Pressure build up in gas tank

[jemmd]

Lost my gas cap key so replaced it with a 08 GSXR locking gas cap that I had laying around. Suprise! perfect fit. Two of the allen screws line up and cap seals and locks. My concern is when I removed the cap yesterday quite a bit of pressure was released. Due to the GSXR being fuel injected would the venting of the cap be different than the 97 Katana 750 gas cap?

[rexazz2]

thought the Kat tanks where vented Via a hose ???
Is it possible the said hose is pinched

[jemmd]

Vent

I can find no vent in my tank. There is a drain hole in the recess where the gas cap is.

[HemiKat]

A tank has to be vented. Pure physics, if something leaves an area, something has to take its place.... unless its a vacuum but then no fuel would leave at all.

Dont know about the cap, but there is a vent on the tank somewhere.

[kevin2502000]

A tank has to be vented. Pure physics, if something leaves an area, something has to take its place.... unless its a vacuum but then no fuel would leave at all.

Dont know about the cap, but there is a vent on the tank somewhere.

+1

[md86]

The whole in the rim is the vent . But if the seal on the new cap seals off the cavity that hole sits in ..... FI likes pressure , carbs don't .

[tone]

The hole in the rim is a water drain to prevent water sitting in there & rotting the tank or building up & eventually leaking into the the tank ! The tank actually vents throught the cap via the internal airway & the keyhole it is usual for some pressure to be released when opening the cap if the bike has sat in the sun for a while & the fuel has expanded

tone

[DumbLuck]

there should also be a vent tube inside the very top of the tank that is routed out the bottom

[Black_peter]

Old timers (in Rich's case really f'ing old) win again..

The hole in the filler neck drops straight down through the tank. It is for draining rain water and gas overflow.

The Tank vent is at the front of the underside of the tank. This tube runs up to the "ceiling" of the tank. I suspect your old cap leaked and that was venting the tank.
Check all the hoses under the tank for blockage. Except for the one attached to the gas level sender.. That one is useless. Be careful if you decide to blow them out or clean them some how. You don't want to dump a bunch of crap into the tank..

[jemmd]

Tone

Thanks,
I did have pressure blow off on a hot day. Thats what started me worrying about the GXSR cap. The bike runs fine and does not create a negative pressure within the tank so that proves its venting somewhere. I can find no vent as stated by Black Peter. I have had the tank off and looked.

[erok011]

hey BP did you get your name from the Grateful Dead song?