Question: Why was the biggest two-stroke bike 500cc? [Archive]

nudedaytona

16th July 2008, 16:54

avgas

16th July 2008, 16:57

er they had 750+

also 2 stroke diesels go 6L+

i suggest you do some research

MSTRS

16th July 2008, 16:59

There were several 750 2 strokes. Suzuki GT750 'waterbus' springs to mind
The problem was getting rid of the heat the bigger capacities produced, until water cooling was introduced.

Mr Merde

16th July 2008, 17:01

Anyone know the answer to this one:

Why were two-stroke motorcycles never bigger than 500cc?

Or did a manufacturer try making one bigger? It's something I've always wondered?

Would the power-to-weight advantage be diminished at larger sizes, or would they use too much oil?

Seem to remember a kawasaki 750 triple that screamed. In fact at the time of its release one was expected to remove ones brain before attempting to ride this machine.

Badjelly

16th July 2008, 17:05

Why were two-stroke motorcycles never bigger than 500cc?

The ones I can think of > 500 cc:

http://en.wikipedia.org/wiki/Suzuki_GT_750
http://en.wikipedia.org/wiki/Kawasaki_triple
http://www.superbikeplanet.com/evantz750.htm

Many of the 500 2-strokes were built to race in (or were replicas of bikes built to race in) MotoGP, which had (until 2003) a 500 cc limit.

Badjelly

16th July 2008, 17:09

Seem to remember a kawasaki 750 triple that screamed.

It was more of a braaaack-ring-ding-ding-clatter-roooar sort of noise. It's remarkable how much mechanical noise a big, air-cooled, two-stroke can make with so few moving parts.

rogson

16th July 2008, 17:13

Multis don't count - here's the granddaddy
http://www.superhunky.com/nov00rsMaico760.html

Choco

16th July 2008, 17:13

MSTRS

16th July 2008, 17:14

It was more of a braaaack-ring-ding-ding-clatter-roooar sort of noise. It's remarkable how much mechanical noise a big, air-cooled, two-stroke can make with so few moving parts.

Or more likely to have been...
Ringa-dinga-braaarrrppp-crunch...as it put the unfortunate pilot into a tree.
Lethal powerband and worse frame

puddytat

16th July 2008, 17:15

A Kiwi by the name of Steadman has built a 750 3 cylinder racer based on RM250 bits...:clap::niceone:

nudedaytona

16th July 2008, 17:20

Did they make anything bigger than 750?

paturoa

16th July 2008, 17:21

Probably one of the scariest was the Yamaha OW69. Some web sites say it was 680 cc and some 600cc - either way it was a beast at Daytona.

sidecar bob

16th July 2008, 17:24

Check out this weapon!!!
Kenny Roberts' TZ750 dirt track racer.
http://www.motorcyclemuseum.org/classics/bike.asp?id=42

Kenny once said "They dont pay me enough to ride that thing"

Badjelly

16th July 2008, 17:27

Did they make anything bigger than 750?

I'm not aware of any production 2-stroke any larger than this. When the Suzuki & Kwaka 750s came out ~ 1970, 750 cc was about as big as motorbike engines got (ignoring oddballs like Harley, Vincent & Ariel). Then Kwaka moved to 4-strokes and built the Z1 900. Power outputs and engine capacities continued to climb, but the 2-strokes were left behind.

svr

16th July 2008, 17:43

Old Motorscrapers have 2 stroke V12 twin turbo, twin supercharged diesel engines (aboot 12l I think). They don't go that fast but with open pipes make a 500GP bike sound pretty gutless!

Pedrostt500

16th July 2008, 17:44

Yamaha had the TZ 750, though it wasnt realy a production bike, the big 2 stroke were killed off when the USA brought in emmisions controlls in the 70s with the catilitic converters, fitted to their cars.

Motu

16th July 2008, 18:16

Anyone know the answer to this one:

Why were two-stroke motorcycles never bigger than 500cc?

Or did a manufacturer try making one bigger? It's something I've always wondered?

Would the power-to-weight advantage be diminished at larger sizes, or would they use too much oil?

Total capacity or cyl capacity?.Plenty of 750cc total capacity as posted by others.But 500cc is pretty well the limit for cyl capacity....I think the KTM 550cc would be about the biggest I've heard of....at least production bikes anyway.2 stroke diesels have some pretty huge cyls - marine diesels are nearly always 2 strokes.

rogson

16th July 2008, 19:03

As I alluded to earlier Maico made a 760cc 2-stroke air-cooled single a while back, and make a 685 2-stroke single now.

http://www.maicouk.co.uk/html/supermoto.html

MVnut

16th July 2008, 19:20

Seem to remember a kawasaki 750 triple that screamed. In fact at the time of its release one was expected to remove ones brain before attempting to ride this machine.
Only the frontal lobe:banana:

Kawasaki 750 triple 'widow maker'.
My old man got to ride one once, scared the shits out of him!
That bike was the fasting thing on the road at the time and had drum brakes front and rear :shit: crap handling too!

