Hmm... that noise isn't normal...

Hi,

My old faithfull GSX600F decided to start screaming tortured metal noises
at me.

Its done 40,000 miles of average abuse including 4 recent high-abuse track
days. It's a 1991 FM model.

It started by making the noise of squealing metal (as though metal is being
sheared from something spinning rapidly...) On soft acceleration it was ok,
but give it a bit more and then it started a horrific clunking noise coming
from the gearbox area. (Simlar sound as a chain slipping on a sprocket...)

Looking inside the sprocket cover I find nothing except a few freash
shavings of metal swarf - cant see where they came from, the sproket and
chain look fine. So, I'm guessing something inside the gearbox has given
up.

Looking in Haynes it seems the only way to get into the gearbox is to remove
engine from bike and, well, dismantle the whole engine. (Q1) Is this true?

From the symptoms I'm suspecting a sheared gear, creating masses of
fragments of metal and carnage everywhere inside the engine. (Q2) Is the
whole engine therefore likely to be a lost cause?

So I suspect an engine translplant will be the best way to fix it. (Q3) What
years of bikes have the same engine to allow a simple transfer?

(Q4) Is it a simple transfer for your average home mechanic or is it a
guaranteed nightmare?

Ta muchly for any help,
Steve

 

Phone round the bike breakers, and see if they have an engine to fit your
bike.

See what sort of money they are looking for, and then strip your original
engine, and see if its possible to repair for less money than a s/h engine
is going to cost.

Finally you need to look at the amount of money you are going to need to
spend, in comparsion to selling bike for spares and buying something else.

k

 

Get the engine slightly warm and drop out the oil into a clean basin to
see what appears. Look for fine metal swarf contamination in the oil and
big chunks of metal in the basin!

 

Stevie wrote

Like Hog says, before doing anything silly like replacing one stuffed
engine with another, a little diagnosis may save you some money. It may
not but you will learn something from it.

 

Phone round the bike breakers, and see if they have an engine to fit your

£130 for one of relatively unknown history.

The bike is quite a mess (bodge repaired after a high side), most items are
at least superficially damaged so minimal spares value. If however I can fix
the engine, it's worth plenty to me. (I've had the bike for 15 years so I
have a slightly illogical affection to it) ...and it saves me £2k or
whatever on a new bike...

 

my SZR660 suffered very similar symptoms. IIRC, it was the crank
bearing partially seizing.

 

Seriously - our ZX7R race bike ate its gearbx, and it didn't make much

OK, I've drained the oil. There was nothing major in there except a few
little bits of swarf, but the magnetic drain plug is *covered* in iron
fillings.
www.hpjw.co.uk/temp/gsxsumpplug.jpg

The chain and sprockets are fine, I'm 99% sure it's not that. But it really
did sound like a chain slipping on the front sprocket.

I can't explain the few bits of swarf inside the sproket cover though? Is
there a way through from the gearbox to inside the sprocket cover? That
reminds me, there was also a chewed up rubber ring type thing in there. A
bit like the two bits of rubber that go either side of the sprocket.

Other than taking the front sprocket off, what else can I investigate
easily?

Ta so far!

 

Well while the sump is drained get the side cover off the engine and
have a look at the clutch, damage there could cause some noise. Once you
have the plates out you can rotate the centre and feel for any roughness
turning over the gearbox in each gear in turn, drive chain off
obviously.

You are quite sure that the chain/sprockets and rear wheel bearings are
ok first?

 

Well while the sump is drained get the side cover off the engine and have

OK, I'll try that.

Pretty sure, I'll triple check though, as the chain and front sproket were
the last thing I had touched, which is a usual clue as to what's just gone
wrong! I had replaced the chain 100miles earlier - put onto old sprockets
(didn't have sprockets in stock and it was an emergency fix). The rear
sprocket looked as new, but the front one was showing a bit of wear so I
turned it over.

Another thought to put into the thinking pot: I did tighten the chain a
smidge more than I would normally, but not *too* much (IMHO!). What would be
destroyed if it were caused by a too tight chain?

 

<slinks down in slightly in chair with embarrassed feeling> Oh shit. Looks
like that's the front runner for now... I'll go and investigate.

And the possible consequences of such a failure are (including swarf in the
engine for starters... )

How easy is it to replace? Engine out job?

 

It's definitely the output shaft bearing. The outer seal is gone and the
ball bearings I can see are not evenly spaced. That explains the tortured
squealing noise. The clunking noise was caused by the sprocket hitting the
sprocket cover when under load. See pics.
www.hpjw.co.uk/temp/awpoo.htm

So what's the size of my task now...? Looking in Haynes I suspect it is a
major job - remove engine, remove clutch, seperate crankcase. All 3-spanner
jobs, but all look complicated and it's new territory for me :-(

What sort of bill from the friendly local mechanic am I looking at? :-(

Although it appears there is a bearing retainer (see pic). I don't suppose
my luck stretches as far as "I just need to take that off, whip the bearing
out, pop a new one in..."?

 

is "output shaft bearing" the same as "crank bearing"? If so,
amazingly, my suggestion for a mechanical related query was sort of
correct.

 

is "output shaft bearing" the same as "crank bearing"? If so,

Sorry Darsy, the crank bearing is on the end of the crankshaft, this is on
the end of the final gearbox shaft.

You get half a point though for getting 'bearing'. Ken and Hog have 3 points
each for being useful, however Champ is in the lead with 10 points. ;-)

 

aha - I thought it was a bit odd.

heh.

 

darsy wrote

Typewriters, monkeys and shit.

 

Well TBF I went out for lunch. As soon as you say over tight chain it's
"check the output shaft bearing".
As you tell us your not up for splitting the engine yourself there is a
bodge you *might* get away with. I'm blue skying here mindewe.

Pick out the remains of the seal, A circlip in a groove on the outer
race retains the bearing. I checked the fiche.
http://www.streits.com/fiche_section_detail.asp

Loosen the crankcase bolts with the exception of the cylinder head but
don't prise them apart to break the gasket surface.
Dig out the remains of the balls and the retaining ring.
Slide the inner ring of the bearing off the output shaft.
Dremel action could then take out the outer race by splitting it in two.
Heat the case and drift in a new bearing with *lots* of bearing fix on
the outer race (you won't be able to get a new circlip in obviously).
Tighten down the cases again.
Flush gearbox through with lots of paraffin, moving the gears around
from the clutch end.
Cheap oil in for 5 miles then flush again with some decent stuff.

It sounds hideous but such things have been accomplished before,
especially in the situation when the cost/hassle of an engine strip
outweighs the value of a machine. Andy Bonwick would be the expert but
he's a bit far from you.

 

If the engine is fucked, then yes, it is. As others suggest, have a good
look around for simple-to-repair culprits. Clutch bearing, for instance.
Is the sprocket secure on the output shaft? And so on.

I don't know whether you're up to an engine strip: the tone of your
question suggests not. In which case, simply pulling the engine apart
will be a waste of your time. And engine rebuilds are rarely cheap.

The early (pre-Slingshot, but ICBW) GSXR750 lumps fit into the GSX600F.
The Bandit 600 engine probably does, but I dunno.

 

Unlikely, although as Champ says, you have little to lose, and as Hog
says, you'll need to heat up the cases. And popping the bearing in the
deep freeze for an hour or two would also help.

Oh, and don't let any of the loose balls fall into the gearbox

 

In that case an 1100 engine should fit as well.
It sounds like an opportunity rather than a problem.

 

Um as I said the Fiche shows a retainer ring set into the case/outer
race hence it will need dremmeled out