Frank...

[Stachi]

Recently married a 1986 Force 125 block to my 1989 leg. Had block bored to accept Wiseco pistons /wrist pin sets. Timing is set on 28 BTDC . Carb idle mixture screws set at 1 1/4 out. Engine backfires at idle. Usually stalls engine. Much fun when docking in the wind. Compression is good in all cylinders. What the heck am I missing ?

 

[Frank Acampora]

If the ignition is known to be good, then backfiring, especially at idle is usually a lean condition. First step is to be certain the timing and carbs are synchronized. Check the idle speed. It needs to be 700-750 RPM in the water in forward gear. Then if that doesn't cure the problem the next step is to remove, inspect, disassemble, and clean the carbs.

 

[Stachi]

I just noticed this in one of your posts,.... you suggest removing plugs before adjusting timing. I have been adjusting timing with the plugs installed, plug wires grounded to block, defeat interlock switch, WOT control position. Is this my problem ?

 

[Frank Acampora]

With plugs in or with them out It really doesn't matter. Of course, the engine will spin a little faster with the plugs out but that won't affect the timing.

I do it with plugs out because it is easier to ground the plugs with my grounding jig. Less draw on the battery so less time I need to recharge before starting the engine.