Carb or coil/plugwire problem?

I have a 1982 Gpz750 (KZ750). And i was have problems with it before and someone on this site told me to clean the carbs and change the plugs. I did that and now the bike runs better it fix the problem of fuel coming out of the exaust but now, i ride the bike to work and at the exact same point in the trip everyday it starts to bog and it wants to stall i pull in the clutch and rev it a bit and it works again kind of runs rough though.

I also noticed that it doesn't like to rev much higher than 4000 rpm for the first bit after i start it, once i get on the highway it accelerates slowly but the rpms do get over 4000. the other night i took it on a short ride and road it kind of hard trying to get lots of fuel going through the carbs to clean them out and the bike ended up stalling on me and wouldn't start for a bit. it finally started after i played with the choke and i was able to ride it home. I'm scared to take it out again.

Would this be a carb problem or could it be my coil is overheating or something and not putting out spark. or could it be faulty plug wires?

Hi Kawi,

It's possible that the vent in the gas tank isn't working. After riding for a while the fuel flow is restricted by the vacuum present in the tank.

Next time it happens try opening the fuel fill and see if it doesn't start running better right away.

KZCSI

kawi750 wrote:

...Would this be a carb problem or could it be my coil is overheating or something and not putting out spark. or could it be faulty plug wires?

Definitely do what KZCSI says about the fuel cap.

But also I like where you're going with your thinking about heat. There are two things that commonly are affected by heat in the way you describe: coil (like you said), and valve clearance.

The way you described the same spot in your commute it bogs down... that *exact* same thing happened to me on one of my 750s, day after day. I checked the valves, and one exhaust valve was only *just* tighter than minimum spec, leading me to think it wasn't the cause, but I got a shim and did it anyway, setting it high within spec. It turns out that it *was* the cause.... bike runs near-perfect ever since...