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hi all,i'm having major problems with carb icing,when it gets to about 4 degrees the bike plays up and its hitting -6 now.my old t140 never suffered so would it be possible to fit amal carbs to my thruxton. thanks.
 

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icing is because of pressure drop at the throttle butterfly. the old ones were closer to the head and transferred heat, these are insulated by the rubber intake sleeve, so the carb heaters are meant to do that job.

first move is see that your heaters are hooked up and working, next move for cold is a bit of dry gas to keep the water in suspension and keep the revs reasonable...tho that ice is water in the air more than in the gas... you can't change humidity, so the ultimate answer beyond the carb heaters is engine heat...maybe restrict the engine cooling like when the school buses and big trucks block their radiators with cardboard.

an oil line might be a good heat source if you looped it around the carb outlets.

there's an invention for someone to jump on...
 

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Kawasaki actually did someting a bit like that on some of their ZX series bikes in the 80's. I think they used the engine coolant circuit, but they basically routed some pipes around the carbs to prevent icing, and it worked.

I would not, absolutely NOT put amals on your thruxton. Good carbs in the day - but really the ones on your bike are much better.
 

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hi all,i'm having major problems with carb icing,when it gets to about 4 degrees the bike plays up and its hitting -6 now.my old t140 never suffered so would it be possible to fit amal carbs to my thruxton. thanks.
4deg is that 4F OR 4C? If its 4c I dont know why it would be iceing .Could be its just way lean. If its 4f you are ether crazy or a tuff man lol
 

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Good point Mike. The metric system is pretty simple. Water freezes at 0 and boils at 100 :)

Maybe a little gas line antifreeze would help.

Personally I did some work on the bike and wanted to make sure I hooked everything up right so I thought hmmmmm I wonder if the bike will start at -25C. I didnt expect it to since I had the carbs drained and the bike pretty much winterized but I turned on the fuel, pulled out the choke and after a some cranking it fired up and ran like a top. I let it run for about 15 minutes then shut it down.

Beautiful thing to hear those TORS roar after 2 months of silence.
 

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I know what carb iceing is but havent had carb heaters on my bike in over year never have had iceing.I have seen alot of these bikes so lean they wont hardly run till they get warm though.
 

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I know what carb iceing is but havent had carb heaters on my bike in over year never have had iceing.I have seen alot of these bikes so lean they wont hardly run till they get warm though.
Carb icing is not a matter of rich or lean - it is moisture in the air that freezes. As a pilot with a carbureted engine I am acutely aware of icing conditions. The temperature drop across a venturi can be as much as 30*F, so carb ice can (and does) easily occur at 45F in high relative humidity conditions. It happened on my Kawi W650 so often despite the carb heaters that I was stopped by the side of the road on more than one occasion while I waited for the venturi ice to melt.

Dick
 

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If we're talkin 4 degrees F, then the major icing would not be my MC carbs...it would be me or parts of me!:(
 

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icing fix

greabo,

I haven't had icing problems in Scottish winters with any of my Triumph triples or twins, but did have serious bother with icing on my M900 and Buell M2. The Buell just wouldn't run in winter without the use of a petrol additive I got from the Harley dealer. It was a wee bottle of stuff called 'idle boost' and the bike ran great with it, no more icing in winter, maybe you could give that a try. Silkolene also make a similar additive, but I can't remember what it's called.
 
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