Gas evaporating

[imcgyver]

Hello I have a 1980 LG and I finally found out why I have a cold start problem, the gas is evaporating from the carbs because when I turn the petcocks to prime cold start fine, if I leave the petcocks turned to on it will be a while before it starts, granted it is hot out here but I wish I did not have to set to prime every cold start, we have 10% ethanol in our gas, another issue I found is after filling the tank right before winter storage and looking in at the start of riding season I noticed about 1/3 of tank of gas missing. any one have similar issues and/or fix?
Thank you for our time and response.
Ron

[WMarshy]

I've never heard such a thing. Might be in your oil after storage. Thats a lot of gas to evaporate from a tank. I have stored mine indoors in a heated basement (~85F) with gas in the carbs and it does evaporate but not from the tank like that.

Are you leaving it in direct sun during that storage period?

[TopCatGr58]

Hey there Mcgyver,

Well, Denver is at a higher alititude, the air is a lot thinner/less dense so there's more room for fuel to evaporate into it. The gas tank has a vent in the gas cap for normal operation/venting. For Winter Storage, you might try putting a peice of sheet rubber/nitrile fuel resistant across the gas cap opening before putting the cap on to make a better seal!?

As for the hard starting, again, it sounds a bit odd for your bowls to vent that much, but that's partly why Yamaha put a PRIME function to the petcocks. I'm at sea level so I don't see much evaporating at all.

Perhaps others near your altitude and humidity/dryness can report similar or dissimilar experiences!?

T.C.

[CaptonZap]

Check your oil level, and make sure that the gas didn't magically teleport to the crankcase.
I have that problem if I go for a long ride and come back and park it. The heat from the engine evaporates some fuel out of the bowls.
Also, if I park on the sidestand after getting things warm, when I come back after fifteen or twenty minutes, the fuel has evaporated and causes a rich mixture in the intake tract, which requires full throttle and crank on the starter till it catches. Five minutes, no problem, it catches first crank. Cold, choke and away we go.
What part of Denver are you in?



CZ
I-25 and Alameda

[skids]

One of my 3 xs11s needs priming to start after sitting for a week, it does. Not leak into the crankcase. No gas stain at the bowl taps either,

[donebysunday]

Hello I have a 1980 LG and I finally found out why I have a cold start problem, the gas is evaporating from the carbs because when I turn the petcocks to prime cold start fine, if I leave the petcocks turned to on it will be a while before it starts, granted it is hot out here but I wish I did not have to set to prime every cold start, we have 10% ethanol in our gas, another issue I found is after filling the tank right before winter storage and looking in at the start of riding season I noticed about 1/3 of tank of gas missing. any one have similar issues and/or fix?
Thank you for our time and response.
Ron

Depending on how long it sits ? ? Yes I think you could loose that much fuel from simply re-filling the float bowls over and over. My bike usually does not sit for over a day but I noticed that it runs ruff until the bowls fill on ON position. I would use the off as I do and in your case prime for a minute then turn to ON and start. JMO P.S. always turn the fuel valve to off and if parked over night or longer use the center stand to try and keep all the bowls level.

[jjz28]

Check your oil level, and make sure that the gas didn't magically teleport to the crankcase.
I have that problem if I go for a long ride and come back and park it. The heat from the engine evaporates some fuel out of the bowls.
Also, if I park on the sidestand after getting things warm, when I come back after fifteen or twenty minutes, the fuel has evaporated and causes a rich mixture in the intake tract, which requires full throttle and crank on the starter till it catches. Five minutes, no problem, it catches first crank. Cold, choke and away we go.
What part of Denver are you in?



CZ
I-25 and Alameda

That's what I was thinking.

[motoman]

That's what I was thinking.

As a Colo. native, not happening. As CZ stated, better check your oil level, as you may very well have a leaky float needle or two. Years ago(30+) living in Durango, winter stored my Venturer in metal shed with full fuel tank. Never an issue with fuel level dropping in tank, and always fired right up in spring. Never an issue here at my location now either, although doesn't get stored here winter, gets ridden on and off. With two scoots, at times one or the other will set as long as 4mo. with temps summer time regularly bumpin' the 100's. In a nutshell, got somethin' else goin on as evaporation to that extent is not gonna happen unless fuel cap is left flipped open.

[imcgyver]

Oil level is fine, no gas smell in the crankcase just oil, burns off a little, does not take much to top off after a few hundred miles (bottom of sight glass to normal level), on a hot day after work I need to prime to cold start.
Ron

[donebysunday]

As a Colo. native, not happening. As CZ stated, better check your oil level, as you may very well have a leaky float needle or two. Years ago(30+) living in Durango, winter stored my Venturer in metal shed with full fuel tank. Never an issue with fuel level dropping in tank, and always fired right up in spring. Never an issue here at my location now either, although doesn't get stored here winter, gets ridden on and off. With two scoots, at times one or the other will set as long as 4mo. with temps summer time regularly bumpin' the 100's. In a nutshell, got somethin' else goin on as evaporation to that extent is not gonna happen unless fuel cap is left flipped open.

Not a bad idea during off times to open the prime once a month just to keep the float bowls full. JMO