Author Topic: Canister under rear of seat?  (Read 274 times)

Offline willowstreetguzziguy

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Canister under rear of seat?
« on: August 29, 2025, 03:39:48 PM »
What does the canister do that is located under the rear tail section of my 1200 sport?
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Offline Dr. Enzo Toma

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Re: Canister under rear of seat?
« Reply #1 on: August 29, 2025, 04:05:33 PM »
Can you tell what's plumbed into it? I'm not familiar with the 1200 sport, but a plastic canister on a motorcycle is often a charcoal canister as part of the EVAP system so that your fuel tank doesn't vent to the atmosphere and smell of gasoline fumes, or perhaps a breather box for engine blow-by.

Offline willowstreetguzziguy

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Re: Canister under rear of seat?
« Reply #2 on: August 29, 2025, 04:41:01 PM »
I believe it’s the charcoal evaporator canister. What is its purpose?
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1993 BMW K75S Pearl White (sold)
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Offline guzzisteve

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Re: Canister under rear of seat?
« Reply #3 on: August 29, 2025, 04:50:43 PM »
It cleans all the gases that don't get burnt, fuel & oil goes through there. Most  are disconnected to avoid runability issues.
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Offline Dr. Enzo Toma

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Re: Canister under rear of seat?
« Reply #4 on: August 29, 2025, 06:42:40 PM »
If it is a EVAP charcoal canister, then yeah, it absorbs fuel vapors so they don't vent into the atmosphere. Most modern vehicles have them as emissions controls. Unless the system is not functioning (easy to clog if you overfill the fuel tank), they don't tend to be a determent to performance and are often worth leaving in place just so if you park in a garage it doesn't fill the space with the smell of gasoline.

Offline Wayne Orwig

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Re: Canister under rear of seat?
« Reply #5 on: August 30, 2025, 08:15:23 AM »
The fuel tank vents fumes into it. They are collected un the charcoal inside. Another line goes to the intake and vacuums the fumes into the motor and burns them.

The good, the fuels system stays somewhat 'sealed' so the gasoline in the tank does not go bad as fast as an opened tank.

The bad, if you overfill the tank, raw gasoline can saturate the canister and you end up with a poor running motor until the raw fuel gets vacuumed out.
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Offline aklawok

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Re: Canister under rear of seat?
« Reply #6 on: August 30, 2025, 10:04:07 AM »
 Having been familiar with the evac can on my Cali. ( I don't know the physical layout on the 1200) I thought " gee this waste of space next to the battery could be used for storage". But due to how the battery is secured I could not just pull it out without making something to keep the battery sliding around and just left well enough alone.
Anyone else have a good elimination solution?
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Offline guzzisteve

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Re: Canister under rear of seat?
« Reply #7 on: August 30, 2025, 10:48:53 AM »
I got rid of many, Breva's are in tail piece not used for anything else. Hose from manifold has a T in it, take out T and hose at T runs down to fresh air, then run 1/8" vacuum line from L to R manifold. Cut hoses at can and run one down to fresh air. Get rid of can & 20' of hose. I been taking this crap off since they been putting the stuff on.
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Online Tom

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Re: Canister under rear of seat?
« Reply #8 on: August 30, 2025, 12:13:24 PM »
MGNOC NM State Rep.  Matt Forslund removed the EPA Emission system from my LeMans Nero Corsa after the MN National drowning.  He had his rolling workshop/travel trailer w/girlfriend & 2 Great Dane puppies.   :grin:  We changed out the oil 3 times and he said to get the bike hot.
I rolled west on I90 and stopped in the middle of MN.  The bike was hot.   :thumb:

The engine/trans/rear end needed the oil changed, fortunately the battery and electronics didn't go under water.  I was the last one out with a bike.  There was one guy that lost everything that was the last guy out of there.  He was only wearing shoes and shorts.   :shocked:
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Online Bulldog9

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Re: Canister under rear of seat?
« Reply #9 on: Today at 12:22:08 PM »
What does the canister do that is located under the rear tail section of my 1200 sport?

That's the Charcoal Canister for the Evap System. Same setup on the Breva and Norge.

I removed the whole system, let the tank vents to atmosphere down with the gas and oil lines down below, then connect the air bleeds on the intake manifold with a line connecting them.
« Last Edit: Today at 12:25:25 PM by Bulldog9 »
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Online Kev m

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Re: Canister under rear of seat?
« Reply #10 on: Today at 02:54:49 PM »
The fuel tank vents fumes into it. They are collected un the charcoal inside. Another line goes to the intake and vacuums the fumes into the motor and burns them.

The good, the fuels system stays somewhat 'sealed' so the gasoline in the tank does not go bad as fast as an opened tank.

The bad, if you overfill the tank, raw gasoline can saturate the canister and you end up with a poor running motor until the raw fuel gets vacuumed out.

I have only ever eliminated one of these systems and it was a mistake judging from the smells in the garage afterwards.

So I've personally had a good at least half dozen bikes with a working EVAP (including all of our current fleet) and I have never, EVER had a single problem because of it.

Which leads me to this question. Has anyone REALLY ever had that happen? How badly would you have to overfill the bike for that to happen? Would you have to immediately park it in the sun on a 102°F day too?

I'm skeptical but curious.
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