Triumphrat

CarlosFlys

(Posted this on email list, thought it'd be of interest here as well)

Preparing the Thruxton for AHRMA race, shop put on a Catch Bottle to catch any overflow fluids (AHRMA requirement).

They made the hose into the bottle too long, so that it touched the bottom. The next time I filled up the tank, and took a nice deep lean corner, some gas came out and filled the bottle about a 1/2 inch. Problem was, it was over the end of the tube... which means the gas tank had no ventilation, which means it was a big vacuum, which means the carbs were not getting any gas! I had to keep revving the heck out of it to keep the bike from stalling!!! It would warm up just fine, but after the first couple of stop signs... DOH!

Figured it out on 2nd day, kinda funny actually. So a note to everyone: don't fill up your gas tank anywhere near the top - it will just come out the first corner you take anyway, and douse the back tire with gasoline!

grumpy_1944

I fill my Bonnie up to the bottom of the inner ring. Never lost a drop of fuel in a turn.

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Bill;
I took the road less traveled---------now where in the hell am I??

CarlosFlys

Check again; that's where I always used to fill mine up to (the lower "ring"). Notice the tiny hole when you look down into the tank? That's the spill hole.

Fill up your tank like you usually do, put the gas pump hose back in it's cradle, then tip your bike over to the right as far as you can stand it while the gas cap is off....

RedBird

The inlet vent to the fuel tank is the fuel tank cap. Fix it and ride!

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Larry
2003 T-100 (790cc), NARK, NH Togas, 8100 rpm rev limiter, 158 main jets, 42 pilot jets (less than 1 turn out on pilot screws), stock needles--no shims. 13 A/F ratio from 1100 rpm to 4000 rpm; 12 A/F ratio from 4000 rpm to 6000 rpm; 13 A/F from 6000 rpm to 8100 rpm.:D
2007 Tiger 1050--White:D--SW-Motech crashbars, Skidmarx rear hugger/chain guard, Calsci +7 windscreen.

David86

Read this thread because I have some problems with my -04 bonnie I bought some days ago.

Twice it died for me, both times after I had used up around 6-7 liters of fuel. I checked the rubberhose going from the bottom of the tank to the bottom of the bike and found this right after the check valve (i believe it is, with UP written it).



As you can see, its bent in a weird way, and i believe it's blocked.

I just took it out and will see what happends tomorrow, i'm quite sure that this was the issue, but now I read here that it's not the vent for the tank? But that just doesn't make sense, the check valve is obviously put there for preventing fuel to leak out. But if its not letting air come in the other way, then what is the purpose of the hose? It's blocking both ways? Pardon, but that just doesn't make sense.

My problem with this is that if its true then my solution wont work and I may be stuck somewhere tomorrow along the road

I should mention that the filler cap is not stock on my bike, it's another one with a lock on it. And the only place I can see air come thru it is in the key hole...

Black Dog

Next time it stops, pull over and open the filler cap. If it's hard to do, or there is a sucking noise as you open it, then the tank isn't venting properly.

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2002 Sprint ST 955i

1995 Yamaha XT600E

www.goingfastgettingnowhere.blogspot.com

David86

I did that and it didn't make any noises, but it did seem to help. It also helped open to reserve (my theory is that the preassure increases and therefore the fuel easier gets down to the carbs for a while untill the fuel level drops some more).

The thing that seemed to make the problem go away completely was fueling up.

I also have the theory that the bike might not like to get wet, first time it happend was an early morning with morning dew and the 2nd time was after i washed the bike. But the problem still occured 2 hours after I washed and driving 25 km.

mikeinva

+1 on that I run a stright hose with no tip over valve never spills a drop

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Why do I feel young on my bike

PAAS

That hose is the overflow hose to allow fuel out if you overfill the tank. The one-way valve is to stop fuel coming out if the bike falls over (i.e. you crash). The hose will allow air in to the tank, but the main tank vent is in the cap. You should only suffer fuel starvation if both the cap vent and the overflow hose are blocked. Your overflow hose looks incorrectly routed to me. It shouldn't be going around that bolt but straight back and down the back of the left side of the crankcase through a wire loop in front of the footpeg. There should also be another hose going through the loop - the carb vent hose. The tip over valve should be fitted in a clip on the front of the airbox.

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Paul.

Herts. UK
Aubergine & White 05 T100 (865cc) with numerous mods.
(Previously Ducati Monster S4 and several UJMs)

mikeinva

The tip over valve has caused alot of trouble over the years .If it sticks the tank wont vent.That is the tank vent hose the tip over valve is there in case the bike flips over in a wreck to keep gas from flowing out.Unless you flip over you dont need it and in that case it prob wont mater anyway lol.

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Why do I feel young on my bike