standard bore 750 cylinder in tough shape

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ILLF8ED

ILLF8ED

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What’s the opinion? Salvageable or toast? I could use a cylinder for my ‘72 that is already +.040.

standard bore 750 cylinder in tough shape
 
More angles to look at David? Are there any broken fins? Any cracks in the casting? How do the bores look? Cosmetically, it doesn't take much to clean them up if they are ok mechanically.
 
The cracks can be seen in the photo. Left piston completed blew up inside. Lower bore extension missing on one side and a crack from the bottom of the bore to the cylinder flange. Flange is not cracked.
standard bore 750 cylinder in tough shape
 
Wasn’t me. It was part of an incomplete ‘70 I picked up recently.
 
I salvaged a barrel set having one breakout as yours has. This was done by a technique called metal spraying. Two breakouts would just be more of the same.

The crack concerns me more. Welding tends to make the crack spread. The spread might be controlled by first drilling a small hole where the crack now ends, then welding the crack and hole. Even if you could get in there where you need to drill, there is no guarantee this will work however.

I would rather start with a rough, rusty barrel, bore and hone to a reasonable std oversize, than invest in this one.

Slick
 
It could probably be sleeved. But I think you would be better off sleeving, plating or boring your .040 cylinder if it is worn.
 
Stephen Hill said:
Slick, what type of welding are you suggesting be used for a cast iron bore?
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I seized a piston way back in '67 and broke a chunk out of the cylinder base same as in this one. Took it to a welding shop, guy took one look and said "metal spraying". That is all I know of the technique except it is some sort of sintering. It is still living well in my barrels to this day (had the barrels off about 2 years ago).

As far as welding a crack, I am no welding expert, so I would confer with a specialty shop having TIG, MIG, etc.

Stephen Hill said:
It could probably be sleeved. But I think you would be better off sleeving, plating or boring your .040 cylinder if it is worn.
Click to expand...

I am no fan of sleeving an air cooled engine. Even if a shop has the skill and technique to make it a success, there is a heat transfer penalty ..... the junction of the new liner with the casting will never transfer heat as readily as a cast in liner. Shops who have a good technique can get it good enough that most owners would never know their engines are running somewhat hotter. Less than good technique is an overheat waiting to happen.

Bores can be brought back to a std oversize by nickel plating. The thickness of the nickel plate can be whatever one wants to pay for ..... one can bring a worn 0.040 over bore back to 0.040, or 0.030, or all the way to std.

Nickel plating is expensive, but has the additional advantage of a hard wear resistant bore when completed. One will wear out many sets of rings before the bores need more attention.

I would not bore a worn 0.040 cylinder to 0.060 ..... I think that is pushing the limit of the cylinders strength. Sure, plenty of people have gotten away with 0.060 oversize, but where do you go from there? Junk the barrels is where. Better to retain the strength of the original liner, and bring it back to a good 0.040 over by nickel plate.

Slick
 
I posted in the chance someone had experience saving such destruction. It has standard bore and all the fins intact. Probably best to pull the lifters and send the rest to the metal recycler.
Thanks everyone for the responses.
 
Its a boat anchor.
Start your build with a solid foundation, it will save you both worry, grief and money in the long run.
 
Take all the useful bits off and chuck it on EBay as mancave clock / steampunk / flower pot / beer chiller item.
 
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