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PR: Proprietary Items Bagster harness and tank bag

Ian Savage

Well Known and Active Website User
VOC Member
I made (with mum on the sewing machine) half a dozen of these using a cover similar to this,
Altering the tank cap location and nipping it in at the seat end of the tank for a better fit.
 

MartynG

Well Known and Active Website User
VOC Member
My experience with tank bags on a Comet is when securely mounted - the bike is a no-go. Base of the bag seals the fuel cap breather and starves the motor of fuel.
 

peter holmes

Well Known and Active Website User
VOC Member
I know the tank cap needs to vent air, but I have ridden with tank bags fitted for literally years, on both bikes I regularly ride, Comet and Rapide, never once have I had an engine cut out due to fuel starvation, I think it would be quite difficult for a tank bag to make an airtight seal.
 

oexing

Well Known and Active Website User
VOC Member
If I remember correctly you don´t need a cap with a hole in the chromed top at all. The spring loaded steel insert inside that presses on the rubber seal got a hole of course. BUT this insert is movable and does not seal to the chrome top - so any air from within the tank can exit to free air around the insert to escape from under the chrome cover down the tank filler neck. A tank bag cannot block this - except it seals perfectly all around the neck.

Vic
 

MartynG

Well Known and Active Website User
VOC Member
Vic,

There is also a cork gasket under the filler cap that makes a complete and perfect seal with the filler neck of the fuel tank.

I have twice been stopped on my Comet the side of the road with an inexplicable die of the motor and no amount of coaxing would get a restart UNTIL I removed the tank bag - I could hear the whistle of the air rushing thru the hole in the fuel cap as it broached the unintended vacuum inside the fuel tank. Stuck a bit if roadside timber (small) next to the fuel cap to keep the breather hole clear - fixed. Never used a tank bag since then.

I have had a related experience with a car about 20 years back. Car rolled to a stop, engine dead and would not restart. After about 10 minutes it would restart only to die around 10 minutes later - what a circus performance - run, stop, run, stop, and so on. Turned out to be a baffle in the silencer that had come loose and blocked the outlet of the exhaust. When the motor stopped if I was quick opening the bonnet you could just hear the compresses gas in the exhaust forcing its way past the exhaust gasket manifold to freedom.

Martyn
 

vibrac

Well Known and Active Website User
VOC Member
I can't think that even if cap restriction is a common problem which I doubt for clever Vincent owners its easily solved. Pity is I don't think we have the critical mass to get a proprietary bag tank cover made I know baglux were approached years ago.
I find haversacks make my back ache and top boxes are ugly on classic bikes and can affect the handling to be able to swap a bag between bikes would be wonderful
 

Bill Thomas

Well Known and Active Website User
VOC Member
I think the petrol tank must be full to the top To stop the Bike ?.
I have never had trouble with a Magnetic tank bag.
I am out of touch now, but if my Car Tank cap is not sealed, The engine warning light comes on !!.
No clue as to why ?.
Some of this late Bikes and Cars are just too much for me.
Don't think I could drive a car that keeps switching off when I stop ??.
I think there will be a lot of Knackered Starters about soon ?.
 

Vincent Brake

Well Known and Active Website User
VOC Member
My experience with tank bags on a Comet is when securely mounted - the bike is a no-go. Base of the bag seals the fuel cap breather and starves the motor of fuel.
every time in the rain, (and always riding out with a tankbag)
when it starves fuel, i think, oh blimy broken down again.

but before the old man dies, the old man quickly remembers:
move the bag a bit and ride on.

happy man
 

vibrac

Well Known and Active Website User
VOC Member
My 1925 Douglas engine stops when I stop but that because it doesnt have a clutch. very green!
Actually it probably is! If you think about it that Douglas has had nearly 100 years to offset the cO2 used up when it was made no wonder the Tesslers and other electric milk carts dont ever mention that calulation. Something to mention if your 70 year old Vincent has its green credentials criticised by some brainwashed teenager.
 

peter holmes

Well Known and Active Website User
VOC Member
If I remember correctly you don´t need a cap with a hole in the chromed top at all. The spring loaded steel insert inside that presses on the rubber seal got a hole of course. BUT this insert is movable and does not seal to the chrome top - so any air from within the tank can exit to free air around the insert to escape from under the chrome cover down the tank filler neck. A tank bag cannot block this - except it seals perfectly all around the neck.

Vic
A good way to test this theory, or to test the tank bag fuel starvation phenomenon, disconnect the carburettor float bowl fuel feed with the fuel turned off, put your finger firmly over the fuel cap vent hole, turn the fuel on and wait, if no fuel flows you have a perfect vacuum. Would drilling a similar size hole to the vent hole just a knats down from the top radius/corner of the cap solve the vacuum problem without creating a petrol leak problem? I won't be experimenting as I have never experienced this problem, but if you would like to use a tank bag, and lets face it, it is the best way to carry easy to get to items, specs, phone, wallet etc, unless that is like me you forget to zip up the top clear view compartment, as I did riding back from the West Bay Meet a few years ago and lost an iPhone!
 

oexing

Well Known and Active Website User
VOC Member
In the photos fuel caps and one oil tank cap. There is only one seal, from spring loaded lower component to tank filler neck but no seal between lower dish to chromed top cap. So no hole in top cap required, all breathing would be via the space between dish and top cap down . So I´d say blocking the top hole is not the problem but having a magnetic tank bag sealing a lot of tank space around the filler neck will starve the tank from breathing.

Vic
P1080892.JPG

P1080894.JPG
 

BigEd

Well Known and Active Website User
VOC Member
VOC Forum Moderator
I have had a Bagster tank cover and tank bag on my Ducati ST4S for probably 15 or more years, good quality. A downside of many tank bags is that you have to take them off to access to petrol filler caps. The Bagster gets around this in a convenient by having two spring-loaded catches at the back that when released allow the bag to be pivoted forward on the two front fixings. The two front-fixings are fairly quick to release should I want to remove the bag completely leaving the tank cover in place.
I also have an inexpensive magnetic tank bag (purchased ages ago at Lidl) that I used on my Rapide. Cheap and cheerful but very convenient however when I fitted an aluminium tank it was no longer convenient as it had to be held on with an inconvenient selection of straps.
Peter's mention of a Bagster Harness and tank Bag suggested that could also be a solution for me and enable me to use the tank bag from my Ducati. A bit of research found two places that sold the Bagster EasyRoadEVO harness. I ordered one from BargainBikerBrands on Thursday and it came free post post yesterday. I had a quick trial fit last evening and it looks as if it is all going to fit. (OK, so the Ducati bag is red but I like red :).) I've posted a couple of photographs below showing the harness in place. This aluminium tank has a central filler hole so this harness works for me. It could also be a good starting point for someone that was prepared to modify one to give access to the standard tank filler cap.
bagster_easyroad evo1.jpg
bagster_easyroad evo2.jpg
 
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