# petrol lawnmower (Briggs & Stratton)



## disco_monkey79 (17 Jun 2014)

Hi

I've just got a petrol lawnmower for the first time (2nd hand). 

It mentions on their website about using fuel stabilizer, to stop the petrol (or gas, as they prefer) from going stale. Do people bother with this?

Happy to buy some if it really is helpful/needed, and equally happy to save some pennies if not really required. 

Ta!

p.s. any suggestions for a good online (i.e cheap!) spares stockist?


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## Spindle (17 Jun 2014)

Hi

Never used it nor found the need to - I've never had trouble starting petrol driven power tools at the beginning of the season and certainly not due to 'stale' petrol, never needed 'stabiliser', otherwise known as snake oil :wink: :wink: 

Regards Mick


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## Eric The Viking (17 Jun 2014)

It's a very good idea over winter.

I left unleaded in my bike's tank for a few years. I'm re-coating the inside soon, but when I emptied it out, the fuel taps and filters (inside the tank) were completely solid with 'varnish'. It dissolves in meths, but it's horrible to deal with, and I'll have to get the carbs ultrasonically cleaned.

I think the additives stop this happening.


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## disco_monkey79 (17 Jun 2014)

Thanks both.


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## Harbo (17 Jun 2014)

My Briggs must be nearly 40yrs old and I've never used any additives. I generally run it nearly dry every Autumn and in the spring change the oil and clean the air filter. 
Apart from a new exhaust , still in original condition and works every time.


Rod


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## bugbear (17 Jun 2014)

The additives are to stop it going "gungy" when left for a long time, either in a can, fuel tank or carburetor.

Over winter is the obvious case for a lawnmower. I didn't use additives, didn't drain my tank, and had to have the carb cleaned, which cost more than the additive. Lesson learned.

Googling tells me the normal name for what happens to old petrol is "varnish", and it's horrid stuff; plenty of reports from people with fuel tanks, lines and carbs needing expensive cleaning. 4-6 months seems to be the timescale.

http://www.sterndrives.com/old_fuel.html

I use Briggs & Stratton "Fuel Fit", around 7 quid for 250ml. I'll check the mix ratio tonight (if I remember)

OK, I have B&S "Fresh Start" fuel stabilizer; preserves fuel for up to 24 months. For each 2 gallons (11L) of fuel add 5ml for normal use, 12.5 ml for long term storage.

BugBear


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## Mark A (17 Jun 2014)

I only put a little bit if fuel at a time in my lawnmower (enough for one or two mows at most). At the end of the season I run the mower 'til the fuel runs out then store it away. My thinking is by emptying the tank and carburettor of fuel there will be nothing left to gunk up.

I don't know if this applies to petrol lawnmowers too, but one step in winterising an outboard motor is to spray fogging oil into the cylinder.


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## Spindle (17 Jun 2014)

mark aspin":3901hlut said:


> My thinking is by emptying the tank and carburettor of fuel there will be nothing left to gunk up.



Hmmm

My thinking is that if I empty the tanks and carbs there will be nothing stopping the seals drying out.

Down time for my garden tools is about 5 months and they all have polymer fuel cells which may be advantageous.

Regards Mick


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## lanemaux (17 Jun 2014)

As my wife is a country girl , she has the farmers attitude towards grass, none shall escape . She has our small lawn tractors blades set for strip mine and goes out once a week to ensure that we have the most clipped field as seen from space. as such we have little need of stabilizers. At the end of the killing season we just run the last tablespoon in the tank dry.


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## Random Orbital Bob (17 Jun 2014)

modern unleaded petrol rots or whatever the term is without question. Every spring when the weeds start up I get the strimmer and the hedge trimmer out. Both are 2 stroke engines. Both cough and splutter and won't rev with last years dregs in. If I fill them up from last years petroil mix they behave the same. I get a fresh petroil mix made up and change the fuel and literally...start first time and run smooth. The difference is that stark. I've never bothered with the additives because I just renew the petrol but that the old stuff has spoiled is beyond question.


