Power Valved and Square bore

[maddog1927]

So the KX has a power valve and is square bore (86mm stroke / 86mm bore), that would seem to be 2 distinct advantages. Why I it not more popular?

[Roostius_Maximus]

made of crap castings, no easy access clutch cover, waterpump is low and in the way, crude looking and big. cracks from port to port are common. parts arent.

its green

[100hp honda]

i dont see no advantages. piece of shit realy. have to split cases to change seals

[Tharrell]

Kawasaki parts are very expensive.

[NightBiker07]

there are kawi followers out there.....the KX's make some serious power too. but in the off-road bike world, hondas are by far the most common. especially anything older.

and YES, Kaw parts can be expensive. not too familiar with their big bikes, but the 65's and 80's are some DAMN good bikes. i bought my 94 used and put 150+ hard hours on it before i sold it. i put chain+sprockets on it and a rear tire..thats IT. sold it running strong, the new owner had had no troubles with it as well......could probably use a piston/rings by now though.....same with the lower end LOL

[2strokeforever]

if it was made good, and the powervalve wasnt a shit design it would demolish the cr
i also found out the crank bearings are pressed into cast IRON races... which are heavy and wear into a oval...
even there electroshit cant stay in the bore... but once its replated its better than iron

[AlisoBob]

The tranny's made of glass..... but less vibes.

[2strokeforever]

basicaly it has a slightly better(in my opinion) power curve, but is heavier, way more parts/complicated, fragile/wont last, and its not a honda

[100hp honda]

heres the bottom line: any billion dollar manufacturer that cant think of a better idea than split cases and pull crank bearings to replace a $10 seal is fukkin stupid. what kind of jack ass would think thats a good design ? kx500 was a pile . guess there was one good thing, it can fit a 72gal tank in case you want that gay look while blasting the dunes

[100hp honda]

fair amount of info on bore/stroke ratio if you search. plenty of theories about whats best. depends on what type of engine and a million other factors i suppose. fastest shit ive seen is what CP does and its over sqaure. some by as much as 20mm. i think 10mm over is probly a good compromise for our bikes. ktm 500 also used nearly the same bore/stroke as cr500. was it coincidende or by design ??? hard to say what them goofy austrians were thinking. i know when you go to far your torque really suffers. 440 for example is 89x70. magazines have claimed its 60hp but i can tell you first hand theres no torque.

[dubious01]

I have never had to change a crank seal, that didn't need bearings too.
On any bike I owned.
Its kinda like changing the waterpump seal, without changing the water pump bearing....

If the KX had a 2 piece clutch cover, so that the brake pedal doesn't take out an entire engine cover, that would be a bonus, along with a proper way to attach a countershaft sprocket, not some dumb c clip, that wears out and wears out the shaft allowing the sproket to dangle like a donkey dink with the shivers.

The jug and powervalve design was state of the art for its time, and in some ways still is, but the quality and reliability was not there.

[100hp honda]

I have never had to change a crank seal, that didn't need bearings too.
On any bike I owned.
Its kinda like changing the waterpump seal, without changing the water pump bearing....

they dont go bad everyday but hang around the other site and youll see a few now and then. youd be mad as a mutha if yours went out tomorow and you had to pull the whole damn thing apart for a stupid seal . the 250 sat for about 4 years and all the seals dried up and leaked, bearings were fine and practically new. glad it wasnt a kawasucki is all im saying

[dannygraves]

I just helped my neighbor rebuild a beat '01 kx250 that he bought for $400. It needed a crank, someone didn't maintain the filter
I like the liners for the bearings, there is less of a risk of the bearings turning in the bore like they are known to on hondas. The trans was the least worn trans I have ever seen, I also like the cog design being oval. Didn't like that the coolant goes through the side cover and case into the bottom of the jug, probably more efficient, but more prone to leaks.

BTW, brand new wiseco crank assembly w/ bearings and seals...$150...SOOOOOOO expensive Kawi part cost the same as yamaha, honda or suzuki parts, don't be confusing them with KTM

IMO, kawi makes a good motor, and they are usually fast bikes, but until recently they were lacking in the chassis department. That '01 kawi as fast as it is looks like an absolute turd next to a '01 cr

[2strokeforever]

I like the liners for the bearings, there is less of a risk of the bearings turning in the bore like they are known to on hondas

youd rather have it a pound heavier and they wear into a oval regularly so you need to sleeve the liner or buy new cases

[100hp honda]

new cr250 has water go through case also. never had problems with mine but i dont really like the idea. if it leaks on the inside oring you pull cases apart . hell with them bearing liners . keep it simple and stone cold reliable=cr500. ktm took that filosophy one step further and eliminated waterpump gear, ran impeller straight off the crank .

[2strokeforever]

i wish KTM would re design there big 2 strokes and slap on direct injection, id sell my 500 af for a ktm 550 with DI and a new chassis, and the kicker on the right side...

[dannygraves]

I like the liners for the bearings, there is less of a risk of the bearings turning in the bore like they are known to on hondas

youd rather have it a pound heavier and they wear into a oval regularly so you need to sleeve the liner or buy new cases

the one I just worked on wasn't oval and the crank was toast, so the whole bottom end was under a lot of stress...

[bearorso]

Without a doubt, the KX500 is a far more modern and advanced power plant than our CR500s. By earlier 2t tech and design levels.

And the modern 4ts take that concept into (literally) another century.

BUT - the big point is, with , even in an incredibly low state of tune (which a std 500, and even most modified 500s, are still in compared to modern 4ts) and a level of simplicity that places the CR500 just above the tech. levels of a stone axe, a basic 500 2t can deliver fantastic performance, and incredible reliability.

So it begs the question : why the hell bother with all the extra complication that does not deliver equivalent benefits???????????????

