Carb icing.

Originally Posted by yorkie_chris

Why would it add oil to the little end unless your rings are knackered. The little ends get plenty anyway.

I reckon it'd just risk fouling plugs, and don't see why it'd stop carb icing unless it simply stops the ice from sticking to the needle.

The spark plug thing! Thats why it would be wrong. Somewhere in my mind there was something about 2-srokes and running rich...adding oil to your fuel may cause a similar problem on a four stroke.

May i ask how much oil per litre of fuel do you add sunshine?

Light aircraft use hot air from the engine to prevent carburetor ice or clear it if it has formed, this is selectable by the pilot and used every few minutes to prevent ice build up or when revs drop because of the ice.

It's not just a winter problem, with sufficent moisture in the air the temperature drop over the venturi in the carb can lower the temperature enough to cause the ice to form so carb heat is used year round. Light aircraft engines are mainly of old designs, four stroke boxer fours are typical just like an old VW beetle. These are low reving and prone to iceing up at low revs which is when you apply the carb heat (some work with permanent warm air like the modified SV being discussed) but this reduces power. It's a noticable reduction on a light aircraft 100hp and 2600 rpm redline are typical figures for this short of machine to give some comparisson to an SV.

yes yc it stops the needle from freezing/getting icy. i dont use enough 2 stroke to worry about fouling the plugs running rich isnt really that big a problem not being able to start/run the bike is a bigger problem tbh.

[yorkie_chris]

I'm surprised oil stops the icing. Isopropanol is the active ingredient in pro-FST and gets added to 110LL in planes to stop icing in real bad conditions AFAIK.

There's no physical way it can oil the little ends though.

Originally Posted by yorkie_chris

I'm surprised oil stops the icing. Isopropanol is the active ingredient in pro-FST and gets added to 110LL in planes to stop icing in real bad conditions AFAIK.

There's no physical way it can oil the little ends though.

The only thing I can think off is the oil leaves a slight coating on the needle(s) which prevents water vapour adhering to the surface in the first place to freeze.

I was wondering how it might lubricate the little ends...are 4-stroke pistons selectivly porous to 2 stroke oil

aaahhhh na, only having a laugh. As i understand it, 2 stroke oil lubricates the bearings (little and large end and I guess whatever else needs it) in a 2-stroke engine when the petrol / oil / air mix fills the area under the piston when itys sucked in on the exhaust stroke

in any case, if you have found it to work, then thats great just be aware of extra carbon deposits occuring on valves and spark plugs

Ice builds up in the intake, and causes the engine to rich cut.

[yorkie_chris]

There's a video of a V-max carb icing up on youtube, the amount of ice is very small and forms around the jet needle, meaning it'll go lean part throttle and misfire.

http://www.youtube.com/watch?v=wZG_sdWuydU

Not enough forms to actually block the intake but it is enough to make it run like a dog.

someone i know pointed out his 2 stroke never stuffers from carb icing so he does it to his 4 stroke through the winter and they always start first time, but he also told me only to use a small amount not to cause any damage (if any is possible) and when i stop using it in the spring to service the carbs, valves and plugs etc. since i used it this month its started the moment i try so im happy enough with it. i also use to be sat a lights and the revs would be at 3k and slowly coming down to tick over (sometimes never got as low as tick over) where as now that never happens either, we will see if its screwed the valves and carbs once its done being cold here.

How much is a small amount per tank full?