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## Phil Pascoe (17 Jun 2014)

I suspect the problem affects 2 strokes more than 4 strokes. But lawnmowers? Grass doesn't get longer than too long, and windows don't get dirtier than filthy. Life's too short. :lol:


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## Random Orbital Bob (17 Jun 2014)

LOL....you're right there Phil  I think it does affect 2 strokes worse cos my 4 stroke mower farts a bit but does still soldier on. It purrs when I put this years petrol in but it doesn't actually stall (with the rotten stuff) whereas the 2 strokes do.


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## dickm (19 Jun 2014)

Spindle":3qw3z7a1 said:


> mark aspin":3qw3z7a1 said:
> 
> 
> > My thinking is by emptying the tank and carburettor of fuel there will be nothing left to gunk up.
> ...


You are spot on there, Mick. Many older mowers have cork seals on the fuel taps, which if left to dry out will p**s out petrol when refilled. DAMHIKT. But have never actually had problems with leaving some fuel in machines over winter (perhaps it keeps better at Aberdeen winter temperatures  ) Many more problems due to dodgy membranes in older Briggs and Walbro fuel systems. Often wonder how 2-stroke engines can be such pigs to adjust when there are only three items which are adjustable?????


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## Random Orbital Bob (19 Jun 2014)

When you could still buy leaded petrol I always used to put it in my bikes (4 stroke) that specified unleaded. My old mechanic swore by it and despite the Honda having a cat it purred like a kitten on the leaded. Long gone now.


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## Bod (20 Jun 2014)

dickm":3hcc8kqs said:


> Spindle":3hcc8kqs said:
> 
> 
> > mark aspin":3hcc8kqs said:
> ...




Remove the cork type fuel tap, leave in jam jar of petrol at least over night, when the action becomes stiff, the cork has swelled to make the seal, refit. Keep a small amount of petrol in the tank for the rest of the season.

Bod


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## fiacha (20 Jun 2014)

As it's second hand, there is no harm in giving it a service. This kit worked out cheaper than buying the oil and spark plug separate. I also put a new diaphram on the carb as I had stripped that to clean out all the varnish that had built up over the years. I'm going to use the stabiliser this year and see if I notice any difference.

I have no experience working with engines, but the Briggs was very easy to work on, and now runs better than than I remember.The revs are stable, no more hunting and sputtering.
The satisfaction of a few hours tinkering in the shed was worth the price of the service kit


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## disco_monkey79 (24 Jun 2014)

Thanks all for the replies. As a quick update, an hour at the weekend saw the fuel tank flushed and the carb de-gunked, and it fired up on 2nd pull of the cord. Well chuffed, for a mower that came from the dump.
And best of all, I mowed front and back gardens in a fraction of the time it took with the [email protected] Flymo


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## bugbear (24 Jun 2014)

fiacha":1vzz2f9w said:


> As it's second hand, there is no harm in giving it a service. This kit worked out cheaper than buying the oil and spark plug separate. I also put a new diaphram on the carb as I had stripped that to clean out all the varnish that had built up over the years. I'm going to use the stabiliser this year and see if I notice any difference.
> 
> I have no experience working with engines, but the Briggs was very easy to work on, and now runs better than than I remember.The revs are stable, no more hunting and sputtering.
> The satisfaction of a few hours tinkering in the shed was worth the price of the service kit



Was there meant to be a link to "This kit" in your post? :? 

Edit; one of these?

http://www.mowermagic.co.uk/acatalog/Br ... atton.html

BugBear


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## NickWelford (24 Jun 2014)

It's a good idea to sharpen the blade regularly too. After all, you probably have a grinding wheel set up.....


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## bugbear (24 Jun 2014)

NickWelford":269ish8b said:


> It's a good idea to sharpen the blade regularly too. After all, you probably have a grinding wheel set up.....



Check it for balance afterwards - an off balance blade at high speed does "wonders" for the engine's main bearing (*).  

BugBear

(*) *really* posh mowers have a separate blade bearing


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