Waddaya supposed to do with cases, again?

....or, the saga of the thirsty ZX9 takes a turn for the worse...

Brief summary: I picked up a crashed '98-model ZX9 last New Year's Eve
and slowly got it back to a stage resembling a bike again. I got it
registered just before the GP and took it down for the trip, where, out
the front of Geoff and Jodie's, a few people had chuckles over its
clattery idle.

Ever since I first got it, the thing's been ridiculously thirsty; like,
12km/L thirsty, where it should be getting 16-17km/L. Playing with the
needle positions and pilot screws helped a teensy bit. Checking the
valve clearances showed them all to be on the tight side of, but still
within, spec.

Today, trying to figure out why the bike was starting to get
ever-rougher at idle while still running strong at higher revs, I had
another go at them, and, when the time came to hand-crank it to bring
another cylinder to base circle on the cams, the back wheel put up a bit
more of a fight than last time.

Pull the plugs out (hmm, they're a bit on the grey side now; strange for
a bike that's still chugging just as much fuel as ever), try again; no
change, the wheel's just as hard to turn as before... uh-oh. Looks like
I'm about to learn how to use Plasti-gage.

Doesn't mean I'm now any less perplexed than before... as far as I
understood it, if big-ends start to go, the bike sounds like WWIII at
idle and gets worse if you actually try to ride it. This thing clunks
and jerks until about 4,000rpm then smooths out...

Insert your putdown here----->

 

Dunno how big end as compared to rod end goes, but if it was a rod end you'd
definately know it. Smoother down low, then clunks a hell of a lot up top,
and you lose a ton of power as well. Greyish plugs? They should be a
brownish colour right? Something else going on here we don't know about?

Cam

 

I was always under the impression that a shot big end creates a low
thumping sound and big vibes, both of which get worse with revs.

What my bike does is clatter and vibe a bit at idle, judder at low
speed, and smooth out at higher revs, with no apparent loss of power...
and it uses 50% more fuel than it should in doing so.

Greyish-brown, like just on the lean side of just right.

In all likelihood. I've never come across this set of symptoms, either
in anything I've had, or in anything I've read in an "Ummm, help,
please, guys" thread on a forum...

 

Silly question: What did the previous owner do to it? Any PHx?

Original head, cams, pistons etc or weird brew? No chance that the tank is
leaking from a damaged thread on the carby that only happens when the bike
is running (sorta like a vac leak)?

No aftermarket advancer that needs the air filter removed, or a super
special one from Dunstgurber that is encouraging things?

No blocked/removed trumpets that really need to be there?

It is a Kwakka, so maybe you need Fred to exorcise it?

Hammo

 

Mm. if its running a little hot as well then ignition timing , it almost
could be cam timing off ?
if you know someone who knows how to use a DTI and a degree wheel , I
wonder if its jetted for a different pipe and you got tsomthing else .
Does it improve with premium fuel ? might be worth changing the fuel
over to the best you can find and then a plug reading although unleaded
doesnt read the same .
good luck as its tough to guess on teh net . ( you tried with out air
filters ?)

 

From the looks of it, he lobbed it at Eastern Creek, then, while it sat
under his parents' carport for a year, thought he'd play with the
carbs... when I first flipped them over, the pilot screws were set to
between 3/4 and one full turn too rich; it was getting 10km/L then and
would bog below 5500rpm, but it wasn't making such a mechanical racket.

The fuel consumption issue can wait. My big worry now is the massive
internal resistance from the motor (which itself makes for a plausible
cause of the excess fuel consumption). The ZX6, I can hand-crank with
the rear wheel easily enough without taking the plugs out (12.8:1
compression). With the plugs *out*, the only way I could get the ZX9 to
move was to grab hold of the grabrails and stomp down on the rear tyre
with all my Ausmoto-normal bodyweight.

That just ain't right.

I know the thud-thud-thud sound a motor makes just before it's about to
put a rod through the cases; this is different. It's a real clatter,
like a very sloppy tappet, except the ZX-9R-C runs direct-actuation
valves, the noise seems to be coming from lower down in the motor and a
vibration at the same frequency as the clatter can be felt right through
the bike when it's happening.

The most perplexing thing is that, even at a standstill, it goes away
above about 4,000rpm, like whatever's flapping around starts spinning so
fast that it becomes stable.

 

Nup. Three bars (out of eight) on the temp gauge in normal running,
dropping to two bars in the cold of the high country and rising to four
after extended idling at red lights in Melbourne.

