Hot Gas?

[alabrew]

Left the shop this afternoon on the '85 K100, about 90 degrees F, with 100 miles on the tank. Rode about 20 miles at 45-50 mph and then jumped up onto the interstate. After a mile or two at 70 mph, bike lost power. I was able to get to the break down lane and keep going at about 40 mph but it was surging - power, no power, power, no power. Limped off the exit, it died but dumped the clutch and got it going again but had to turn on the lever "marked choke that isn't a choke" to maintain an idle. Got to a Chevron and filled up with 3.2 gal. with 124 miles on the trip, so I had about 2 gal. in there. Fired back up and everything back to normal for the 20 miles home on surface streets with speeds up to 55 mph. It has no insulation under the tank and I've not added a Johnny Blanket, think either would have helped?

[alabrew]

Thanks for the reply Johnny. The trip in that morning was about the same - 18 miles on 45 mph roads and then 10 miles interstate.  I was blowing fuel pump fuses this spring and I had tightened the 4 pin into the tank which solved that. I had also cleared the tank vent line while cleaning the tank. New fuel pump and filter at that time too.

The previous tank of gas wasn't name brand and I only got 125 miles on 4.2 gal., it ran much better with this tank until this incident. I'll have to get some techron in there.

It feels like it is struggling compared to the '91 RS. Some of that I attributed to the difference between motronic and jetronic and 8 valve vs 16 valve.

[Chaos]

bit of a long shot but it might be worth checking the HES with a heat gun

[johnny]

greetings...

you are right... its hot gas... thanks for sharing its history in your origional post...

j o

[bizzaro]

Yep, I go with boiling gas.  When the sun is high, and my tank is about half full, it will do that. And once it is hot, and you increase the heat, stop n go, or hard driving(high rev's), it will boil and run like shit, and even stall.  Insulate your tank. Cheap Johnny blanket you can make from an windshield reflector. Usually get a couple out of one reflector.

[Filmcamera]

You can also try using a small oil cooler as a gas cooler, install between the return line and the tank. It worked well for me.

[The Mighty Gryphon]

Do I need to mention that a fuel cooler should have heavy duty construction.  Thin walls like in a coolant radiator are to be avoided.

[alabrew]

Finally! Crossing my fingers I got this figured out. Not related to low fuel/hot gas as it has done it with a full tank but it was always at the end of a hot ride. Had to limp home 18 miles in 95 degree heat last week. Finally heard the fuel pump only pumping half the time so that lead me to the HES. Finally occurred to me that I had one on the '91 RS so I removed both and installed the '91 on the '85 and had a good ride into work today. Expect the same on my warm ride home.