1983 GPz550/KZ550 won't start and I'm flummoxed!

loudhvx wrote: When you check for spark, make sure to check both plug wires on a given coil. One wire won't fire if the other one can't fire, and that situation can destroy the coil or the igniter.

I also did this tonight. Both spark plugs fire at the same time.

Forgot to mention, I replaced the spark plugs today gapped at .25. I will say, with the new plugs the spark doesn't look super strong and bright. Spark is there and I still got bit pretty hard when I was accidentally touching one during turnover.

loudhvx wrote: Is there any chance the cam timing is incorrect?

Beginning to think this may be the likeliest problem?

The thing is, you had pretty decent compression in one of the cylinders. I think if the timing was off by a tooth, that number would have been lower. Also, presumably it ran at some point in the condition it is in (re cam timing). I don't think the timing would have changed since it last run. Not that it can't happen (jumping a tooth while running), but it's pretty much unheard of in Kz550 street bikes.

When you check the plugs, do they come out wet with gasoline?

If so, maybe there is way too much gas. Then starting fluid will not help much.

Are you trying with no airbox and no filters? In that case, I've never been able to get the Tk26 to fire up a motor and continue running without using some sort of restricting plate in front of the intakes (when it's jetted for an airbox). I use a piece of cardboard to cover around 75% of all four intakes.

Are you trying with various throttle positions? Without the proper filter/box combo, you might have to play with the throttle to get it firing.

And BTW, for safety sake, never look into the carb throat area while trying to start. I've seen too many 3 foot flames shoot out of the carbs along with a bunch of gas. That'll leave a hell of a mark on your eyeballs. Also have something near by for putting out fires quickly. A really wet towel would be good to have laying around.

loudhvx wrote: The thing is, you had pretty decent compression in one of the cylinders. I think if the timing was off by a tooth, that number would have been lower. Also, presumably it ran at some point in the condition it is in (re cam timing). I don't think the timing would have changed since it last run. Not that it can't happen (jumping a tooth while running), but it's pretty much unheard of in Kz550 street bikes.

When you check the plugs, do they come out wet with gasoline?

If so, maybe there is way too much gas. Then starting fluid will not help much.

Are you trying with no airbox and no filters? In that case, I've never been able to get the Tk26 to fire up a motor and continue running without using some sort of restricting plate in front of the intakes (when it's jetted for an airbox). I use a piece of cardboard to cover around 75% of all four intakes.

Are you trying with various throttle positions? Without the proper filter/box combo, you might have to play with the throttle to get it firing.

And BTW, for safety sake, never look into the carb throat area while trying to start. I've seen too many 3 foot flames shoot out of the carbs along with a bunch of gas. That'll leave a hell of a mark on your eyeballs. Also have something near by for putting out fires quickly. A really wet towel would be good to have laying around.

yeah, that's another good point, if I were off on the cam timing I probably wouldn't have gotten good compression at all.

When I check the plugs they are not wet with gas,,,which is why I think it could be a fueling issue.

I am trying to start without an air box...I didn't think about the additional air flow. I'll try blocking them off.

I have been trying all kinds of throttle positions throughout the time I've been working on it and haven't gotten any real change based on position.

And thanks for the tip. I've seen some big poofs of flame myself! lol

Going to try the cardboard tonight and see if that helps!

ok so made a small bit of progress tonight.

First, I put some of those pod filters over the carb mouths and surprisingly, it did cough and sputter a little bit. But no start.

After that, I decided to look at the carb diagrams and see if I missed anything and it turns out I did...though I don't know that the low speed start up would require this jet, I realized I *did* miss removing and cleaning them. See below.


So I removed the jet from the #4 carb while it was still in the bike and it was clogged up. I've cleaned it out and will clean out the other 3 soon and see if that helps as well...

Baby steps. I'll get there.

If it's jetted normally, as in for an airbox, I would recommend cutting out a cardboard rectangle to use as a giant choke plate with the pods removed. I've been able to get Tk26 motors to start that way pretty reliably.

You cover the intakes most of the way as you start. Give it some throttle. When it starts you have to open the cardboard up a little to let in more air. It's a juggling act, but not too difficult. Obviously the motor tries to close the cardboard flap, so it has to be pretty strong and you have to have a pretty good grip on it.

But the jets do have to be clean and the fuel flow has to be good, of course.

loudhvx wrote: If it's jetted normally, as in for an airbox, I would recommend cutting out a cardboard rectangle to use as a giant choke plate with the pods removed. I've been able to get Tk26 motors to start that way pretty reliably.

You cover the intakes most of the way as you start. Give it some throttle. When it starts you have to open the cardboard up a little to let in more air. It's a juggling act, but not too difficult. Obviously the motor tries to close the cardboard flap, so it has to be pretty strong and you have to have a pretty good grip on it.

ok, good to go, I'll do that. I did try it last night but taped them on and of course that wasn't super successful. I hadn't really considering just holding it in place to manual manipulate it. I'm assuming we want to keep the tops clear so that the idle circuit gets airflow?

loudhvx wrote: But the jets do have to be clean and the fuel flow has to be good, of course.

So clearly I need to clean out those identified jets, but just out of curiosity, would those even be used/needed during startup/idle? They are connected to Main Jet #86.

The screw-in jet in line with the one you have circled (92062) should have been a #64 jet identified as 92063A. It screws into the carb body.

The main jet (92063), which is a #86 size, is in line with the main metering needle, and it screws into the jet holder 49122.

I'm not sure which, if any, is used during a normal startup. I haven't mapped the ports yet, like I did on the Tk22. The choke/enricher also allows for extra fuel flow so some of it will depend on that as well. But when you use the cardboard, and open the throttle, it will cause the slides to move up (yes leave the very top 10% to 25% or so open). When that happens, the mains will definitely be involved.

Good luck with fixing this bike. Your trial and tribulations highlight two things which are all too common...

1) being in too much of a hurry during the carb cleaning process. Taking your time and doing a complete carb cleaning the first time saves a lot of aggravation and actually speeds up the process. I strongly advocate fully disassembling the carbs, including unganging them, followed by soaking all the metal parts in carb dip or an ultrasonic. Upon reassembly be sure to check all the jet numbers and match them up against those in the FSM.

2) install the airbox and make sure it's properly sealed. The carbs are jetted lean from the factory and open carbs typically won't even allow the engine to fire.