Thus engine look bugered to you ?

[Turbo]

You say that it's 'popping' which could be a timing issue. It's quite common for the flywheel key to partly shear, knocking the timing out slightly and can result in 'popping' and backfiring!

Another issue on some B&S engines is the auto decompression unit in the crankcase. It makes for easier starting but they wear out and can lead to popping. We have a ride-on with a 13hp B&S engine that was 'popping' when you changes the revs. I did most of the things you have already done to your engine & the only thing that helped was increasing the valve clearances. It still pops occasionally but I think that's down to the auto decompression unit being worn & just live with it.

 

[angellonewolf]

Let it warm up, then tinker.
Then if it goes wrong I have a cunning plan.

@The_Yellow_Ardvark could i ask what was the cunning plan

Until you do a wet & dry compression test , there is not a lot else to consider other than crank case compression , worn valve guides and poor carburation .
It's a low compression engine so 15 to 30 psi might be found then a bump up of 10 or more if the bore is worn .
That oily burnt carbon ,, it is localised to one side where the valves are , a bit of crank case compression & worn guides might well produce such a signature . What was the underside of the valve heads like on each valve was one stem well carboned up more than the other ?

That air filter , if it is a sponge one it should be an open cell sponge manufactures one not a gash piece of foam roughly cut to size & stuffed in the housing .
Wash it out in clean petrol squeeze it dry leve it in the sun an hour or so then drizzle a teaspoon of clean engine oil on it roll it in a clean cloth to remove any excess , there should not be oil in the filter housing .

You could try a short trial without the filter in place to see how it runs . If it is one of the paper cartridges with a silicone sealing gasket it should be as dry as a bone .

the plan is to do a compression test later to day if something dont get in the way
thanks for the headsup on what to look for on the compression
yes when i took the pic a lot of the carbon was caked more to the side of the vales the inlet seamed to be worse the inlet side was thick on top and not as much under neath was farly coaked
air filter is new late last year and clean apart from a small amout of oil and ive tred it quite a few times over the years as half the time when doing work on it id never wait till the filter was on before starting it up

You say that it's 'popping' which could be a timing issue. It's quite common for the flywheel key to partly shear, knocking the timing out slightly and can result in 'popping' and backfiring!

Another issue on some B&S engines is the auto decompression unit in the crankcase. It makes for easier starting but they wear out and can lead to popping. We have a ride-on with a 13hp B&S engine that was 'popping' when you changes the revs. I did most of the things you have already done to your engine & the only thing that helped was increasing the valve clearances. It still pops occasionally but I think that's down to the auto decompression unit being worn & just live with it.

ive not cheaked the key i belive i did about a year ago but when working on it today will have a look if the fly wheel comes off ok but ive never hit any thing with it can the keys just shear radomly ?

if its a case of inside stuff now buy the time i buy the piston rings gaskets new valves and the head as its knckard a good 2nd hand mechine and nick the engine off it to replace mine seams the way to go

 

[angellonewolf]

keys there a little bent and dont fit in the beltway that well but I'm assuming as the mower just started going worse and worse if this was the cause it would have been all at one and it's not sheared so how accurate does the timing have to be on these things ?

 

[Screwdriver]

That amount of play could give you 8 degrees of error. It needs to be better than that!

Make up a key from mild steel and either hammer or file it into shape. Won't be any worse than the one you already have. As for going all at once, it might just have slipped or ended up in random positions.

Chances are this motor doesn't run badly for a reason, it's most likely a combination of multiple issues.

 

[angellonewolf]

 

[The_Yellow_Ardvark]

@angellonewolf

Shame I can't travel.
I have a tin of those Woodduff keys here.
Sorry mate.

 

[Morrisman]

That amount of play could give you 8 degrees of error. It needs to be better than that!

Make up a key from mild steel and either hammer or file it into shape. Won't be any worse than the one you already have. As for going all at once, it might just have slipped or ended up in random positions.

Chances are this motor doesn't run badly for a reason, it's most likely a combination of multiple issues.

For a side valve lawn mower engine it will probably run happily plus or minus 20°. But like you say, a combination of wear and tear across multiple components adds up to a real mess.

@angellonewolf

Shame I can't travel.
I have a tin of those Woodworth keys here.
Sorry mate.

Woolworths keys, not Woodworth.

 

[The_Yellow_Ardvark]

Woolworths keys, not Woodworth.

https://www.amazon.com/OES-Genuine-Crankshaft-Woodruff-Key/dp/B0044A69PC

 

[DAPPH]

View attachment 225741 View attachment 225742 keys there a little bent and dont fit in the beltway that well but I'm assuming as the mower just started going worse and worse if this was the cause it would have been all at one and it's not sheared so how accurate does the timing have to be on these things ?

