Possible coil failure?

[Beau-Kat]

Hey y'all.

My 2000 MMLTD (41,000 miles) accelerates just like it should under hard throttle going up through the gears. Seems to run great then.
However, it vibrates (misfires?) when I try to accelerate at higway speeds like 50, 60,70, etc.. Acts somewhat like if you tried to accelerate in 5th gear running 20 mph. Shakes.
I checked thoroughly and really don't believe it is anything in the drive train like the middle drive gear bearing or anything in the shaft or rear diff.
From what I see using my timing light, I think my front two coils, wires, plug caps, whatever are the culprit. Took them out (such a pain) and did the resistance test on each item. All checked well within tolerance.
Carbs are synched up perfectly.
I've been wrenching for 37 years and am looking for the simple. Don't want to buy coils if not needed.
Any body had any wires or wire insulation failures.
Any ideas?

Thanks.
Rusty

[Squeeze]

Hi, check the Vacuum Line to the Sensor for the Ignition for Leaks. After that, measure the Sensor. The Procedure should be described in the Workshop Manual.

For me it seems that the Ignition runs a little late. The TCI computes the Manifold Pressure to advanced Igniton, and that is not proper working.

[Beau-Kat]

Thanks for the response.
Are you referencing 1st or 2nd generation bikes? I have the 2nd generation and can't follow your response referring to the vacuum lline to the ignition sensor.
Rusty

[concours]

Hey y'all.

My 2000 MMLTD (41,000 miles) accelerates just like it should under hard throttle going up through the gears. Seems to run great then.
However, it vibrates (misfires?) when I try to accelerate at higway speeds like 50, 60,70, etc.. Acts somewhat like if you tried to accelerate in 5th gear running 20 mph. Shakes.
I checked thoroughly and really don't believe it is anything in the drive train like the middle drive gear bearing or anything in the shaft or rear diff.
From what I see using my timing light, I think my front two coils, wires, plug caps, whatever are the culprit. Took them out (such a pain) and did the resistance test on each item. All checked well within tolerance.
Carbs are synched up perfectly.
I've been wrenching for 37 years and am looking for the simple. Don't want to buy coils if not needed.
Any body had any wires or wire insulation failures.
Any ideas?

Thanks.
Rusty

E G G Z A C T L Y !!!!!!!! I got the same stuff, chugging, lugging sound, low power, poor economy (25 mpg) and I've fixed a lot of machinery over the years... heck, my WIFE noticed and asked if something was wrong..... but it comes and goes, miss mixes in with the V-4 uneven cadence... hard to say for sure...