Lapping Titanium Valves

[Hellraizer547]

I have now read 4 pages of links through google on the subject of lapping Titanium valves and of concluded to:

1) Yamaha states that if you are going to lap the heads one has to purchase a new set of valves, lap the heads and throw out the new valves, purchase another set of valves to install. (how does this method seat that exact valve to that seat?)

2)The expensive way is cutting new seats and installing new valves (if the valves are off due to the manufacture welding our valves together how do we insure a propor seal?) Note: our valves are welded together to cut costs, they are not lathed from a block of Ti

3)Do not cut new seats, do not install new valves. Use a sacrificial set of Intake and Exhaust valves to lightly lap the heads and use gloves, water/soap to clean deposits off of original valves. (thinking of going this route)

The main reason why we cannot lap our Ti valves is due to a .02mm thick coating which protects the valves from heat. (Is this true with the Yamaha Ti Valves?) Without this coating the valves will burn up much quicker, the life will be a fraction of a properly installed valve.

What do you guys prefer?

 

[afm199]

Do not lap Ti valves, they are coated. I use a couple old sacrificial valves to lap the seats. Works fine, you don't need 16 new ones. Don't lose sleep about the exact valve fitting the seat, that's mostly BS. They are all machined quite closely and you won't have a problem. I've done full head seat laps and installed USED but almost new valves with no leakdown. In fact I generally buy 1000 mile used heads for a few hundred bucks on Ti valve motors.

If you are building a full race superbike motor, you might want to spend another couple thousand bucks ( at least) and do it the "proper"' way.

If the seats are bad enough that much lapping is needed, time to cut them.

 

[ALANRIDER7]

Use Dykem Blue to see how the seats look.

 

[Hellraizer547]

Thanks Ernie. My r6 is almost stock, it only has advanced timing and thinner head gasket. I don't see this engine pushing more than 110 hp. I want the bike to be prod legal next year.

 

[DannoXYZ]

Titanium valves are also more flexible and softer than steel. They actually bend a little when the seat isn't perfectly concentric with the stem. Ends up sealing better than a stiffer steel valve in that same configuration.

However, you do need to replace if the hard surface coating is worn off the valve. The coating is for hardness, not heat. Titanium already has much better heat-insulation than steel (lower thermal conductivity). Without the coating, the softer Ti will gall and stick to the seat. Best combination is Ti valves with beryllium seats. The beryllium is much harder than steel and has much higher thermal-conductivity. Helps transfer heat away from the seat and valve to reduce chances of burned valves.