Unfortunately I narrowly missed out on a cheap parts bike recently for my 83 GS650GL and now am tempted to ante up for a GS650 shaftie ignitor (32900-34210). I've serviced the carbs to death (five times out total!) and then determined that failure to rev freely (above about 3-4K) is definitely ignition. I proved this by unhooking the HT lead off of number 4 cylinder plug, inserting a fifth plug into this HT wire, and watching this extra plug fire in low light with my sharp-eyed son. Didn't even need his eyes to see what happens. So while running on three cyls, watching number 4 plug wire firing a grounded plug, bright strong blue spark at low RPM changes to feeble more orangy spark at higher RPM. I checked the pickup coil resistance is right in midrange of spec. I'm convinced the carbs are perfect; this thing really wants to rev, in fact will give a couple full great revs before bogging with the symptom I described. I knew it wasn't the ignition coils but since I had a brand new in package aftermarket set on hand for my 850 I changed them anyway. Exactly same symptom. So I'm about to pony up for an ignitor but wanted to be sure it's not like some Hondas where there is a separate pickup for the advanced timing that I should be considering? The other thing I'll try to do is to heat the pickup for testing, since I do get a brief excellent rev out of it before failing.