Oil tank cap leaky

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speirmoor

speirmoor

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Has anyone else got this issue? (850 MK3) I put two of the cork type gaskets under it and it still leaks after a spirited ride. I made a thicker silicone gasket yet still oil. Oil is at Low mark on stick,new oil lines all round and new filter. With cap off and engine running there is a lot of turbulence in the tank from the engine breather but that healthy isn't it? Vent line is clear to atmosphere.
 
It uses only one piece of cork. Press down the cap hard then twist it fully to the right. There should be spring pressure happening. The cork will compress a bit after a while but that's O.K. the spring pressure gives it a good seal ,mine has never leaked. Naturally you have the reed valve installed by now ?
 
What reed valve? When I eliminated the stock plastic air box and went to a KN I just extended the breather from the oil tank that used to go to a seperator then to the carb balance tubes and airbox. I extended it to run down the right side of the frame as an old style rod draft tube. Vents the crankcase great! But to original post, are you sure it's the cap that's leaking?
 
The reed valve mod will reduce the hurricane force SUCK/BLOW in the oil tank.
 
Is there a big point to the mod? Has not been an issue for...ah, a lot of miles. Some times I think we tend to brain fk perceived problems.
 
I had the XS valve on the breather for a while and it still had a lot of air coming out of it. Can I run the breather to the atmosphere without going to the oiltank? I know Ducati do it on their bikes
 
I have 2 corks in mine too and it helped but didn't stop. I was thinking about a rubber or silicone one like maybe you tried, but haven't yet. Of course mine has a totally different breather.

Dave
69S
 
Torontonian said:
Press down the cap hard then twist it fully to the right.
Click to expand...

speirmoor, are you doing as Torontonian says, i.e., screwing the oil filler cap down (reasonably) tight, and not just turning it until it "latches"?

With the cap screwed down, the internal cap spring should be fully compressed.
 
I had it on the latch as going beyond that didnt seem natural. I guess I was doing it wrong but even with the thicker silicone I'm still getting leakage.
 
speirmoor said:
I had it on the latch as going beyond that didnt seem natural. I guess I was doing it wrong but even with the thicker silicone I'm still getting leakage.
Click to expand...

After latching the cap, it must still be tightened (turned approx. 60-90 degrees) so I would suggest you re-fit a single standard cork gasket and re-test.
 
Biscuit said:
Is there a big point to the mod? Has not been an issue for...ah, a lot of miles. Some times I think we tend to brain fk perceived problems.
Click to expand...


It all depends on what you call an issue. The reed valve mod keeps the pistons from drawing air into the crankcase on the upstroke. When a crankcase is full of air, the piston downstroke, especially on twins with a 360 degree firing order, compresses the air. This can cause oil leaks and as well, rob some power. It's not a big deal if you have no oil leaks, including the crankshaft seal. You won't get a drastic increase in power by installing a reed valve.
 
I had the same problem, spewing oil out, it turned out to be that I wasn't screwing the cap down tight,never did on my trident and it didn't leak from there but the commando sure does.My breather from the tank disappears out the back keeping the number plate lubed, you can here the difference in when the caps down tight when you first kick it over, it breaths threw the pipe and not 1/2 out the cap
 
Biscuit said:
Is there a big point to the mod? Has not been an issue for...ah, a lot of miles. Some times I think we tend to brain fk perceived problems.
Click to expand...
Other than it's the driest bike in my garage(thanks to the sage advice here), nope. :mrgreen:
 
One cork gasket and screwed down tight did the trick. Went for a nice jaunt yesterday evening around the city. First time in a long time there was no oily film on the right pipe,right swing arm and rear brake caliper after a ride. Happy Days.
 
I'll have to try that on mine. I may have been also not tightening it down.
 
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