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Last season I installed a permanent silicone valve cover gasket. A very logical and economical thing to do, for good reasons including cost of replacing paper gaskets.
But, I began to struggle to solve a mysterious exhaust fume problem behind my windjammer fairing. I thoroughly inspected the headers, mufflers, gaskets and seals. Re-welded the muffler joint, and replaced all four header gaskets, and the two outside pipe seals, re assembled using copper exhaust system rtv. Added hose clamps to the valve cover to air box breather hose. Sealed and tightened everything.
The problem disappearred for the first hour of highway riding, but then re-appeared and got worse to the point where I had to carry my head high or to the side to get fresh air. I could smell it any time I accelerated. Not fun, and dangerous, as carbon monoxide exposure is cumulative. There is no safe level.
The last thing I forgot about. The silicone gasket is relatively thick and springy, if that is a word. When I checked the bolts holding the valve cover, the bolts were quite loose. Tightened them down to a firm hand tight, and the exhaust fume problem is solved. A paper gasket doesn't have this problem because it is hard, thin, and goes on with gasket cement. An unforeseen problem with a silicone gasket.
The silicone gasket takes a lot of compressing. Mine is new and hadn't quite "bedded in" yet, and when it got hot, was allowing gases to burp out. Right under the tank, where the fumes would re circulate in the still air behind the fairing.
I will keep an eye on those bolts, and routinely re tighten them.
But, I began to struggle to solve a mysterious exhaust fume problem behind my windjammer fairing. I thoroughly inspected the headers, mufflers, gaskets and seals. Re-welded the muffler joint, and replaced all four header gaskets, and the two outside pipe seals, re assembled using copper exhaust system rtv. Added hose clamps to the valve cover to air box breather hose. Sealed and tightened everything.
The problem disappearred for the first hour of highway riding, but then re-appeared and got worse to the point where I had to carry my head high or to the side to get fresh air. I could smell it any time I accelerated. Not fun, and dangerous, as carbon monoxide exposure is cumulative. There is no safe level.
The last thing I forgot about. The silicone gasket is relatively thick and springy, if that is a word. When I checked the bolts holding the valve cover, the bolts were quite loose. Tightened them down to a firm hand tight, and the exhaust fume problem is solved. A paper gasket doesn't have this problem because it is hard, thin, and goes on with gasket cement. An unforeseen problem with a silicone gasket.
The silicone gasket takes a lot of compressing. Mine is new and hadn't quite "bedded in" yet, and when it got hot, was allowing gases to burp out. Right under the tank, where the fumes would re circulate in the still air behind the fairing.
I will keep an eye on those bolts, and routinely re tighten them.
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