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Chain Saw Collectors Vintage chainsaws and other air cooled gas engine saws, collecting and restoring.

Chain Saw Collectors

Mall 7 Chain Saw Help Getting Running


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  #1  
Old 07-11-2018, 10:24:38 PM
Swapfoot Swapfoot is offline
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Default Mall 7 Chain Saw Help Getting Running

I am trying to help my father in law get his Mall 7 going. He completely disassembled the engine and has put it back together, but it won't run.
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We have tested the compression and it has about 30 psi when cranking it over. I have checked the coil and it has 0.3 ohms between the primary terminals. It has approximately 3.7 kOhms from either of the primary wires to the secondary terminal. I hooked up a D cell battery on the primary terminals and it will produce a spark at the plug. I also, spun the engine with the plug out and it sparks.

I squirted some fuel into the cylinder and cranked it and nothing happens. The spark is hot enough to ignite the fuel with the spark outside of the cylinder. I just wanted to see if the spark was hot enough to do that. When I put the plug back into the head and spin with while squirting fuel into the intake, nothing happens.

My timing light won't register the spark when I am turning it over. I also checked the points and they seem to be working correctly. I can't time the engine, but just within a rough estimation the points are opening several degrees before top dead center. I can't find any way to alter the timing.


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The coil doesn't seem damaged, although there is some very light cracking in the body of the coil. I have some compression, some spark, some fuel, I believe the timing is close enough to run poorly, and obviously air. I don't know where to go from here.

He would really like to have it running before he displays it. Any help would be appreciated and thank you in advance for your help.
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Old 07-12-2018, 10:08:17 AM
Ed Radtke Ed Radtke is offline
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Default Re: Mall 7 Chain Saw Help Getting Running

check compression with throttle wide open.you need alot more than 30
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Old 07-12-2018, 10:00:27 PM
s100 s100 is offline
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Default Re: Mall 7 Chain Saw Help Getting Running

If you have a good spark when the plug is out of the engine but not when it is installed something is clearly wrong in spark land. The easiest possibilities are a bad spark plug that won't fire in the cylinder for some reason or a bad spark plug wire that is shorting out against something when it is installed. Look things over and as you do ask yourself what changes when the plug is installed? When you install some shrouding or other parts ir is possible that a piece or a too-long screw fouls a wire, either primary or secondary. This could include he wire to the stop control.

I take compression gauge readings with a huge grain of salt. I recently bought a brand new gauge and all it would read on any of my small engines is something around 30 psi, both the engine I was working on and other known good engines. I tested the gauge against several others and while the others all read virtually identically the new compression gauge was off by 10psi at 100 psi. It also had a long hose and an adapter block all of which created excess volume, materially affecting the pressure seen at TDC.

Focus on the spark for now, or so I say. If the ignition system is working properly then the engine should at least fart when you turn it over with fresh gas squirted into the cylinder. Something is wrong here.
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Old 09-14-2018, 04:58:47 PM
Andrew Mackey Andrew Mackey is offline
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Exclamation Re: Mall 7 Chain Saw Help Getting Running

Does the engine bounce between strokes when it comes to a stop, or does it just mush to a stop with no bounce? if it just stops with no bounce against compression, then you have compression issues. plug gap should be .025. point gap around .018-20. Any carbon or wet fuel on the plug? if so, it won't fire under compression. If the engine was completely dis-assembled,are you sure the piston was installed correctly? if reversed, engine port timing will be affected - it won't intake or transfer the fuel/air internally. how old is the fuel? proper fuel/oil ratio? Should be 12:1 SAE 30 NON-Detergent oil - NO MODERN LUBES! 12:1 is 11/2 cups oil to 1 gallon of gas. DON'T lean out to 16:1, it will be too lean on oil and will damage the bearings!
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Old 11-13-2018, 03:51:15 PM
Andrew Mackey Andrew Mackey is offline
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Exclamation Re: Mall 7 Chain Saw Help Getting Running

Any luck with getting your Mall running? One other quick note - spark should occur with the piston about 1/8" before Top dead center You can set this with a test light and battery, with the coil disconnected. Connect battery negative to the engine block. Positive to the probe ground clip, probe to the points connection. Turn engine so that the piston is 1/8" from TDC, by placing a small screw driver in the spark plug hole and watching upward movement. Mark TDC at the top of the head, on the screw driver shaft, and make another mark 1/8" above the TDC mark. Turn engine backwards and then forward until higher mark is just visible. Place probe on points connection and rotate mag block against rotation until points JUST open, and then lock down mag plate. Timing should now be set.

Note: if the plug is wet with gas, the engine wont fire under compression. The new crap gas shorts under compression. Are you sure you have not flooded the engine? My 7-H floods easily, only one or 2 pulls with the choke on, as many as 5 or 6 choke off to clear it out. NO RESISTER PLUGS! The coil was the weak point on the malls - the phenolic covering cracks with age, allowing the coil wiring to corrode. If the coil goes bad, it probably will have to be re-wound. NOS coils probably are bad in the box - age ruins the phenplic resin they used.
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