Yamaha TRX850 Enthusiasts Forum

Almost 15km from home yesterday the bike started to act like starved of fuel so went to prime and off again the onto reserve and started to feel a little surgey once more so I went back to prime and left it there till I found a petrol station just down the road. Fueled up again just taking 10 litres but only 190km travelled. After utilising the screw type fuelcap off the trackbike tank I have a sneaking suspicion it may not be breathing properly. with the bike sitting in the sun for a few minute I've gone to unscrew the lid and noticed a pressure build up blowing fuel past the seal and tread as soon as I've started to unscrew it..
The breather under the cap runs thro a small tube in the tank and out the bottom where there is an overflo pipe connected...correct???
I've just noticed with the fuelcap on and sealed with the fuel hoses disconnected when on prime fuel flows out for a few seconds then stops and breathes thro the tap...
If thats the tank breather I've just got to find if thats blocked or the caps breather is sealed from the tank breather.
..

Yep you`re corect Cobba, it does sound like a breathing issue. Maybe your old girl needs some Ventalin?
Some 0.5 mig wire will find it`s way through the breather hose / pipe.

problem solved...breather line was clear... it was the aftermarket screw cap that I took off the trackbike tank, the breather in it was sealed up... I also noted when I drilled it out it didnt actually sit over where the breather pipe was anyhow(it was almost 180 degrees opposite) so it would more so spew fuel if it was full out and around under the screw cap body then down the breather onto the rear wheel Problem solved by replacing it with another std lockable one....

old trail riding trick, 1/8" or 3mm diameter ball bearings, put them in the breather tube of your mates bike.
He gets 5 k down the track and flames out. Opens the filler looking for fuel (letting air in) -finds plenty so kicks her over and kazooom, she is good for another 5k.
Meanwhile you are spraying spittle inside your helmet from laughing so hard, some 20k ahead of him.


bagger
(luckily retired from that cruel sport)

Hi bagger, that's a good old trick but it can go bad - a mate of mine did it to a guy he worked with & after having "poor running/cutting out issues", the guy took it to his local dealers (who obviously hadn't heard of this trick) who proceeded to strip the carby a few times, then the top end of the motor etc - by this time, the cost of the fault tracing was getting quite expensive & the owner was not too happy when the cause was finally diagnosed! The guy had some suspicions as to who the culprit was but couldn't prove anything - not a happy situation in the end.

harden up, its trail riding remember.
Perhaps he should take up netball.