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by T Batnes
Tue Sep 01, 2020 8:49 am
Forum: Four stroke
Topic: What kind of valves...?
Replies: 10
Views: 824

Re: What kind of valves...?

Hi, new valves arrived. Shiny stems as before. Contacted G&S who confirmed that they are indeed plasma nitride coated. They are polished after coating. Cannot see difference between a coated and a non-coated valve stem. So, only way to be sure is to purchase valves from current stock at G&S.
by T Batnes
Tue Sep 01, 2020 8:49 am
Forum: Four stroke
Topic: Sticking exhaust valve?
Replies: 28
Views: 2062

Re: Sticking exhaust valve?

Hi, new valves arrived. Shiny stems as before. Contacted G&S who confirmed that they are indeed plasma nitride coated. They are polished after coating. Cannot see difference between a coated and a non-coated valve stem. So, only way to be sure is to purchase valves from current stock at G&S.
by T Batnes
Sat Aug 22, 2020 2:13 am
Forum: Four stroke
Topic: What kind of valves...?
Replies: 10
Views: 824

Re: What kind of valves...?

I got in touch with the makers of the valves I got, G&S valves. They told me that the valves I have in my engine are old, probably from the 90's, and not coated in any way - just polished. The exhaust valve is made of a stainless steel (214N) not compatible with a cast iron guide, and no wonder ...
by T Batnes
Fri Aug 21, 2020 10:47 am
Forum: Four stroke
Topic: Sticking exhaust valve?
Replies: 28
Views: 2062

Re: Sticking exhaust valve?

Adrie, I got in touch with the makers of the valves I got, G&S valves. They told me that the valves I have in my engine are old, probably from the 90's, and not coated in any way - just polished. The exhaust valve is made of a stainless steel (214N) not compatible with a cast iron guide, and no ...
by T Batnes
Thu Aug 20, 2020 6:59 pm
Forum: Four stroke
Topic: What kind of valves...?
Replies: 10
Views: 824

What kind of valves...?

See mark on pictures of Ariel NH350 valves... G&S valves in UK makes these. Are these the same as the club spares and Drags sell? How does these valves compare to NOS Ariel valves in therms of risk for seizures/galling? http://www.gsvalves.co.uk/phone/index.html 20200820_193305.jpg 20200820_1933...
by T Batnes
Wed Aug 19, 2020 11:35 am
Forum: Four stroke
Topic: Sticking exhaust valve?
Replies: 28
Views: 2062

Re: Sticking exhaust valve?

Are the new valves made off a stainless steel perhaps? In my business, ship building, we never use stainless steel bolts on exhaust flanges, due to too much thermal expansion and the risk for loose connections that leak exhaust fumes into the engine room. If larger thermal expansion on a stainless v...
by T Batnes
Wed Aug 19, 2020 9:05 am
Forum: Four stroke
Topic: Sticking exhaust valve?
Replies: 28
Views: 2062

Re: Sticking exhaust valve?

Adrie, I have a set of old valves that are good. I'll have a look at them and see if I can use them. Will clean up the valve guide. I took off the lower valve spring bottom collars, and found that the halite washer below it on the exhaust valve was blackened from heat and had disintegrated... also t...
by T Batnes
Tue Aug 18, 2020 4:39 pm
Forum: Four stroke
Topic: Sticking exhaust valve?
Replies: 28
Views: 2062

Re: Sticking exhaust valve?

Carb is a 1" Monobloc. Seems to be rich enough.. piston crown and inside of head covered in pitch black soot. Only valve disc is light in colour.
by T Batnes
Tue Aug 18, 2020 3:30 pm
Forum: Four stroke
Topic: Sticking exhaust valve?
Replies: 28
Views: 2062

Re: Sticking exhaust valve?

Pictures of guide and stem.
20200818_162623.jpg

20200818_162641.jpg

Something has 'appened. Heat, yes... that is my theory also. Too late ignition? Should I advance it a tad more?
by T Batnes
Tue Aug 18, 2020 9:50 am
Forum: Four stroke
Topic: Sticking exhaust valve?
Replies: 28
Views: 2062

Re: Sticking exhaust valve?

Some friends of mine came up with a theory of why this happened, and they insist it must be due to valve float/bounce, not a sticking valve. I have a Franklin P2 cam (similar to a HS MkI-54), so the cam is a bit more demanding than a standard cam. The speed at which the incident happened was 55-60mp...

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