FS: MZ ETZ 300

Quite how long various bits last, gods only knows, but it does sound a hoot.
Perhaps they'll be the next big thing after monkey bikes become passe...;-)

Jon H.

 

If i can get my new book of Barclaycard cheques in the next couple of days
I'll race you too it. Trouble is, if it's gone, I'll prolly start sniffing
round your GN too. Now there's a bike i really would look silly on...

JH

 

GN250?

Horrible.

Strangely, I quite fancy a TU250X, mind...

 

Prolly the 300 bottom end is stronger/more modern than, say, a nold 125.

Bigger, see?

--
Platypus - Faster Than Champ
VN800 Drifter, R80RT
DIAABTCOD#2 GPOTHUF#19
BOTAFOS#6 BOTAFOT#89 FTB#11
BOB#1 SBS#35 ANORAK#18 TWA#15

 

I can accept that.

Bigger = Better, very true

Just curious about the cc sizes.

"When I was a lad" your regular two-stroke engine sizes were 50cc
(mopeds) 100cc & 125cc commuter thingies. Suzuki's GT185cc, Yamaha's
RD200 were the next step up. Then everyone did 250cc and 350cc, until
the KH400 and RD400 came along. etc, etc.

Admitedly MZ (and CZ's) were perhaps a law unto themselves, so they
developed the next optimal engine size - as they saw fit - of 300cc.
But a 404cc conversion shirley must be from some racing series or
something?

 

but Simon, it was made in a Communist country...

 

There are a number of aftermarket 300cc kits available, it's also
possible to bore out a 250cc to the limit and slap in a 300cc piston.
It's not one of those. Hence the 'genuine' reference.

As to the 404cc, I suspect that's the biggest readily available other
make piston that works with the ports. When the bore is taken out to
accommodate, it equates to 404cc.

Although I'm /sure/ I once saw a GDR plod bike marked as 400cc. Probably
didn't...

The MZ racing, IIRC, is strictly 250 with little in the way of chassis
modifications. In race trim they can embarrass a lot of bikes.

In non-race trim they embarrass a lot of owners.

 

Rounding error.

GT185=182cc
RD200=195cc
RD250=247cc
RD250LC=249cc
RD350=349cc
RD350LC=347cc
KH400=399cc
RD400=398cc

MZ125=123cc
MZ250=243cc
MZ301=300cc

However, the 404 is a conversion, not a model designation from the
factory's marketing department. So it will, at a guess, have the 301's
stroke, and a stupidly oversize piston. I don't know the 301's bore and
stroke, but at a guess, the dimensions will be fairly close to square.
So:

300cc = 74mm x 70mm
404cc = 86mm x 70mm

86mm is fucking big for a 2-stroke. An 80mm stroke would give

300cc = 69mm x 80mm
404cc = 80mm x 80mm

Even with a long-stroke engine, it's a big piston, and a shitload of
metal off the inside of the barrel. Hmmm.

ISTR Jawa having a 400cc 2-stroke single in a crosser.

--
Platypus - Faster Than Champ
VN800 Drifter, R80RT
DIAABTCOD#2 GPOTHUF#19
BOTAFOS#6 BOTAFOT#89 FTB#11
BOB#1 SBS#35 ANORAK#18 TWA#15

 

'tis tidy, innit. If I had 300 notes to spare I could buy it for me Mother,
who keeps making noises about wanting a bike again (used to be summat of a
biker in her yoof, had a 1000 vincent among several others)

 

Damn good front brake by non MZ standards of good. IIRC it was a brembo iron
rotor?

 

<snip general cc sizes of 70s/80s strokers>

So, you'd not suggest it as sesible for a ride to work, winter hack.
However, as a piss-taking stealth type thingy...

Not that I've ever had a bike where what it said on the tin didn't
match what it'd really do. Not me Mr. Not at all...

Crossers, law unto themselves.

Although I was considering a Husky 460cc (IIRC) automatic at one stage
because I'd broken my wrist and couldn't pull a clutch in. Physio
finally sorted the problem and I got a sensible 1200 Bandit, as you
do.

 

Depending on state of tune. If it was a big, soft, torquey thing it
would be lovely to pootle around on, keep up with traffic etc. OTOH
something with a powerband 300rpm thick, huge spanny and bakelite
part-worn Pneumats would be different...

You've been bad, haven't you?

--
Platypus - Faster Than Champ
VN800 Drifter, R80RT
DIAABTCOD#2 GPOTHUF#19
BOTAFOS#6 BOTAFOT#89 FTB#11
BOB#1 SBS#35 ANORAK#18 TWA#15

 

Today? No.

