Triumphrat

greabo

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.

modre

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...

propforward

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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mikeinva

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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Why do I feel young on my bike

Calliway

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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Pokeyjoe

Its not quite that simple. The venturi action of air going through the carbs causes a temp drop as the air expands and enters the intake. Icing can occur above freezing.

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John
3-7-77
Some people are like Slinkies. They're really good for nothing. But they still bring a smile to your face when you push them down a flight of stairs.

mikeinva

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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Why do I feel young on my bike

dkreidel

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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'09 T100 50th Anniversary- Togas, Hagons, PC V
'09 T100 green/white- Togas; PC III
'07 T100 tang/opal- Togas, Hagons, Sun rims (18" rear)
'06 Scrambler blue/white - Arrow 2>1; Sun rims 19" F&R, Maxxis DTR
'68 T120R - original owner

mikeinva

I am not saying that being lean is causeing iceing .I am not sure his is iceing anyway .If they are lean they run worst when the motor is cold.

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Why do I feel young on my bike

RedBird

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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Larry
2003 T-100 (790cc), NARK, NH Togas, 8100 rpm rev limiter, 158 main jets, 42 pilot jets (less than 1 turn out on pilot screws), stock needles--no shims. 13 A/F ratio from 1100 rpm to 4000 rpm; 12 A/F ratio from 4000 rpm to 6000 rpm; 13 A/F from 6000 rpm to 8100 rpm.:D
2007 Tiger 1050--White:D--SW-Motech crashbars, Skidmarx rear hugger/chain guard, Calsci +7 windscreen.