GPz900 Performance Mods
bi...@cc.newcastle.edu.au
bottem end and mid range.
I don't mind scarificing some top end in order to achieve this.
First thought was to install a dyno jet kit and go up two teeth on the
rear sprocket.
Any other ideas, advice would be of great benefit.
Also looking for any pics, articles, urban myths regarding modified 900R's
Thanks
Bruce.
Ray Thomas
bi...@cc.newcastle.edu.au wrote in article
<1998Aug19...@cc.newcastle.edu.au>...
> Trying to make my 1985 GPz900R go a little quicker, especially in the
> bottem end and mid range.
>
> Any other ideas, advice would be of great benefit.
I don't want to be the bearer of bad news BUT - what model is your 900???
If it is the A2, then I would keep an eye on your camshafts, every A2 I
know of (including mine) has had severely pitted cam shaft lobes. It seems
that one pit happens (somehow) and then oil gets in the pit and can't be
compressed so pitting grows. I sent my cam off to some metal experts and
they couldn't find anything wrong, suggested it was insufficient oil to
head or faulty cam followers - I sold the bike at 13,000 kms (from new)
when the SECOND cam failed - Kawasaki didn't want to know!
Sorry to ruin your day
Regards Ray Thomas
bi...@cc.newcastle.edu.au
>
> I don't want to be the bearer of bad news BUT - what model is your 900???
>
> If it is the A2, then I would keep an eye on your camshafts, every A2 I
> know of (including mine) has had severely pitted cam shaft lobes. It seems
> that one pit happens (somehow) and then oil gets in the pit and can't be
> compressed so pitting grows. I sent my cam off to some metal experts and
> they couldn't find anything wrong, suggested it was insufficient oil to
> head or faulty cam followers - I sold the bike at 13,000 kms (from new)
> when the SECOND cam failed - Kawasaki didn't want to know!
>
> Sorry to ruin your day
>
> Regards Ray Thomas
clock. Have had it ever since, alway been slight pitting in one cam, never
seems to get any better. This bike has now got 80 000 kms on the clock, sat
still for seven years, not started for about 5 years. 10 000 kms ago the
bike came out of retirement. Has not missed a beat since, once i sorted the
carbies, I did nothing to the motor except adjust the tappets. Only replaced
a cam chain and tensioners years ago. I've been more than happy with that.
I have hear of the pitting problem. I understand that latter models had
larger oil feed line for the head, or larger oil orifices. Something like
that anyway.
My two cents worth
Bruce Donaldson
Kevin Gleeson
>In article <1998Aug19...@cc.newcastle.edu.au>, bi...@cc.newcastle.edu.au
>says...
>
><snip>
>
>>carbies, I did nothing to the motor except adjust the tappets. Only replaced
>
>BTW: if anyone's got the time to bother explaining, what exactly _are_
>tappets? I hear the word all the time, but have never had it defined...
>
>Craig Motbey
>1983 Honda CM250(The Heffalump)
Tappets are the things you hear breaking just as the Heffalump hits
13,000 rpm :-)
They are the little bit that rocks up and down and opens and closes
the valves, actuated by the camshaft. Hmmm my mechanical explanations
leave a little to be desired don't they?
Cheers
- - - - - - -
Kevin Gleeson
Imagine It
3D animation and graphics
Hobart, Tasmania, Australia
ke...@imagine-it.com.au
http://www.imagine-it.com.au
aus.motorcycles bike page
http://www.imagine-it.com.au/ausmoto
- - - - - - - - - - - - - - - - - -
Craig Motbey
Nick E
> I have hear of the pitting problem. I understand that latter models had
> larger oil feed line for the head, or larger oil orifices. Something like
> that anyway.
I think that A1's were retrofitted with a larger external oil feed to the
head, the later models had larger oilways cast into the heads themselves.
I had an A1 for 4 years, the longest I've ever kept a single bike. Great
machine. Very senstive to tyre choice and tyre pressures though. Maybe
something to do with the 16" front end? My current 'Blade is just as
tough to set up right at the front !
Have fun, Nick
Theo Bekkers
Kevin Gleeson wrote in message <35dc642b.166458640@wingate>...
>c.motbey....@unsw.edu.au (Craig Motbey) wrote:
>
>>BTW: if anyone's got the time to bother explaining, what exactly _are_
>>tappets? I hear the word all the time, but have never had it defined...
>>
>13,000 rpm :-)
>
>They are the little bit that rocks up and down and opens and closes
>the valves, actuated by the camshaft. Hmmm my mechanical explanations
>leave a little to be desired don't they?
I believe the name was originally given to cam followers on side valve
engines. On a side valve (this is for young people) the camshaft operates
the cam followers which pushed directly on the valves. In a modern engine
tappet clearance is used to refer to the gap designed into the valve train
which allows the valve to fully close under expected engine operating
temperatures. On a low cam, pushrod motor, such as my Guzzi, the valve train
consists of cam lobe, cam follower, push rod, rocker and valve. In such a
configuration there is a lot of expansion in the 'train' as the engine heats
up, the cylinder also gets longer as it heats. Valve clearance is calculated
to take this expansion into effect. On a Guzzi motor the clearance is
adjusted by a screw and locknut built into the rocker. Most, but not all,
overhead cam motors have shims which need to be changed to adjust the
clearance. My old Mercedes has an overhead cam and rockers with adjustment
being incorporated into the rocker pivot post. As an engine wears valves bed
into the valve seats, cam lobes wear, necessitating adjustment of the
'tappet' clearance.
