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Colder Temp Running Thoughts

3K views 14 replies 6 participants last post by  Comanche 
#1 ·
Hi All,

Since the temps have dipped a bit around here I am noticing the bike running slightly different. On the ride home from work today it was about 35F. The bike warmed up a few minutes on full choke and I took off with the bike still on full choke and eased it back to fully off choke after maybe 5 minutes of run time after setting out.

The bike was a bit hesitant off idle for quite a long time on the way home. It was fine at idle and under decent throttle.

Is that purely due to not reaching operating temperature? How long do you think it should take to get to normal operating temp with that kind of outside temperature?

Could it be a jetting issue? It has a fully stock air box and the exhaust is stock other than slip on Harley OEM mufflers. The carb currently has the stock jets and the idle mixture screw is about 2.5 turns out.

In warmer temps the bike will run fine with the choke fully off within a couple minutes.
 
#2 ·
I live about 3 miles from work, and many times I need the choke at least part way on during this ride, usually about 1/2 way. Once I get up to around 45-50, I can open it all the way with no issues. Has been jetted, open pipes, K&N filter, and grampsized filter housing.
 
#6 ·
Getting cool as well up here. I had my bike out yesterday, just to the gas station to fill the tank before she goes into hibernation. She ran like crap, coughed, sputtered, didn't like it at all. Ran better on the way home, total run was around 6 kms.
 
#7 · (Edited)
Is that purely due to not reaching operating temperature? How long do you think it should take to get to normal operating temp with that kind of outside temperature?

As you know your engine works by burning properly mixed fuel and air and combusting it, and that air and fuel (in your case) come from a carburetor. Fuel burns best in a fine mist (atomized). What happens when it's cold, is that the fuel condenses in the carb, intake manifold, etc. and doesn't become a fine mist. It's much sloppier and more like droplets of fuel than a tiny mist. It becomes hard to control the mixture correctly and harder to burn. The choke, as you know, makes it run a little richer, which helps it to run in these conditions.

That's why it'll take a while in the cold. The engine may warm up, but it's the carb and intake that need to warm up in order for the bike to run smoothly. That's why some small airplanes have 'carb heaters' to keep the fuel atomizing at high (cold) altitudes! (Also to prevent the carbs from freezing!)

Not much you can do about it other than run with the choke as you have been until it warms up. But, doing so doesn't hurt anything other than your gas mileage!

I've wondered though, how hard it would be to retrofit the 900's fuel injection system to the 800. The engines are very similar, as I understand it the 900 is a bored out (or maybe just lengthened stroke or something?) and updated 800. I wonder if the intake, throttle body (which contains the fuel injectors) and related components could be modified to fit the 800. I dunno, would be tremendously expensive and time consuming... BUT... it would be a solution! Then it'd fire right up in the winter good to go! (The fuel is under pressure and shot through an injector in this case, so it stays atomized)
 
#8 ·
Yeah I have already decided that my next bike will be fuel injected since it will cut the pain in the ass factor greatly. Especially when buying used. Though I am enjoying my 800 greatly and am looking toward to having it for the whole riding season next year.

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#9 ·
Yep, fuel injection is the only way to go with a cruiser or touring bike. This is my 9th bike but my first with fuel injection. Just push the button and by the time you put on your gloves and helmet (at least down south), it'll idle down on its own and let you know it's ready to ride.
 
#10 ·
Yeah, unfortunately funds were tight for my second bike since I got laid off in May and have had a temp position since September. So I found the 800 for $1500, and sold my old GS for $950. I might keep the 800 for a little bit but I am sure when I find a good permanent job the itch will come to get something newer and slightly bigger.

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#11 ·
Some of us old guys who bought a 900 for one last fling will be selling them with low mileage. They'll have been cared for like a baby. Should be able to get a deal. Those from down south are usually ridden between 60-90 degrees by older riders. When I get ready to sell mine I'm putting it this site for someone looking to move up from a 500-800. For you fanatics, notice I said "some" and "usually". Depends on the arthritis, degenerating disk and old injuries.
 
#12 ·
My story is similar to many, bought an older 800 just to get back into riding again after a 35 year sabatical. Thought if I liked it I'd get something bigger and if I didn't I'd sell it but I'm finding that I really like it. Too bad the seasons pretty much over up here and I'll have to wait 4 months until it warms up again. In the meantime I'll add a few extras that I'll pick up at the bike shows over the next few months and polish her up over the winter to get her looking good for the spring.....
 
#13 ·
Since removing EPA components from California Models makes the bike run cooler I was wondering if reconnecting it during the cold weather season would help resolve this cold temp sputtering and operating issue? I know it sounds far-fetched but what does an expert think?
 
#14 · (Edited)
No expert, but I'll give you my opinion.

Most of the cold weather sputtering is from a cold carb. I doubt a few degrees warmer engine coolant will warm the carb up enough to solve it. Again, the issue is fuel condensing in the carb and not being the fine mist it should be, due to a cold carb. These carbs are used for a variety of bikes and applications, perhaps you could find an electric carb heater? An old hunting buddy had an ATV he had bought from a guy way up in canada that had a carb heater. It plugged into the wall and kept the carb warm, and it would fire right up and run nice and smooth in the winter!

You could also look into 'micro squirt' fuel injection systems. Chances are someone somewhere has already done the conversion on the bike with the same (or very similar) carb. It essentially converts the bike to throttle body injection. Then you have the pressurized, atomized fuel your engine is yearning for in cold weather! Of course for the price of doing that, and the cost of some likely needed fabrication, you could just trade it in for an already fuel-injected 900 (or 1500 FI, etc.) and come out ahead!
 
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