used the wrong words saying full depth but im saying in regards to getting your rebores out of a cylinder.

 

[Bluesman]

I'm just saying, SOMEBODY touched it. No, a .040" deep chamfer isn't going to make the motor blow up, but if someone is clueless enough to do that, the rest of the motor is questionable.

 

[Blaaster]

I would not be letting dad do it!

A machinist that knows what do would be a better choice!

 

[Awk08]

dustin, please stick to only one thread per topic



posts from identical threads merged into one.