Z250 Single

Motor Head - yeh thanks. I've come full circle with the float height - pretty sure if I didn't touch it to start with it would be fine, but at least I now know how to do it and can be sure its right.

I'm starting to think that the fouled spark plug is the culprit, as it makes most sense - that the bike doesn't start now after getting more fouled, rather than some other issues happening while it was running well? I bought 2 new plugs today but don't want to waste them, so have gone down to 125/68 main/secondary jet combo. I tried testing the power at the coils, but I literally got 0. I checked the battery and it was on 12.05 so it was pretty low as well, so that's sitting on the charger now. Hopefully tomorrow I can test it again with a full charge and see what I get, cos everything else can almost be discounted now - float levels are fine and carbs should be too? The fouling could still be related to the compression I'm getting, but we'll see.

Oh forgot - all of this could come down to another case of I didn't screw it tight enough - I checked my pilot jet and it was just sitting in its place very loosely, so that's been tightened up now.

So tomorrow we'll see.

Jo - what you're describing, needing to be super gentle on the throttle and it stalling when you rev it too hard or fast is exactly the issue, on top of the other stuff like smoke and fouling I'm getting. It's strange cos I imagine you are running the factory jets as you're running the air box set up? I would have imagined that you would get more reliability than that? The new muffler sounds exciting - that's something I want to look at down the track just cos mine is so rusted, I'm worried my exhaust will rust right through.

Also looking at Renthal Fatbars or something similar - looks like I need to go up in diameter to get something with a smaller sweep. You guys have any experiences with these?

As far a I know mi carb is untouched internally however one thing I did do before it speed stalling when revved was I replaced the petcock screen and washer and mi muffler actually did fall off by the looks of it I have the slip on part of the muffler but the megaphone is gone all thats left is a rusty ring where the pipe starts to flare out lol

Sham, you can replace the plug, or if you have a Butane or Propane torch, get it burned clean. Between the oil, and the loose pilot jet, it would be fouled. The jets need to be tight, but they can be overtightened. Sorry there is no spec for this. Once they seat, just give them a small bit of pressure tighter. Doesn't take to much, those slotted heads can be distorted quite easily. But as you found out, not enough, and it can become lose. Once lose the jet doesn't meter anymore.

Too tight intake valve clearance can cause backfire through the carb, when combustion within the cylinder partially escapes past the slightly open intake valve that isn't fully closing.

This condition worsens as the engine gets warmer.

Would assure that each intake valve clearance is within specs.

Good Fortune!

Woohoo - super happy. No more plug fouling! It wasn't the main or secondary jet, the valve clearance or anything like that - it was just a loose pilot jet!



Checked the power going to ignition coil as well and it was surprisingly good - battery was reading 12.5 or so, coil was reading at 12.4. Took a while to get a reading, grounding it to the frame was giving me readings of 0, but the front forks did the job.

Road around the driveway a bit and it was great - bike was very consistent, didn't want to stall or anything like before. No white smoke or brown/black smoke, even at the higher ends of the revs.

However, there are new issues - noticed I am getting a bit of an oil leak, and the cam chain tensioner casing (?) is cracked. Not sure when that happened, but it was definitely after I checked the crankshaft timing a couple months ago. Will have to see if I can get a new part. Does the crack indicate that there are other issues I need to be aware of?




But then I got greedy and thought I'd take off the centre stand seeing as I can't use it. Bad move. It turned out to be surprisingly difficult and I needed to remove the exhaust as well to slide the metal tube out to free the it. Ended up stripping the hex nut at the exhaust mount near the rear tire, dissembling the exhaust mount only to find the spring was too difficult to remove, tried to put it back together and realise the spring was then too strong and couldn't quiet get the mount back in place. On top of that, I cut the centre stand spring, so now it drags along the ground. So - no more riding until I can get it off. I may have to just grind off the thing. Bah.

But that aside, pretty happy. I can now focus on other aspects of this baby.

Thanks for all the help and encouragement.

Jo - if you're still having to watch your revs on the bike, you might have an issue with the jetting. Mine doesn't do that anymore. From what I think, my issue was that the more I revved, the richer my solution got and it pretty much choked out the engine, as the loose pilot jet wasn't doing much as Motor Head said. Maybe you have a similar issue?


Video of the bike idling.

Oh and for future reference, for anyone interested, I'm running a Keihin CV32 (stock carb for the z250 D) with a pod filter. Main jet = 125, replacing the 98. Secondary jet = 68, unchanged.

Sham,
You need to get another cam chain tensioner, that one that you have is no good now. You could possibly have quite a failure if you keep running it. Please replace that before you have a big issue.
I think, from looking at your photo, that the nut on top, which is a locating guide pin, was installed in-correctly. When you tightened it down, the housing broke. I don't know what your finances are, whether you would buy a good used unit or maybe an APE manual tensioner. But if the cam chain is not tensioned properly, to tight wears stuff out, and to lose it can jump time. The tensioner is still an active part from Kawasaki, it is used still on many ATV-Quads.
Glad the lose Pilot got the plug cleaned up. Give your crankcase a sniff, it may well be contaminated with fuel.

My issues with reving cleared with running and petcock cleaning had to blow out the proverbial cobwebs and now with original filter need to readjust pilot screw have a nice steady 3k rpm idle lol oh and while I am here gonna hijack ure thread for a moment and ask about the thought of draining oil filling crankcase with fuel and letting suit for a bit to clean up oil window

And one more thing not that it will help much now but on the center stand spring or any spring that pulls really if you put stand down just a little it creates.gaps in the spring then take pennies (or if you have giant australian pennies washers might work better ) once all.these spaces are filled when stand is raised spring will remain streched and pop right off for new install.bend spring insert on both sides saves alot of beer blood and mud trying to replace springs

Motor Head - thanks for the heads up. I"ll definitely shelve the bike for now and wait for parts. Have put in an order with z1, so I've added that to the list. Hate how long it takes to get here but...

Jo - the pennies trick sounds like a great tip - I'm still having difficulties putting the exhaust mount back to its original position (screwed onto the pillion footpeg) so I will try to stretch out the spring that way. I'm not sure about using petrol to clean up the oil gauge - from the microfiche it looks like the gauge can be removed. The part itself has been superseeded and is now under 920491577?

www.cmsnl.com/kawasaki-1980-kz250-d1-kz2...t/50887.html#results

If you take the clutch cover off, where the sight glass is, you can clean the glass. Brake clean spray, or maybe carb clean spray, and a Q-tip will get in there. May need to Soak it to soften the crud.

Ty Motor Head yea guess gona have to yank the starter and side cover oh well need to yank the slip on part of the muffler off anyway for a new slip on is it by chance possible to pull out the window and replace with cover still attached yup I am being lazy given the fight with muffler remnant and new tires is enough work lol