Dyno print out

[c-m]

I have a ZX9R 1999 model with about 27k on the clock.

The bike is totally standard apart from a carbon can company end can.

I love the bike and it rides well, but there is something not quite rigtht. What can you tell by this print out?

https://img26.imageshack.us/img26/5573/25022007055.jpg

[c-m]

does this look ok?

I'm finding that bike is really bogged down around the 3rpm mark and the power starts coming in all of a sudden. Not great for the winter.

How do i adjust the carbs to fix that?

[Billing]

when was it last serviced? if it hasn't been serviced for ages then it won't help the running.

other than that i don't know what to suggest :S
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[Kickstart]

Hi

Nothing obvious and certain, but there is a drop in the power at ~35mph (which could well be the 3k mark), but that is close to the start of the run and might not really be meaningful. However looking at the mixture it appears to start of VERY leak and then go pretty rich to start with before returning towards normal. That 12:1 is a bit rich, probably a bit too rich.

My GUESS would be that the slides are opening too far when the throttle is whacked open, then returning to a better position. Almost like their movement isn't damped enough. Possibly playing with the springs and the size of the holes in the slides would help this (ie, basic Dynojet kit fiddling), but probably best to have a word with a bod who is good at setting up engines on a dyno.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[G]

On my zx9, it's quite noticeable that it works better pulling on the power as the revs increase from low down, rather than going straight to wide-open-throttle. This is more obvious in higher gears, where on a 600 it would definitely have serious problems, but mine (which is downgeared and tuned to some degree) you can get away with more.
Mine isn't great from low revs, but on the dyno graph I've got, it's quite obvious the fueling is off there.

[c-m]

Any guestimate how much i'm looking at to take the bike to someone and have them smooth out the rev range and optimise fueling?

[woodyfjr]

Before you do anything with the carbs sort out the valves and give it a good service first.
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[chris-red]

It's a high reving sports bike sports bike must redline at what 14k? They don't usually work below 4k. I thought that was fairly standard on 600 sports. I don't exactly think there is a problem. If you want something that doesn't bring the power on quickly buy a cb500.


That dyno graph I assume is top gear(maybe 5th) roll on, If you are sitting at idle in top gear(or 5th) and crack the throtle there is gonna be some lag.
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[Kickstart]

Hi

It is a ZX9R not a 6R. Think the red line is at 11~12k.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[G]

Pretty sure it's 12k (haven't had the clocks on mine for a while).
In low gears it provides 'brisk' acceleration up to 4k, then altitude control above that, but as said, mine is downgeared a reasonable chunk, etc.

[c-m]

its things like pulling away from the lights thats a problem. It will start to go nicely but between 2.5-3.5rpm is will splutter and jerk and barely move, then all of a sudden a rush of power comes in. If i'm not careful this can easily spin up the rear in the cold damp conditions.

The valves and carbs were done just 3,000 miles ago, they're not due again for another 4-5k

[Kickstart]

Hi

My FZ750 used to be like that when it had a Micron exhaust. Well known problem with Microns on them (and solved when I put a Laser pipe on it), and on those was difficult to avoid just by playing with the jetting. Don't know on the ZX9R though. The FZs do suffer from worn atomiser tubes screwing up the mixture as well, which I thinkthe ZX9Rs suffer from as well.

It was a total pain when trying to get onto a roundabout at a normal pace in the wet. Clutch out, not much happening, naturally putting more throttle on, and then suddenly then engine wakes up.

A decent dyno shop should be able to advise you but not sure where any are over your way.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[stevo as b4]

[c-m]

Only E and F models had a cat and produced less power than the C models.

I am using the original 4 into 1 exhaust. The common opinion is that just a change of end can should not require a rejet. However common opinion is also that the carbs on the ZX9R were particularly sensitive (fickle) about changes.

[woodyfjr]

Have a look at the diaphams you may have a small hole which would cause poor fueling.
____________________
If you don't pay your exorcist you can get repossessed.

If you have to rev it! Don't Buy it!