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Gas leakage through cap?

651 Views 5 Replies 5 Participants Last post by  vulcan500rider
Just got a Ninja 650 used. The gas cap is making a squeaky pressure releasing sound. Is this normal? It's almost like it's not air tight.

Also, hubby rode it home and only got 36 miles to the gallon. This may be because he was going 80 and he is a big guy so there was a lot of wind resistance. Still, the owner said he got around 50mpg and his wife got about 55mpg when she rode it.


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there is usually a rubber sealin the cap ur might be corroded
If it is making a squeaky pressure sound, then the gas cap vent is probably plugged, and the expanding air is trying to squeeze out.
As I understand all bikes with a vacuum petcock make these sounds time to time. It's the release of vacuum created as the gas drains into the carbs. Perfectly normal. Your tank technically isn't air tight and all of mine have done it, some vent designs are just louder than others.

36 miles to the gallon is low but not unheard of. 50 is in line with what you should be expecting on this bike. The worst I've had on my 500 (pillion, highway riding) was 41-42 mpg, and the best was 56-58 if the throttle was absolutely babied. All bikes are different and some 500 riders claim 75-80 mpg (lol!) so remember to take it all with a grain of salt.

A can of seafoam and a filter cleaning, along with properly inflated tires (35-40 PSI) will probably improve your MPG. Enjoy. :smile:
I will take a closer look and see if anything is pinched or blocked. Thanks for the info!
I will take a closer look and see if anything is pinched or blocked. Thanks for the info!
The vent hole can be very small so you might have to look for it. You've heard the term "your mileage may vary" - that's why different people with different styles will get different mileage on the same bike. I have the C90 and people claim to get 40 to 45 mpg. I'm lucky if i get 32. I had a Honda Rebel and was getting 60 while everyone else is getting 75 plus. I'ts just the way you ride it.
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