Carb Anti Icing ideas

[ducpainter]

Iirc the kit on my bike had a tap that redirected the oil from the cooler to the float bowls and back to the oil system. It made for very messy plumbing. It bypassed the cooler via a simple on/off tap. I had a vinyl cover on my Shovelhead's Lockhart oil cooler and I reckon that made a difference on that bike.

I don't think the heated oil set up is a bad idea...if the oil gets hot. The oil doesn't on a bike with a cooler on a 40 degree day.

[koko64]

You'd reckon it should get bloody hot quick enough to do the job ay? A cooler cover is an option; it certainly made a difference on my Shovel. The oil lines to the carbs are a mess though and really get in the way when servicing the carbs. I'd sooner wrap the manifolds or have the less messy plumbing of a couple of wires to the bowls.
Me mates ZX9R had coolant heating the float bowls and his bike froze its Keihin CV carbs more than my Mikunis ever did. I'm guessing the problem is further up the intake tract, and that's making me want to try the manifold wraps.
Only one way to find out, and we sure have the weather for it.

[ducpainter]

The water temp on the ZX9 get up to normal on a cold day?

I don't think you can get an electric element with enough power to do the job on the volume of air required.

An electric element with inso might work on the float bowls, but it still will be a PITA to service.

[koko64]

I reckon the thermostat barely opened. I thought the coolant would warm up quicker than oil, but not reach as high a temp when warmed up. Amazing how the CV slides cause the issue. Strange thing is the Kwaka had short, rubber manifolds unlike the long alloy ones on the Harley and Ducati.

[koko64]

Tested the bike on this cold morning with no exhaust wrap on the manifolds. Although the bike took awhile to warm up, it did not have any freezing issues. A factor in this could be the stock airbox . I note that the last two bikes with open airboxes had a great deal of problems with carb freezing, much worse than this bike and a 900SS also with closed airboxes. Also, the one bike with ported inlet manifolds, all things being equal, also had less carb freezing than the others. Not a big sample, (only four bikes), but noteworthy.

Anyone experience this, or did you find no difference?

[Howie]

The only time I experienced icing the bike still had a closed air box.  It does make sense that a closed air box would help since the air might  have a nano second or so to warm up.

[ducatiz]

I doubt there's a market for it, but it seems like someone could make a float bowl with a pass-thru to put a small heat element in and heat the bowl. 

Wouldn't need to be much -- just enough to keep it above freezing -- but IIRC gasoline freezes at about minus 40F..  where the hell do you live again?

[ducpainter]

I doubt there's a market for it, but it seems like someone could make a float bowl with a pass-thru to put a small heat element in and heat the bowl. 

Wouldn't need to be much -- just enough to keep it above freezing -- but IIRC gasoline freezes at about minus 40F..  where the hell do you live again?

Just like with fuel tanks the problem seems to be more with the associated water in both the fuel and atmosphere rather than the fuel itself.

Pretty sure water freezes at the same temp regardless where you live.

[Howie]

More an atmospheric problem.  40 ish^oF, high humidity air.  Carb venturi effect.  Temperature drops.  Humidity in air freezes.  Colder, no moisture in the air to freeze. In conventional carbs the throttle plate wants to freeze open.  Our Mikuni carbs, the needle freezes.  FCRs rattle enough to keep ice from forming.

[ducatiz]

Just like with fuel tanks the problem seems to be more with the associated water in both the fuel and atmosphere rather than the fuel itself.

Pretty sure water freezes at the same temp regardless where you live.

That would be untrue!  It depends on altitude (pressure) too, just like the boiling of water.. :-)

http://www1.lsbu.ac.uk/water/water_phase_diagram.html



Why don't the add-on CV carb heaters work? 

[koko64]

Case of should work in theory but not in execution. Also possibly other factors messing with the plan. My theory is that the long manifilds have such a ram air effect as to freeze down their length. Others have suggested this to me over the years so I thiught I'd wrap them and try and solve the problem "downstream", so to speak.

Electric method lacks oomph to heat the carb body and oil method doesnt get hot enough to heat the fuel in the bowls. Former puts element into the carb body and latter warms the bowls with an oil jacket.

Those methods dont give enough heat so I thought engine heat from the heads transferred to the manifolds and trapped there could be the answer. Maybe. My view being that upstream solutions have failed.

[koko64]

More an atmospheric problem.  40 ish^oF, high humidity air.  Carb venturi effect.  Temperature drops.  Humidity in air freezes.  Colder, no moisture in the air to freeze. In conventional carbs the throttle plate wants to freeze open.  Our Mikuni carbs, the needle freezes.  FCRs rattle enough to keep ice from forming.

It doesnt get too cold down here by world standards but we have pretty humid cold as DP and Howie have described.

Never seen this issue with any slide carb be it Amal, Mikuni or Keihin. Never an issue with a straight butterfly carb be it Bendix, Keihin or S&S, but only CV carbs on a range of bikes including Hondas, Kawasakis, Harleys and Ducatis, both liquid and air cooled.

[ducatiz]

Warm the manifolds?

[ducpainter]

It doesnt get too cold down here by world standards but we have pretty humid cold as DP and Howie have described.

Never seen this issue with any slide carb be it Amal, Mikuni or Keihin. Never an issue with a straight butterfly carb be it Bendix, Keihin or S&S, but only CV carbs on a range of bikes including Hondas, Kawasakis, Harleys and Ducatis, both liquid and air cooled.

If you think about it...

it makes sense because the CV slide has no return spring. It relies totally on vacuum.

[koko64]

Warm the manifolds?

Yep, by trapping heat with exhaust wrap. I'm gonna give it a try.

If you think about it...

it makes sense because the CV slide has no return spring. It relies totally on vacuum.

Absolutely.
It's design modulating air velocity in front of the butterfly or slide rather than via a butterfly or slide is the issue imo. The two air metering devices, one after the other is what complicates things. So there's a lot more going on than just a mechanical part getting frozen stuck, but the air velocity issues (by design) which cause it. I don't have the book learning to explain it properly, but the CV concept of keeping air velocity high independent of throttle position is the culprit in my unlearned opinion.