Chrysler/Force 85hp block
Owner complaint: Poor Idling, smoking, no-power...
There are two main causes for the problems described. Poor temperature control and incorrect fuel/air mixture. The engine used for the outboard and the L-Drive was actually a pretty dependable engine. However, two normal service items were, that the carbs had to torn down and cleaned when they started to varnish, and the thermostat in the head and the by-pass poppet valve in the block, seem to need cleaning and/or replacement more than similar engines.
The second most probable cause for a problem stems from attempts to correct running problems, caused by the above, by changing the synch and link adjustments. Synch and Link is the procedure to calibrate the timing between ignition timing advance and carb throttle plate opening. Tampering with or not following the procedure, properly, will cause "off idle" and acceleration problems in any two cycle motor.
My first suggestion is to run a compression test, since head gasket failure was also a result of operating this engine with cooling and/or fuel problems. If this seems "perfect", you can move on. If your in doubt remove the three fuel transfer port covers (item 33) and look at the sides of the pistons, looking for scuffing and/or piston ring failure.
Note: The poppet (items 62-66) are located on the lower part of the block and helps control the cooling water flow. This poppet valve and the pocket it sits in, often become clogged with silt and corrosion. It needs to be pulled and cleaned every couple of seasons..... or a partial or complete overheat will occur. Be sure to pull the thermostat and check and/or replace at the same time.