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Discussion Starter #1
Be working on my bike the last while doing various stuff and had the tank off and on a few times

So I will try and be brief

Normally when I lift the tank and remove the lines fuel will come out the vent pipe (if I remember correctly it eventually stops) but I normally just put a small pipe over it with a screw in the end to seal it and stop the fuel coming out - so far so good everything normal


The last time I put the tank on I forgot to remove this little pipe so the breather remained blocked for a short time, it resulted in fuel starvation and hesident throttle when I opened it - no worries I checked and there was my little blocking pipe still connected so removed it, everything seemed ok but not fully tested on a long run

After that I had to remove the tank again and noticed something different - no fuel came out of the vent pipe which I thought was strange and unusual but didn't give any more thought


A couple of days ago I was on a long run 150km and during that time I suffered from fuel starvation - open full throttle and it started to hesitate for a short time tank was about 1/5 full, I filled her up with fuel as normal and didn't have this happen again on the return ride back home, doesn't mean it won't happen again and shouldn't have happened in the first place.

Does anyone know how this vent system actually works inside the tank - could I have damaged something by not removing my little blocking pipe - could there be fuel in there blocking the vent because I didn't remove it and rode the bike a short distance.

So basically how does this vent work - I know something had changed since it didn't drip fuel the last time I removed the tank (before the long ride)

How does this vent thing work ?, is there a pressure/one way valve that I may have been damaged by not removing my little blocking pipe and going for a short ride, I know there is an overfill at the top of the tank beside the filler but that is something entirely different

Anyone know how this vent actually works and what it is connected to inside the tank
 

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Discussion Starter #4
I know something has changed not quite sure what, maybe the problem will never happen again but didn't really get a chance to do some heavy throttle running as I had a friend with me on a smaller bike (200cc) and was painfully slow riding lol


The open throttle hesitation was only happening for about 15km then refueled - but it was severe a 100% fuel starvation on hard throttle - ran normal below half throttle - twist up it died
 

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Geoff
Sorry for the delayed response.
Ok there are 2 tubes out the bottom of the tank.
The larger is connected to the large hole you see when the cap is open. This one comes into play if you splash fuel on the area around the filler neck.
The second smaller goes to a metal tube/baffle that has a small hole on the bottom. this one supply's the path for the tank vent to keep the tank from vacuum locking as the tank is drained of fuel during normal running.
Hope this helps you out.
 

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Discussion Starter #8
cheers mate for looking - I am hoping it was just a one off glitch - 15 years never happened before lol

not even sure how I can simulate the experience as it was a wierd day of abnormal riding staying below 100kmph for almost 200km so my mate on his 200cc bike could keep up - I think my Bird was starting to complain lol staying below 2k revs and 5% throttle for so long
 
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