Inlet valve seals

Has anybody had trouble with inlet valve seals. I have been through 3 sets & they have fallen apart in no time at all. They were from RGM under a Norton part no. but did not come in a Norton logo packing,so I am not sure they are genuine Norton. I have not yet spoken to RGM but does anbody have any experience of this? The top part of the seal breaks away & oil consumption goes through the roof

I bought also from RGM...but have had none of the two sets self destruct....what mine did was to pop off the valve guide and do just what you said...send the oil out the exhaust pipes...clouds of it. My problem turned out to be the valves themselves....a makers name stamped on the shaft that rubbed and caught, and eventually pulled the seals up and off. removed the high points on the stamping and all is well again. Any chance of some simular reason with your bike? Best of luck.....

Are you using any fuel additives? Toluene or benzene , for example can damage rubber components.

Valves and guides are new, but there are no marks on the shafts & I am running standard 850 with no additives on mono 40 oil. I noticed that seals do grip valve quite tight which would cause a lot of flex in the seal which breaks up int 2 portions. It stays put on the guide though.

Geoff said:

Has anybody had trouble with inlet valve seals. I have been through 3 sets & they have fallen apart in no time at all.

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Geoff,
if these seals are made of the appropriate rubber material and the valve stems aren't "rough", they usually last for quite a while. However, due to the heat in the cylinder head they tend to harden with age, and then come off the walve guide and begin to oscillate with the valve they're sticking to, thereby pumping oil through the valve guide into the combustion chamber.

Geoff said:

They were from RGM under a Norton part no. but did not come in a Norton logo packing, so I am not sure they are genuine Norton. I have not yet spoken to RGM but does anbody have any experience of this? The top part of the seal breaks away & oil consumption goes through the roof

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The best cure for that sort of problem is to use high quality valves (eg "Black Diamond") as well as valve guides of top-notch bronze material ("Colsibro") ensuring the valves have a minimal clearance in the guides, which makes the funny liitle rubber parts superfluous.

Geoff......what can happen is overcompressing the springs with the valve compressor, the retainer crushes the seal against the guide top and part shears it. Someone else mentioned this some months ago. It's a possibility. I also have the RGM variety and so far OK.
The point about clearances is a good one. I had a Cyl Head Shop valve job in March and valve to guide fit is tight....no rock at all. Still, I kept the seals in place.

Thanks folks, I rang RGM today & they say that they sell hundreds of these seals & have no problem. I am thinking Kieth is right about crushing them when assembling, & I will take loads of care with this. I am loath to replace guides as they are perfect, but it s worth looking at posh ones next time they wear out