Using 98 Petrol in a B&S 625 Series Mower: Is it Safe?

Hello, I refueled 98 petrol by mistake in a canister (at a new station). I have 10 liters of it, can I pour it into the mower? The engine is a B&S 625 Series. Thanks in advance ^^

And why not?

I don't think 10 liters will fit...

You can easily run a gasoline engine with fuel with a higher octane number than recommended by the manufacturer.

You can - the only downside is the slightly higher price of this fuel

krzywy1 wrote:

And where does that certainty come from?

If you knew what octane was, you wouldn't be asking this question. And the manufacturer usually gives the minimum octane number.

There will be absolutely nothing. In old cars, driving on the so-called blue - it was probably 78 or 86 octane, after pouring such 94, the car "came more horses".
You won't notice the difference in the mower. Neither will the mower.

balloon3 is right. I have a car that says 91 octane fuel in the manual. And where do I get this fuel? You can go up, you can't go down.

music wrote:

Can I put 98 petrol in the mower?

It has already been answered many times, but we still don't know if you are going to start the engine of this one.

@RedWork_898 Briggs & Stratton is an engine with a very low compression ratio resulting from the design valve , practically insensitive to LO of fuel. With a higher LO, engine power will drop imperceptibly, with no other consequences.

This mower has the most primitive and simple combustion engine that it will run on any gasoline.

He would even pour some baptized fuel from abroad into the mower and it would run like mad
The octane number is the anti-detonation ability of the fuel, which is why engines with a higher compression ratio usually have the recommended LO 98. Exceeding the lower limit, the engine will start knocking, i.e. self-detonation, an undesirable effect - it's not diesel . In my Fabia Euro 4, LO 95 is recommended, but LO 91 can only be used conditionally without "shoeing"
several decades ago you could dream of such fuel as today and those cars that have survived (and there are a lot of them) - they normally run on 95 and 98.

krzywy1 wrote:

Does that mean there are no upward limits? and can such fuel be used continuously, without affecting the life of the engine and components? Because my friend suggested it.

But what effect are octane supposed to have on engine life? Do you even know what it is? Of course you don't, because you wouldn't be asking these questions. So I don't know what you're worried about.

It won't burn 98. It only smells bigger and that's it

78db78 wrote:

and the mower has the most primitive and simple combustion engine that it will run on any gasoline.

This is true, because B&S has not changed the basic design of this engine since the thirties uw, maybe apart from the deterioration of the quality of the materials used - plastic timing gears instead of brass ones.

Hello, the only "problem" with high-octane fuel is that it is intended for highly compressed engines, e.g. this 98 octane gasoline - it is for engines with a compression ratio of at least 10: 1, and even better 11: 1. And only in such engines, such gasoline burns fast enough and gives adequate power. On the other hand, "bottom valve SV" engines have a fairly low compression ratio, usually from 5: 1 to 7: 1 maximum, and work best on fast-burning low-octane gasoline, i.e. 60-70 octane at most. Then they have the best power and the least overheating (because the combustion cycle begins and ends / lasts quite short with low compression).
When fueled with 95 or 98 octane petrol - you would need to significantly speed up the ignition in low-valve engines (to "make up" for the lack of 4-5 compression ratios for such petrol). If this is not done "on the dyno" - the bottom valve engine burns such gasoline for a long time, often until the exhaust valve is opened, which causes combustion flames to come out of the muffler and the engine is weaker, sometimes even by half, it develops only 50-60% nominal power.
For example: old motorcycles M72 - 750 SV: on "blue 78-octane petrol, they developed maximum speed almost as in the manual (because they were factory-made for 68-72 octane petrol). In the 60s/70s, that is about 105 km/ h "solo", and with sidecars - approx. 95/100 km/h.
However, after pouring "yellow 94 octane" into the tank - the maximum speed dropped "solo" to less than 80 km/h, and with a forklift - to 70-75 km/h, for example, at night you could see "red/hot exhaust elbows" at 30 - 40 cm from the cylinders even, because this "yellow 94 octane" was still burning when the exhaust valves opened and no exhaust gases flowed into the exhaust elbows - only flames from the combustion chamber, 94 octane fuel was burning for so long - because the factory engine had a compression ratio of about 6:1.
There was also no possibility of accelerating the ignition to such 94 octane gasoline, because the ignition cam is at the end of the camshaft, and the movement of the breaker plate - only allows you to delay the ignition when starting the engine and accelerate it to run later in a rather small range - up to about 78 octane gasoline.
In the 1980s, there was still a "green" 86 octane car and these "dolniaks" were still driving on this one, but practically none of them reached 90 km / h.
The conclusion is simple - "bottom-valve" engines use 60-72/75 octane petrol at the most, because they have a very low compression ratio and such petrol burns very quickly in them, and as the "octane increases" - the fuel burns slower/worse - longer and gives less and less power to the engine, the exhaust manifold overheats, the exhaust valve "burns out" and most often also - the exhaust elbows burn out quickly, sometimes "fire from the exhaust".
Regards

I totally agree. The problem is in the ignition setting. If it can be changed, then it's ok.

My mower only works on 98 as it should, on 95 it had no power and I wanted to return it under warranty as damaged.
And it was also refueled by mistake.

The rubber components of the system will fall apart.

Plus corrosion where oil doesn't "reach"

There is a Brazilian version of this ethanol engine - a stainless steel tank, PVC fuel lines and a slightly different carburetor design.

Hello, alcohol fuels: ethanol / methanol have 'LO' 100-120, but their calorific value is even half that of average gasoline - that's why, for example, diesel engines can use a compression ratio of 14: 1, because alcohols are suitable for such compression very resistant/anti-knock...
But because of this low calorific value - it is necessary to use main jets even '5 - 10 times bigger' in slag carburetors than for petrol fuels. Because of this: low calorific value of alcohols [high fuel consumption], high 'LO 100 - 120', etc. - ordinary gasoline engine, low compression - will be half as weak as ethanol / methanol flooded, but it will work 'so-so'...
Such fuels [alcohols], on the other hand, cool the engine very well 'from the inside', because they have a much better 'heat of vaporization' - than gasoline, which is why diesel engines can have much less fins on cylinders/heads and are therefore much lighter than similar gasoline engines - which must have very large cylinder/head ribbing.
Regards.

As for the free fuel, yes. Whenever something goes wrong, the losses are not big. Once in a crisis, my father flooded the siren 105 with wave solvent and kerosene, about 2 kerosene for 1 solvent, because there was no fuel far from the gas station, but near the store We made it to the station unscathed with the exotic stench from the exhaust pipe. Two-strokes are resistant to muck, but not resistant to lack of lubrication.

@palmus Due to the lack of oil, I squeezed a few sardines into the tank in my puppy years. It smelled strongly of fish, but it didn't go away. In Libya, in the old days, we also poured kerosene into MI-2, because JetA1 was missing. Slightly higher gas temperatures behind the turbine and that's it.