 

I had one of the very early disc braked export ETZ 250's, they were
fitted with actual Brembo items (calliper and master cylinder and cast
iron disc). Later machines had copies made under licence.

 

Platypus wibbled incoherently

The aircooled and LC RD250s, from the YDS7 of 1970 until the Jap and
Aussie market RD250LC F2 of 1992, shared the same bore and stroke, which
brought them out at 247cc.

The above applies to the 350 variant, from the earliest YR5 in 1970 to
the last of the Brazilian made LC models in 1994. They were all 347cc
and shared the same bore and stroke. I've fitted piston kits from 1994
model LCs into a 1973 RD350 before. The RD400 has the same piston
diameter, just a longer stroke.

Correct


--
Lozzo
ZZR1100D, GPZ500S, CBCBCB750RSRSRS
BOTAFOT#57/70a, BOTAFOF#57, two#49, MIB#22, TCP#7, BONY#9,
ANORAK#9, DIAABTCOD#14, UKRMT5BB, IBW#013, MIRTTH#15a/16,
BotToS#8, GP#2, SBS#10, SH#3, DFV#14, KoBV#3.
Url for ukrm newbies : http://www.ukrm.net/faq/ukrmscbt.html
www.mjkleathers.com

 

Interesting.

I know it was a common "trick" to stick the 350 aircooled top-end onto
the 250.

So, will a 350 piston kit fir a 400, or is the piston skirt longer (or
something) because of the longer stroke? Could be useful information
if I ever get the RD back on the road.

Or, staying *slightly* on topic, are there any know big-bore kits /
setups for the RD400. ISTR that Fharon <sp?> did one and that there
was a water-cooled kit. Or am I thinking of the same thing.

 

Big Tim wibbled incoherently

BTDT a few times

The piston kits commonly available for 350LCs have a slightly longer
piston skirt and this fouls on the conrod of the 400 engine[1], but
otherwise they are the same in dimensions. You simply have to carefully
file away a small beak that protrudes from the bottom of the piston
skirt. There is sometimes a difference in the porting windows in the
rear of the pistons, the C and D model 400 had round windows, the E and
F and the LC range had square ones. It makes no difference to a C or D
if you fit the later pistons, but fitting early pistons to a later
engine strangles them somewhat.

You can use DT175MX pistons to take it out to 430cc, but they aren't
reliable enough unless used in conjunction woth a water-cooling set-up,
which brings us to....

Fahron made one, amongst others. I owned a Fahron water-cooled RD400 for
about 4 days back in 1983, it was an absolute rocket-ship and pissed all
over tuned 350LCs.

[1] A longer conrod and wider sweep of the crank web makes this happen.
The conrod is at a greater angle when the big-end pin is at 90 deg to
the crank centre, effectively makeing the whole shooting match wider,
hence the different (deeper) crankcases for 400 models.

--
Lozzo
ZZR1100D, GPZ500S, CBCBCB750RSRSRS
BOTAFOT#57/70a, BOTAFOF#57, two#49, MIB#22, TCP#7, BONY#9,
ANORAK#9, DIAABTCOD#14, UKRMT5BB, IBW#013, MIRTTH#15a/16,
BotToS#8, GP#2, SBS#10, SH#3, DFV#14, KoBV#3.
Url for ukrm newbies : http://www.ukrm.net/faq/ukrmscbt.html
www.mjkleathers.com

 

Well, there's Sweller's on the south coast and an even cheaper one on eBay,
though it does need a bit of work, in Glasgow.

JH

 

This one?
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2437914921

Its a very early one ('de luxe' export model as it has a disc, oil pump
and tacho). Genuine Brembos.

Looks as if it needs some work, no MOT, clutch lever, tyres, leaking head
gasket, electrics and its at £165!!! I'd pay about £50 for one in that
state. And probably break it.

I have a manky but good (IYSWIM) 1985 ETZ 300 conversion with an MOT,
maybe £200 - 250 ish. May put it on Ebay to see what happens.

 

I wonder if this (square windows) is why when my RD needed a rebore
and I checked with a Mr R Beckett of the Nottingham Parish[1], he said
that the ports in the piston didn't need opening up like they used to
do

I suppose I'd better get it running again before I try and get clever
with fancy ideas of tuning it up some more.

Ta for that, most informative.


[1] His dad, a Mr T Beckett had meddled about with my internals some
6-7k miles previously. And a jolly good job he did too.