Case Work on Viragos

Have It Done Right

This one makes me a little nervous as it involves the back-and-forth shipping of empty cases: bulky and fragile. Be sure to empty all fittings and just send in the basre aluminum with the cast-in iron parts. Bolt them securely together. Lay multiple layers of bubble wrap around them. Fill with styrofoam "peanuts" or expanding foam. Anything that must be removed or scraped off on our end will incur more costs to you -- if you expect to get them back.

What we'll do:

Chemical dip (unless you ask us to skip it) to strip all grease and dirt. Blasting with several grades of beads, ending with walnut shells. All oil passages will be blocked at this stage. Optionally, we'll powder-coat black or silver inside; your choice outside. Your main bearing bores will be hard chromed down to 90mm ID and the 6308 bearings of your choice will be seated. Bearings that have oiling channels and oil holes could have passages bored into the transmission feed lines in order to make sure that there is no starvation problems as stock these bearings are fed by splash. Case spigots bored to appropriate girth for your application. We'll look into a maximum bore cut with snug-fit aluminum rings for smaller sizes included. All potential obstacles to long stroke cranks will be fly cut off; all iffy protrusions. New dowels for oil passages and a plugged tap hole for those that want to run an oil cooler from near the pressure release, rather than off the filter cover.

That's all that comes to mind at the moment. No prices set. Reckon on $65 each way on shipping. I must get quotes on plating and powder coating and prices on various bearings. All of these procedures take place elsewhere. Before you ask, do NOT ship complete engines for us to build. This location is not zoned for it. And we can't afford to farm it out. Shipping and transportation add up and no matter how good of friends we are with third parties, they won't work for free.

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Face it. Yamaha did practically NO hardening to the XV valve train. Sometimes I think I see a worn discoloration on the valve adjusters. Sometimes something pops off the cam lobes. But there is no sign of any hardened surface - except the rocker shaft. They are as hard as a pawnbroker's heart. You can clamp down as tight as you can go with a vice grip or similar tool, and make no slightest mark on the surface. But they wear out, too. Hard materials are vulnerable to twisting or turning forces, like the rocking of a tappet.

Valves are no different. It is an automotive standard to harden the tips and faces of valves. These are exactly the parts that show the most wear. Divots on top of the stem; burned faces that clean to ridges that won't clean to a nice forty five degree finish. The after-market has hardly acknowledged the XV line, despite there being tens of millions of them. Two of my vendors will modify 500 single valves to fit. Their economy lines run a hundred fifty per valve on up. The cast iron guides seem to last forever. I've put four new sets of valves in guides that remained in spec for half a million miles.

Yamaha still sells these valves. They can't take the heat and they meet the seats eccentrically. Soon they leak, but the bike still runs - poorly. I have found a source of Japanese valves made with tooling that Yamaha had "retired." The stems, tips, and faces are hardened. In appearance, they are identical except they lack the model specifier cast into the face. They are cheaper and more durable. They are not exotic metals or hollow. They are like the valves in a typical car. They are like stock except they require adjustment less often, and don't require being re-ground until your rings wear out.

You may notice a bit of blue smoke upon deceleration when the engine is hot. Or on any high-mileage motor. The stock valve guide seals are no special rubber and wear out quickly. The stock cast iron guides are just about the only part of the valve-train that lasts the way they should, but they require some clearance, and some oil is bound to find its way into the combustion chamber. Viton is a synthetic rubber with many of the characteristics of Teflon - without the work hardening. Resistance is near zero, they are oil tight, and they'll outlast the rest of the top-end.

Yamaha still holds these (920 and up) valves available. Depending on your local Yamaha dealer's thoughts on what consitutes a liveable margin, expect to pay somewhere aroung $275 for a set.

Valves

Coming: over-size valves in in standard material. And - titanium valves in standard sizes and in over-sizes. Some thoughts on these.