I only run it on premium, and now have a round trip to the GP worth of
data; over 2200km, the best it got was 14km/L droning south between
Canberra and Jindabyne, and the worst was 11km/L flogging it between
Cann River and Cooma on the way back. 12.5km/L would've been about the
average, and it wasn't making as much mechanical noise as it is now.

Like I told Hambone, right now, priority one is to figure why the hell
it's so hard to crank over and why it's making such a racket at low
revs, but smooths out higher up...

 

Ah, so have the epa plugs been drilled (if they have them on this'un)?

What was the damage to the bike and have you string lined it (re: turning it
over)?

Hmm. That has always been the way it responds? The clutch is light and
responsive and does all the acceptable rattling on release?

It stays stationary too? It doesn't murmur at all?
What filter is on it?

H

 

Well if its still tight when the plugs are out then you have a chain or
something stretched / dropped a tooth etc.. you may need to seek help ?
in person
if its not tight sans plugs then I still siggest can timing .I had a
trumpy in 69 that was a little warm but importantly idled like a pig and
was flat below 2500 , exhause cam was 1 tooth out .. ( thats about 20
deg ?) but it would still do over 110 MPH ... got some help and with the
tooth reset ( my fault when I put the bonnie cams in) went faster and
idled perfectly with a healthy lope and quitened down a lot.
I expect its a different isue but you need to do the basics.. start
with the long handled screwdriver and go from there ( I wonder if the
cam chain tensioner is stuffed)
Foulcans have this problem when the tensioner dies and the cam chain
slaps to death
good luck

 

Bizarre suggestion of the day: is there any way to check the state
of the camchain? A really fucked up camchain can make odd noises
at low RPM and go away at high RPM, and can drag on all sorts of
things, and will stuff the valve timing and thus efficiency up.

If the bigends are going, I'd expect to see metal shit in the oil.

-----sharks

 

Coming in late and haven't read all the thread but yes that's what it
sounds like, a very dull knocking noise.

I'd suggest exhaust side cam chain problems - exhaust because the
mixture is OK, high fuel consumption from having to waste energy turning
over something that doesn't want to turn and /or having to force the gas
out an too small orifice because the exhaust valves aren't opening properly.

JL

 

Indeed, and it's not clattery.

JL

 

No, no, you've added value:

Wild Arsed Guess + Wild Arsed Guess > Wild Arsed Guess.

-----sharks .

 

And what hand does a pair of W.A.G's beat ?

Bastard. It was a carefully thought about (for at least 3 nano seconds)
"Considered opinion"

JL
(I'm starting to get really good at this procrastination thing - ya
reckon there's a job in it ? Public service perhaps ?)

 

Probably should update this...

....hand-cranking the motor with a ratchet on the end of the crankshaft
turned up no more resistance than normal.

Going cross-eyed with a torch, showed that the cams are in phase, at
least according to the camwheel and ignition trigger markings.

Tried the camchain tensioner next. Popped the spring out first, then the
tensioner retaining bolts and, unlike every other time I've taken one
off, the tension on the chain didn't crack the seal between the
tensioner body and the head... hmmm.

Showing the tensioner to a Kwaka mech later on resulted in his
muttering, "Yeh, the spring_is_a bit weak." His advice; advance the
tensioner by hand before reinstalling it.

Okies...

Paranoia got the better of me, so I'm replacing the borderline among the
shims, and getting a set of what I'll know are stock main jets. If that
doesn't fix it, I'll start fielding offers of treefiddy annakikinnanuts
for it.

 

So if I've got this straight, there's huge resistance to turning it over
via the back wheel, and no particular resistance to turning it over via
the crank ?

Errm, 'scuse me for commenting on the bleedin' obvious, but perhaps you
should investigate further the connection between said wheel and the
crankshaft....

JL

 

Hey! I was going to say that!

-----sharks

 

Addendum: should've mentioned I tried it both in neutral and in gear.
With the bike in gear, I had to look to see whether the back wheel was
turning, that's how imperceptible the difference in resistance was.

Beats the scheisse out of me even more now than it did before...

 

Hmmm. So it was previously near impossible to turn over, and now it
turns over freely...

Time to split the cases. Something broke between now and then.

JL

 

Hang on, just re-read your posting, do you mean it was impossible to
turn the rear wheel both in neutral and gear, or that it is NOW easy to
turn it over when previously it was difficult.

If the first then your problem isn't in the engine it's in the gearbox,
no ? If it's in neutral and it's hard to turn there's either a chain or
gearbox issue.

If the second, then something has changed between then and now, if it
was only you extracting the camchain tensioner and replacing it, then
maybe something there was the problem, otherwise something has broken...

JL