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Briggs & Stratton ZZ problem.


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  #1  
Old 03-12-2011, 08:49:11 PM
Military Dave Military Dave is offline
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Default Briggs & Stratton ZZ problem.

Does anyone have any new suggestions for my non-running ZZ engine. I have performed a valve job, the bore, piston and rings are in great shape. The compression is very good. The electrical components are in great shape and at the specific values, where I was advised to have them. I took the carb. apart, cleaned it and inspected it closely and found it to be near new. The fuel tank is clean and rust free.
I was able to get a few small backfire flames out of the carb. last nite. This morning I bought a new spark plug, Champion D-16. I am getting plenty of electricity at the plug, but no go. I got 4 good positive barks out of the engine, then a backfire which promptly closed the choke and flooded the engine out. She refuses to light off and run. I am using an old drill motor to turn the engine over. It turns around 450 R.P.M. If I were to try this one pull at a time, my right arm would have fallen off a long time ago.
I don't really have an idea where to adjust the main jet and air/fuel mixture screw settings. I read on here main jet 1&1/2 turns out, and a/f mixture 2&1/2 turns out. What am I doing wrong?
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  #2  
Old 03-12-2011, 11:31:52 PM
trowel
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Default Re: Briggs & Stratton ZZ problem.

that does not sound right, you have the screws set right, it sounds like your timing is too retarted, did you pull out the cam or piston?,
cheak the flywheel keyway, it may be bent or getting ready to shear off, pull the head and see if the intake valve sticking open.
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Old 03-13-2011, 01:37:12 AM
Military Dave Military Dave is offline
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Default Re: Briggs & Stratton ZZ problem.

When the P.E. 75 unit was given to me, it was dumped off at the WW2 museum where I volunteer. I took the engine apart as in, flywheel off, electrics off, head off, cooling shrouds off, etc. I did not remove the cylinder, (bore in great shape), or take the bottom end apart. The exhaust valve was only slightly stuck open. Meaning, a few shots of P.B. and a slight push with my thumb, and it snapped closed.
I removed the valves and did a proper valve job. The key is in excellent condition. I have the valve lash set, intake .014", exhaust .018" cold.
Perhaps it is just that the engine has set without working, it does not want to wake up. Maybe it's bashful at how beautiful she now looks as I did a factory refurbishment. I don't know.
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Old 03-13-2011, 01:41:39 AM
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Motorhead Motorhead is offline
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Default Re: Briggs & Stratton ZZ problem.

As trowel said. Maybe when you reinstalled the flywheel the key slipped out and now the flywheel is out of time. You also didn't mention the points. Are they set right and clean on the contacts?
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Old 03-13-2011, 04:12:48 AM
Military Dave Military Dave is offline
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Default Re: Briggs & Stratton ZZ problem.

I displaced the key in several attempts at flywheel installation. When it fell to the inside of the flywheel/magneto, I heard it and reset it. The points are new and clean and at .020".
What ever the problem is, it is going to the most simple and overlooked. Or, it is going to necessitate a complete internal overhaul.
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Old 03-13-2011, 07:00:21 AM
Ironsides Ironsides is offline
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Default Re: Briggs & Stratton ZZ problem.

Military Dave,if you are certain that your ignition timing is correct then it may well be valve timing,remember you were given this engine with no other info.I would access the side of the engine that allows me to check valve timing.Good luck,Norm
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Old 03-13-2011, 07:32:59 AM
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James Bosma James Bosma is offline
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Default Re: Briggs & Stratton ZZ problem.

Here is a link to the manuals for the older Briggs and Stratton engines http://www.briggsandstratton.com/engines/support/frequently-asked-questions/Antique%20Operator%20Manuals/?body_0$tbKeyword=antique%20engine%20manuals ...... Jim
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Old 03-13-2011, 10:05:46 AM
Heins Heins is offline
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Default Re: Briggs & Stratton ZZ problem.

Dave, I would check the valve timing by taking the valve cover off and turning the engine until both valves are off their seats and that is when the piston should be a TDC. Mark the crank with chalk and turn the engine and see if it sparks at that time. And see if the piston is at TDC when the valves are both off their seats.
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Old 03-13-2011, 10:46:33 AM
25Eagle34 25Eagle34 is offline
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Default Re: Briggs & Stratton ZZ problem.

Dave, I have the manuals for the PE-75 gen set and one manual has about 31 pages about the engine including repair and overhaul. What letter series is your gen set? Send me a PM if you are interested. Thanks, Don

Last edited by BTPost; 03-13-2011 at 01:39:01 PM. Reason: Fixed Policy Violation.....
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Old 03-13-2011, 04:04:31 PM
K D Redd K D Redd is offline
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Default Re: Briggs & Stratton ZZ problem.

You may have already fouled the Champion Plug. There are some guy who will not use a Champion Plug on a bet. I have seen them claim that Champion skip as step in glazing the porcelain of the plug making them to easily foul with today's gasoline. I do use Champion on most thing and I have had little problems with them. The BUT to this is The two ZZs I pulled from the junk with the bad coils, I am running AC C-86 s in them. Try the simple things first. Change the plug.

Kent
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Old 03-13-2011, 06:15:54 PM
RSCurtis RSCurtis is offline
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Default Re: Briggs & Stratton ZZ problem.

That's a good point. Another thing you can do to cheat a little on what may be a marginal ignition system is to reduce the plug gap to about .010" and see what happens.
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Old 03-13-2011, 10:48:52 PM
Military Dave Military Dave is offline
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Default Re: Briggs & Stratton ZZ problem.

Thanks again guys. I will try all the suggestions. I will keep you all posted.
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