Lawn Mowers

nomad97

nomad97

Resident Geek
I bought my powered, rotary lawn mower about 5 years ago. For most of that time it has operated trouble free although this year it started to smoke a little. It has a Briggs and Stratton 1.5 hp 4-stroke engine. About 4 weeks ago I decided to strip it down, clean the air inlet, carburetor, fuel tank and replace the spark plug. I also changed the spring on the throttle assembly as the old one was well worn. After I put it all back together it worked like new.

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I have used it 2 or 3 times since the overhaul but yesterday when I went to start the machine - nothing! Stripped it down again today, re-assembled and still nothing. Nearly started but not quite. I thought about this for a while and decided the only thing that has changed since the earlier overhaul was the addition of fuel to the fuel tank prior to yesterday. I tested the fuel to see if diesel had been added instead of benzine 91 and no, it was benzine. Given the age of the mower, and my limited knowledge of what to do next, I decided to return the machine to the shop for a strip down and overhaul.

The owner of the shop was very good and discussed some of the problems with me. He promised not to conduct expensive overhaul work without agreeing with me first. Interestingly, he said these Briggs and Stratton engines came from the USA while I had thought they were cheap Chinese copies. Secondly, he told me that they did not run well on benzine 91 - they needed 95. Clearly this was problem No. 1 - the tank was full of 91. It also got me thinking that maybe I had been given a rather low quality 91 when I had filled up my spare gas tank a couple of weeks earlier. Lets wait and see what the repair shop has to say.

I use the same fuel can to top up the Honda Click and the lawn mower. Got me thinking now, need to switch to 95.
 
Now why did you not post this before NM. I am an expert. I have no less then 10 of these all rebuilt. What your problem was is what is called a cag.
You have to take of the cylinder head and clean the two valves and the burnt build up under the head cover.
How did the pulsa jet membrane look like that is the dual gasket that works like a fuel pump under the throttle body.

By the way it is my hobby and BS they work fine with 91.
 
Rice said:
Now why did you not post this before NM. I am an expert. I have no less then 10 of these all rebuilt. What your problem was is what is called a cag.
You have to take of the cylinder head and clean the two valves and the burnt build up under the head cover.
How did the pulsa jet membrane look like that is the dual gasket that works like a fuel pump under the throttle body.

By the way it is my hobby and BS they work fine with 91.
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Thanks Rice - I might have guessed. I did think about removing the cylinder head but refrained least I got a wigging from SWMBO - especially if I forked it up. I have stripped down car engines in a previous life but that was many years ago. I was a toolmaker's apprentice before joining the RAF and pretty handy with most large machine tools. The dual gasket is not very good and I failed to find a new, replacement membrane and gasket in Surin. I think that is the most probable cause of my problems - it does need replacing. Unfortunately, there are so many different types I was unable to identify the correct one on e-Bay.


Yorky said:
My gardener has a lawn mower.
Click to expand...

She is also a very good cook by the looks of it too.
 
Nomad, how many square metres do you mow at a time (understanding it is probably an under 10 minute job) ?

Does your Briggs & Stratton mower have a push oil-primer prior to pulling the cord for startup ?

Did you specifically use B&S 4-stroke lawn-mower engine oil ?
 
The cow on the left is called Briggs and his mate on the right is Stratton.

rice-cultivation-in-thailand-two-skinny-domestic-cattle-roaming-on-dfr5c0.jpg
 
Coffee said:
Nomad, how many square metres do you mow at a time (understanding it is probably an under 10 minute job) ?

Does your Briggs & Stratton mower have a push oil-primer prior to pulling the cord for startup ?

Did you specifically use B&S 4-stroke lawn-mower engine oil ?
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The mower has been going strong for the past 5 years - usually starts first time every time. It does not have a push oil-primer, unless you mean a push fuel-primer (a little red rubber button), in which case the answer is yes. And yes, I do use oil suitable for a 4 stroke B&S engine. When I stripped it down I surmised I needed a carburetor repair kit although I didn't find the model I needed in town or on e-Bay. Having 'fixed' my machine 2 or 3 times before I did so 4 weeks back and it was running like a good 'un. It rested up for a week and, come hell or high water' it would not start. I even stripped it down again although not as far as the carburetor as I knew the double gasket/seal between the carb and the tank was not good. At that point I decided it was time for the professionals to have a go and took the machine downtown, the big shop by the railway crossing behind Surin Plaza. They did a good job and did some work on the engine and, with my consent, changed out the spark plug and fitted a new carburetor. Tried it yesterday afternoon (lucky - no rain) and it started first pull and cut well. Total time in town - 2 days - total cost 1,800 baht. I think that was a fair price for motor that cost cira 12,000 baht 5 years ago.

I know Rice, myself and a few others do not agree with what the big boss man told me on day 1 but, for what it is worth, he stressed the matter to me again when I picked up the mower. He basically said never use 91 - the engine likes 95 grade fuel. He added, never use PTT because it is rubbish and a much better fuel is Shell or Esso 95 for the engine. Finally, he said it was the low grade 91 that had 'f**ked-up' the carburetor and made it necessary to fit a new one. Make what you will of what he said but he does see quite a few lawn mower engines through his shop for repair on a daily basis. I will certainly try 95 in future.

P.S. About 50 sq mtrs.
 
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Rice said:
All I will say is read.

http://www.briggsandstratton.com/eu/en/support/faqs/fuel-recommendations

Using a higher octane fuel raises the combustion temperature, which is incompatible with your motor. In B&S 4 strokes it can burn out valves prematurely because the engine is not designed for it.

I know that guy does it for a living BUT !!!!! It is a hobby I love. (Some people weave baskets) That is my therapy.
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As I said earlier, my problems started after I refilled the fuel tank. I have also done some research and found this article: https://iluvthailand.wordpress.com/2008/02/08/difference-between-gasohol-95-and-gasohol-91/ . Of note is the following:

Regular 95 (benzene) = yellow

Regular 91 (benzene) = red

Gasohol 95 = orange

Gasohol 91 = green

Surprise, surprise! I have just taken a fuel sample from the gas can and it clearly shows:

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GREEN! The young lady at the filling station has given me Gasohol 91 and not Regular 91 (benzene) which should be red. My Thai is very limited and I usually ask for benzene 91. I have been sold the cheaper alternative. As your reference indicates RICE, B&S do not like Gasohol. Grrrrr!
 
We bought our lawnmower a few years ago from the same shop you talk about Nomad, and the Big Boss told us the same...use 95 only. We have always done so, and no engine problems yet.

mario299
 
Gasoline with up to 10% ethanol (gasohol) or up to 15% MTBE (methyl tertiary butyl ether), is acceptable.

Gasahol 91 in Thailand is 10% ethanol. Well anyway go with what feels right.
 
Rice said:
Gasoline with up to 10% ethanol (gasohol) or up to 15% MTBE (methyl tertiary butyl ether), is acceptable.

Gasahol 91 in Thailand is 10% ethanol. Well anyway go with what feels right.
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The shite we are forced to use here is called P.U.L.P, or OPEL.
It is a modified fuel to prevent the fuel being " Sniffed " by various members of the indigenous population which is a chronic problem.
With the modified fuel not containing certain esters, the fuel does not produce the narcotic effect.
Problem is, this crap settles out a jelly like substance which creates carby issues that can only be treated by using an octaine booster.
 
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