high revs at 100km/h?

[merv]

...I dont know if its been geared down ..what do you all reckon?

Just count the teeth on your front and back sprockets and compare them to what they are meant to be stock. Have you got a owners handbook to look that up? It would be unlikely that any changes have been made to gearing inside the engine cases so sprockets are the best check.

6,000rpm at 100km/hr though sounds about what I'd expect for a 400 and this is backed up by the comments posted so far.

VFR750 does 4,500rpm at 100km/hr with 11,500rpm redline.

My DR250R doesn't have a tacho but doing the calc on the gearing it would be doing about 6,250rpm at 100km/hr on stock gearing, but then it doesn't have the rev ceiling that a small four does and would top out around 9,000rpm I would expect. That's single cylinders for ya.

[georgedubyabush]

At these kinda revs can you imagine a piston breaking free, punching through the tank and smacking you in the chin

My bike red lines at 18500 revs, when you think about what that actually means it's quite amazing.
A piston probably smaller than a shot glass changing direction 37000 every minute (616 times every second) .

Isnt it all about piston speed?
The reason why the 250s do up to 19000rpm is because the piston isn't travelling very far, so the actual piston speed is comparable to bigger bikes and not really so amazing.
The tiny valves must move pretty quick though.

[Kwaka-Kid]

yep, i think so george, and how big/heavy the piston is... i think of the mighty XR500 engine in my garage, with a stock redline @ 6,500. But because its worked up as a race engine it now redlines @ an approx 13,500rpm.... mmm imagine that.. big heavy 500 single revving out to what the modern 400x4's do!

[gpercivl]

yep, i think so george, and how big/heavy the piston is... i think of the mighty XR500 engine in my garage, with a stock redline @ 6,500. But because its worked up as a race engine it now redlines @ an approx 13,500rpm.... mmm imagine that.. big heavy 500 single revving out to what the modern 400x4's do!

Hey KK, you should whack that motor into your VFR frame and go out and kick some serious butt in F3...I had heaps of trouble staying in front of a relatively stock engined XR-650 super motard guy at Ruapuna

[fpsware]

My 400 buzzes along at 6000rpm in 6th at 100km/h...To me this seems a bit high...I dont know if its been geared down I hardly ever need to shift down to overtake and can leave it in top round town at 50-60km/h...seems a waste of a 6 speed cog box...what do you all reckon?

I just recently went from a Suzuki FXR 150 to a Kawasaki ZXR 400. When I first road it I thought my revs were TOO HIGH. Doing 100Km/hr at 6000 rpms seemed to rev too much (red lines at 14000). But after having it a couple of weeks now I feel very comfortable with it. I really don't think anything of it now.

If I want to pass something doing 100Km I just give it a little more gas, there is no need to change down. Its got more than enough grunt to pass. I can do things on this bike in 6th gear that I couldn't do on my FXR in 3rd gear.

[madandy]

OK now i'm happy to say you've all answered well and I agree that having the engine reving at 6Krpm is normal and quite sensible!Esp. hearing from other 400cc riders who rev similar.
It is good ,in a way, to be able to overtake easily in top with just a little twist.

Thanks a lot
Andy

[MacD]

There is some information about the RF400 on this RF site as well as some photos. Supposedly the RF400 has variable valve timing (something like Honda VTEC) so you may find there's a distinct jump in power at higher revs?

There is also a Yahoo RF Forum which has some interesting threads from time to time although you need a Yahoo (email) account to join.

And for an impressively complete site of information on Suzuki bikes check out www.suzukicycles.org . There's a guide to decoding VIN numbers in the FAQ section too.

And yes, I did spend a lot of time searching the web when I bought my RF900

[Hitcher]

Just count the teeth on your front and back sprockets and compare them to what they are meant to be stock. Have you got a owners handbook to look that up? It would be unlikely that any changes have been made to gearing inside the engine cases so sprockets are the best check.

The latest Motomail catalogue has an absolutely wizard table in it that tells you the numbers of teeth front and rear, numbers of links (and the cost) of your ride's bog-standard OEM setup. Saves getting all greasy and having to take your socks off to count teeth...

[SPman]

Having regeared from 16/39 to 16/43, 100 kph in 6th equates to....5102 rpm! (According to my gear ratio program)
With the original gearing it was 4630rpm

[bungbung]

6krpm @ 100km/h on my old GSX400X

[Motoracer]

I suppose this thread's probably gone stale by now... but I'd like to share the fact that my FZR400 revs at around 6800rpm (over 6500 anyway) at 100kmph with stock gearing making it the revviest 400 I've known.

Generally speaking I guess the weight, bore and stroke of your pistons are directly proportional to the revs you can achieve, whereas the number of pistons is inversely proportional to it (due to less weight & better inherent balance).

I've always thought gas turbine engines (like in the Y2k) should be the way to go as there are no reciprocating parts like pistons. Only problems with them are weight and length of the engines..

[slob]

Whoops! That last post was by me, but my browser automatically logged me in as Motoracer...(he's my brother) :confused2

[merv]

I've always thought gas turbine engines (like in the Y2k) should be the way to go as there are no reciprocating parts like pistons. Only problems with them are weight and length of the engines..

Other problems (who remembers the Chrysler turbine car when it toured NZ?) are lack of throttle response - take a while to wind up and then they go, lack of engine braking - reverse thrust flaps needed or something like that eh!, lack of fuel economy and heat - they may have fixed those two in newer designs.

They were great when they tried them in Indianapolis cars but then that was long distance flat out racing with little need to vary the speed rapidly so I doubt they would ever have been any use on a twisty F1 circuit.