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Discussion Starter #1
Hot day, driving to work, look down and notice the tank is sucking inward just ahead of the fuel cap on my 2014 B800.

Get to work, open the tank and hear air suck and the tank goes back to the normal shape.

I called the dealer and he suggested a plugged vent tube.

Anyone else had this? Where is the vent tube? Charcoal canister?
 

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Not 100% sure but i think the vent tube runs behind the engine between the frame plates. Then it runs down to the rear brake lever.
 

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You're in the USA?? Then the tank vents through a carbon canister. The carbon can gets air in through a vent on the side or bottom of the tank which may or may not have a hose attached (I don't have familiarity with the 3 cylinder bikes yet).

The dealer is right, your tank is not venting. Steel F4 tanks have been known to cave in permanently from plugged vents....so have Suzukis, Hondas, etc etc etc.
 

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Discussion Starter #4
Canada, in fact, but the canister is the same.

While fiddling around last night I noticed there is a crude chart on the underside of the seat that shows the venting plumbing and direction.

Now just have to find the blockage! Ugh.
 

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My 2015 F4 did the same thing sort of. When hot it would expand like a balloon and blow cap open a soon i turn key to open for fuel. Then i noticed after i got fuel and ran the tank low and bike cooled down in garage it would suck in badly. It creased the tank. This was all in about 2 weeks. Bike was only 2 months old. Warranty got me a whole new tank but i was told it was venting issue through evap canister.
 

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Don't overfill those tanks!!! The evap can will get contaminated and the charcoal will lump up and block the system causing all kinds of havoc.

An evapectomy is the best solution. I guess the North American market are all getting Kalifornia spec bikes now (evap system only required in that state). Makes sense from a inventory management point for a small volume company like MV.

Farmer, this should be a warranty issue. In the USA we have a Federal Emissions Warranty that covers components for 5 years or 30,000 kM. Maybe Canada has something similar?
 

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Bwaaaaaaah!
 

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Discussion Starter #13
Update.

Didn't completely remove the evap cannister. After talking with the dealer, I'm a bit nervous they'd invalidate warranty.

So a couple weeks into detaching from the evap... and the tank has not sucked in since.

However, the bike has developed a quirk not present before.

When slowing down, clutching down, the bike will cough a bit and has stalled a couple times. I assume this is related to the evap. Maybe I didn't completely block off the one tube? Other threads on removing evap have not mentioned this happening.
 

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Update.

Didn't completely remove the evap cannister. After talking with the dealer, I'm a bit nervous they'd invalidate warranty.

So a couple weeks into detaching from the evap... and the tank has not sucked in since.

However, the bike has developed a quirk not present before.

When slowing down, clutching down, the bike will cough a bit and has stalled a couple times. I assume this is related to the evap. Maybe I didn't completely block off the one tube? Other threads on removing evap have not mentioned this happening.
Fellow Canadian here. Sucks your dealership talked you out of it. Mine was pretty supportive. My "evapectomy" is a little different because I didn't actually block of my vac line. The dealership re-routed mine to the air box because the charcoal box never actually blocks that vacuum hose. I haven't noticed any adverse affects (stalling etc), and the dealership said the AF mixture is good with that setup. Of course YMMV. Where are you located by the way?
 

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Ed................COFFEE.................Captain JACK Sparrow

Damn spell check....that's my excuse and I'm sticking to it!!!!! :loser:
 

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Discussion Starter #18
@fchan,
So did the dealer not block off either tube? My understanding was that one tube had be left alone, the other blocked.
Guess I could just unblock the one line I currently have blocked to see what that does.
I'm near Windsor, btw.
 

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@fchan,
So did the dealer not block off either tube? My understanding was that one tube had be left alone, the other blocked.
Guess I could just unblock the one line I currently have blocked to see what that does.
I'm near Windsor, btw.
Cool, Edmontonian here so you're too far for me to come by haha. But yes, that is what the dealer did. It does go against what a lot of others have done and are recommending on this forum but it doesn't seem to have changed anything on my bike. Give it a shot, take it easy on the bike and see if it makes things better. Let me know how it goes.
 
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