Are these valves shot?
Posted November 05, 2009 - 09:43 PM
Before cleaning (I brightened this pic up so you could see a little better)
close up of the pitting. Upper valve is an intake, lower is the exhaust...
Posted November 06, 2009 - 06:32 AM
Posted November 06, 2009 - 07:19 AM
I have been down this road before and if it were me, I would go ahead and replace them while I had it torn down. The bike is old and probably has a lot of hours on it. I just feel more comfortable riding across the desert in a vehicle that is either new or completely re-built.
Posted November 06, 2009 - 07:31 AM
The valves should be taken out so you can inspect them and the valve seats. If they are worn have the seats recut and put in new valves and guides so you don't have to worry about it. A good machine shop will only charge about $100 to install guides and touch up the seats.
Posted November 06, 2009 - 10:30 AM
Before you do you could fill the combustion chamber with fluid and see if any leaks into the ports. quick but effective test. even if they don't leak you still need to inspect the sealing area on the valve and the seat.
Posted November 10, 2009 - 04:57 AM
Posted November 10, 2009 - 06:40 AM
They do not need to be replaced unless the stems are bad or the faces are so bad that they can not be refaced. Unlike the 426 and 450 from 2001 up, the valevs in the 98-2000 are stainless and do not wear the same way as the Ti units. also, they are 100% stainless and are not hard faced like the Ti units so they can be reground.
A good auto shop can resurface the faces and trim the length on a souix valve machine, then it is a matter of ned guides and cutting the seats. Guides are cheap and surfacing the seats is about 5 bucks a valve seat. You can rebuild that entire head for $150 including labor if the valve stems are withing tolerance......so, grind the valves, cut the seats, replace guides and new valve seals and you are good as new.....