Beryllium valve seats?

[brewster426]

What's the big deal with beryllium valve seats? I saw some pictures of them, but can't really find much info about it. I'm hoping someone is smarter than I am that can fill me in.

[eastside 400]

BeCu seats are mainly used in titanium valve applications. The BeCu is a softer material then traditional seats. Titanium valves are actually softer then a stainless or stock valve so the need a seat that isnt as hard. The BeCu seats also transfer heat alot better then iron seats do.

[brewster426]

So basically it helps to not mushroom the valve?

[R3Concepts]

Pulls the heat out of a Ti valve quicker and more effectively than a powdered metal seat.

[d3ktrix]

Since we are on the topic of valves...

Am I correct in thinking that with these bikes, the valves do most of the wearing and not so much the seat?

[eastside 400]

on the honda 450 and 250f's the intake valves have wear issues, on 06+ TRX and all CRF 450 and 250's, the intake valves are titanium but they dont use a soft enough seat material. There are also some issues with the OEM valves themselves being poor quality along with valve springs that might not be strong enough for rev limiter use. The valve spring issue is mostly on the 250f's.

The other problem is that with the UniCam setup with the rocker for the exhaust is that it actually pushes the valve side to side and not directly up and down, this wears out the stock valve guides on the exhaust side, using bronze guides helps alot but wear still happens, last year my exhaust valve stems actually wore undersized causing play at the guide with bronze guides...KTM's design for unicam head is much better then hondas, they use a rocker on a shaft that actually sit more overtop of the exhaust valves so it pushes it straight down

[brewster426]

Thanks for the explanation.

[R3Concepts]

Originally posted by eastside 400
on the honda 450 and 250f's the intake valves have wear issues, on 06+ TRX and all CRF 450 and 250's, the intake valves are titanium but they dont use a soft enough seat material. There are also some issues with the OEM valves themselves being poor quality along with valve springs that might not be strong enough for rev limiter use. The valve spring issue is mostly on the 250f's.

The other problem is that with the UniCam setup with the rocker for the exhaust is that it actually pushes the valve side to side and not directly up and down, this wears out the stock valve guides on the exhaust side, using bronze guides helps alot but wear still happens, last year my exhaust valve stems actually wore undersized causing play at the guide with bronze guides...KTM's design for unicam head is much better then hondas, they use a rocker on a shaft that actually sit more overtop of the exhaust valves so it pushes it straight down

There are no issues with the OEM quality of the Ti valves. It's the heat and debris taken into the motor that ruins the valves. Any time the motor takes in debris, the valves gall and the coating is worn off and they cup. The stock OEM guides last much longer than bronze guides. The bronze guides are much softer than the OEM guides.

To the OP an Ampco 45 seat would do just fine, even with a Ti valve.