Answer me this!

Totally baffled by my 1982 Gpz 750 problems - that are now magically cured.

After rebuilding carbs (stock jetting) and petcock I would get a bad stumble after 6 miles. Next time it would start up and run great until I hit 6 miles. Cleaned carbs again. Rebuilt petcock only to find the crappy K&L rebuild kit was a culprit. It would not stop fuel when on On or Res. I ended up putting in old parts and that seemed to fix that problem.

Anyway, today I thought I would give it another try. It started to run rough shortly after take off and after about 3-4 miles I had the throttle pinned and was only able to go about 35 MPH. I flipped petcock to prime to make sure it was getting fuel. Still ran like crap for another mile or two then I switched it over to Run. I was about 100 yards from home and it started to perk up. I decided to keep riding and went about 25 miles without any issues. Ran fairly strong - slight stumble off of idle. It took it home and opened the pilot air screws a 1/4 turn and took for another ride. That helped the off idle stumble. Now running great.

This is what I don't like (or understand). After 3 weeks of tinkering, cleaning, adjusting, etc., it is now running great. I kept doing the same thing over and over expecting different results (definition of crazy person) What suddenly happened? I am afraid to take for a long ride given that I don't know what magically fixed itself after 20 hours of tinkering, etc.,

Guessing it was a fuel problem all along, just don't know what magically got fixed.

I'm thinking coils.
Steve

Is the tank clean or is there some rust?

I'd replace the petcock with a new OEM version or rebuild it with OEM parts. Also, make sure your fuel cap is venting properly.

Not sure - I didn't touch the coils other than to check the plug wires. I checked the gas cap for venting. I just took it for another spin (3rd time today) and all is good. Starts up, smooth idle, nice power, no bogging down. Everything I thought it was before (dirty carbs, petcock, coils, plugs, etc.) and over the last 3 weeks of cleaning, checking, etc. it now runs great. Seriously, not sure what magically happened that made it start running fine today. I have invested a lot of time into this issue and was about to give up and turn it over to someone else when it just started running great.

I will go with factory petcock replacement parts. The K&L stuff was shit. And $35.

You scared her talking that way. :whistle:
Steve

tri650 wrote:
I will go with factory petcock replacement parts. The K&L stuff was shit. And $35.

I've had terrible issues with K&L brake system parts. It doesn't surprise me you had problems with the petcock parts.

BTW, I told Z1 Enterprises about one particular K&L master cylinder issue and they basically told me to stuff it. I still buy stuff from them but have not forgotten this.

I've found other suppliers too. :dry:
Steve

I will go back to the original place I bought it (through eBay) and let them know the situation. Probably won't get a refund but I'll feel better.

Mine ran similar when there was sediment in the tank that would go down and clog a jet them work it's way through.

But the flaky coil culprit is another prime candidate.... and NO, there is no way in hell you can bench test a flaky coil. It will read good then start arcing down after it warms up.

Guess how I learned that.

I wonder if the oringal problem was the vent in the gas cap being clogged.

A few weeks ago I checked this out - i opened the gas cap as I was riding. That didn't do anything. I also took everything apart on the gas cap. This is really baffling. After so many problems it just suddenly starts running fine. I am taking out today for an extended ride. I guess this will let me know if the problem is still solved.

One more thing. The plugs all look normal. I did notice before that the 4th plug was not registering any color - just bare metal. I messed around with the plug wires to make sure there was a connection. Now that plug is tan.

There are vents on the carbs too.
Steve