That's how I see our 500 against other power plants. The other big advantages the CR500 has is its lack of weak points/ engineering stuff ups, which the KX500 has.

And the inherent power of a 500 more than makes up for the traditional benefits of a square, or more often, an under square bore / stroke format of 2ts. The piston (combined with the ports) is the "valves & cams" - the size , the lift, the duration, the timing (that's part of how I get people to understand 2t function - you'd be amazed to realise how many people have no idea....) Longer stroke allows more duration, more variation in port timing - yes, this is a very simplistic and far from fully correct explanation, but true), and that is why it has been so common on 2ts.

Real DFI will release the 2t from this, as the entire charge will not be determined by the ports, stroke, bore size. There are myriad versions of DFI, by the way - right up to the potential for the entire charge of fuel and oxygen being delivered via the injectors into the combustion chamber alone. But that would be utterly impractical on a motorcycle, for a whole bunch of reasons - compressors, pressure accumulators/ chambers, multiple injectors, wildy complicated and powerful electronics, with big electrical power demands , etc, etc, etc.

The irony with our CR500 engine, is that it's far from optimal (with carburettor into barrel / case induction) over square dimensions is the way 2ts will be able to go with the various DFI systems that (hopefully) will be put into use to to deliver clean, economical and still more powerful 2ts, with incredibly wide power bands, whilst still being simpler/cheaper to make / work on and maintain. And their continued lack of stress / lower needed level of tune, will make them ever more reliable than the wildy overstressed 4ts. The over square dimensions will bring the wide rev range to 2ts that 4ts use to make their power, on top of the 2ts ability to have more torque and power than a 4t. I still find it laughable that we are now into an era of 12000 RPM 450 4ts. 2ts will not have to go for massive revs for power, but tuners/ designers will have many more options.

Check the Bore / stroke ratios on the E Tec outboards - it is very close to what the CR500 sports.

When you look at what 4ts have become, and will / would have to become (there's still a lot of further developments to come with them) with a logical mindset, to compete with a DFI'd, modern, Same Capacity 2ts (none of this bullshit smaller capacity for 2ts should be allowed to go on further, though Honda will do everything they can to keep the status quo), 4ts should be the first ICE engine format to be sentenced to extinction.

As a side note, a relatively new OZ magazine will be publishing in it's next (I think) issue, a comparo between a KX500 (the one that won the last 500 title by a 2t in Oz - I think David Armstrongs bike?) and a KX450. The dyno charts are quite an eye opener - in terms of power and torque we sure have not gone forward. Usability, yes: it's easier to control a bike with less power, over a much wider rev range than the 2t - and that's why the average bloke feels less intimidated by a 450. And, from speaking to the editor in a conference call with the owner of a suspension business I work part time at (who is the tech. editor and conducted the dyno tests), and I, many of the riders were scaring themselves, wearing themselves out on the 500, by revving it like the 4t 450. Stupid, stupid, stupid. They no longer understand the concept of using the grunt, and making the big motor drive.

[2strokeforever]

what id really like to see is a big bore rotary bike heres a dyno chart of a 50cc rotary motor!!!!!! 48 horsepower!!!!!!!! look at the torque curve (blue) 34 lb-ft of torque!!!!!! a 500 only has 45 ft lbs and its 50cc!!!!!
take a good look at the dyno chart....
the peak power is only at 9000 RPM, thats low for a 50 cc motor and the best part is there so under developed that theres plenty room for improvement
heres the same dyno chart with a ktm 450 (in pink) Wink added on

keep in mind the 450 is 9 times bigger, so id say the rotary has insane torque, remember torque is measured and hp is calculated using it.. so if a motor has more torque at X rpm than motor B it means it has more torque at that rpm too
(RPM X torque) /5252= horsepower

[dannygraves]

my buddy Dan's 3rd gen (93) rx-7 could spank the shit out of nearly everything on the road, it was bone stock and 1.3l of displacement... stock for stock it walked all over my '93 stealth tt, I finally spanked his car when I put some big-ass mofo turbos on, had he done the same (and kept it together) he would have had me by atleast a full second in the 1/4 mile.
I was riding shotgun in that car when in a single ride we spanked a ls-1 camaro ( modded) and 2 mustangs 1 early and 1 late sn95 one of the mustangs was on gibson and we actually launched over the train tracks

[bearorso]

I know next to nothing about Rotaries, but love them - if only for the way so many 'Big Engine' or 'Muscle Car' devotees (such as my 2 brothers) seem to hate them so much.

We've quite a few new RX8s in my quiet little suburb, gorgeous little cars. And on my street there's a group of young blokes that drag race an RX7 based car - every now and then they'll start it up and do a lap around the block, I guess for tuning purposes. It sounds ballistic and looks hilarious with it's wheelie bars hanging out the back. I pulled him over one time, the driver thought I was going to give him heaps, but when I just asked him to show me a launch, his jaw almost hit the floor. Mine did when it showed how much it needed the wheelie bars.....

Hercules / Sachs campaigned / sold (though not many) a Rotary in Enduro / Six Days. And Norton won at least one Brit Superbike Championship on their Rotary, plus IOM races. The new owner of Norton has stated they will race and produce the Rotary again - They took it to the IOM to race it with Michael Dunlop on it but pulled out after testing at Jurbury Airfield - not enough time for set up etc, as the bikes had only been taken out of the National Motorcycle Museum just before the event.

[dannygraves]

if you want to see something wicked, check out the 20b mazdas, its a 2.0l triple rotor and a bad mofo! I've seen people make custon cranks and bolt an additional midcase in to make a quad rotor 2.7

[bearorso]

You're kidding, surely?

Lunacy, I say.

But a very, very cool sort of Lunacy.....