Restoring a bore

[WLB]

What do you all do to restore an aluminum bore that is tapered or scored too bad to use.

My first thought would be to install a cast iron liner as I have literally done hundreds on motorcycle and ATV cylinders that I can bore all the way through but the typical Briggs and Tecumseh would require that I mount the block upside down and bore going up. I can do that on my boring bar but don't have a reliable way to center the bore and insure that it is on the original centerline since I have found that the top of the block is not always perpendicular to the centerline of the bore.

Any ideas?

Bill

 

[FirePowerMinis]

I use a Kwik Way boring bar to cut for sleeve, pushing block up against the bottom of the plate. Non-perp situation would be tougher.
Millennium can plate most any hole. A lot of money compared to being able to cut it yourself for a sleeve, but durable. Add some gapless rings and piston coating, and it should last about forever.

 

[Neck]

I'm having a hard time trying to visualize your boring bar setup! Chosen few on this site would even attempt boring a cylinder, let alone a block. I have done it on a diesel engine block but that bar clamped to a companion cylinder, and bored down. I have seen it done in a vertical mill, which made it look easy. Most here would probably scrap a Cool Bore and try to find a block with a factory iron sleeve, that or have it bored in an engine shop. Show us what you have for a boring bar setup.

 

[WLB]

I'll try to take a picture of it this afternoon. Just happen to have a motorcycle cylinder I need to bore. Of course that lets the bar go through the cylinder and bore down.

Firepowerminis, how do you get the top of the block perpendicular to the bore centerline? If all the blocks were perpendicular from the factory I would have no problem boring up through the block.

 

[Newoldstock]

Firepowerminis, how do you get the top of the block perpendicular to the bore centerline?

Not adressed to me but I strongly sugest you take this question over the Bob's 4 cycle.

Speaking of clones only
The reason is the pistons only go in these engines one way.
So I suspect there is some offset between the bore and crank centerline.

Depending on what kind of engine and how it was roiginaly built you could screw yourself if you are not reboring it in a way that works with the originaly geomtery of the engine.

Just a though....

 

[FirePowerMinis]

Maybe? My K341 Kohler's are offset too far, wrong way, stock, so I move the bore closer to the valves. Aids flow, reduces chamber volume, lessens thrust.

Plenty of engines are moving toward an offset bore, in the opposite direction K went.
I move the bore on my Honda upright and horizontal singles, to make big bore without moving studs.

I guess each situation needs to be spec'd out?

 

[WLB]

I'm an old dinosaur and couldn't figure out how to post a picture so I put it on my website for now, www.wlbsite.com click on User galleries at the top, then click small engine boring bar. click the picture twice to enlarge.

I'll have to get my son to show me how to post pictures here before the build off:smile:

I realize that it would not be practical to sleeve a Briggs or Tecumseh unless the value of the bike would be greater with the original engine.

 

[WLB]

The old dinosaur has learned a new trick