This motor was running fine on Friday and today I changed the flywheel to an electric start one and now I can't get the slightest attempt for it to fire. Flywheels look identical, keyway to magnet position look exactly the same I have spark and cannot get the slightest kick out of it with starter fluid and drill starting it. Got me stumped. Any thoughts?
1 is there a nut holding the flywheel on or a ratchet for the old starter.If the ratchet is just hit a small amount to tighten, the key can break.
2 is the motor electronic ignition or points.
3 did you get measuring calipers to measure the width of the flywheel so the crank nut doesn't bottom out before the flywheel nut completely tightens as the flywheel key can break that way and also if the old ratchet nut isn't tight enough.sometimes the tapers are slightly machined differently and one flywheel will sit slightly lower and this can cause the crank nut not to tighten correctly.
4 are the magnet spacings the same and north south poles in the same position.
5 are the 2 flywheels both cast iron , shouldn't be a problem here as I haven't seen an alloy 10.5 flywheel.
6 has the coil been removed or touched to fit the flywheel. as coils can fail just with temp changes and movement.
7 Ensure that the new flywheel's magnets are strong with a flat screw driver.
I would check the flywheel key hasn't sheered and magnet strength.
I have had engines work fine one day then the next day it wont start even though you are still getting a spark and after putting another coil on they run again.(same thing with spark plugs)
Also if you just install the coil quickly ,I'd just double check it hasn't been put on upside down if that's possible.
Usually I measure the tapers in both flywheels to make sure they are close enough so there's no problem.
If it still won't run I think we both do the same thing and disconnect the kill switch wire in case of a short.
Hi Max, thanks for that, Original coil and no problems with spark. As far as I can see flywheels are identical except for the ring gear. Got me stumped, all I can do is put the original flywheel back on and see I can get it started Put the original flywheel back on it and still not the slightest kick from it. I'm loosing faith in this Briggs rubbish, Chondas are so much better quality
Norm, Have you even bother to check the valves clearances? When get to close to zero clearance they can get to where they will not start due to ramp decompression at the top of the stroke. Valves can stick open when this close to Zero clearance.
I don't see many L-side (Side Valve) engine any more but when I did I would get in engines that started one day and the next day would not due valve clearances.
If it's got at least 50 psi compression and the muffler isn't blocked with starter fluid it should fire unless the coil is breaking down under load (spark plug installed)
I just don't trust old coils as I've had too many engines that have spark but don't run, then when I change the coil they are fine.
I checked it this morning Max 60 psi I have changed the coil , maybe I will try another one, just for kicks and giggles I'm thinking it might be a decomp problem with this one as well today when I went to check the compression I pushed the button and it smoked up the new starter solonoid so to check the comp I went back to jumper lead straight onto the starter motor
I always prefer to take a coil off a running motor Norm when an engine won't run if I have one as it saves time if it doesn't run because you can then look else where for the problem.
I remember once when I had a Briggs Quantum that wouldn't run and I replaced the coil 4 times before the coil was good and it ran again ,one coil was removed from a motor with a thrown rod and the coil still didn't work.
Originally Posted by NormK
I pushed the button and it smoked up the new starter solonoid so to check the comp I went back to jumper lead straight onto the starter motor
When I was a kid starting an old motorbike with a car battery I burnt out the starter wiring and the solenoid and thought it would do the same thing using a car battery on a mower, I remember asking an Auto electrician if a car battery would work on a mower or will it burn the starter circuit and he said the starter circuit only draws the amps it needs from the battery so it won't burn out the starter circuit .
As we know A lot of the time if it starts quickly you don't have a problem with a car battery but there is still the chance that too many cold cranking amps in the battery will damage mowers and motor bikes. starting system.
Cold Cranking Amps (CCA): Car batteries typically have a much higher CCA rating than motorcycle/ mower batteries. As a result, they can deliver a lot more current than what the motorcycle’s / mower's starter and wiring are designed to handle. This excess current can potentially overheat and damage the starter motor, solenoid, or wiring.
