The plot thickens.....

For those who came in late, my bike overheated at the GP on subday, and
suddenly started maling loud rattling and chuffing noises.

RACV recovered it to BM Ringwood.

Had a call this evening from Chris at Ringwood BM.

They tried turning the motor over by hand, and it went smoothly,
He queried how long I had ben having problems and who had set the
valves, since both valves on the right cylinder appear to have about 2.5
mm clearance, while the left are OK, if just a tad tight. Apart from
the right hand throttle cables being a bit loose, there doesn't appear
to be anything wrong with the bike. (They haven't lifted the heads off
yet, just made an initial investigation.)

The thing is, this problem came on very suddenly - within a single
revolution of the motor.

So what is it that can go suddenly wrong that will give a loud rattling
noise (and a chuff chuff) and make *both* exhaust the and inlet valves
open up by so much on one side only.

I can't imagine both cam followers collapsing together, or two out of
the four cam lobes. Pushrods move nicely. and the rocker gear seems to
be fine - just out of whack.

The bike was idling nicely right up until it made it's sudden change.
The day before it had been pulling strongly and smoothly as I negotiated
some of the more interesting hills of south Gippsland two up at a
<cough> brisk pace. I know it was running smoothly.

Ideas?

Moike

 

Both push rods collapse?

Boxer

 

In aus.motorcycles on Sat, 22 Oct 2005 00:37:09 +1000

When it happened to me, it was one valve only, and it was a pushrod
collapsing at the cam end.

Seems unlikely that both would go at the same time, but it's not
impossible.

Zebee

 

One stud pulling could increase the load on the one next to it, and
that could pull too?

Can't think of anything else they share, except the camshaft!

Ask on the Airheads list ...

-----sharks

 

Its called Character....

 

It's a super-bike and as such has super-powers.

Nev..
'03 ZX12R

 

If it's doing it on both cylinders and started at the same time then it has
to be one thing that drives/affects the two cylinders. Maybe the cham
chain(s) have jumped one tooth? I'm not too familiar with the valve
actuation on those bikes. They have a small chain off the crank to camshaft
and then pushrods up into the head?

 

~
I think it's actually called "longevity".

Hondas are getting it now too; I hear some VFRs are actually doing
30-40,000 before breaking down....

 

Why don't you go and getfugged! (tm)

mine got 29k out of the regulator before i replaced it.

Johno


Beer? bandage?

 

John said....

Oi. I got 230 km out of mine before I had to replace the petrol in the
tank.

 

Buy johno only rides to his letterbox and back.

 

Have the barrel/head retaining studs pulled out of the block? That
happened to me with a VW beetle motor a few years ago, but it also
caused a massive oil leak (which you haven't mentioned, so I assume
wasn't happening?)


BTH

 

Good thought that is BT cause it does happen to airhead boxers, usually only
one stud is prone to it though, not all four.

Al

 

Yeah. Thought about that, and eliminated it for the same reason. The
bike is apparently running, but seems "really out of tune" according to
the normally knowledgable mechanic (a specialist in old boxers).

It was running *really* well the day before on a 'spirited' two-up run
through the hills, and was still running quite nicely right up until it
suddenly started sounding ill. ("Suddenly" - as in within a revolution.)

My best guess at the moment is that a cam follower has let go, and
somehow caused another to give up in sympathy - pergaps due to a
bouncing fragment - but I don't know enough about the precise
arrangement of that part of the bike to know whether that's possible.

Oh well, I'll just have to wait and see what monday brings....

Moike

 

Thought about that, and looked in the Book of Lies, but I can't
see how it'd manage it. Better get the spanners out!

-----sharks

 

Book of lies Sharks? Would that mean that you're not a big fan of BM
manuals?

Stu

 

It's UKRM'ism that's been bought to ausmoto - The "haynes book of lies"
referring to the dubious accuracy of the Haynes aftermarket workshop manuals

JL

 

In aus.motorcycles on Mon, 24 Oct 2005 13:07:36 +1000

I dunno, we were calling them that long before I found usenet...

I suppose because they've been "differently accurate" for a long time.

Zebee

 

Oh, ok, well it's the oldest reference I've heard of as "book of lies".

Pre my getting on the internet(1995) the most common phrases I'd heard
regarding it were variants of "useless piece of crap" "not even good for
toilet paper" and "why the **** did I waste my money on this bloody thing"

Maybe I wasn't talking to sufficiently arty enough home mechanics

JL

 

Hmmm, I've always found them pretty good, despite the name .
The 'lies' are generally omissions ... No worse than the factory
workshop manuals in that regard, anyway.

-----sharks