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B&S 35 classic, easy pull, hard recoil not starting, advice?

#1

M

Mechanima

Hi,

I am trying to "recommission" a small push mower with a B&S 35 classic engine.

This was laid up without oil or petrol.

I have petrol and oil in now, have left it 48 hours to soak through.

Now the cord pulls very easily and smoothly (I am left handed and it has to be pulled with right hand), little puffs of smoke come out of exhaust after a couple of pulls, and it nearly catchs, but it doesn't start, and the closer it gets to starting the harsher the recoil.

I do not really know what I am doing but am eager to learn, I have a feeling it is a very tiny problem and anyone who did know what they were doing would start it in seconds. :smile:


#2

Briana

Briana

Hey there - WELCOME to LMF!

I moved your thread to the Small Engine & Mower Repair Forum. :smile:


#3

M

Mechanima

Thanks :smile:


#4

Trcustoms719

Trcustoms719

Mechanima said:
Hi,

I am trying to "recommission" a small push mower with a B&S 35 classic engine.

This was laid up without oil or petrol.

I have petrol and oil in now, have left it 48 hours to soak through.

Now the cord pulls very easily and smoothly (I am left handed and it has to be pulled with right hand), little puffs of smoke come out of exhaust after a couple of pulls, and it nearly catchs, but it doesn't start, and the closer it gets to starting the harsher the recoil.

I do not really know what I am doing but am eager to learn, I have a feeling it is a very tiny problem and anyone who did know what they were doing would start it in seconds. :smile:
Click to expand...


Do you have the tools do do a compression test?
You might have a stuck valve from it sitting without oil in it.
Have you checked for spark?


#5

M

Mechanima

I don't know if I have the right tools to do a compression test...what would I need? (i have a lot of tools for various reasons).

Definately a spark because of the little puffs of white smoke out of exhaust as it gets close to starting.

One odd thing is that the oil I put in is still clean and clear. I didn't leave it sitting up myself, I got it that way.Everything was dry and the dipstick and (brand new) spark plug were practically welded in. So a stuck valve makes a kind of clueless common sense to me.


#6

M

Mechanima

Well I did some intensive googling, worked out that I do not have tools to test compression AND that getting the head off is not a big deal...also, I *felt* the compression was wrong right away (a sort of hiss as it was pulled that felt and sounded to high pressure, so I opened an engine for the first time in my life (BIG THRILL :biggrin:) and sure enough upper valve (outlet?) was well stuck so I sprayed it with WD40 and gave it a sharp tap with hammer and a rubber handled tool. This freed it, so I sprayed in some WD40 and put it all back together.

First couple of pulls had a worse recoil than ever but it feels better and seems to be settling...I am beginning to suspect plug is bad (I had to destroy the brand new one to get it out and this is one out of spare engine, could be in any shape - though it looks ok).

Can't get a new plug till at least tomorrow.

Any more enlightenment?


#7

Trcustoms719

Trcustoms719

Mechanima said:
Well I did some intensive googling, worked out that I do not have tools to test compression AND that getting the head off is not a big deal...also, I *felt* the compression was wrong right away (a sort of hiss as it was pulled that felt and sounded to high pressure, so I opened an engine for the first time in my life (BIG THRILL :biggrin:) and sure enough upper valve (outlet?) was well stuck so I sprayed it with WD40 and gave it a sharp tap with hammer and a rubber handled tool. This freed it, so I sprayed in some WD40 and put it all back together.

First couple of pulls had a worse recoil than ever but it feels better and seems to be settling...I am beginning to suspect plug is bad (I had to destroy the brand new one to get it out and this is one out of spare engine, could be in any shape - though it looks ok).

Can't get a new plug till at least tomorrow.

Any more enlightenment?
Click to expand...
See.., a compression test would have told you the valve was stuck without having to take it apart.:laughing:
Did you clean the carburetor real good yet?
If it's been sitting over a year the carb could be dirty.


#8

M

Mechanima

True...but it wouldn't have unstuck it (and I wouldn't still be high on being a person who has *GOT INSIDE* a real live internal combustion engine :biggrin:).

Left stand a while it started to cough and almost start, which sounds a bit like my regular mower when the carb needs a clean out.

Also, I think some of the hard recoil could be because I have been pulling the cord too enthusiastically, now it is free it seems to try and "catch" at a very light pull.

Rain stops play for now, but my next move with certainly be to clean out the carb, unless it starts.


#9

Trcustoms719

Trcustoms719

Mechanima said:
True...but it wouldn't have unstuck it (and I wouldn't still be high on being a person who has *GOT INSIDE* a real live internal combustion engine :biggrin:).

Left stand a while it started to cough and almost start, which sounds a bit like my regular mower when the carb needs a clean out.

Also, I think some of the hard recoil could be because I have been pulling the cord too enthusiastically, now it is free it seems to try and "catch" at a very light pull.

Rain stops play for now, but my next move with certainly be to clean out the carb, unless it starts.
Click to expand...

Ok, keep me posted.


#10

M

Mechanima

It finally stopped raining for a while...so...time to get the carb off...except it is this strange little plastic thing with a primer bulb that doesn't make sense compared to the mikumi carb I clean out on my regular mower...so I googled to see how to clean it and found that they don't need much cleaning and there isn't anything you can strip...BUT...the diaphragm gives problems...

I had to practically dismantle the mower to get the carb off (providing a learning opportunity in terms of coil gaps later :confused2: ) and found that there was a spare piece of old diaphragm somehow stuck in with the gasket (did not seem helpful) and the actual diaphragm had been torn off one of the screws, probably while fitting it. Not in a functional area, but it would definitely interfere with the seal and tension.