Disc brake front on all H2s..... what's wrong with the handling....you ever ridden one ??:argue:

Motu

16th July 2008, 19:28

As I alluded to earlier Maico made a 760cc 2-stroke air-cooled single a while back, and make a 685 2-stroke single now.

http://www.maicouk.co.uk/html/supermoto.html

Sorry - I saw your post but chose to ignore it for reasons I refuse to disclose....

pete376403

16th July 2008, 19:36

It was more of a braaaack-ring-ding-ding-clatter-roooar sort of noise. It's remarkable how much mechanical noise a big, air-cooled, two-stroke can make with so few moving parts.

Most of the noise was air cooling fins ringing like bells. Hence the move to water cooling. Also space limitations - each air cooled cylinder needed about 50mm worth of fins around the barrel, but water cooled barrels could be much closer together. Add a big dollop of air induction noise (carburettors)Finally add the noise transferring through the sides of the expansion chambers (regardless of the amount of muffling at the chamber outlet) and you've got a pretty rackety package, albeit a fast, rackety package.

I really miss my old (air cooled, noisy) IT400

TLDV8

16th July 2008, 19:49

TLDV8

16th July 2008, 20:00

These are Kawasaki H2's (late 1971/1972),not to be confused with Kawasaki H2A's (1973) or H2B's (1974) or H2C's (1975)

fwiw

<img src=http://i30.photobucket.com/albums/c345/manurewa/H29.jpg>

This was fairly standard though. (Redline was a fairly low 6800 rpm) but never let the truth get in the way of a good story.
Of course porting,34mm carbs and a good set of pipes was another thing. (90 hp perhaps back then,over 100 is not hard these days.)

<img src=http://i30.photobucket.com/albums/c345/manurewa/H2B.jpg>

At the time there was probably little need to increase the capacity (The H2 engine will bore to 780cc) but being aircooled the piston clearance was fairly big without increasing the (71mm) bore size further.

Seem to remember a kawasaki 750 triple that screamed. In fact at the time of its release one was expected to remove ones brain before attempting to ride this machine.

The 1969 Kawasaki H1 500 had the biggest rep like that but only because of the sudden HP increase around 6000rpm

nudedaytona

16th July 2008, 20:21

Can anyone tell me what porting means? Something to do with the cylinder heads?

TLDV8

16th July 2008, 20:42

Can anyone tell me what porting means? Something to do with the cylinder heads?

Two stroke's have passages in the cylinder wall (ports),the fuel mixture goes from the crank cases to the combustion chamber via the intake ports when the piston travels down.
Altering the height etc changes the timing (like a modified cam in a four stroke)
Go to crazy with the porting and the power band becomes very narrow.

<img src=http://www.scooterhelp.com/tips/engine/_piston/sf.piston.replace10.jpg>

banditrider

16th July 2008, 20:44

Old Motorscrapers have 2 stroke V12 twin turbo, twin supercharged diesel engines (aboot 12l I think). They don't go that fast but with open pipes make a 500GP bike sound pretty gutless!

Then there's these: http://people.bath.ac.uk/ccsshb/12cyl/

Had a look at an 8 cyclinder marine diesel once: twin turbo-charged 2-stroke diesel, a think it was 24,000hp at 150rpm. Bore was 900mm and stroke was 1800mm. Turbos were fan assisted. Only a tidler...

Boat was a small container boat and it had 2 of them that got it to 23 knots. it also had at least 6 (maybe 8) smaller 8 cylinder diesels of 1,200hp for generating onboard power for reefers and what not.

pete376403

16th July 2008, 21:16

When I was at IBM I got asked to service a data logger printer on a container ship. The logger was down in the engine room. The engine in that boat was a dirty big nine cylinder, the crank had a flexible coupling between the fourth and fifth cylinder, to allow for the boat hull flexing in heavy seas. I also recall seeing a spare turbocharger strapped alongside one of the bulkheads, the exhaust scroll would have been about two metres in diameter.
But think the OP was about two stroke BIKE engines, so maybe this doesn't count.

Coyote

16th July 2008, 21:52

Multis don't count - here's the granddaddy
http://http://www.superhunky.com/nov00rsMaico760.html
Dead link. But yes, the Maico is badass.

The new one must be even better with newer technology behind it. It's so good, the Americans are taking it and putting their own brand on it!
http://www.motorbikes.be/en/ATK/2004/700%20Intimidator/

Coyote

16th July 2008, 22:05

Sorry - I saw your post but chose to ignore it for reasons I refuse to disclose....
Go on

10 characters

nudedaytona

17th July 2008, 08:56

Two stroke's have passages in the cylinder wall (ports),the fuel mixture goes from the crank cases to the combustion chamber via the intake ports when the piston travels down.
Altering the height etc changes the timing (like a modified cam in a four stroke)
Go to crazy with the porting and the power band becomes very narrow.

