Winter fuel

[ThePsuedoMonkey]

I noticed the price drop on fuel this weekend (~$0.55) and thought "yay, cheaper gas!" I fill up my baby and head out on the freeway, she starts getting bogged down about a mile down the road and I start to panic (please don't be oil). Pull off: nothing seems wrong. Start up: idle was low (~900RPM). Stopped at a station and poured in 1/3 bottle of octane booster (so much for cheap gas) before the idle got past 1200RPM. Put premium in her today instead!

 

[happy61]

I've been running premium with a dose of Sta-bil in mine since my rebuild. I don't put that many miles on it anyway so it's no big deal. I've put more in it than it's worth anyway so what's a few bucks extra for fuel.

 

[OliverB]

You really don't need premium gas in these engines. The compression ration isn't that high on the XS400 and sometimes premium will bog down an engine not designed to run on it. My Owner's Manual specifies "Regular" gas. Mid grade will do the job just fine. I don't notice any difference in how my bike starts or runs between Winter and Summer gas in my area but I don't think our area mandates Winter formulation fuels like some states. I do use Sea Foam in gas I keep at home during the Winter. A stabilizer really isn't necessary in any engine that is only idle for a few months. Gas does not deteriorate that rapidly. Sea Foam helps reduce varnish buildup on standing, though. The CV type carb just doesn't like to be idle for weeks at a time. They are most always harder to start and not as responsive to throttle for a bit after they sit idle for more than a week or two.

 

[happy61]

The fuel may be more critical on a two stroke engine. I have all kinds of starting problems with my sno-blower, weed whacker, mantis, etc. The dealer tells me not to mix more fuel than I can use in 30 days. They blame just about everything from poor starting to the national debt on lousy ethanol gas. Might be just their standard excuse.

 

[OliverB]

Interesting. I mix 1 gal. two cycle fuel each year and use it in my weedeater and leaf blower. Have done that for years and never had an issue. Yeah, I think a lot of things are incorrectly blamed on ethanol fuel.

 

[bcware]

I have always run regular gas in my '78 and I have never had an issue. All I have noticed is that these bikes are cold blooded and a bit fussy when it comes to idle (I am always adjusting mine, even while riding). The idle is too low when the engine is cold, but returns to a stable level once it is up to temperature.

Are you sure you're not confusing the colder weather with a change in fuel quality? If it's colder outside the bike is going to take longer to heat up and cool down faster which could cause a low idle.

 

[ThePsuedoMonkey]

Nah, I don't think this one was due to weather: it was still ~55 degrees and I had been riding for about half an hour before this with no issue, though I hadn't been going more than 60 before that. Michigan is kinda known for cold winter weather, so the fuel stations probably put lots of butane into the fuel. Maybe I'll try again though, since I still have the remainder of that octane boost.