Valve Advice

Hi,

After some rough running and low compression on my Z100A1 (35k miles) I decided to take the head off and clean and check it out.

The valve faces are all like this one - concave.



It looks beyond repair to me, so I figure I'm into a new set of valves.


On Z1 they are selling stock and stainless steel valves for the same price. So the question is - are the shiny ones better?

All advice gratefully received.

Thanks,

JB

The only gripe about stainless is that, in general, stainless has lower strength and hardness than carbon steel. At least, that is the reality of stainless for gun barrels and frames. The main attraction of SS is it rusts less (it does rust, just not as easily). I am not sure I know why that would matter for valves. There may be a great advantage of SS valves, I just am not aware of what it is.

J, In the day, stainless valves and phospher bronze guides were the a common step on big motor conversions, usually w/ oversized valve/seats. your' valves show exceptional wear,chances are your' guides and seats are similry worn. I'm a fan of Oe, but regardless, since its' appart, check valve to guide clearance es. as this will effect valve seat areas . paramount is consistant sealing area., then snug fit. valve guide seals can only do so much. as to stainless as opposed to stock, sorry, I,ve no background, except that I've @ 10 k miles on stock valves running pump gas without probs. luck G

i use stock type valves on my street rides and stainless on my dragbikes that use over sized valves but i would not have any problem using them on the street either. stainless valves are more forgiving if they do hit something that is one of the main reasons i use them racing that and i can get them in oversizes.

I'm in agreement with the other KZR members, if you have that much wear on your valves, then the valve guides need to be closely inspected. Then perhaps a 3-angle valve grind is in order along with new guides and valves.

looks like a lot of miles on that head, so in my mind like the others, a complete valve job including checking valve guides and seats may need to be repalced also, but the valves are needing to be replaced

Thanks all.

I'll buy the valves first, stock I think, and then see what the movement is like - but probably end up with new guides as well.

I'm starting to think that the head may not be the original. The paperwork backs up the 35k miles on the clock but the wear does seem excessive.

I'll take the barrels off this weekend and check the rings and sleeves while I'm at it.

Thanks again,

JB

JB
Check your PMs before you buy any valves.

Jay

bountyhunter wrote:

The only gripe about stainless is that, in general, stainless has lower strength and hardness than carbon steel. At least, that is the reality of stainless for gun barrels and frames. The main attraction of SS is it rusts less (it does rust, just not as easily). I am not sure I know why that would matter for valves. There may be a great advantage of SS valves, I just am not aware of what it is.

The first being weight. As the stainless heats up, it gets stronger, cold it is weaker then steel. I believe that the swirl marks ground into the head of the stainless valve, do aid in flow.

kzz1p wrote:

bountyhunter wrote:

The only gripe about stainless is that, in general, stainless has lower strength and hardness than carbon steel. At least, that is the reality of stainless for gun barrels and frames. The main attraction of SS is it rusts less (it does rust, just not as easily). I am not sure I know why that would matter for valves. There may be a great advantage of SS valves, I just am not aware of what it is.

The first being weight. As the stainless heats up, it gets stronger

Interesting, I never heard that before.