boring a cylinder

[Vman]

ok, just a shot in the dark.....has anyone had an old nasty jug and had it bored to resurface the cylinder? i'm gonna be ripping apart an old XL12 and i believe the piston may need replacing and the cylinder may have problems, so i am wondering if i can bore the cylinder maybe .010 to .020 over, get rings with a larger OD to accomodate and or get/make a new piston.
also, can anyone tell me the material used for the pistons and jugs?

does all this sound too crazy....or is it possible?

thanks

 

[Simonizer]

ok, just a shot in the dark.....has anyone had an old nasty jug and had it bored to resurface the cylinder? i'm gonna be ripping apart an old XL12 and i believe the piston may need replacing and the cylinder may have problems, so i am wondering if i can bore the cylinder maybe .010 to .020 over, get rings with a larger OD to accomodate and or get/make a new piston.
also, can anyone tell me the material used for the pistons and jugs?

does all this sound too crazy....or is it possible?

thanks

I would run a ball-hone through the cylinder first and see how it cleans up. 240 grit, 300-400 rpm using varsol or diesel as a lubricant/coolant. I think you may be surprised how effective this is. I am giving this suggestion based on previous information that you may have had a static seizure from an extended exposure to moisture etc. If the cylinder is scored due to a lean condition, air-leak, etc., different measures may have to be considered based on the extent of the damage. Cheers.

 

[Vman]

thanks for the info, i'll have to get me a 240 ball hone,,,that may do it as the the piston is not siezed up, but i assume its gonna have some issues.
hmmmmm ......diesel fuel. i have used many different coolants and have actually found WD-40 to work the best for boring and cutting aluminum and alloys....never tried diesel fuel, but might give that a try next time my coolant tank runs low.

 

[Simonizer]

thanks for the info, i'll have to get me a 240 ball hone,,,that may do it as the the piston is not siezed up, but i assume its gonna have some issues.
hmmmmm ......diesel fuel. i have used many different coolants and have actually found WD-40 to work the best for boring and cutting aluminum and alloys....never tried diesel fuel, but might give that a try next time my coolant tank runs low.

For machining aluminum, I use Relton A-9. For honing, Varsol, diesel or WD-40 will be fine. Try to find a hone that is about 1/16" larger in diameter than the bore. You can be quite aggressive as you will only remove a fraction of a thou if honing for 20 seconds or so. Also try to keep a rapid reciprocating motion to match the rpm. This will give you that nice cross-hatch pattern desired.

 

[Al Smith]

Machining aluminum is not hard,getting a good finish is.I personally use Trim CE,which is auto industry standard inorganic coolant.If I desire an extremely fine finish I use diamond tooling.
Industrial honing oil is basically just kerosene with a fire retardant.Straight K1 or diesel works just dandy.All the honing oil does is keep the hone stones[or balls] from loading up with metal dust.My choice of hones for small engines is a Lisle precision hone ,which has a micrometer type size adjustment.A ball type hone or standard 3 stone hone is a good choice for clean up of the cylinder and for deglazing.You can not,however,use these types for resizing or rerounding an elliptical cylinder.For the job as described,they may be ok.

 

[bugfart]

Can the cylinder be re-chromed?
I only ask this out of ignorance.

 

[TonyM]

I know there are places that specialize in reboring/sleeving and Nikasil plating for motorcylces. I'm sure someone out there can rechrome as well.

 

[ehp]

recroming can be done by US crome in the states , but the major problem is the jug has the head on it so most places willnot touch it , if the head was cut off the jug like on racesaws alot of places can do it then but most want the tranfser bridges left in the jug to help keep the bore straight.

 

[Vman]

can it be bored and not chromed?? will it last?

 

[ehp]

On a crome jug no you cannot just bore it with out recroming it now on most jugs you can make the jug a bigger bore by 2mm or so and recrome to the bigger size piston as long as the pin size is the same and skirt lenghts arenot a problem, I have never used US crome before so not really sure on the cost but my guy up here that plates my 090 jugs and stuff is not cheap, a 090 jug to be welded up and plated is $400 and that is a stock bore jug

 

[Vman]

ok, gonna keep my fingers crossed when i open it up, with some luck, all will be ok...i hope

 

[Al Smith]

There also is the option of turning and pressing in a cast iron sleeve,my fix to the problem.With an xl-12 however ,the cost would not justify the end results.On e-bay,as a normal rule,an xl-12 doesn't bring much money but would be a cheaper alternative for repair parts.By the way,good luck.

 

[Vman]

if i came accross a parts saw, do the red xl12's differ from the blue xl12's?