That key way in on the below deck end of the crankshaft . Once the mounting head is secure on the taper they don't move much unless the blade whacks some thing like a concrete edge mole hill or surface roots . That could cause problems at the top end of the crankshaft by getting the timing magneto wheel to also shudder and start to shear the shear pin as it move out of best timing , as well as often putting a slight bend in the crank shaft .
The genuine B&S aluminium shear pin is not a steel woodruff key nor is it a simple locating key, it is there so if you hit something with the blade when cutting grass/weeds etc....it shears and allows the engine to turn a bit more instead of a coming to a dead stop snapping the end of the crank off or snapping the con rod etc .

When you got it running was it heavily vibrating & noisier than you'd normally find such an engine when running it ?

 

[Morrisman]

https://www.amazon.com/OES-Genuine-Crankshaft-Woodruff-Key/dp/B0044A69PC

My joke fled far over your head.

 

[angellonewolf]

That key way in on the below deck end of the crankshaft . Once the mounting head is secure on the taper they don't move much unless the blade whacks some thing like a concrete edge mole hill or surface roots . That could cause problems at the top end of the crankshaft by getting the timing magneto wheel to also shudder and start to shear the shear pin as it move out of best timing , as well as often putting a slight bend in the crank shaft .
The genuine B&S aluminium shear pin is not a steel woodruff key nor is it a simple locating key, it is there so if you hit something with the blade when cutting grass/weeds etc....it shears and allows the engine to turn a bit more instead of a coming to a dead stop snapping the end of the crank off or snapping the con rod etc .

When you got it running was it heavily vibrating & noisier than you'd normally find such an engine when running it ?

ive made at the moment a key as said earler in the thread it fits nicer and i know its not the same as a original key but at this time
its not worth spending money on this mower if what i had done yesterday had fixed the ruff running i would have coughed out for a new head and gasket as i know the one i got is knackard ive used locktight to seal the helicoil in there and its fine for the moment ans sealed the old gasket with gasket paste so theres no leak coming from that end the valves should be ok ish after what i done yester day

no ive never hit any thing with this mower and how its running is ok but its just poping and farting and not vibration no more than ive ever noticed

 

[angellonewolf]

mower running

you can hear it more at the end as it warms up

 

[The_Yellow_Ardvark]

Sounds like a B&S.

Leave it for now.

Hunt for a replacement.

 

[angellonewolf]

Done a compression test 80 psi with throttle open 90 with oil in the bore throttle open

Done with 2 compression testers

 

[angellonewolf]

earler today i even refitted a newer fly wheel put a differant coil new spark plug and gaped

 

[Screwdriver]

Sounds like a lawnmower...

 

[angellonewolf]

at the end of vid pops and farts

and when in use as it heats up it looses power used it to cut the grass in the back garden and buy the time i used it for 10 mins it was hardly running

 

[DAPPH]

ive made at the moment a key as said earler in the thread it fits nicer and i know its not the same as a original key but at this time
its not worth spending money on this mower if what i had done yesterday had fixed the ruff running i would have coughed out for a new head and gasket as i know the one i got is knackard ive used locktight to seal the helicoil in there and its fine for the moment ans sealed the old gasket with gasket paste so theres no leak coming from that end the valves should be ok ish after what i done yester day

no ive never hit any thing with this mower and how its running is ok but its just poping and farting and not vibration no more than ive ever noticed

The more I've thought about it today it is a worn engine and worn valve guides . It's getting a bit of crankcase compression so will blow oil mist up the worn valve guides , the inlet induction stroke sucks the oil mist in to the cylinder along with th petrol mist then ignites , that's why there is an oily residue on the inlet valve area . Any oil in the exhaust port get pushed out with the hot exhaust gasses & will burn a fair bit & carbon up the silencer eventually . So it's a case of, " New engine James , it's beyond economical repair " ( BER)

Just seen your post #77, you describe an engine in exactly the state I've mentioned .

 

[angellonewolf]

yes ive come to the same its more then the engines worth

ive been looking on ebay facebook etc for a 2nd hand mower with the same engine i need

missed 1 in a job lot for £30 that would have done allways late to the party

ive been looking for months before doing the job on this one but as im now out of jobs to do round the house

 

[slim_boy_fat]

@angellonewolf

Shame I can't travel.
I have a tin of those Woodduff keys here.
Sorry mate.

Verniers + post.