TOPIC:

So this morning when I went to the garage, I had a nice puddle of fuel under the tank (I had it off and sitting on a saw horse so I could check the static timing) The fuel tap STILL doesn't want to seal off properly and fully shut off when the bike is turned off, and the tap is in the ON position. I've recently replaced the diaphragm skin itself, and stretched the spring a little to tense up on the plunger. Today I took the tap off and replaced the o-ring on the tap, and the round rubber gasket that lets the fuel run to each setting. The tap STILL doesn't close off fully, so I'm thinking this is where my float bowl issue is coming from (not just having floats slightly too high). I'm considering a few options- one being to find a replacement used stock petcock and try that out, I like the simplicity of setting it to ON and not having to worry about shutting the tap off every time. Or I'm considering an aftermarket petcock now. What are people's experiences with stock units, as in have you had issues like mine? What else could I try to do to save my stock unit? And if you've run an aftermarket petcock, what do you think? I'm starting to think that this is why my cyl #2 is still running a bit rich as there is still a small amount of fuel making it past the diaphragm.

At idle, the F mark is just a hair to the left on both 1-4 and 2-3. I think this means my timing is slightly advanced at idle? When I set the idle to 3,000 RPM, the timing marks to the right of either 2-3 or 1-4 line up. Should I then adjust my low idle timing? It idles super smooth and doesn't hiccup on take off.

After letting the bike warm up, I went out for a 10km shake down ride, Gave it a few hard smacks on the throttle to check to see what response would be, did a few slow roll ons, and it all seems to be fine throughout the full range to redline. What I can say from the limited number of KM's so far is what a difference. Easier cold starts, snappier throttle response, and it picks up HARD throughout the rev range. I'm impressed so far.

Here's what the plugs look like at idle after being ridden for 10km. From left to right is cyl #1 to #4. One is ok, a little rich if anything. 2 is where I'm having either the leaky valve stem seal or the damn petcock issue over fueling the cylinder. 3 is pretty well right on the money- a nice coffee and cream tan. And 4 is a little lean it looks like . BUT #4 I'm running a Champion N3C plug on right now because I don't have 4 NGK B8ES to run. The N3C is the equivalent to the B8ES, but could be a little hotter of a plug, I'll be picking up 4 new NGK B8ES today and I'll do a shakedown with it later.



I'll post pictures up after I get some mileage on the new plugs. Any input with my issues is always appreciated.

Devin

WAIT!

NGK-B8ES is NOT the correct plug! It's temperature range is too cold for the KZ650. The correct spark plug is NGK-B7ES or ND-W22ES-U. The very first issue of the Kawasaki SHOP Manual (printed April, 1976) showed the wrong plug type. Kawasaki discovered the error and every later issue of the Kawasaki SERVICE Manual shows the correct plugs (see image below). I learned this the hard way having run the wrong plugs for years and then always wondering why they tended to foul. Ed

There's so many conflicting posts between which plugs to run on these bikes I just re-checked my manual as well and see that it is, in fact, a B7ES that I should be running. Thanks for the save, Ed! I'll pick a new set of B7ES up today then and give them a go. I'll have to do a few plug checks after to make sure I'm not running hot with this new plug. I'm sure it will work out just fine on my bike I'll also re-do my pilot tune after.

Ed- are you still running the stock petcock on your old girl? Have you had any issues like what I'm going through? I remember last year you were really helpful in getting some issues sorted out with the over fueling I was having issues with.

Devin

I'm still running the stock petcock, but the ones that came on the 1977 KZ650 models are manual, so they tend not to leak. The later, automatic ones, with the diaphragms tend to have problems. I suspect the problems with the diaphragms can be attributed to diaphragm age and ethanol fuel. Ed

Ah ok, so you're in the lucky end of the spectrum. That could be the case with things aging, but everything in the unit is fresh- the diaphragm, the o-rings, the round seal under the tap... I'm at a loss.

I have the same problem with my 1000. I haven't had time to get into it but I'm suspecting the diaphragm plunger has a sharp edge on it that is hanging up so the o-ring can't seat. I was planning to pull out out and polish a small radius on it so it can move freely.

I haven't been able to put it to practice but that's my theory.

GPZ- I like your thinking on this... Maybe it's worth me draining the tank again and seeing what I can find in that area, see if the plunger or-ring is maybe getting hung up. I'll have to make sure there's no gas junk anywhere and clean it up well again. It's just frustrating dealing with the same issue so many times and not fixing it fully... If you get to yours before me, please let me know what you find with it.

Alright, Wrench, this one is for you.

I have roughly 500km on the Dyna ignition now, and all I can say are positives with it. Incredibly easy cold starts even if I let the bike sit for 4-6 days. Choke on, touch the starter and she fires right up. It pulls WAY harder and smoother than with the points. overall, if you can afford to do the swap, do it! It's pretty easy to do (minus a few little tricky bits in interpreting the Dyna instructions).

I finally ordered in some B7ES plugs to see if that helps to clean the plugs up a bit. Nowhere in town had them, which I found kind of strange in a town of 110,000 people with tons of auto and small engine shops. So once the plugs get in, I'll be sure to get some mileage on them and do a good plug check.

One question- while cruising in fifth gear at roughly 1/4-1/3 throttle, the bike sounds like it "burbles" a bit. I'm not worried about it as it doesn't seem to affect performance. But I'm just wondering if anyone has an explanation? Remember it's running pods, 720cc kit, dyna jet stage 3 kit, 4-1 exhaust. I'm thinking it's a mix of the exhaust and pods. No biggie.

Devin

"Burbling" can mean rich. It could be on one carb.
Steve

Hey Devin,

Thanks for the update on your Dyna install & performance. I am definitely going that method soon after i get my bike up 'n running & bugs worked thru. New exhaust too.
What's the deal w/ your petcock? I just went thru a head scratcher on this too & finally pulled the trigger on a new petcock from Z1 that is made for zuki but fits kz & others here say works. Mine is not rebuildable due to tophat plunger style
But now i have every piece to rebuild the later O-ring style (even the spring) so if it helps, i've got ur back. Just lemme know.

Steve- if that's the case, I know which one it is... that damn petcock diaphragm is starting to give out on me again... any suggestions for a simple on/off tap? Something like a pine would be what i'm after.

Wrench- no worries, anything to help a fellow rider out yeah, that's a good call with the ignition and waiting a little. Best to be safe. As for that petcock... i'm ready to throw the thing out. I out a rebuild kit on it this spring, and changed every part over that the kit came with. Seemed to not let any fuel past for maybe 400km or so, but now it's starting to suck fuel again I feel. On cold starts, it kicks some unburnt fuel out the tail. Then like Steve was suggesting- low to mid range cruising the bike has a burble, which could be that petcock cylinder pulling fuel again... so i'm thinking I just say f#*k it and buy an on/off tap and call it a day. Could you possibly link me to the petcock you got? I'd like to see this one. I also need to get an in line fuel filter on the bike... every once in a while a jet catches something and the bike will stumble. One small bug worked out at a time... all I care about is that I have a sweet ride that no one else has in my town

I actually got some good comments about the bike when I went to my Kawi dealer who is partnered with a guy that does old British and Harley work. His mechanic and I had a good chat about the work I did and how much he loved it. Turns out her had a '73 Z1 but sold it! Then the owner came out and admired it and said the same thing- awesome work with the bike, definitely paid attention to detail and he really approves of it feedback like that is killer.

Thanks guys!

Devin

I depend on my reserve. On/off won't work for me. I don't like to push. That Susie petcock looks pretty good. I have two inline filters. Any dirt bike shop will have them.
Steve