Invested 5 euros in a new diaphragm and gasket from ebay, and tried to seat the old one better to see if it helped, or even changed anything.

Had to mess around resetting the coil gap a bit...

...then nearly died when it finally sprung into life :eek:

No fluke, it is now starting on the first light pull reliably. I will replace the diaphragm because it will not hold long like that...but my only worry now is that the engine seems to be racing. It has a governor and idle spring, not screws...don't think it is the throttle because it won't shut down even at the lowest point manually...

Any ideas?

PS Only starts on first pull when warm...still troublesome to cold start at all.


#11

Trcustoms719

Trcustoms719

Mechanima said:
It finally stopped raining for a while...so...time to get the carb off...except it is this strange little plastic thing with a primer bulb that doesn't make sense compared to the mikumi carb I clean out on my regular mower...so I googled to see how to clean it and found that they don't need much cleaning and there isn't anything you can strip...BUT...the diaphragm gives problems...

I had to practically dismantle the mower to get the carb off (providing a learning opportunity in terms of coil gaps later :confused2: ) and found that there was a spare piece of old diaphragm somehow stuck in with the gasket (did not seem helpful) and the actual diaphragm had been torn off one of the screws, probably while fitting it. Not in a functional area, but it would definitely interfere with the seal and tension.

Invested 5 euros in a new diaphragm and gasket from ebay, and tried to seat the old one better to see if it helped, or even changed anything.

Had to mess around resetting the coil gap a bit...

...then nearly died when it finally sprung into life :eek:

No fluke, it is now starting on the first light pull reliably. I will replace the diaphragm because it will not hold long like that...but my only worry now is that the engine seems to be racing. It has a governor and idle spring, not screws...don't think it is the throttle because it won't shut down even at the lowest point manually...

Any ideas?

PS Only starts on first pull when warm...still troublesome to cold start at all.
Click to expand...
First replace the diaphragm. then you You need to stretch that spring a little at a time (see pic link below) that will make the engine idle down like you want.
http://i43.servimg.com/u/f43/15/73/00/59/briggs10.jpg


#12

M

Mechanima

Thank you :smile:

Looking at diagrams I see the governor control bracket is bent down and obstructing the lever too (I couldn't make out whether it was supposed to be or not) that might explain the racing...

I will change the diaphragm, and while I am doing that clean out the tank, because a few minutes of mowing kicked up the reason the machine was broken down in the first place...someone had stuffed compost into it that was not visible when the tank was empty and I first checked.

No time tomorrow, but I think I may be a bit hooked on these little engines now.:biggrin:


#13

Trcustoms719

Trcustoms719

Mechanima said:
Thank you :smile:

Looking at diagrams I see the governor control bracket is bent down and obstructing the lever too (I couldn't make out whether it was supposed to be or not) that might explain the racing...

I will change the diaphragm, and while I am doing that clean out the tank, because a few minutes of mowing kicked up the reason the machine was broken down in the first place...someone had stuffed compost into it that was not visible when the tank was empty and I first checked.

No time tomorrow, but I think I may be a bit hooked on these little engines now.:biggrin:
Click to expand...



Oh.., yeah there really fun to play with when you can take your time with them.
They will always be a hobby for me but, i make money fixing other peoples stuff too.
I've been repairing cars/trucks alot more lately, not many mowers needing to be fixed around me i guess. A lot of the people by me pay to have there lawns mowed.:thumbdown: :laughing:


#14

M

Mechanima

No...mowing lawns doesn't have anything like same potential for fun :(

I will take it easy, repair what I can find and see how I go. A lot of people here use ride ons, but I am in mountains so plenty of push mowers for the tricky bits. :)


#15

M

Mechanima

This little demon is STILL playing up...(meanwhile I restored another one (same engine) that looked like two piles of scrap and rust on monday to the point where it really is starting on the first pull and purring like a kitten reliably.)

I flushed the tank and cleaned out the carb again today and got a couple of teaspoons of bits of grass out of the tank, and a teaspoon of water. Started and ran too fast for a couple of seconds, cut out when I turned throttle down (usually it runs on and ticks over) and would not start again. I am wondering, is it possible that tiny residual bits of muck in the tank and carb could still be causing blockages?

Sometimes the pull cord feels too free (like a rachet turning), sometimes there seems to be too much compression, when it's close to starting the recoil can get harsh (less so since the latest tank clean). Could muck in the tank and carb cause all this? It's only been flushed twice so far.


#16

M

Mechanima

Thought I had better update this in case anyone with a similar problem gets drawn here.

When I finally got together enough of the right tools to remove the flywheel with the help of a little innovative thinking and got up my courage I found that the shearing pin had split, diagonally, top to bottom.

Pop a new pin in and after sailing around in a cloud of white smoke for a while this little mower is now perfect.

I also learned that changing a shearing pin is a lot less scary to do than it sounds...and all that denial to avoid it was a total waste of time, work and gaskets.


#17

J

jamesslcx

Hello Mechanima, good job! Glad you stayed on it and got it running. Thanks for sharing your experience, you taught me to not give up and check everything. Beautiful country you live in hope to visit it one day.


#18

M

Mechanima

Almost impossible that there could be so much wrong with a relatively new little mower isn't it?

Still, all better now. :thumbsup:


#19

J

jamesslcx

Yes Mechanima, but you should have much pride and satisfaction in knowing you can fix those problems! Cheers!


#20

M

Mechanima

Thanks, it was a bit of a crash course in lawmower repair in a single machine, wasn't it?

I am dead pleased with self.
:biggrin:


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