I shall start at the beginning.

I picked this CBR600F2 (1992) about two weeks ago. This F2 had been laid down at least two times. The frame was unscaved but I was given the after market fiberglass (FUBAR) fairings with the bike.

As far as mechanical. It looked, sounded and ran like a champ. It has approx. 32K on it but apparently rebuilt approx. 6K ago according to the previous owner.

With the fairings already off and fancying the "steetfighter" look, I figured it being the cheaper route that sill fulfilled my desires on two wheels.

I rode it for three days to and from work, naked w/ the headlamp zip tied on. Everything worked fine. It was a little bit loud for my tastes with the D&D race pipe, but it was growing on me each minute I rode it.

Anywho, I stripped her down and, seat and tank come off and started assessing the situation of tucking wires. Utilizing what I learned from my dad, who was an RF Tech and my previous electronics experiences with building circuit boards and installing radio systems for the department of interior for the state of NM, I started shortening the harness to fit into the lower portion just in front of the intake tubes. It had been awhile sense I had done this kind of work, but eh, it's like riding a bike.

In the process I wired in the aftermarket gauge with tach, speedo, and indicator lights. I tested thing a couple of times as I went. Started it up a with the fuel that was still in the lines and made sure everything was working as it should as I went.

Well, I got done, tucked the wires and started it up. Sweet! started riding around the lot at my work (where I had done my project) everything seems good, seems completely normal. I hit the road and within seconds I new something was wrong, It wouldn't rev over 6 grand. I went around the block going all the way through 3rd gear, and pulled into the lot. Sitting at idle, it would rev all the way to approx. 13k, no problem.

I thought it might be restricted airflow so I made several attempts, one with the two tubes of the air box removed, one the cover of the air box removed completely, and then with no filter. I went with no filter because I had cleaned the K&N filter that it came with and thought I might have put too much oil on it. All tests came out the same, didn't want to rev over 6k.

I check the interweb for a solution and found some of the same issues of not revving but they seems related to the carbs and this seems extremely unlikely because it was working just fine 3 days before I took the damn thing apart but sprayed it with carb leaner anyway..

My next conclusion was that I had wired something erroneously. (when I picked up the bike the Black/Blue wire that is the positive for the fan was not connected). Upon initial inspection I found that the ground that went the the fan was hot! 12 volts. ZWTFBBQ!? The bike wouldn't start without it being grounded, even though it's "hot". Testing the continuity found that all the ground everywhere, as they are all connected anyway, are all "hot". Myself and my totally awesome Asian friend who has superior brain power than myself, went over the whole harness that I had modified and then some at least three times and found only one error. I had switched the brown/black wires and be black wires from the right hand starter/kill switch. Even after rewiring them correctly, there was no diff. (took it around the block at no avail).

The only thing I can logically put together right now is that, at some point I fried the regulator/rectifier and it has caused the ground to be charged with 12 volts! and that the reason it won't rev over 6k is because at this RPM the stator is generating enough voltage to "cancel out" the ground, or 12v, once it reaches 6k RPM, whichever, I don't know my head hurts.

Please help!!!

 

If you think its the rectifier, it would be fairly simple to just unplug it and give it another go. The bike runs off the battery anyway. You would have a little bit of time before your battery died to see if it is the rectifier.

I've never heard of this happening before, unless a bike is starving for gas, or getting too much air. Keep in mind that an engine free revving has no load and can rev to the limit without much gas. Under load, it takes alot more gas.

does it backfire at all, or does it just not go over that rpm? If it doesnt backfire, I'd suspect its just starving for gas.

have your battery checked as well. It may shorted internally. Its a simple test that can be done at most autoparts stores like autozone and its free. A load test will confirm if its good or not.

 

I just disconnected the R/R and tested the lead, still hot.
Tested the battery, it's good.
The only thing I did along the lines of the neutral safety or kickstand switch was wire the indicator lights.

So I was talking to one of my friends this morning who is a Nissan Master tech. Now I feel like a moron. Going back to the basics of electronics, he said "of course it has 12 volts going to it until it's grounded. You haven't completed the circuit". Though this is extremely basic, it makes my head hurt. and this is why the bike won't work until I ground it.

So it looks like my problem isn't in the wiring.

I just don't get it sense it was working just find 3 days ago. I'm going to try and clean out the fuel cut off switch assembly on the bottom of the tank. Perhaps some gunk got knocked loose when I moved the tank around.

 

I know on the F3 that once you get above a certain speed, there is an air valve that switches over to a high speed. It works off of the speedo. I don't know if this setup was used on the F2 though.

 

Just checked the book for that, looking at the wiring diagrams

the 91-94 has a mechanical speed sensor and I can't find any switch that seems related to switching once at speed.

The 95-98 does show an electrical speedo and sensor so it appears that I have escaped that potential issue.

 

In any electrical circuit be-it 220v,110v or 12v etc. a ground wire will have voltage if it is not grounded AND the other end of it is connected to the fixture with power on the opposite end of the fixture (positive wire). for example, if you hook up the positive wire of a light socket to 12v and there is a bulb in the socket and the ground wire is not touching anything you Will have 12v at the ground wire. the filament in the bulb acts as a wire and carries the voltage if the circuit is not complete. If it is a motor, same thing, the winding in the motor act like a wire and allows the voltage to travel through and "out " the ground wire. ONLY if the ground is not connected to ground. It sounds like the ground wire you are talking about may also ground some other things on the bike. Any chance the throttle cable is binding or restricted? Possibly by a wire tie from your previous work? It would rev to limit in neutral but may not allow you to twist the throttle all the way when in gear as the throttle has to turn more to get rpm's up while riding.

 

Gotcha ya on the ground, that's what I learned from my tech friend. So it's properly grounded now and still no change, won't rev over 6 grand.

Last night I hooked up the fuel tank next to the bike with some longer hoses and ran it so that I could inspect the carbs while it was running. I had one of my other friends, who is more familiar with the mechanics of a bike, look at it too. nothing seems normal. Fuel is even on all carbs all the way through throttle and nothing sticking.

I took off the fuel shutoff switch/fuel **** and broke it down. Cleaned it with carb cleaner and blasted it out with the air compressor. Also blasted air into the main fuel line that feeds the engine. Put it all together, took it around the block and... the problem still remains.

 

just verified, there is no restriction on the throttle cable.

Also just called my local Honda bike shop and they have never heard of such a problem.

 

I just pulled the carburetors off and pulled the needles out and blasted everything with carb cleaner. All the needles look pristine. Put it back together, warmed it up. Moment of truth: Hit the road and... and... 6k max.

I'm going to go drink a beer for now. I'm depressed at this point.