Just about to finish off a whole lot of customising work, and put bike back on road for summer, and want to air a fitting question I have, for your valuable opinions, in advance of trying it out. I have generally been running the bike with the carb oil warming set up, as standard, and do appreciate them. But I'm considering leaving out the switch, simply because it gets rid of an annoying fitting problem plus gives a better choice of oil hose route. Now my question is this, could it be a bad idea to run the bike all year round with warm oil to the carbs? My hunch is 1. that it is likely to make no difference on long rides in hot weather even, or even generally a good idea, because the bike reaches and keeps a sane operating temperature.... 2. But then again, around town in traffic is quite different, esp in summer, and may perhaps raise fuel temperature too much... or is that unlikely to be a problem?
TBH I've left mine in the on position for years and occasionally turned it off in the summer and noticed no difference. The former owner rode through the Alps in cold weather with a mate who didn't have carb heaters on his 900 and apparently there was a noticeable difference particularly at high speed.
For years I didn't even know what the lever was, in fact mine looks more like an oil take off point for pressure testing or something. I rode all over Speyside with the heating off in summer, autumn and in to winter until it was too cold and the roads too icy to ride on and never had carb icing, as far as I was aware anyway. I have, however, heard about someone in London who had one without the oil heating and he had problems at times - usually when overtaking on full throttle.
I had carb icing problems on mine when I first purchased the bike. Didn't even know about the switch on the lines till I looked on this forum. Mines left in the on position all the time. Mines a '92 bike but fitted with the temp gauge. Temp looks to go a bit sky high when stuck in traffic, but not noticed any ill effects. From what I've gathered, these engines all run hot anyway. Be a lot simpler if it had no temp gauge, then I wouldn't worry about it
I'm sure its only certain meteorological conditions that cause the icing.. depends on where you live too...
You need to retain the switch really. In theory, if left on during the summer the bike will run leaner if the carb settings/jetting are unchanged. The hotter fuel will be less dense so your air/fuel ratio will change. Hard to quantify by exactly how much though. For Autumn riding in particular you'll notice carb icing as it's the relationship between relative humidity (anything over 80%) and lower ambient temperatures.
my '92 900 never had the heater, but one memorable icing instance was summer, silly early in the morning, not very cold just chilly, me trying (failing!) to keep up with mate Simon on his Blackbird in the Motorway dash to Dover. So yes it does happen very occasionally in my experience. (big throttle openings etc.)
That's it. the answer I had to hear, as I suspected, density and hence air/fuel ratio. I'll keep the switch. But tell me, Travelling Man, how do you keep your hat on, at speed over 40 mph? Buy the way, thanks for all answers folk. Although some doubt exists about the need for a heater or carb icing, or its variability I have found it necessary for cold autumn riding and beyond, as a rule. In freezing winter, essential, over the past few years. On such days, Start up and ambling is OK, but on opening up, I'd say about half to 3/4 range in third and fourth gear, engine splutters due to icing. Come to think of it, it seemed sort of Humid AND Cold on those days. I have often been surprised when needing to switch it on, it's definitely not only the temperature, and so atmospheric pressure, ambient temp and humidity, probably combine to make a difference.
how about fitting an inline oil thermostat that would do away with the manual valve and regulate the temperature
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