www.zxrworld.co.uk

Only 2hp less than the 650 equivalent?? How did they manage that. As someone posted its probably a sleeved down 650 motor.

think it looks a bit ugly myself.

i quite like that! wonder if there are any plans for a new zx4r?

I don't like the er4n but the er4f looks nice. As for the 70bhp, that kinda all depends on the weight really. If they make it nice and light still, then it could be a real hoot and good mpg as well!

Hi only had quick look looks good is it coming to the uk and how much will it be any ideas?? i think unless its a big differance people would rarther have the 636???

i doubt it's sleeved down, more likely destroked, allowing it to rev faster, and flow nearly the same air/fuel mis as the 650s. I know the 650s are nicasil plated bores, so this should allow a very gih rev ceiling without meaning constant re-hones etc. On the other hand, if you do split a ring, the re-plating costs another £90ish on top of all the other crap.

Those who are in the know a little more than me can correct me if/when i get this wrong, but regards engine size/ratio vs bhp...

an engines rev limit is limited by the speed of the pistons in the bores. In a long stroke harley (... tractor...) the piston will reach this speed at low revs, since on each rev the piston is sent up and down over a longer distance. On our little zxrs, with *tiny* stokes, this limiting speed won't be reached until much high up the rev range, maybe 16,000 for a good engine. This means that for a given stroke, the power then depends only on bore (all other factors being equal).

This works the other way too. Keep the bores the same, and increase the stroke, and the engine will reach its rev limit lower down (mmm, torque...), reduce it, and you have to rev even higher for the ponies.

In short, if kwak Japan just sleeved down the 650 engine, then the engine would have to rev alot higher and harder make the same power, pushing up the piston speed dramatically and screwing with your engine life. Drop the bore instead of the stroke, and you can rev higher without altering the max piston speed, and hence flow the same air/fuel to kick out the same power. mmm, revvy!

Not sure i see the point tbh. The zxr is great because it matches a tiny light chasis to a tiny light and turbine-like engine. The er4f/n will take a tall heavy bike with a revvy engine. not ideal. after all, twins are built for torque, not revs.

Sod it, I say we just built our own new bike - the zx4r, take a 636 engine, de-stroke it to 400cc, give it a 17,000rpm rev limit, fuel injection, ram air, and modern big piston forks and... well, everything else is fine right?
who's interested?!

I really miss the old 250 I4 4 stroke screamers

The CBR250 has a Bore/stroke, 48.5 × 33.8 mm (1.91 × 1.33 in) and revs to 19,000rpm.

Think i'd much rather see a more modern one of those.

I think one of the other limiting factors is valve springs (or whatever you use) being able to open & close fast enough...

yup, hence why many years ago ducati went down the desmo route. to me the whole springs vs desmo thing is like telescopic forks (like most bikes use) vs telever or girder forks. many decades of racing development vs a better orginal design. even piston vs wankel for that matter.

looking at these bikes they look more like a modern gpz400 than a 400 superbike. still, with a bit of work and better forks, i think they could be promising (after all, no other good 400s about are there?)

looks toad,
it looks like a 125

Don't know where they are getting 70 BHP from as the home market is spec'd at 43PS

http://www.kawasaki-motors.com/mc/400ne ... other.html

The All black looks tasty & the 250R's are being snatched up quicker than they can make them.

MM!

The candaian spec model 400R also says 43PS

http://hellforleathermagazine.com/2010/ ... first.html

Let's do any easy numbers comparison for all three bikes:
650R: 71bhp, 49lb/ft, 204kg/449.5lbs, .35bhp:kg, .24lb/ft:kg
400R: 42bhp, 27lb/ft, 203kg/447.5lbs, .20bhp:kg, .13lb/ft:kg
250R: 30.5bhp, 16lb/ft, 170kg/375lbs, .18bhp:kg, .09lb.ft:kg

The new 400's a lovely looking motor, shame they wont be here in the UK!

I'm still after a decent zxr250 (2-R)

Wait till you see the new ZX-10R

Revamped everything on it including motor !

Looks great but wish they would drop the ninja crap , make the brand look tacky

Was looking at a Black one yesterday - the ZXR & ZRX were in danger for about a minute

Be nice to have a new bike but I'm happy with what I've got.

Don't mind " Ninja" so much - got to be better than "ThunderAce" and a bit above "FireBlade"

MM!

I have a 2009 ER6N and it is a lot of fun. VERY easy to learn tricks on and build confidence (turning circle is soo tight!!) and it is a lovely fun bike. Useful too. Power is good. Outdrags older fireblades at the lights. Which is fun. When you have been riding for a long time, and you just want something easy to ride with no delusions of grandeur, the ER6N is great for that.

I see no point at all to a 400cc twin engine. and if they managed to squeeze a revvy inline 400 ZXR type engine in there, it just wouldn't work. They uprightness of the bike lends itself to a more torquey twin motor for the slower speed maneouvres. And the ER6N is only £90 a year to insure fully comp for me. Same as a ZXR400. It's horses for courses... I'd stick to the 650 twin or 400 4cyl.

(Though I have seen a nice TZR250 3XV for sale near me....)