Hope this helps
Theo
Sam Michaelson
> c.motbey....@unsw.edu.au (Craig Motbey) wrote:
>
> >BTW: if anyone's got the time to bother explaining, what exactly
> _are_
> >tappets? I hear the word all the time, but have never had it
> defined...
>
> Tappets are the things you hear breaking just as the Heffalump hits
> 13,000 rpm :-)
>
> They are the little bit that rocks up and down and opens and closes
> the valves, actuated by the camshaft. Hmmm my mechanical explanations
> leave a little to be desired don't they?
<digs out old Devo album>
'I hear a noise
And it's a tappet
The noise annoys
Must be a tappet'
(with apologies from Mr Smith, I'm sure I pinched that from one of his
columns)I think the problem is that there is a limited capacity for
waving your hands about on a ng whilst explaining something mechanical,
thereby limiting your capacity to impart information. It's true; with
one arm not working properly, my ability to communicate has been
compromised. Hmmmm, one of my distant relatives must've ridden a
Ducati.....
Sam (Boadicea's Mummy)
Peter Bernardo
>
>
>
> BTW: if anyone's got the time to bother explaining, what exactly _are_
> tappets? I hear the word all the time, but have never had it defined...
>
> 1983 Honda CM250(The Heffalump)
Craig the tappets are the actuating arms for the valves in most engines
they are pushed down by the cam lobes onto the valve and the valve
springs
return the valve to the closed position
peter
Geoff Hansford
>In article
>says...
>
><snip>
>
>>carbies, I did nothing to the motor except adjust the tappets. Only
replaced
>
>tappets? I hear the word all the time, but have never had it defined...
Tappets are those little kids you see doing tap dancing Pooh :-)
Geoff_San
(Running & Ducking)
Hamish Benjamin Alker-Jones
>In article <1998Aug19...@cc.newcastle.edu.au>, bi...@cc.newcastle.edu.au
>says...
Depending on what sort of motor you have, ie 2 or 4 stroke.
I always have trouble adjusting the tappets on 2 strokes, can anyone explain
that to me?....................
The tappets in a 4 stroke are moved by cam shaft which is either above the
engine or below it (Mod vehicles).
The cam is driven from the crank and as it turns it opens the valves, either
by 1 direct contact with the tappet, or 2 pushing a push rod which opens the
valves.
In the cas of the cam being above the tappets, ie over head cam, there are
less mechanical bits in comparison say with my old V8 that uses push rods to
actuate the valves as the cam is below the tappets.
There are several good sites on the net that have animated pages that show
all this technology in motion.
Adjusting the tappets, is a good way to ruin a weekend or vastly improve
it. Depending on whether you have "shims" that can be added to adjust the
height of the tappet with regards to the piston's TDC positioning.
Some tappets come in vastly coloured .....(wanders off looking for coffee)
Hope this helps.
Hang on, you wont ever see this as you have killfiled me? Oh well.
Cheers
Hamish
><snip>
>>carbies, I did nothing to the motor except adjust the tappets. Only replaced
>BTW: if anyone's got the time to bother explaining, what exactly _are_
>tappets? I hear the word all the time, but have never had it defined...
>Craig Motbey
>1983 Honda CM250(The Heffalump)
--
"Did you see the size of that chicken"?
Pro-Choice, ALWAYS
Clem Doherty
Hamish Benjamin Alker-Jones wrote in message ...
>
>I always have trouble adjusting the tappets on 2 strokes, can anyone
explain
>that to me?....................
>
read, especially the bit about cams being under the engine]
Hamish, it's time to take the "happy" medicine again....
(ducking and running)
Clem
Hamish Benjamin Alker-Jones
Oh, ha ha clever clogs, I suppose you think its funny to laugh with 3 million
people on the dole!!!!
Yes, thanks for pointing that out Clem, the cam is indeed not under the engine
but under the valves, ie below the valves, and above the crank.
Mate, its more than that, if only I could get some sleep!!!
Hamish
Ps youre still a bastard!!!!!!!
Clem Doherty
guessed; substance abuse)
>
I know the chicken one too! I just need more time!
Hamish Benjamin Alker-Jones wrote in message ...
Hamish Benjamin Alker-Jones
Clem, have you got it sussed yet?
Do you need a hint?
BTW, what the company standing on Canberra?
Catch ya
Hamish
--
Clem Doherty
it's gone further away! Put me outta my misery!!
Clem
Hamish Benjamin Alker-Jones
Ok Clem, I'm hoping you are gonna kick yer self.
It was Young Guns, preparing for battle in the traditional Indian way
communing with the spirits and all that. When one of then say before
vomitting "Did you see the size of that chicken?" in a rather distorted
voice. I think it was something he ate?! Psychotropics, wonderful things
when used with complete disregard for their powers.
Cheers
Hamish
BTW, how is the Home brewing going? Still keen?
Catch ya fella