Anyone know what compression should be on an M John Deere ?

Hi, Need what compression should be on an M, kinda thinking my head gasket might be leaking some. Gonna put a compression tester on it and check it. Thanks

Here are values for the "M" according to Field Service Bulletin 259:
Compression ratio - gas, 6.0:1; All-fuel, 4.7:1
Compression pressure (starter) - gas, 110; All-fuel, 85

im reaching 95lbs is that suitable?

Quite adequate at 95 PSI. You might get more if the throttle was wide open with the choke off and all plugs out but there is really no need to re-do. Anything above 50% of stated pressure will still run fine with lots of power. You have a very healthy engine, right next to new in my opinion.

(quoted from post at 14:16:41 04/16/15) Quite adequate at 95 PSI. You might get more if the throttle was wide open with the choke off and all plugs out but there is really no need to re-do. Anything above 50% of stated pressure will still run fine with lots of power. You have a very healthy engine, right next to new in my opinion.

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I did notice on both cylinders that when I pressed the release button on the gauge that some fluid that looked alot like coolant sprayed out. Not sure it was but could be. The strange thing is, I have replaced the plugs, adjusted the points, timing, replaced intake gasket, rebuilt carb. and rewired the ignition system and replaced the switch. Still getting a little pop back in the exhaust have an engine surge. Any ideas? For the surge I think maybe the governor needs adjustment. Thanks

Did you time it with a timing light? I had thought I had my MT timed real well with using the procedure in the owners manual but I was wrong. When I did the procedure M-Man has put on this board many times with the timing light I got WAY better results. I highly recommend using the timing light.

I did use M-Mans method after the books method didn't work, still has a little pop back.

adjust the valves?

Don't know M at all, but I do know timing is rarely an issue to be concerned with too much. You had a prime moment there when you could have found out what the coolant looking like liquid might have been. Your tongue man, TASTE it - if it's sweet you know it's antifreeze. Just be sure to spit out as much as possible afterwards. Old school trick that still works. I would certainly try a bottle or two of Bar's leak before taking the head off to find out where a coolant leak might be coming from - just be sure to avoid silicate type of leak stop and insist on the old formula of concentrated molasses and plant parts (pepper works here) for your first try at a stop leak. Cylinder head repair, block sealants are most likely made with water glass (silicate) which was the main ingredient in the cash for clunkers program done many years ago - they put it in the oil directly though and it would lock up the reved up engine within a minutes time. No fixing that one without an entire tear down and boring out of the glass deposited on the cylinder walls. This stuff you do NOT want to buy or use. They have it right next to the good stuff so watch what you buy.

I would be looking at the carb for surging issues, don't quite know what you mean by pop back at all. Lean conditions lead to backfire in the muffler where the mixture isn't good enough to light off with the spark plug but waits until it is in the hot muffler stack where it does go off with a bang. Perhaps your pop back is a border line case of this? With little pops on occasion? Enrich the main jet and lean the idle screw to limit black smoke if some appears, not knowing if you even have those adjustment screws. Governor could still need adjustment, but I would look at carb mixture for surging/backfire issues if the easier governor adjustment gets you no where.

You do not want to put any kind of stop leak in a thermosiphon cooling system.

Since no water pump I assume no circulation and clogging the radiator? I have a small leak in one of my flues but I can try soldering that.

I'm convinced the governor needs adjusting, I just don't know the methods needed to complete it. I can hold the throttle steady by hand and it will actually run good and smooth, but let it go and the surging returns...

It circulates but it's more of a gradual type as it's just a matter of heat rising. The hotter water keeps going up until it hits the top of the radiator where it falls and cools to return in the bottom. You need forced circulation for a sealer to work.

Page from service manual is posted on your gov thread. Hope it helps.