ULH cylinder repair

[Jerry Wieland]

This is a couple of pictures of a used at standard 13 ULH cylinder that I have. I would like to hear from people on hoe they fix this and maybe what caused it. I have noitced that this is a somewhat common crack on UL's in general. I magnafluxed it and the crack does not extend into the base flange so I got lucky there.

Jerry

[Steve Slocombe]

Dear Jerry, that's a rare cylinder and you got lucky. On the VL I'd cut it all off flush at the cylinder base flange, put in a long cylinder sleeve, then shape the sleeve base to match the original cutouts.

[Jerry Wieland]

Steve


I appreciate the input. Have you ever had problems with sleeves. I find that on high mile knuckleheads the evidence points to running hotter. A sleeved knucklehead cylinder needs at least a .001" more clearance than a solid OEM cylinder. My 1946 EL had a sleeve slip at 70,000 miles. I was running stock +.005 over pistons in it just because I had lots of them and had no place else to use them. I got this engine hot in Sturgis in 1999 and at 30,000 miles I had to replace the pistons and rehone the cylinders and at that time everything else looked fine. When I put +.030" solid OEM cylinders on it at 70,000 miles the rear sleeve had slipped downward about .050". I had no idea this had happened because everything outwardly was good. A friend of mine had a sleeved cylinder bust after 3 seasons of good mileage.

Anybody else have an opinion on these ULH cylinders and what fixes they do?

Jerry

[fabercycle]

Jerry,

I'd braze it. I've seen alot of JD cylinders with such repairs, and old timers say when you sent them back to the factory to be taper bored, that's how HD fixed cracks like those.

[knuckleheadtim]

I agree with fabercycle; braze it. Vee out the crack on the outside, drill a small hole at the very end of the crack, and grind any scale back away from the vee. Heat the cylinder cherry red (a wood stove works great), and hand wire brush the area before brazing. It must be buried in ashes or speedy dry to cool slowly, preferably overnight. It's easier than it sounds, and very strong.

[Steve Slocombe]

Dear Jerry, I haven't had problems with sleeves, but that's because I dream of putting the mileages on bikes that you are doing. The last couple of years I've been breaking in newly rebuilt bikes for a couple of hundred miles each then selling them. In another couple of years I'll have most of my parts built into bikes and can start putting serious miles on my keeper bikes.

One tip is not to weld those trenches in flathead cylinders you get when the piston pin comes loose. I've had one such cylinder and of course the weld was so hard that the boring bar wouldn't go down. These cylinders now go into what Europeans call 'Easter Egg' motors - display motors with no internals and preferably no usable parts. Is that happening in the US as well?