No power above 6000 rpm

Hello all,
Yesterday, I drove my 82 Seca 750 to school in the heaviest rain you could imagine and then home without any problems. When I got home, I removed the valve cover to check the valve clearances(i commute 500+ miles a week on my bike and recently replaced the cylinderhead). They were all within specification, so I then performed a colortune setting of the pilot jets. I now have a misfire above 6000 rpm, the bike will continue to accelerate all the way to redline but it lacks power(like less power than it has at 2000rpm).
I suspect it may be the TCI because I used the starter to turn the bike over while performing the valve shim check without any of the plug wires attached to the plugs. I know its not the pilot jets because I drove to the store after the valve shims and before the pilot jet setting and the problem first manifested then.

I used my timing light to check the timing and noticed the timing advances from an idle until it reaches 4000 rpm, and then it ceases to advance anymore. Is this normal for the TCI or is this likely the culprit? Here is a video I made of the timing-
http://www.youtube.com/watch?v=SQVlB0ci ... e=youtu.be

Im also going to check the resistance on the coils but hopefully someone more familiar with the bike can chime in and give me some pointers.
Thanks in advance!

 

Ok so I checked the coils-
Primary resistance for both coils was 2.7~2.8 ohms
Secondary for coil 1-4 was 22k ohms
Secondary for coil 2-3 was 27k ohms

I checked secondary resistance through the two spark plug wire caps for each coil

 

How about let's back up and revisit what YOU did.

First off, valve clearances are checked with the motor stone cold. If it wasn't, check them again with it "overnight" cold.

Next, doing any ColorTuning would come after doing a running vacuum sync. How about put the pilots back where they were, or at 2.5 turns out, and check your sync. THEN ColorTune as needed.

As far as spark advance, I know the 550s are at full advance at 4000rpm, check your manual. I wouldn't be surprised if they were the same.

 

Ok, so the bike was running fine, I had previously replaced the cylinderhead, properly shimmed the valves, cleaned/rebuilt the carbs and synced the carbs a few months ago. I never got around to colortuning the engine, so yesterday I intended to perform this final task to smooth out the idle a bit.

I checked the valve clearances first just to make sure the valves were settled in because I have put a few thousand miles on the bike since the rebuild. They remain unchanged and within specification. I also assume the vacuum sync is still within spec but I broke my manometer so I didnt reperform the test yesterday.
After checking the valve clearances I had to drive the bike to the autoparts store to get a spark plug socket(someone else "cleaned" my things and threw away many tools). On this ride to the parts store I first noticed the misfire above 6000rpm.
After this, I performed the colortuning with my YICS tool and was able to lower the idle screw slightly as I had one rich and one lean cylinder.

The bike still has the lack of power above 6000 that started yesterday. The only two possible causes I can think of are the fact that I had to remove the fuel tank to access the valve cover and this might allowed a speck of dirt to fall into the fuel line; or the ignition system was damaged by my turning over the engine with the spark plug wires disconnected and the valve cover removed(though I have always done this practice in the past). Like I said before the bike was driven through a torrential rainstorm yesterday morning so that may also be a possible cause

I drained some fuel from each carb bowl just to be sure. I drove the bike onto the freeway and around the neighborhood to be sure, yet the problem hasnt resolved itself.

 

If the ignition was off when you turned the motor over with the plug wires disconnected it shouldn't have damaged anything.

Have you checked some basics, like the air filter? Did it get soaked in the rain?

Did a fuel or vacuum line get kinked in the process of the fuel tank R&R?

How do the plugs look, now? That might provide a clue.

 

My guess is the advance is ok, most engines don't need advance after 4000 rpms. Also if it is digital and works at all it would be working in it's full range. If it were analog it could be working in a limited part of it's range due to things like a capacitor going out of spec. Even that should be a gradual change. I have to admit the sympton looks like lack of advance.
I don't think it is in the pilot system. It it was off far enough to cause high speed trouble it shouldn't idle at all.
Even thou the resistance reads good on your coils you may have one breaking down. Often you can expose ignition coil and wire problems by having the engine lightly loaded in high gear and then increase the load and very slowly open the throttle. This works good going on the flat lightly loaded at low rpm and when the hill comes let the engine lug slightly and then open the throttle slowly. If it misses it is an ignition problem.
That was a bunch of words - hope it helps.

 

You were both right, I checked my service manual and it said full advance it attained at ~4000rpm.

The bike magically started running normal today, I suspect the fault was caused by the rain yesterday and that sitting overnight/today allowed it to dry out. I suppose its time for me to go around the bike with my big tube of dielectric grease to prevent this from happening in the future.

 

mmm dielectric grease

 

If this was caused by coils, the grease will not do a damn thing... dynacoils to the rescue

 

When you're Taching 6-Grand.
If you are in a WOT situation that does not hunt, bog or stall.
The first thing I'd check is the Throttle Cable Adjustment.