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View Full Version : B & S 28v707 turning over no start


vintagecar
Oct 1, 2006, 04:30 PM
I have picked up the engine above that sat for 3 years. Brand new battery as f last night and it wants to turnover but never does. The red wire to the starter where it bolts to the starter gets VERY HOT! Is this the problem? The starter does engage the flywheel and has plenty of power spinning it, there is a strong spark and fuel is being delivered... what gives?

thebriggsdude
Oct 2, 2006, 01:23 AM
I'm sure the battery was put in right? Negative to black (thats grounded to the frame) and red to positive?

vintagecar
Oct 2, 2006, 03:41 PM
Yes battery is secured with wing nuts to the right terminals on the battery posts. I'm going to remove the spark plug to see if there is spark going through the plug. From the spark plug wire to the plug there is a solid spark. The other thing I want to test is putting some gasoline in the carb to see if that helps. Although I did squirt some starter fluid in there and it didn't even sputter like it wanted to turn over.

robc68fb
Oct 5, 2006, 12:54 PM
I have then same motor & recently have had it torn apart 3 times trying to fix the damn thing (ran it low on oil-hence my problems with it) before I ended up getting another used motor that would run & not give me problems.

The starter engages & turns the flywheel when you turn the key, right?
Does it fire at all?

On mine I had to set to the throttle to choke when I started it, once it fired then I could take the choke off & it would run.

Just thought of something else, when I got the used 12.5 motor for my mower, it had sat for a while too. Luclkily I took a few things apart to inspect/check before I bolted it up to the mower & tried to start it.
Anyway, the intake valve ended up being stuck open. That could be a possibility for you to explore. Either valve stuck open would cause problems. It's not terribly difficult to take the cover piece off that covers the valve stems & springs to see if one is stuck open or not.

Like I said, I've had mine old one apart a few times now & have become fairly familiar with the 12.5, so if you need any help with what to do there, let me know & I will share what I know.

Hope this helps

vintagecar
Oct 6, 2006, 06:01 AM
Thank you for the suggestions. I did take the carb off the engie and cleaned it up, it was fairly gummy and the butterflys didn't open and close. The starter does engage and sping the flywheel. The engine just turns over and over and over, but no sputters like it wants to start. I have tried the throttle in all positions and still the same effect. With the carb off I can see one of the valves is this supposed to be that way? How do I tell if it is stuck or not? Can I try turning the engine over and see if it moves, or is that bad practice?

robc68fb
Oct 6, 2006, 06:40 AM
You could remove the head to expose the combustion chamber & then hand-turn the flywheel & see if the valves are seating & going up & down like they should. (You may need to replace the head gasket after removing the head if it comes apart) You may be able do this without taking the head off, but you will probably only see the intake valve, as the exhaust valve is below it. You may be able to see the other valve if you have the muffler off too, I'm not sure on that one.

If one of the valves is stuck open, I did the following to mine: With the head & carb off, there should have been a breather tube that goes to a retangular shaped part mounted to the side of the block. (This rectangular piece has two screws holding it to the block & it covers the valve stems & springs) I had taken mine off & sprayed some WD-40 on the valve stems & around the holes they go through towards the combustion chamber. At this point, I used a rubber mallet & tapped the sticking valve back down & then worked the flywheel by hand & made sure both the valves went up & down like they should & then put everything back together.

Hope this makes sense the way I explained it. Good luck with it.

thebriggsdude
Oct 6, 2006, 11:57 PM
Yes you will see the intake if you take the carb off, exhaust if you take the muffler off.. if you have those off... be easier to pop the head off.


Is the engine actually getting gas? Try some gas or starting fluid (not much!) down the carb and see if it fires first.