Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.

Leaving bike with fuel tap on - petrol overfilling carbs?

Share
avatar
jimbobs63
the 800
the 800

Posts : 258
Location : London, UK

Leaving bike with fuel tap on - petrol overfilling carbs?

Post by jimbobs63 on Fri 19 Aug 2016, 2:58 pm

Hi,

I just came back from holiday on Wednesday, and went to start the bike to make sure it was ok for work yesterday morning, only to find that as soon as it started, petrol starting dripping down from below both carb float chambers onto the air filter housing.  Switched off quick!  Tried again and same thing.  Seemed like quite a serious leak, similar but not as bad as one I had over a year ago when the vacuum pipe perished.

So yesterday evening after I got back from work I thought I'd look again at it and try to see what was going on.  Started it up again - no leak!  Revved up, still no leak, so rode it to work today with no further bother.

So, it got me thinking:  I know it's recommended to switch the fuel tap to off if not using the bike for a while, and I didn't do that this time (simply forgot) - is it possible that the carbs float chambers just got overfilled with fuel over that time I was away, and the excess somehow spilt out when I first started it?

Whatd'yafink?

Jim
avatar
rob75
Rossi
Rossi

Posts : 50
Location : Holland

Re: Leaving bike with fuel tap on - petrol overfilling carbs?

Post by rob75 on Fri 19 Aug 2016, 4:16 pm

The fuel tap is vacuum operated, so no engine vacuum no fuel.
I suspect the float bowls dried up leaving the float pins dry. Any small amount of dust od dried out rubber tip may keep one open when starting and cause flooding. Switching the engine off, leave everything to soak may have solved the problem.
Keep looking for leaks the comming days.

Regards,
Rob
avatar
jimbobs63
the 800
the 800

Posts : 258
Location : London, UK

Re: Leaving bike with fuel tap on - petrol overfilling carbs?

Post by jimbobs63 on Fri 19 Aug 2016, 4:38 pm

Thanks rob, that's helpful. 

Yeah, I'll keep an eye out over the next few days.

Jim
avatar
Alvi
Running out of unique names
Running out of unique names

Posts : 188
Location : Isle of Man

Re: Leaving bike with fuel tap on - petrol overfilling carbs?

Post by Alvi on Fri 19 Aug 2016, 8:37 pm

I got my cb5 from a neighbour who hadn't used it for at least 5 years. He said he started it from time to time, but not for quite a while. The petrol tank was empty & when I removed the dipstick, thin black stuff poured out - all the fuel had emptied into the sump! The bike wouldn't start - it seems the fuel had dissolved the air fiter on it's way. Once I removed the filter it started straight away. I stripped the fuel tap, but couldn't see anything wrong with it. I stripped & rebuilt the bike & got it back on the road. A few days later,I struggled to start it. I checked the dipstick & the level was above the max mark. I always left it with the fuel tap off, so I got a replacement tap off ebay. That was 18 months & 10k miles ago & it's never misbehaved since. I still don't know how the tank drained into the sump, I still have the same pipework, just the tap was replaced. Might be worth bearing this in mind if the problem recurs?

Sponsored content

Re: Leaving bike with fuel tap on - petrol overfilling carbs?

Post by Sponsored content


    Current date/time is Wed 20 Sep 2017, 3:15 am