Home › Forum › Ask A Member › More 135 Johnson problems › Re: More 135 Johnson problems
As for the rough running part of your 135…have you checked the compression? It MUST be up around 120 psi and no cylinder can be 10% less than the highest psi. These motors needed to run the UL77V spark plug. If someone installed the L77JC4 or QL77JC4 spark plugs, it would run too hot and burn a piston, causing the dome to melt and ruin the motor. How do you "know" the motor is running on all 4 cylinders? Do you have a spark checker that can test the gap at 7/16th of an inch? Do you have a peak reading voltmeter that can read the voltage of the triggers and the power pack? My guess is that you replaced 4 ignition coils and wires for no reason. You have another problem, if the issue is ignition related. Make sure you remove the high speed jets and clean them out. There are 4 of them, two on each carb. This is just my opinion and the normal disclaimer applies.