<img src=http://www.scooterhelp.com/tips/engine/_piston/sf.piston.replace10.jpg>

I don't recall seeing any holes like that in the cylinder I recently took off.

The only hole I can remember seeing was the exhaust hole. There were holes in the cylinder head, but they seemed to be for coolant to flow around on the outside of the cylinder.

vifferman

17th July 2008, 09:08

I don't recall seeing any holes like that in the cylinder I recently took off.

The only hole I can remember seeing was the exhaust hole. There were holes in the cylinder head, but they seemed to be for coolant to flow around on the outside of the cylinder.
The pic is of a piston-ported two stroke (the piston covers/uncovers the ports). There were also two-strokes with disc valves, which had a spinning disc with holes in it.

rogson

17th July 2008, 09:24

Link to Maico 760 article in my original post (#7) fixed.

Specs I've seen for current 685cc LC model are 82HP, 101kg - bloody hell!

BIHB@0610

17th July 2008, 10:19

Check out this weapon!!!
Kenny Roberts' TZ750 dirt track racer.
http://www.motorcyclemuseum.org/classics/bike.asp?id=42

Kenny once said "They dont pay me enough to ride that thing"

Who taught you your ferocious "advanced googling" skills Bob? I'm mightily impressed ;)

James Deuce

17th July 2008, 10:27

Must be a 4 stroke RS250 then.

The inside of an RGV250 looks like this, so your RS must too.

<img src=http://www.rg500.de/Zylinder.jpg>

The Junkers JU86D used by the Luftwaffe for High Altitude Recon (46,000ft in 1940!) was powered by the Junkers Jumo 205C a vertically opposed 2 stroke diesel.

http://www.dundee.ac.uk/museum/mecheng/3001.htm

<img src=http://www.dundee.ac.uk/museum/mecheng/Dscn0034a.jpg>

nudedaytona

17th July 2008, 10:41

Oh yeah, I remember those holes now.

So what would be easier, boring cylinder out or changing the ports.

James Deuce

17th July 2008, 10:44

There's plenty of info in making porting changes to RGVs. All of which are a bit dodgy.

I know there is a 300cc kit out there for RS250s. You should do some digging on that because the end result will be better than having a go with a riffler file.

The best thing you could possibly do is talk to this guy. The 465cc kit in my RG400 had RG500 and GSXR750 riders really scratching their heads.

http://www.stanstephens.com/rgv.htm

imdying

17th July 2008, 11:14

Long story short, the biggest ones available were the biggest they could make whilst still be elligible for racing. When the sizes for the classes got smaller, so did the Win on Sunday Sell on Monday bikes.

Grub

17th July 2008, 11:22

..... what's wrong with the handling....you ever ridden one ??:argue:

Ahem ... have you? These bikes were lethal. The frame flexed so much that the geometry of the bike would change several times in a corner. Yes, they were the Falcon GTHO of the bike world ... they killed people. Oh ... and they sounded GREAT!

imdying

17th July 2008, 11:36

Ahem ... have you?Given that it's already Thursday, then yes, MVNut has probably ridden his one this week ;)

Grub

17th July 2008, 11:38

Given that it's already Thursday, then yes, MVNut has probably ridden his one this week ;)

He's got one? He rides it? He's alive? He's mad!

Choco

17th July 2008, 12:04

Disc brake front on all H2s..... what's wrong with the handling....you ever ridden one ??:argue:

Only repeating what i've been told (dont shoot the messenger) :dodge:

Badjelly

17th July 2008, 12:14

Kawasaki 750 triple 'widow maker'.
My old man got to ride one once, scared the shits out of him!
That bike was the fasting thing on the road at the time and had drum brakes front and rear :shit: crap handling too!

Disc brake front on all H2s..... what's wrong with the handling....you ever ridden one ??:argue:

The 500 (H-1 aka Mach III) came out before the 750 (H-2 aka Mach IV) and originally had drum brakes. The 500 was the one that first got the scary reputation.

Mikkel

17th July 2008, 12:34

He's got one? He rides it? He's alive? He's mad!

If you only knew... :D

He's not that mad though.

Grub

17th July 2008, 12:57

If you only knew... :D

Got a bit of an idea, I doubled the owner to work for 6 months on Mach III (drum brake) since he'd lost his licence on it .....

He flies 747's for Air NZ now ... kinda worrying really

Mr Merde

17th July 2008, 13:08

So how many of you have ever ridden a bike with large drum brakes?

4 leading shoe brakes had a lot of feel to them.

