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New barrel and piston for Husky 365


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Stubbys comment is what I am getting at. You put oil and petrol in the fuel tank, both burn in the combustion process so it is reasonable to suggest that two stroke fuel is a mix of petrol and oil not just petrol.

 

The two trains of thought are that petrol is the fuel content on a two stroke fuel or the oil and petrol are the fuel.

 

On conventional saws, it is easy to lower the H screw to drop the high speed revs thus controlling the engine RPMs reducing the risk of overheating and seizure....but what happens if the manufacturers bolt on an Autotune module and the control of over revving is down to electronics. Say these saws started having issues with knocking out their bottom ends due to the lower consumption of what I call "Fuel" (OIL and PETROL).

 

Personally I would stick a dollop of extra oil in the fuel mix to help the bearings get a bit more lube on them....oh, and use a higher spec 2T oil like the synth ones that the manufacturers tell us to use on their lean burn strato engines.

 

Having seen some low hour autotune engines take out their main bearings, you can see why I think this!

 

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1 hour ago, spudulike said:

Echos trials on 40:1 will be interesting to hear but would really need to get comparisons on cylinder temperature and max rpm to get a true comparison.

I agree, did not get around to testing today though. The little I tested before, oil brought down the temperature, as did running on the rich side. Am told the oil carries the heat away out the exhaust, I had saws that I was unhappy with, they were running hot in my estimation, so I played about with different amounts of oil in the mix, and altered fueling, and could always lower the temperature, have them four-stroking, nice plug condition, and no failures, I like to do what I can to make things last, give me an old 650 rpm lister any day, that stuff is older than me and still going on just about every continent, well until the scrap men get their eyes on it.

 

These new oils are something am getting used to, they really do work in a completely different way.

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I always thought it quite simple that the higher the oil ratio the cooler the machine will run. Ive seen many a poor running saw that has a fuel tank full of ribena, it has zero chance of seizing. Just run your saws at 50:1 with a good synthetic oil and dont worry about it.

It doesn't cost much more than a cheap mineral oil, 70p ish per 5 litre of fuel is the real cost. It doesnt stink like mineral oil and it certainly doesnt coke up the engines as much.

 

 

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10 hours ago, Mark_Skyland said:

I always thought it quite simple that the higher the oil ratio the cooler the machine will run. Ive seen many a poor running saw that has a fuel tank full of ribena, it has zero chance of seizing. Just run your saws at 50:1 with a good synthetic oil and dont worry about it.

It doesn't cost much more than a cheap mineral oil, 70p ish per 5 litre of fuel is the real cost. It doesnt stink like mineral oil and it certainly doesnt coke up the engines as much.

 

 

Well that is what I thought but some say it will lean the engine and cause seizure - Personally I think it is misguided and stems from thinking that more oil means less petrol and therefore the engine will run hotter due to less fuel but in reality, the oil is part of the fuel so there is no leaning effect and like you, I see many machines, mostly home owner and farmers machines, with "Cherryade" in the tank which struggle to make any revs at all!

Not sure I am going to go on with this as it is a bit like arguing religion!!!!!!!!!!!!!!

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There are a lot of variables. I put more oil in the mix at one time, left the carb as it was, just to see how it would effect the saw, it ran cooler, even without adjustments.

It seems to me that some engines cope with different mixtures and take it in their stride, some are more susceptible to such. 

There is a lot we do not know in regard to how effective any Two Stroke engine design is at lubricating the lower end and the cylinder below the rings, all we can do is monitor any given situation and adjust as best we see.

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