cylinder boring

[catch2otwo]

going to be over hauling my brothers 400ex. we plan to put a 416 kit in it. the cylinder will have to be bored. Question is how much would it be and where should i bring it to get it done? just a dealer like bettencourts or somewhere else?

[Paul_E_D]

The dealer will ship it out to a machine shop, and charge you extra. Just go straight to a reputable machine shop...

[SSearchVT]

Before taking it to a machine shop - have the piston, rings, and bore recomendations from the overbore kit manufacturer. Most dealers are able to do 0.010 or 0.020 over kits - above that is outside what their equipment can do.

[elwood206]

carquest has a network or machince shops, they came highly recommended to me and did a great job on my overbore, only 60$ for a 50cc cyl bore up to 60cc

[catch2otwo]

so any recomendations for reputable machine shops in the south shore area? and elwood, your saying carquest will be able to bore it out?

[elwood206]

a carquest machine shop, yeah. the local carquest shop should be able to tell you where the closest one is

[richw]

I always went to shops that do diesels. You will get better accuracy.

[TLRMan]

I always went to shops that do diesels. You will get better accuracy.

HUH?

I would NEVER bring a cylinder to be bored by a dealership...
There are no more great machinist's that exist at dealerships.

And why does the type of fuel running thru the engine have to do with the accuracy of a bore?
I think you may believe the equipment used to do the boring is a lot better, and this is what you look for anyway...
It's the honing that brings in the dimensions, not the cutting of the cylinder...So it is best that you start out with a good machined bore before finishing.

[gmdboston]

These guys are among the best. I've used them and most of of my Road Race customers use them:

http://www2.nepracing.com:8080/

[richw]

Why diesels....

1st Diesels operate at much higher pressures then gas engines
2nd All bore tolerences must be kept much closer then rebuilding gas motors.
3rd they are working on much more expensive motors
4th Because of above they usually have better equipment and people.

[TLRMan]

Why diesels....

1st Diesels operate at much higher pressures then gas engines
2nd All bore tolerences must be kept much closer then rebuilding gas motors.
3rd they are working on much more expensive motors
4th Because of above they usually have better equipment and people.

1. Motorcycle engine cylinders are made of a different material. But the practices should be the same regardless... may I also add that there is technology out there that they are trying to develop is to machine the cylinders the shape they will be in when running and not perfectly round. Now figure that out...and a properly designed piston isn't round to start with anyway, it's more elliptical, and gets round once it heats up..this is why you must ALWAYS warm a race engine up before putting the screws to it. Actually, you should warm EVERY engine up....More so importantly, a diesel.

2. If holding +/- .003" is a problem, then the person that's doing the work shouldn't be in the business. I hold +/- .0001 on a lot of the work I do. (not engine cylinders) BTW boring/honing cylinders should be a no brainer. Measure the piston, match the bore + the clearances...

3. This is why I would never bring a bore job to the dealership.
You are looking for 10+ years of experience.

4. same answer to 3...The machines we have cost from between $500,000 to over $1,000,000...and if you don't have the right guy in there, it doesn't matter how expensive the equipment is...

Here's another thing to think about...Some of my racing 2 cycle engines only had one ring, some didn't have a ring at all!

The cylinder was machined and honed with a taper, and then was coated with a hard industrial chrome, which then was honed again with the proper taper. Pistons where made of an aluminum alloy called a390....Made 400 HP per liter on nitromethane naturally aspirated.

The stuff I get myself into....

Here's a cad drawing of one of my piston cylinder head designs.....

[RadHawk]

This goes a little deeper than just boring for oversized slugs...

If you are installing .010" or .020" over pistons then most any GOOD machine shop can do that for you.
As always though, consult with the prospective cylinder boring shop to ensure that they can provide just exactly what you want them to do.
Bring them the piston and jug and supply them with the tolerances given buy the mfr. of the piston AND the recommendations of the mfr. of the motorcycle.
Example, Wiesco pistons can operate with a much closer tolerance than stock OEM pistons due to make up and depending on whether the engine is air cooled or water cooled..

If you are talking about replacing said pistons with a "Kit" that really bumps up the cc's then you MAY be looking at boring the sleeve(s) out of the original cylinders, pressing in a new sleeve and then boring that to the new pistons.
Another example.
I just converted my Son's XR 200 to an XR's Only 215 Kit, that was the latter process because the sleeves would not take that much boring...
FYI.

Cheers,
Rob

[TLRMan]

This goes a little deeper than just boring for oversized slugs...

If you are installing .010" or .020" over pistons then most any GOOD machine shop can do that for you.
As always though, consult with the prospective cylinder boring shop to ensure that they can provide just exactly what you want them to do.
Bring them the piston and jug and supply them with the tolerances given buy the mfr. of the piston AND the recommendations of the mfr. of the motorcycle.
Example, Wiesco pistons can operate with a much closer tolerance than stock OEM pistons due to make up and depending on whether the engine is air cooled or water cooled..

If you are talking about replacing said pistons with a "Kit" that really bumps up the cc's then you MAY be looking at boring the sleeve(s) out of the original cylinders, pressing in a new sleeve and then boring that to the new pistons.
Another example.
I just converted my Son's XR 200 to an XR's Only 215 Kit, that was the latter process because the sleeves would not take that much boring...
FYI.

Cheers,
Rob

+1

[TLRMan]

These guys are among the best. I've used them and most of of my Road Race customers use them:

http://www2.nepracing.com:8080/

I'd let Pat do work for me anytime!

[catch2otwo]

thanks for the help guys, the 400 is just going to a 416 so no sleeve req. So when i get ready to talk to the shop, i will need the following, bore size (as of now), kit, and manufacturer bore specs? is there anything else i need to tell them?

[richw]

There may be 2 clearence specs

Race tomorrow

Break in and long life...

ask

[gmdboston]

thanks for the help guys, the 400 is just going to a 416 so no sleeve req. So when i get ready to talk to the shop, i will need the following, bore size (as of now), kit, and manufacturer bore specs? is there anything else i need to tell them?

Bring then the cylinder, piston, rings, and head.

[rebelpacket]

Millennium Technologies

I send my cylinders out there. I give them the piston-to-bore clearance I desire, and they do the rest. Week after you send them out, they send them back, ready to go.