Have to prime to fill float bowls when sitting more than 24 hours

[mattd1205]

Hi,

Ive noticed when my 78 GS750 sits more than 24 hours. I have to prime my bike in order for it to start easily. It usually takes 4-5 seconds for the fuel to stop flowing (clear fuel filter). I don't remember needing to do this on my other GS' that I had in the past. The carbs were cleaned a few months ago and I didn't see any real wear on the needle and seat. I know the floats themselves float properly and don't sink when placed in gas. Is this normal? Should I be pressure testing my float pins and seats?

thanks in advance
Matt

[chuck hahn]

You shouldnt. If it just 4 seconds or so just choke it and go.

[Nessism]

Did you check fuel level in the bowls? It's important to do this, not just set float height. Assuming the fuel level is correct you shouldn't have to prime after only 24 hours unless it's super hot outside.

[mattd1205]

@nessism I did both. Everything seems fine on that front. It's about 70 degrees out today but a little cooler in my garage.

thanks
Matt

[mrbill5491]

I have to prime my fuel bowls if the bike sits for a few days, doesn't matter the temp either. A minute or two and it's fine. Starts right up.

[Tom R]

Sounds odd, like others stated earlier... usually over a week of sitting for mine. Did you check the fuel level on the bench or bike? While running?

[Buffalo Bill]

So it must be leaking out, that means the needle valves aren't tight.
You'll have to find out why. The floats are set too high, or the needles need to be replaced.

[bwringer]

Is your bike magically producing oil?

(In other words, double and triple-check for gas in the oil.)




The only other thing I can think of is if you left the tubes off the bowl vents, gas could evaporate a little sooner.

[Buffalo Bill]

Is your bike magically producing oil?

(In other words, double and triple-check for gas in the oil.)




The only other thing I can think of is if you left the tubes off the bowl vents, gas could evaporate a little sooner.

I noticed how quickly the gas evaps from carbs during July. A few hot days and I gotta prime them too.

[hannibal]

Are you using choke after it sits for a day?

[hillsy]

The only other thing I can think of is if you left the tubes off the bowl vents, gas could evaporate a little sooner.

That's the first thing that popped into my mind - you'd be surprised how quickly fuel can evaporate when those vent hoses are left off.

[hillsy]

Is your bike magically producing oil?

(In other words, double and triple-check for gas in the oil.)

And with this ^^^ if the fuel is flowing past the float valves the bowls would be full, not empty.

[mattd1205]

Actually I did leave them off when I cleaned the carbs.. I don't recall my other GS series bikes having the vent tubes attached either but it's been awhile. I'll try that first before I tear into the carbs again.

thanks guys!
Matt

[mrbill5491]

Actually I did leave them off when I cleaned the carbs.. I don't recall my other GS series bikes having the vent tubes attached either but it's been awhile. I'll try that first before I tear into the carbs again.

thanks guys!
Matt

Yup, put them back on, there are there for a reason.

[bwringer]

And with this ^^^ if the fuel is flowing past the float valves the bowls would be full, not empty.

Whoops, yeah, you're right. Good point.