# 1 cyl OHV 14 hp vertical B&S I&C



## indianajo (Apr 15, 2009)

I've got a 98 Murray 42" rider, originally came with a 14 hp single cyl B&S OHV I&C engine. The coil went bad 6 years ago, I bought one from PrimeLine 7-01651, Installed it with a piece of paper between it and the flywheel like they showed me on magnetic pickups in emmision vehicle course at community college. It backfired a lot, I kept restarting it and finally it caught fire and burned the plastic intake manifold and air cleaner off. I bought a new engine, a B&S Diamond I&C 14.5 hp 28N707. Good performance last 5 years, finally the coil went dead a rainy week ago. I've ordered a new primeline coil. I'm not happy with my B&S dealer, he sold me a coil for a 8 HP B&S last year in a nice box that didn't spark at all for $20 more than primeline. (no, the wire wasn't grounded). So if this backfires, what do I do? No side to side adjustments on these, just in and out, I push in against the paper and tighten.
5/13/10 Received a Primeline coil from O'Brien's that was in stock in Indianapolis. The reason it was in stock was that it was previously installed (screw scratches on the frame, no baggie) and didn't work. The clerk at my store promised to flag it as defective when he sends it back. Got cash back, didn't reorder. At least the refund worked, Miller's small engine B&S dealer charged me $20 more for a genuine B&S coil than turftractor would have for a Primeline, but it didn't spark and he died before I could get my money back. Put on the coil from the engine that backfired and caught fire, it didn't work either, too long on the shelf I guess in high humidity. Tried a new Champion plug with the new coil, no spark. The magnet is strong enough to hold a 1/2" combination wrench up. Ordered a Primeline coil from turftractor.com, hope they are still shipping from the factory. No, the shutoff wire is not shorted, I tested it with a meter (it is grounded with ignition off, open when on) I didn't even have it connected during these trials. Grass is up to my knees and it is going to rain next 4 days. Weird, turftractor only sells plugs in boxes of 8 and they are twice as expensive that way ($32) as RC12JY at Obriens' by the each.


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## indypower (Apr 13, 2010)

"too long on the shelf I guess in high humidity"
That does NOT cause a coil to go bad.
Back fireing is cause by:
1). Carb dirty or not adjusted correctly
2) Timing off. Sheared flywheel key.


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## indianajo (Apr 15, 2009)

Thanks indypower. The flywheel key wasn't sheared. I stopped the mower because the steering link was broken, then after some time in the rain I had to change the coil to get a spark. it just started backfiring when I changed to coil to one from primeline. It was installed upside up. I used the gap carboard. I finally got the newer 15.5 hp single cylinder motor (2003 production date) going with a new coil from primeline, but it wouldn't spark a new plug set .025". I had to close the plug to .010" to get any spark. I did use the gap cardboard to set the coil gap. I don't know why braking the steering column in a field and letting it sit a week would cause the spark to quit. I am forced to conclude my flywheel is below standard magnetic force, although why leaving it sitting in a field for ten days would cause this I don't know. The magnet will hold a 1/2" combo wrench up, so it has some strength. Unless I can figure some way to recharge the flywheel magnet with a starter solenoid, I'm going to weld a tab on the flyhwheel and make a prox pickup to run a battery-coil ignition. This engine has plenty of compression, it is not nearly dead but I am not going to spend $100 for a new flywheel.


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## IH farm boy (Aug 29, 2010)

id try a different brand of coil , do you have a napa store close buy


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## wjjones (May 28, 2010)

That air gap should be between .010" and .012". Plug should be .030" you need some flat gap gauges that are metal, i tried the cardboard style as well they arent very accurate. Let us know how it turns out..


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## dangeroustoys56 (Jul 26, 2010)

Id say something with the timing is off or carb is messed up. 

Ive bot tractors sitting in weeds past the hood sitting for years , i drag em home and after some cleaning /checking , i dump gas down the carb ( i clean it after i know it runs), check the oil ( change that after it runs too) , crank it over and see if it fires- 90% of the time they do. 

Even my 86 GTII 18HP twin had its entire intake filled with rusty water, i cleaned it up, changed the plugs and fired right up.

Id check the flywheel key ( physically pull the flywheel off) , put a new one on it ( theyre a couple bucks) clean the flywheel edges ( i find most spark problems are due to rusty flywheels) where the magnet is, reset the magneto gap ( i use a plain old oil filter box lid ) - i leave the magneto loose, put the cardbord between the flywheel/magneto , spin the flywheel till the magnet lines up with the magneto, the magneto should snap to the flywheel. Tighten the bolts on the magneto, then hand spin the flywheel to remove the cardbord. Spin the flywheel around a few times to make sure it spins even/straight, and that the crank isnt bent.

Ive done that on tons of tractors and never had an issue.

That also leads me to believe somethings up with the carb- catching fire means too much fuel....

Before changing the flywheel, id buy another cheep tractor with a decent motor first- its always cheeper then buying a new motor.


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## indianajo (Apr 15, 2009)

IH farm boy said:


> id try a different brand of coil , do you have a napa store close buy


No, Napa has moved away, but the last time I b ought a lawnmower part from them, they were selling Primeline parts, same as Carquest, and O'Brian's.
Carburator problems do not cause the spark to not occur. One tests the spark by 1. hooking up a spark plug with correct gap on top of the mower touching ground with the body 2. Moving mower to the shade 3. cranking mower and observing white spark or lack thereof. 
Mower has been running the rest of the summer with 0.010" spark gap. This is okay but indicates at some point it will no start and there will be no further recourse than replacing the flywheel with a new one (not used deteriorating in a junk yard). Anybody know how to change the flywheel magnets?


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## dangeroustoys56 (Jul 26, 2010)

Have any Cub cadet dealers nearby? I bot a briggs magneto from them - they carry all kinds of replacement briggs pieces .
Usually when it comes to flywheels, i replace them if theres an issue- in all my years of tinkering, never had the magneto magnet go bad, usually the problem would be rust on the flywheel. 

I have had the stator magnets fall out tho- thought i threw a rod, but the magnets inside fell off and locked up the motor - i removed them and took the stator out, since it was a beater tractor, it didnt matter- if i put that motor on something else id replace the flywheel and stator off a parts motor i have .


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