Something completely non-military

Keith Webb · #1 16-10-05, 11:28

Anyone with experience in Briggs and Stratton small engines?

I've just been given a small ride-on mower with a Briggs IC 5 HP motor in non-running condition.

On removing the spark plug I noticed the electrode had been hammered sideways. It looks like someone has fitted an incorrect plug with a longer reach and this has been clobbered by the inlet valve.

As there's not a lot of compression (and there is spark) I think the inlet valve has been bent.

After fitting a correct plug the only firing I've been able to get is a little pop through the carburettor.

Is this a reasonable diagnosis?

My original ride-on with a 12 hp Briggs has "put a leg out of bed".

Bob Moseley (RIP) · #2 16-10-05, 11:47

Hi Keefy
I think you are on the mark. I just bought one of these engines attached to a fire pump at a clearance sale. Put a new set of point in it, fitted a new O-ring in the Davy pump and Bobs your Uncle. Whip the head off and have a look. They are a simple engine.
Bob

Snowtractor · #3 16-10-05, 20:39

Assuming it is a 4 stroke of course. I just rebuilt a Kawasaki 185 that has an unloader valve for easier starts. In colder weather if the oil is too thick it will be sticky and cause the valve to stay open a hair too long so the exhaust valve was bent. Lots of spark no compression . You could find TDC and put 5 psi into the air inlet and see if it any air comes out anywhere. Turn the engine a bit and open the intake valve and see if air comes out your exhaust or your engine oil fill plug, if the latter then the rings are gone, and the former means exhaust valve issues.
Sean

cliff · #4 16-10-05, 23:01

: you mean you guys got grass to mow down there.

It's all brown and not growing at all up here

cheers
Cliff

Keith you may be :dh:

Keith Webb · #5 16-10-05, 23:24

Quote:

Originally posted by cliff
: you mean you guys got grass to mow down there.

It's all brown and not growing at all up here

cheers
Cliff

Keith you may be :dh:

Yep, it's nice and green down here and the mower places are going ballistic with customers.

Although you could be right about :dh: it's also a gift horse and I'm going to look it in the face. At least it has a brand new cutting deck.

Thanks to Bob and Sean for your input too - this one isn't old enough to have points but other than that it's a very simple L-head design so I may just whip the head off. I used to have one of these motors on a mulcher and had to do a major repair once when a tent peg was inadvertantly put in - the mulcher did a half-turn, stopped dead, sheared the key and worse, bent the crankshaft so badly I had to hacksaw it off to get the crankcase apart.

Lynn Eades · #6 17-10-05, 00:17

Keith, you may have a problem as small as a bit of carbon sitting under your inlet valve. Most of them run j8's or cj8 plugs. Taking the head off should reveal all. I have reused the head gasket in the past with success. It does sound a bit suspect with a damaged plug though. Check your valve seats are tight.

Lynn Eades · #7 17-10-05, 00:21

I believe your diagnosis is correct.

Bob Moseley (RIP) · #8 17-10-05, 00:27

Quote:

this one isn't old enough to have points

Hi Keefy - I'm not sure about the above comment. There would possibly be a set of points underneath the flywheel. They were fitted in the older engines.
Bob

Col Tigwell · #9 17-10-05, 02:03

If you mow on any sort of incline, the B&S is not a good engine.

At 500 hours mine put a rod through the block, and it is caused by the spalsh feed just not being good enough on inclines.

Your stating problem may be caused by the engine flywheel keyway. What happens if the engine encounters any nasteys, the key itself is design to bend, so the engine timing is out, as the key allows the flywheel to move. Not a bad idea, and I suspect that could be the problem.

Also these engines should not be run on multi grade oils, You can buy straight 30 grade oil, from B&S.

I doubt if there is much wrong with the engine, as you appear to have good compression.

Flywheel off, is where I would start, bet you can buy the special key straight off the shelf. Do not use a normal one, as your protection will be gone.

Regards

Col

Lynn Eades · #10 17-10-05, 11:30

Keiths motor has good spark. Usually when the flywheel key is damaged the spark drops off to a point where it won't fire, so it's probably not the key/timing.
Bob, the later Brigg's have a solid state ign. no points- much more reliable.
On the oil thing, As you say with the Briggs motors a mono grade oil is required. So too do the Ford V8 flat head motors,require a mono grade oil. ( I know it, but cannot remember why. I think it is to do with heat transfer)

centurion · #11 17-10-05, 20:38

I'm impressed by the knowledge shown of this very civilian engine by all of the previous responses . I've one on my lawn tractor (yes even in England some of us have lawns big enough to justify a ride on but not the country size spreads you probably have in the antipodes - or is that sheep ranches?) and when it refused to start at the begining of this year I had some trouble diagnosing the problem (it turned out to be a carb problem that vanished after sonic cleaning). My biggest problem was getting hold of a decent manual and my nearest B&S dealer was about 30 miles away through country roads so I tried B&S's web site. This promised all the manuals downloadable but when one tried none of the URLs actually worked. Ringing the dealer revealed that they didn't stock physical manuals. A quite word with a friendly local agent for John Deere tractors (the smallest of which is about five times bigger than my little machine) pointed me at the problem. For future reference I'd like to get hold of a manual. Short of flying off to the USA does anyone out there know of a likely source?

Keith Webb · #12 18-10-05, 12:55

In what might be called a providential happening, there is a hard rubbish collection in this area at the moment, it's been some 10 years since we've had one.

As I drove to work this morning a sign on a piece of junk caught my eye: it read Briggs and Stratton!

I spoke to the owner who was still in the act of dismantling a Deutscher ride-on so the collectors would take it - and to my surprise found it did indeed have a Briggs engine, an 11 Hp model.

I brought it home, cleaned and re-gapped the plug, added some fresh fuel, and after a few pulls on the starter away it went and ran quite sweetly.

So the plan will be to put it onto the old ride-on and the problem will be solved. Now what to do with all the old mower bits!

I think I'll also persist with the 5HP version.

Bob Moseley (RIP) · #13 19-10-05, 02:06

Hi all
I think Keefy has found a new love, Briggs and Stratton engines. Next thing you know there will be a page on his website. It is also interesting to note that if you take the first letters of the name of the engine you finish up with BS. Is this appropriate or what?

Keith Webb · #14 19-10-05, 05:10

The B&S is just a machine to do a job...

Now, a Blitz.... there's poetry for you, whether in motion or a pile of rust.

So no Briggs page for the site... so far at least!

Tony Smith · #15 19-10-05, 10:25

Quote:

Originally posted by Keith Webb
The B&S is just a machine to do a job...

Now, a Blitz.... there's poetry for you, whether in motion or a pile of rust.

So no Briggs page for the site... so far at least!

You'd need 8 B&S engines just to come close to equalling a Ford Sidevalve V8! Even with Keith's new Hot Rod equipped 11hp version, 8 of them would only make 88hp which just doesn't cut the mustard.