Ixion

17th July 2008, 13:08

Ahem ... have you? These bikes were lethal. The frame flexed so much that the geometry of the bike would change several times in a corner. Yes, they were the Falcon GTHO of the bike world ... they killed people. Oh ... and they sounded GREAT!

I owned the 500 Kawasaki, drum brake model, for a while. It spent every evening plotting how to kill me the next day. Fortunately, for me, I got rid of it before it succeeded. Not so fortunately for the subsequent owner. It killed him. I found the remains in a wreckers a year or so later.

In hindsight the handling was probably no worse than most of the big Jap bikes of the time. But the combination of the hinged frame, and a vicious two stroke power band, and non existent suspension (well, what it ahd didn't sdeserve to be called suspension) was bad news for riders accustomed to the much more fogiving Briddish iron.

The brakes were fine, if you weren't racing. Certainly better than the 6 inch cast iron SLS hub ornaments on most bikes.

Badjelly

17th July 2008, 13:21

Not so fortunately for the subsequent owner. It killed him. I found the remains in a wreckers a year or so later.

Jeez, you'd think they'd bury him or cremate him or something!

That's verging on bad taste isn't it? :no:

Ixion

17th July 2008, 13:43

By accounts, by the time the Kockasucky got through with smearing him over the road, there wasn't enough in one piece to do much with.

In fairness, it should be noted that all thius was long before the graduated licence scheme. And the Mach III was very popular with a certain sort of noob as a first bike. (and, almost invariably, last bike also)

Motu

17th July 2008, 18:00

So how many of you have ever ridden a bike with large drum brakes?

4 leading shoe brakes had a lot of feel to them.

I've ridden a Benelli 650 with the large Fontana 4 leading shoe front brake....the spokes were only a couple of inches long.It was on,then ON really,really ON! Not very suitable for a road bike.My Water Bus had the 4 leading shoe,which was sorta ok....hard to tell as it was a heavy bike to haul up.

MVnut

17th July 2008, 19:00

Ahem ... have you? These bikes were lethal. The frame flexed so much that the geometry of the bike would change several times in a corner. Yes, they were the Falcon GTHO of the bike world ... they killed people. Oh ... and they sounded GREAT!

But you can make frame flex work for you, and get another couple degrees of lean ..........timing is everything (and big cajones helps):scooter:

FilthyLuka

17th July 2008, 19:09

I've always wanted to put a H2A engine with a few tweaks into a GSXR750 oil boiler frame and see what happened :confused:

James Deuce

17th July 2008, 19:12

Madmax put one in a ZXR750 frame.

<img src=http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=52854&d=1170670593>

http://www.kiwibiker.co.nz/forums/showthread.php?t=38837

People have Goldfish memory syndrome on this site. It must be the motorcyclist to head injury ratio.

FilthyLuka

17th July 2008, 19:33

Madmax put one in a ZXR750 frame.

People have Goldfish memory syndrome on this site. It must be the motorcyclist to head injury ratio.

Thats hardly a 750 oil boiler frame...

Probably considerably heavier than one aswell

nudedaytona

18th July 2008, 09:19

Are they air-cooled? Where's the radiator?

bungbung

18th July 2008, 09:30

Air cooled, no radiator.

The Deltic was 2 stroke too: http://en.wikipedia.org/wiki/Napier_Deltic

nudedaytona

18th July 2008, 09:35

I see so that's what those big fins around the engine are for.

rok-the-boat

20th July 2008, 23:23

I've got a 115hp V4 1800cc two-stroke downstairs - a boat engine. And I have seen a 350hp V8 2 stroke boat engine.

cold comfort

22nd July 2008, 21:04

cs363

22nd July 2008, 21:15

Old Motorscrapers have 2 stroke V12 twin turbo, twin supercharged diesel engines (aboot 12l I think). They don't go that fast but with open pipes make a 500GP bike sound pretty gutless!

Yep....ever seen a Terex or Euclid dump truck? Some of those things use up to V16 two stroke diesels (Detroit Diesel), Cummins also make big 2T diesels.
Some of the biggest 2 strokes are some ship engines....and they ain't small at all!

Not to mention outboard motors if you want to talk big two stroke petrol engines, I think there have also been two stroke aero engines in the past too.

But, back to motorcycles of more recent times I think 750cc was the biggest commercially available 2T engines, though plenty of people have built hybrids - only the other day I was reading an article on a converted Kawasaki H2 750 that had an extra cylinder grafted on for a capacity of 1000cc!

laRIKin

22nd July 2008, 21:25

If you want you can buy a nice new 2008 ATK700 685 or 615cc Intimidator.
Single two stroke dirt bike with 78hp to play with.:drool:

gammaguy

22nd July 2008, 21:26

truth is because of the 2T engines inherently superior power to displacement ratio compared to a four stroke,they didnt NEED to make them big.Small=light=better power to weight=less weight=less wait.simple innit?:2thumbsup