G'day All, I have a recalcitrant 1979 Suzuki X7 - it will only run on the RH cylinder - virtually regardless of what I do! Bike was running well a few weeks ago, then started missing on LH cylinder. New coils (the old ones were too short to put on new plug caps), new plugs (twice), new plug caps (twice) but still only RH cylinder starts. Rebuilt the carbs - standard jets etc, standard air box. The battery shows 12.3 volts, both plugs spark (whitish blue) when not screwed in, but resting against the head and kicking over. The engine will not start with only one plug screwed in (ie trying to start on only one cylinder) on either cylinder. The engine normally starts and revs OK, but only RH is firing correctly, LH is missing (but removing the plug cap, the sparks are still there). Plug check shows both plugs wet (but not flooded). Removed LH exhaust & silencer - some carbon but not blocked - maybe the silencer has a bit too much?? The LH piston seems to be OK - no holes, not a lot of carbon. I am at a loss what to look at /check next. Have thought of the starting device (since it is the LH cylinder giving problems? Can the CDI unit be starting to fail and not providing enough strength for both cylinders to fire under compression?. Could the reed valves be starting to fail (especially LH cylinder)?. Any suggestions/help/advice appreciated. Arthur
Well done. Could well be the culprit! I really should have thought of that. Might take a while though. Cheers, Arthur
Welcome Arthur. Does the L/H cylinder fire when you have the choke on = air leak on intake. When you had muffler off did you try to start engine to see if cylinder firing = blocked muffler. If both plugs firing then PEI should be ok. Do both cylinders have good compression? Maybe crank seal, but I would be checking all external pieces before stripping the engine.
check the connections to the coil if those spade crimps are loose you will get a miss fire. cut about 10-20 mm off the ht lead and screw the cap on again. Check wiring loom especially around the central of the frame where it has a tendency to rub.