vfrMatt86 Posted April 4, 2015 Share Posted April 4, 2015 Hi, I've been a VFR owner for about a decade now, picking up an 86 VFR 750 in college. Recently a 96 VFR 750 followed me home and I've been spending sometime baselining it for the upcoming riding season. When you start it up in the morning oil that has dripped onto the exhaust burns off. I degreased the engine and while running there were no leaks. Once the engine was clean I checked it the next morning after it had sit for a night and it was VERY apparent that it has an oil leak coming from the front valve cover gasket. What has me scratching my head is why the oil leaks from the top of the engine after the engine cools. I can't imagine the engine remaining pressurized after it's shut down. And the amount of oil that's seeping out seems more than just residual oil that's draining past that particular spot in the valve cover gasket. Anyone have any insight or theories as to what's going on? Link to comment Share on other sites More sharing options...
vfrMatt86 Posted April 4, 2015 Author Share Posted April 4, 2015 So after thinking about it a bit more I'm assuming that the vacuum pressure created while the engine is running is keeping the oil from seeping. And I must be underestimating the amount of oil that's up in the head that drains past the valve cover gasket at shut down. And....if I'm right...it looks as if I've tracked down another vacuum leak, which is always fun. Link to comment Share on other sites More sharing options...
Member Contributer zoomzoom Posted April 4, 2015 Member Contributer Share Posted April 4, 2015 Here is just a thought but I'm not an engine expert. Perhaps the last time the valve cover was off (for a valve inspection / adjust maybe) the gasket wasn't put back just right and it is pinched somewhat or was pinched and then repositioned. If the gasket was damaged in some way or maybe torn (I think it is just a round rubber seal if I'm not mistaken) it might leak in one location or another. As the engine warms up and gets it might cause the gasket to expand a bit and stop the leak but as the engine cools and the gasket shrinks, perhaps it leaks at the location you are mentioning. The front cylinder head does sit at quite an angle so there is likely a reasonalbe amount of oil pooled in the front of the valve cover when you shut the bike off, before it drains down to the oil pan over time. Maybe remove the valve cover and check for damage to the gasket and/or replace it to see if that solves the problem. Another possiblity might be that one of the bolts that holds the valve cover in place might be loose and allowing oil to leak through. Again, not sure, but should be relatively easy to see if one of the valve cover bolts is looser than the others. Not trying to be condascending or anything of the sort but sometimes it's the most obvious things that we ignore because they seem too simplistic to check. Link to comment Share on other sites More sharing options...
vfrMatt86 Posted April 5, 2015 Author Share Posted April 5, 2015 Well.. you're more right than I am. I started the bike up after work today and inspected the leak while it warmed up. Sure enough it was leaking while it was warming up but stopped once it was warm. I'll get those gaskets changed and add that to the list of things I need to do to it on the next nice day; thermostat, sparkplugs, coolant, oil, filters, compression check, carb boots, carb sync, mounting 8 spoker, more degreasing, chain cleaning and waxing! On an unexpected note I noticed that one of the vacuum port plug was missing. So I capped that and now it idles MUCH more respectably. The smoother idle also quieted down my clutch basket rattle. Which is HUGELY annoying!! I mean.. a major vacuum leak on a carb shouldn't effect anything, right? I'm curious how much it will effect the fuel mileage. Thanks again zoomzoom for the reply. Stay safe out there! Link to comment Share on other sites More sharing options...
Member Contributer zoomzoom Posted April 5, 2015 Member Contributer Share Posted April 5, 2015 Whereabouts in BC are you from?? If you're anywhere near Kelowna perhaps we could get out for a ride some time. I never had the equipment to balance the carbs on my old 97 VFR but the dealer did it for when they did a valve adjust and man did it run a WHOLE lot better after that. LOL Link to comment Share on other sites More sharing options...
vfrMatt86 Posted April 7, 2015 Author Share Posted April 7, 2015 I wish I was in Kelowna, sadly I'm down by Vancouver now. Link to comment Share on other sites More sharing options...
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