Yamaha XV Cylinders

I am a bit at odds with the machine shop I use, so I may wax a little bitter; I'll try to stay objective.

Gen I engines - those that had recesses in the cylinder top for the head gasket and cam chain tunnel o-ring -- include the first few (pre-tariff) years of the 750 Viragos, all of the 920s, and (I believe) the TR1 in all its variations; that is to say ALL 981cc twins intended for sale in the Eastern Hemisphere. These had a relatively complex topology for the sleeve. From observation, I would go so far as to hazard that the sleeve was placed in a mold and the cylinder cast around it. Except - I have seen cylinders with the crank bob-weight cut-aways rotated out of true; so I'm not sure. I do know that 920 (at least) sleeves are a VERY tight fit in the cylinder.

Later models (in the Western Hemisphere at least) have a more "standard" shape for motorcycles sleeves - cylindrical through the aluminum of the cylinder, necking down a little where they slip into the case; all with a 2mm (or so) thick flange extending out 3-4mm on the top. They are not a particularly tight fit in the cylinder. I have dropped a thousand core about six inches onto concrete and had the sleeve pop up out the top as far as it had extended below. I have trained a MAPP gas torch onto 1100 cylinders out of curiosity and had the aluminum drop off in less than fifteen seconds. The thousand cylinder that I dropped? I put some punch marks into the sleeve surface - for "traction;" smeared red Loctite all over; and tapped the parts back to where they usually are. I checked that the cut-aways were aligned properly; then shipped it off to be bored. Afterward, it went to the Czech Republic and I trust the pressure of the torqued-down head to keep it in place. The machine shop bored without problem or comment.

I reckoned on fixing the trueness of that 920 cylinder myself. I applied heat for about ten minutes, and even with some rather smart blows from a rawhide mallet, I could get no movement. I chucked it up in the press. At three tons it started to move in small slips. I had to quit with the sleeve flush with the cylinder base; it was still fighting. The newly exposed sleeve gleamed like it had been freshly chromed. One of the 1100 sleeves fell out dingy and with a track indicating the leakage of some fluid down its face. This cylinder had been inside a (poorly) running engine earlier in the week. . .

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I haven't been able to find quality cylinders (or heads) lately. I must epoxy-fill divots in gasket surfaces; I bond on broken fins from donor (700 and 750) parts. The cheapest I can find heliarc is $35 a touch; and I still must shape the fins. Over the course of years and several dealerships, I dealt with a particular machine shop. They had a girl run a route to about thirty franchised dealers and independent shops. I'd hand over cranks, cylinders, whatever. And I'd get them back the next day - except across weekends. I became friendly with the co-owner, even having Thanksgiving dinner 1985 with him and part of his crew at the parts chaser girl's house. Work for my own projects was free.

Flash forward thirty years. There is no girl; parts must be dropped off and it might take two weeks; one pair took a month. The current proprietor (the original's son) will fabricate nothing, nor tackle "experimental" jobs, even if I offer to sign a waiver. In the old days, a cylinder was never flagged as needing additional work. Now half the cylinders need skimmed as they won't sit square in the mill. All I do is scrape off gaskets. Yamaha had no problem finishing these cylinders. I recently dropped off two sets of 1100 cylinders for 99mm kits (they drop right onto TR1s). The first bored without a hitch. The second? The sleeves spun with the bar; they had to be knurled and chemically locked. Surfaces are $35 each, the knurling is $55. I am losing money.

I'm barely at break-even now; if I raise prices enthusiasts will do without. I am at a loss . . .