Join Date: Nov 2009
Location: Lander, Wyoming
The whole point of the OEM's use of a thick rubber valve cover gasket was to make it re-useable.
The only points which might have required use of a sealant should/could have been at the 'eye-balls' on the cam chain tunnel on the LH side. FWIW, I quit using sealant on that Genuine Kawasaki gasket in that area in about 1990!
But the Suzuki DRZ400/Kawasaki KLX400 or RMZ250F/KX250F valve cover gasket will leak everytime at the 'eyeballs' if sealant is not used in the area.
As to almost any of the paper based engine cover gaskets, proper preparation of both surfaces is usually the most important. CLEAN, Smooth, Degreased & Dry will usually allow the resin which is usually impregnated into the paper base materials to adhere to the surfaces.
The use of oils or greases to allow re-use of these gaskets May allow the gasket to slip out of joint surfaces & leak. Especially near pressurized areas like the oil passage to the external oil pipe & the oil filter itself, which can have up to 85 psi of cold oil pressure. (How many ever use a steel straight edge or surface plate to confirm an engine cover is Not Warped?)
Modify at "YOUR OWN RISK"!
Still riding my 1987 KL650-A1. 84,000+ miles & counting