Whenever I ride my bike fuel is escaping from the breather pipe and down through the cable tidy rubber onto the crank cases. What can i do to prevent it ? The evo cap looks a similar design to my rev 3 and 4 cap and they never did this. I read a previous post and someone suggested a one way valve. Ive looked and because the inner diameter of the breather pipe is 3mm no valve ive seen is small enough. Its going to ruin the paint on my engine if it persists. Could the cap be faulty ? Would a longer pipe with a higher loop above the cap prevent this ? Could i even run a longer pipe down to near the swing arm where the carb overflows exit or would this cause syphoning ? I see beta sell a billet cap with an upwards rather than side exiting breather. Anybody know what diameter pipe fits on these. You can buy one way nipples for off road bikes but they fit 6mm hose. Any ideas ?

I think it must be a faulty cap, can you try one of your riding mates fuel caps on your bike. Never had a problem with our four evo's.

Edited September 12, 201312 yr by jfc

i had one go bad on my 290. replace the cap..all will be good...wire brush the threads on the new cap..makes it nicer to screw and unscrew

Thanks for that. Will get a new one.

your lucky...they usually fail with the check ball stuck closed...they run great for about a half an hour then die...no more start,..you check spark.,,,take the carb down...then it starts again...runs..dies..

you get frustrated... and then you open the cap...wooosh...ahhh...new cap time...

that went on for a couple weeks. until i figured the cap issue..almost traded in the bike over it..

something so simple can ruin your head..

just a small spring and check ball... invest in the race cap...red and better quality...stock cap is 50.00 race bling is 75.00 i think...worth the extra money..