9.8 running on one cylinder

Some of you may have read some of my past posts about taking three old 9.8s and making one good one. Where I am at now is, the engine is running on the upper cyl only. I checked the compression, both cyls hit around 95psi one one pull. If you pull it again, it will hit 120. I am not sure of the proceedure for checking the compression but both cyls are very near the same and I think my gauge reads low anyway. It will run very low rpm's with the one cyl that is hitting so I dont think it has a compression problem. I can take the plug wire off the lower plug and place it near the head and a spark will jump, but if I stick it right next to the tip of the spark plug no spark will jump. This tells me my spark is arching to ground somewhere before it gets to the plug. This motor is a late 60's with the magneto type with no coils, all the ignition is under the flywheel. I started this motor up briefly several times during the swapover process and some times it would run on both cyls and somethime just one sometime and somethimes it would run on one and the other would kick in and out. Now it will only run on the one cyl all the time. I have also removerd the kill button and taken it completly out of the picture. Anything you can do to help an AUTO mechanic out?

Re: 9.8 running on one cylinder

Each cyl has it's own set of pts, cond and coil so you will have to remove the flywheel and ck them

Re: 9.8 running on one cylinder

The wires that attach to the points attach to a screw that passes thru a plastic insulator. If there are cracks in that plastic, spark will leak there.

Re: 9.8 running on one cylinder

It's a older magneto engine Willy, but that insulater will drive alot of people nuts on the phazer pt engines

Re: 9.8 running on one cylinder

You can swap the ignition parts from one cylinder to the other and track down the problem that way, if it is an ignition issue.

Re: 9.8 running on one cylinder

I havnt checked yet but does that mean my motor has no points

Re: 9.8 running on one cylinder

Can you tell us the serial number of the motor/ignition that we are talking about? I'm a bit confused since you indicated that this was put together from three other motors. If it is the "older magneto type" it will have points, condensers and coils under the flywheel, one set for each cylinder. If you have no points it is a newer ignition.