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
I just wasn't sure how thick the alloy is in that spot but knew around the spark plug the alloy may be thicker, If you think that will work looking at the head, it's worth trying .
Ok further along the road with the OHV motor, at least I have a spark plug in the head no just have to see if the Enfield decomp will fit straight in or if I have to make an adaptor for it, hope not
The copper pipe idea I think was when using 2 Victa decomps or if there wasn't enough room for the decomp in the head.
The Royal Enfield ,I've seen 2 types ,one manual and one cable operated that released compression into the exhaust port, You shouldn't have any trouble screwing the decomp straight into the head.
I see there are Harley decomps that are built into the spark plug hole but a little expensive.
Lot of different bike ones out there that are cheap ,I guess the only other concern is if the decomp closes to late after compression and sucks in dirt.
All good now Max, fired up instantly and runs like a dream, Briggs are just a shithead company doing what the do on the cam, it is designed to fail. Anyway that is 2 motors saved from going to the scrapper with the aid of a couple of Victa decomps Big problem for me now is I am out of oxy and there are some jobs I can't do without oxy
Yes Norm, Briggs should have fixed all the motors for free ,but not likely ,heard of a few breaking at 20 hours use, so not great for Briggs and now people refer to them as Breaks and scrap em.
This good decomp fix can at least stop the motors getting thrown out.
I did hear that in 2020 Briggs redesigned the ACR on the cam but I haven't heard how reliable the new cams are.
Originally Posted by NormK
Big problem for me now is I am out of oxy and there are some jobs I can't do without oxy
Yes I have the same problem ,the last bottles I had were dirt cheap second hand ,you do see them for sale on market place from time to time.
Another option is to get the bottles filled but is $200. for small D bottles.
I've been using the LPG torch more instead of the oxy kit for heating and lead /soldering etc.
I thought possibly another type of oxygen less pure than what's normally used would work but it won't work, the only thing I've found that may work cheaply is pure oxygen for a scuba tank but it's not legal to do ,but could be possible to use and only around $5 to fill a D sized bottle.
The scuba tank with LPG would be cheap for brazing and cutting.
Yes Max, the bottles I have been using I was given about 8 years ago, I only use it for real problem things for that reason. Sometime there is no alternative. It is the $200 deposit that hurts, but that is a lot better than paying the yearly rental that you had to pay for CIG bottles Anyway I am super happy with the fix on these motors, just the OHV one took longer because I had to make the adaptor because of the angle I had to drill at to clear everything and still keep inside the head gasket. Because of the angle I needed a long thread spark plug so it could pick up enough threads. Motors start so easily now, and Briggs couldn't figure that simple thing out. Why would anybody want to replace a crap cam that has failed with a brand new crap cam that you know will fail. Anyway a good outcome
And I'm not going into business providing changeover modified heads for the world market because there is probably a market for them because it is much simpler to change the head, than splitting the cases to replace a cam that is prone to fail again
Ok so my latest problem with this flathead motor is it is not charging. I am getting 25 volts ac from the stator (which is what they say it should put out) but with a new rec/reg plugged into the stator wires the battery remains sitting on its pre start figure of 12.4 volts. Any thoughts?
Just checking I assume you did bring the motor to maximum rpm to check the voltage. as we know If the engine is running at a low RPM, the output of the alternator may not be sufficient to raise the battery voltage significantly above its current state. At low RPMs, the alternator may produce less voltage and current, which may result in little or no charging of the battery.
To charge the battery effectively, you'll want to ensure that the engine is running at a higher speed to allow the alternator to produce the necessary voltage for charging.
So most likely you've done the above and still not charging ,you would think that just leaves a problem with the battery or the regulator ,assuming the wiring is correct and no problem with the motor earth to frame,
a few steps to troubleshoot the issue:
Check Rectifier/Regulator Wiring: Ensure that all connections between the stator, rectifier/regulator, and the battery are secure and free from corrosion or damage. A poor connection can prevent proper charging.
Check the Rectifier/Regulator: Even though you have a new rectifier/regulator, there is a possibility that it could be faulty. Test the rectifier's output with the engine running. You should see a DC voltage reading of around 13.5 to 14.5 volts at the battery terminals if the rectifier is functioning correctly.(this step was done / possibly bad regulator)
Measure DC Voltage: Use a multimeter to measure the voltage across the battery terminals while the engine is running at a higher RPM (around 3,600 RPM). This can help you confirm whether the rectifier is functioning. If you see little to no increase in voltage, that indicates a problem.
Check Battery Condition: Ensure that the battery itself is healthy. If the battery is old or has internal issues, it may not hold a charge even if the charging system is working correctly. Consider testing the battery's condition separately (e.g., using a load tester).
Inspect the Stator: Although you are getting the expected AC voltage from the stator, it can still have issues. Inspect the stator for any signs of damage, such as burnt windings or internal shorts that may not be immediately visible.
Ground Connection: Confirm that the ground connections from the battery to the frame and engine are solid and free of corrosion. Poor grounding can sometimes affect the charging circuit.
Test under Load: If possible, measure the output while the mower is under load or at higher RPMs, as some systems may require a certain load before they begin to charge effectively.
Thanks Max, Wiring is all new, battery is new, rec/reg is new, I have ordered a new stator but I don't believe this is the problem. I have worked for years on Enfield charging systems so I have a rough idea how they work and this system is so much simpler, plug the rec/reg into the stator and connect the red wire from the rec/reg to battery positive, can't get any easier than that. Got me a bit stumped at the moment. If the stator is putting out 25 volts ac with the revs it is running at then it should be fine for the dc side as well
When a new part hasn't been tested on a working system you don't know if there is a fault with the new rec / reg , especially when purchasing parts online.
Every other part sounds good ,except possibly a fault in the stator or rec / reg.
I usually just list all the check list of fault finding if any one else has a similar problem and I find it quicker to run though a list so nothing gets missed, I knew you could do these blind folded by now but I don't always trust new parts to work.
