Cipper Shredder Compression

[plpitts1]

Hello,
I have a Buerr #655 Shredder Chipper with a B&S 5 HP motor Model #130212 4007 01 91081407 that will not start, not even if primed through the plug hole. It has a new carb on it. Compression is 55psi at best, but I believe it has a compression release. The shredder is always engaged. The plug appears to be getting wet, and I am getting good spark. Before I start tearing into it, I wanted to get a second opinion on the compression of 55psi. I’m also thinking that I would need more than the minimum compression to get it to fire due to it being under load all the time??
Thanks,
Pat

[bgsengine]

Hello,
I have a Buerr #655 Shredder Chipper with a B&S 5 HP motor Model #130212 4007 01 91081407 that will not start, not even if primed through the plug hole. It has a new carb on it. Compression is 55psi at best, but I believe it has a compression release. The shredder is always engaged. The plug appears to be getting wet, and I am getting good spark. Before I start tearing into it, I wanted to get a second opinion on the compression of 55psi. I’m also thinking that I would need more than the minimum compression to get it to fire due to it being under load all the time??
Thanks,
Pat

First, try a new spark plug. (or borrow a known good plug from another piece of equipment, should be a J19LM or RJ19LM , but CJ8 , J8, and CJ14 plugs can also "sort of" work to get it to fire up, if nothing else available. ) could easily have a plug that shows spark when testing, but won't fire under compression.

[grunt]

You may have sheared the flywheel key If you accidentally put something to thick in the hopper and stalled the engine.
Now the timing is off and preventing ignition, at the correct time.

[KE4AVB]

You may have sheared the flywheel key If you accidentally put something to thick in the hopper and stalled the engine.
Now the timing is off and preventing ignition, at the correct time.

plpitts1, I would agree with Grunt on the sheared flywheel key. If the flywheel timing is off it doesn't matter how compression or fuel you have it simply will not hit. If it is sheared remember to torque the flywheel clutch starter to spec or it will shear the key again the first time it starts. Also spark plugs do give trouble under compression if they are bad. Just because it sparks outside the engine doesn't always mean it is good; even new plugs straight out of the box can be bad. The only way to know for sure is use of known good plug.

Being a 1991 model I would also check the valve clearances as a L-head valves wear the valve decreases until there is none or less. This will increase the decompression release time lowering the compression even more than usual. I just got through with a 171400 series where I had a negative .003 valve clearances of course the engine was worn out and was requiring a rebuild due to abuse by the owner; no oil.

BTW these direct drive shredders are hard to get going anyway or at least the one I have due the heavy weight of the chipper/shredder assembly. I have to pull several times just to get the speed up for it even to get it even start. Once it hits then it goes from there.

[RoyM]

I suspect a leaking head gasket or burnt exhaust valve, both of which are easy to check. The engine has to work to get that shredder up to speed then continues to coast on shut down. The latter means cool fuel and air is being drawn into a hot engine with no spark available, the rapid temperature change is hard on the valve and head.

[JandL]

You stated

Compression is 55psi at best

even with the compression release that compression should be above 90 at the LEAST. Do a leak down test and determine where the problem may be. Or get a new engine on it and go to work

[RoyM]

He won't get 90psi on a good day if the valve clearance is correct. I always figured 75 for a new engine, 60 bare minimum to get it running with the old flat heads.

[plpitts1]

Hello,
Put a new spark plug in, but know luck. Come to find out the key was sheared. I put in a new key and got it started after many pulls. Of course as soon as I got it started a customer came in and I had to shut it down. I’ve not been able to get it going again (after many more pulls, nor did I get to spend much more time on it after that, so I’ll look at it again Wednesday when I go back. Probably look at the valves.
I sure appreciate all the input. I will update later.
Thanks,
Pat

[plpitts1]

KE4AVB – Do you know the correct torque for the flywheel clutch starter, or better yet where I might get this info in the future? I tried searching B&S website but came up with nothing. And I’m guessing I need a special tool (other than torque wrench) to do this with.
Thanks,
Pat
PS - yes, this is an admission that I did not follow your advice completely. My bad.

[bgsengine]

KE4AVB – Do you know the correct torque for the flywheel clutch starter, or better yet where I might get this info in the future? I tried searching B&S website but came up with nothing. And I’m guessing I need a special tool (other than torque wrench) to do this with.
Thanks,
Pat
PS - yes, this is an admission that I did not follow your advice completely. My bad.

Briggs Service manuals available for download in many different places. for one: http://bgsemgineclinic.com/downloads/ You will probably want the single cylinder L-head service manual. They do make a special tool for the starter clutch removal and installation that works with a 7/8" socket and torque wrench. Lots of them on eBay - Search on Briggs Starter Clutch Tool , Briggs OEM part number 19244 starter clutch wrench, or its aftermarket versions.