Carb heaters needed?

[m1tch_1987]

Hi all,

I am using an SV650 engine as a race engine rather than a road going engine, I know that I have carb heaters on my early engine but the question is, do I need to keep them?

I am guessing they are just used for cold starts in the winter or are they also used to reduce carb icing when the engine is running?

[johnnyrod]

They're there for when the engine is running on cold-ish days (or worse). Some people say they're useless, I've also been told that you'd know if they weren't working (some people on here had that problem). I'd keep them.

[yorkie_chris]

Nah get rid.
I've iced the carbs with them fitted and permanently on. More complexity.

You can get round carb ice by adding a small dosage of isopropanol to the fuel.

Take it you are not intending to race in freezing fog? :-P

[speedyandypandy]

You can get round carb ice by adding a small dosage of isopropanol to the fuel.

Take it you are not intending to race in freezing fog? :-P
You never know.
http://motorcyclemaniac.files.wordpress.com/2011/11/gsxr-icebike.jpg

[m1tch_1987]

Hmm a mixed bag of answers it seems lol the engine will only be run at a drag strip so won't be open or running when its snowy etc. Would it make a difference if I was running a different fuel eg meths rather than petrol? It will only be used for a 1/4 mile at a time :D

[yorkie_chris]

Don't worry about carb ice. It will be fine.

[m1tch_1987]

Don't worry about carb ice. It will be fine.

Ok :) the whole engine will be exposed when running so im sure I can warm the carbs up if needed manually :D

[yorkie_chris]

They'll have an eighth inch of ice on them by the end of the 1/4 but meth doesn't seem to cause carb ice lik epetrol does

[embee]

2 things I can see here.

1 - for what you're doing, no you don't need them as YC says, you really don't, honest.

2 - you're going to be running wide open throttle for a short period, the probability of getting icing under these conditions is very slim indeed.

The heaters are an attempt to reduce carb icing on the road, which usually happens at temperatures just a little above zero and small throttle openings held for prolonged periods when the pressure drop across the throttle causes the temperature change and moisture to freeze out and build up in the inlet tract. Running WOT minimses the press drop so tendency to ice is much less anyway. Aircraft can get icing in quite surprisingly high temps but they are up in the clouds etc. so very different atmosphere.

If you were running alcohol fuel it would probably reduce the tendency for ice to form inside the tract, just as IPA does when added to petrol, the alcohol attaches to the water which interferes with the crystallisation (as I understand it).

Even if you did get icing, the heaters won't do anything significantly useful anyway. You don't need them.

[m1tch_1987]

Thanks embee, so basically I just need to run WOT all the time then :D shame :P

[yorkie_chris]

Aye and don't be alarmed when ice forms on the outside of carbs, it's when it forms inside on the jet needle that it causes issues

[m1tch_1987]

Aye and don't be alarmed when ice forms on the outside of carbs, it's when it forms inside on the jet needle that it causes issues

Ok, thanks for the heads up, will be interesting as the carbs will be at head height lol