Engine doesn't start anymore....

I didn't get a chance to get new spark plugs but I did try everything you said with the old spark plugs. When I cranked the bike up, it sounded like there was combustion for a second but it didn't hold. That happened twice and after that nothing again. The sound of the engine cranking is different with and without the spark plugs installed. I hear a louder/deeper sound with the sparks on than without. I did notice a strong smell of something burning when I tried all of this. Does that make any sense?

I'll try and get some new spark plugs soon and retry the procedure.

Using starter fluid through otherwise dry carbs helps rule out possible issue of water-contaminated gasoline.

Failure to pull under load might result from the advancer unit being frozen in the idle position.

During the brief combustion with starter fluid, was there smoke from the exhaust?

Good Fortune!

I don't remember noticing much of any smoke. But like I mentioned, I did smell a strong burning odor so maybe it was from the exhaust; I'm not sure.

I'm having the same problem

how is the oil level?
when carbs overflow where does it go? on ground? in crankcase?

P21, I don't see anything on the ground and I do suspect that the oil level seems to have gone up. Can fuel contaminated oil cause such problems with start ups?

There is HOPE!! :laugh:

So I pulled out the rubber hoses from the carbs that connects to the airbox and with the throttle open and the choke disengaged, I sprayed a bit of a starter fluid in each of the carbs air inlets. I then engaged the choke (which I believe creates a negative pressure inside the engine). I then cranked the engine up and for the very first time in two weeks, the bike held combustion for a couple of seconds. It was actually running.

Needless to say, I'm thrilled. So my problems could have to do with the engine being flooded when my float levels were messed up. And I swear my oil level was below the max line on the oil window but it's now way past that which suggests that my oil is contaminated with fuel. I'll change the oil and retry everything with some fresh fuel and see how it goes. I'll keep you posted.

Thanks for your help Patton and everyone else. Keep those suggestions coming.

It's been crazy at work and I've not had a chance to work on my bike until this last weekend. So here's the update:

I spent a lot of time setting up the fuel level in the carbs. I realized that the trick was to wait long enough to look for leaks in each of the carbs. Once I was completely sure that all the fuel levels were correct and there were no overflows in any of them, I put them back on the bike. I then tried to crank the engine and though it was trying to start, it really did not get going. And while I tried to crank it up again and again, it backfired so loud as if a grenade had gone off. I remember reading somewhere here that this could happen if there was gas in the crankcase.

I then decided to drain all the oil since the oil level had gone up since I had filled it before. After all the oil had drained out, and after a quick pause, I noticed a sudden thin trickle of a clear liquid. And when I wet my finger and smelled it, it was pure gas. It took a couple of minutes to drain all of it out. I took out the spark plugs and noticed that they were totally wet.

So could it be that the gas that overflowed actually got down to the crankcase and into the oil reservoir somehow? Is that possible?

I'm going to wait for everything to dry out, refill the oil and put in new spark plugs before re-trying to start the bike again.

Bunty27 wrote: ...So could it be that the gas that overflowed actually got down to the crankcase and into the oil reservoir somehow? Is that possible?....

Yes, that's how it happens.

Where carb overflow circuits are properly functioning, gasoline rising too high inside the float bowl (for whatever reason) is supposed to escape through the overflow circuit and discharge from the overflow hoses exiting underneath the bike.

Where the overflow circuit isn't functioning, gasoline rising too high inside the float bowl (for whatever reason) keeps rising on up into the carb throat from where it flows toward the air box and also flows toward the engine.

The raw gasoline in the carb throat thereafter finds its way into the crankcase.

Good Fortune!

is your ignition timng right :dry:

Wooohoooo!!!!

Draining the oil (and the gas from the crankcase) and putting in some brand new spark plugs did the trick. My KZ550 just came up purring on the first try with ignition on. And with the sparkling clean carbs, the engine sounds beautiful. I did a few test rides around the neighborhood and it felt soooo good!

So to summarize, my float valves and float settings in the carbs were all messed up leading to a big overflows of gas into the engine which prevented proper ignition. Once I cleared the overflow and set the floats/levels in the carbs accurately, all the problems dissapeared. Even the earlier problem with revving issues under load have gone away since I rebuilt the carbs using new jets and I don't ever allow fuel to the carbs without it first going through an inline filter.

I'm really happy that all my hardwork has paid off. Many many thanks to Patton and everyone else who helped me through this issue.

dbc92s10, my bike has an electronic ignition that doesn't require tuning.