Help with JS550 engine issues
My son has a 89 550 which he picked up as a poor running project.
We did a top and bottom rebuild on the motor and just put on a new 44 SBN. The add on's are OP head, Coffman half pipe, West Coast waterbox, OP intake and the 44 SBN I mentioned. The compression is an equal 150 lbs. Let me say that I can't verify the accuracy of my compression gauge but I'm comfortable that they are equal.
Now that we believe it's ready for water we've taken it to the lake and started dialing in the carb. We're having a hard time getting it to tune and I've noticed when I pull the plugs I find the rear plug to be running much leaner than the front. The carb is at about 1 1/2 L and 1 5/8 H. I've tried much carb tuning with various settings but no luck. I'm fairly comfortable with carb tuning which makes me think it's not necessarily the carb. I'm now wondering if it could be a spark issue, whereas the front plug isn't firing as well which makes it appear as it's running richer when in fact it's just burning less.
Is this possible?
If it may be a spark issue how can the quality of the spark be tested? I'm electronically challenged so go easy on me.
Any other suggestions would be greatly appreciated. I would love to rule out some things so I can narrow down the problems.