Starter Motor and Wiring: The starter motor in a mower / motorcycle is designed for the specific demands of the bike's / mower's engine. Using a battery capable of providing more current than the starter can handle increases the risk of overheating, burning out the starter winding, or damaging the wiring and solenoid.
Potential for Damage: If you use a car battery for starting a mower / motorcycle, you may cause the starter motor to draw more current than it is rated for, leading to overheating and possibly burning out components.
Starting Circuit Design: The wiring and circuitry in motorcycles / mowers are usually less robust compared to those in cars. This means that the risk of damage is higher in a motorcycle's / mower's electrical system when using a higher-capacity battery.
Hi Max, the last thing I am concerned about is damaging these starter motors because they are only off shithead Briggs motors anyway. They are going to the scrapper, not wasting any more time on them
I've heard that the OHV Briggs are useless as the ACR breaks on the cam and that's what the above video shows
It's just this thread says flathead (side valve) and I thought the decomp was build into the cam lobe on these motors ,I haven't needed to take one apart for a few years now. I think I have one in parts somewhere I may have a look at the last of the side valve 13 hp motors to see if they changed the cam decomp.
Yes Max, but I am playing with 2 motors here. I have just fitted a Victa decomp valve to a flat head, I will put that on tomorrow and see if that helps, nothing to loose
Hi Max, you can go to the top of the class, tried a third coil that I knew was off a running motor I scrapped, put the head on with the decomp valve fitted and it fired straight up on the starter. At least with the decomp it relieves some of the pressure on the starter so it can spin over more easily so both things have avoided this motor going to the scrap. Now I have to work out how I can fit a decomp to the OHV one, not a lot of room to work with there
Good to hear you've saved this one from the scrappers ,yes I've had a lot of Briggs coils and Chonda coils not work even if you get spark with the plug removed. I've even had new equipment that was a year old that wouldn't run but had spark and then you fit a new coil and they start straight away .
Had a lot of mowers that run well when testing them for a few minutes every few days then after a few more days they won't start and it's just a bad coil.
It's obviously not worth spending around $1000. on a coil load tester.
It's going to be tricky to get the decomp to fit the OHV motor ,it's a pity they don't make spark plugs with a built in decomp.
Hi Max, I'm not sure if the Victa decomp is going to be big enough to relieve enough pressure in the OHV motor, it is a lot harder to turn over when it comes up against compression. I might have to try an Enfield decompressor on that one, get a copper pipe out of the head and then fit the decomp wherever I can. Wish I had kept the OHV head off the last motor I scrapped so I could have played with that one
Yes last time we mentioned the Enfield decompressor with copper pipe and probably with a flare fitting would be best.
Just with the remote decomp pipe you may loose 10 psi as this will add to the combustion camber volume.
With the OHV head there isn't a lot of room with the muffler on one side and the carby on the other ,then with ports and valves in the way ,you may have enough room if you drill a hole on an angle so the bottom of the hole is close to the spark plug thread then the top of the hole is at a distance to not get in the way of using a tube socket to get the plug in and out and as long as it's not in the way of the spark plug lead and cap.
I thought I might have had an Enfield decomp valve here I have had a quick look somewhere there is a box with Enfield spares in it, I will have another look. I'm thinking using a short piece of 5/16th copper tube so I can bend it to where I can set the valve up. See how I get on, be nice to save both motors because they both ran well, just the starting problems
I just remembered there is 2 Enfield motors here so no problems to borrow a decomp valve from one of them to set the OHV motor up. Here is a pick of the Victa decomp valve in the 10.5 Briggs flathead Another thing that surprised me with this was the new starter solonoid I fitted. It smoked up quite badly for the first 4 or 5 times I pushed the start button. I was sure it would have been burnt out because it put out a lot of smoke each time but I kept using it as I figured I had nothing to loose (the smoke was instantaneous the second I pushed the button) Anyway it works fine now and no smoke, no idea what that was all about unless it was some sort of varnish that was put on it
