fitted jet kit to 98 zx9r + dyno graph

[stevew_zzr]

Actually alot of turbo cars run a hell of a lot richer than 11.8:1 - try more like 10.0:1 or 10.5:1.

Yeah tuning to a ratio is not the *best* way to go about things, i'm just noting that on your previous dynographs you were running alot closer to stoichiometric than that.

Turbocharged cars don't suffer from 'back-pressure' problems (unless you do something stupid with the cam profile), detonation is usually due to high intake temps, hot exhaust valves and/or poor heat management.

It's likely that 91 octane petrol isn't knock-resistant enough and hence with the increased advance - will be a pain to tune for.

[mike-s]

i'd take a punt and put plain 95 Ron fuel in there nexttime, see if that makes a diff. From what ive heard bikes run close to detonation on normal 91ron with the 12+:1 ratios they use. Hence some of the manuals for higher performance bikes recommending premium and no less.

Failing that, take the advancer out and see how stock ignition timing works for you, hell it might be more useable.

[SocialSecurity]

my understanding was that turbo engines tend to have less issues with pinging when they have larger turbines/ex housings and better exhaust manifolds (like a tuned length custom jobby vs a stock log manifold) due to the engine being able to get the exhaust gas out better... but thats another matter


as for the original dyno graphs, i have made many changes since then, and have no idea what my currenty ratios are as i dont realllllllly care, im going for the best seat of the pants power, and my 'seat' is fairly accurate

have taken the advancer out and it feels a lot better, tho it needs more work to the float levels (currently on 14mm, which is a touch lean methinks, 13mm was too rich but 13.5mm was just flat... but i bet it would be ideal now with no advancer) ....but i could not be arsed touching them.... i wanna try it with the advancer in and some 98 octane juice which is denser so tends to run a little richer, thus not having to pull the carbs off and piss fart around with floats yet again

[mike-s]

I always took the intake/exhaust/turbo "flow" stufff to mean a better flow of fuel-air/exhaust into and out of the motor.

I've always understood pinging being related to the fuel/air mix detonating rather than burning. Hence if its pinging (i.e. detonating) and you put in a higher RON fuel (Research Octane Number), it will have a higher threshhold before it detonates and will burn hopefully cleanly, and push the piston properly via expansion, rather than detonating and sending a mini shockwave that may hit the piston before it hits TDC (and hence the Pinging sound / hammering the shit out of the engine internals).

<disclaimer>This is where it gets a bit hazy and blurry in my eyes through lack of knowledge</disclaimer>
If you ignite the fuel too early it can cause problems (which i admit i dont know enough about to comment too much on), but if you try stuffing too much air/fuel into a fixed space, you can get detonation/pinging and the above problems. This could be by whacking a turbo on a stock motor, or running too low a RON fuel in a high compression motor.

Which is why they lower the compression ratios in turbo cars/bikes. It can get the expansion from a lot more gas in a small chamber, but it doesnt detonate due to it being too highly compressed during ignition.

So how'd i do?

[SocialSecurity]

i think a quick google will bring up more info than im currently keen to take in


cant wait to try some premium

[Gosling1]

well, jetting is almost 100%

dropped down to staggered 155 (inner) and 152 (outer) main jets and hey hey - crazy power. midrange is really violent now too, using 2nd clip from the top on the needles....

so you are back to stock jets (inner), and 1 size smaller (outer) ? Clip position 1 notch leaner ? and still fluffy under 3k........

Better to run premium in it, run the stock advancer, floats at 14mm (those carbies must be *extremely* sensitive to float height changes....), and slightly leaner on the pilots.....

only my 2c worth, I bet you could teach a few shop mechanics about the quickest way to get those carbies on and orf !!

[stevew_zzr]

my understanding was that turbo engines tend to have less issues with pinging when they have larger turbines/ex housings and better exhaust manifolds (like a tuned length custom jobby vs a stock log manifold) due to the engine being able to get the exhaust gas out better... but thats another matter

Yeah as i said that's more a case of the heat-management not being particularly good. If you can't get heat out of the exhaust valves because the temperature of the coolant/oil is too high, or there is poor flow (as is often the case on a turbocharged motor if ineffective oil cooling devices are fitted or the radiator is insufficient) then getting exhaust gases out quicker will clearly help. But the higher the velocity of the exhaust gas flowing *out* of the turbine housing, the less force the turbine has to force the compressor wheel - so the less power you can make.

But aside from that, the fuel ratio is usually set quite rich because the intake charge temperature is higher, the high combustion peak pressure, and also because manufacturers have warranties to fulfil - and they *purposely* run things at safer levels (and I'm not complaining!).

lets get it straight -> detonation is where the fuel temperature itself is high enough in order for it to activate it's own combustion process - ie before the spark plug has even fired.

If you run too much ignition advance then you could get pinging/knocking - which is similar in that a shock-wave reflects off the piston and back onto the head and so forth, often due to the high pressure causing more 'detonation' which creates other shockwaves (which is why you start losing power). One theory (that i subscribe to) is that due to constructive interference the shockwaves can develop significant enough force to 'wash away' the very fine layer of air near the piston crown which exposes the piston directly to high levels of heat on a focussed area. Hence you get melted pistons.

Back to the case at hand -> sounds like the ignition advancer was stuffing things up, so best to take it out and tune it for the 91 RON. Lower octane petrols will burn *faster* and hence if you try to run too much ignition advance with them - you have to run power-unfriendly rich mixtures.

If you do want to get more hp, then you will eventually need that ignition advancer back in there - or alternatively a completely different ignition management system, and also run a higher octane petrol.

[SocialSecurity]

mate i can get the carbs off, adjust float heights and everything back on ride in ride out in 45 minutes.... it was a 2 hour job on my old gixxer750!


some interesting tech info there.... hopefully we can discuss that further if i ever make a topic "just fitted turbo to my zx9r!!!!11"

mark suggested running staggered needles and floats perhaps, and that im not alone in my problems... the pilot circuit isnt ideal either but its functional... not toooo worried about cruise for now


im definately keen to use the advancer, the bugger cost me $125! and it had a lot more low throttle snap, even if it might have been pinging its tits off... but yeah need to up the octane for that


cheers for the input guys

[Nanna10r]

Just had my 02 9r dynoed n jetted last week. Found just under 8 hp in 38 degree celcious heat. Needles on the middle notch, mains reduced from OEM 165/162 ? to 158/155 s. Gurgles & pops under deceleration & pulls like a "boy scout watching the Pammy & tommy avi" from 5500 rpm through to redline
Why wouldn't anyone run 98 ron in a sports bike ? False economy imho.
Anyone know anything about a possible replacement of the main needle seats i was told you have to buy new carb bodies when they completely flog out.
Cheers Brett

[SocialSecurity]

the 2000 onwards 9R's have different carbys, and as such they jet completely differently...

have you disabled KLEEN? helps with the popping on decelleration


as for running high octane, without the timing advancer i wouldnt bother...

you really need EFI with a knock sensor and O2 sensor to get the most out of 98

[SocialSecurity]

fiddled a little with the pilots and needles with no real success... put everything back as it was ... and stuck the advancer back in (gonna fill her up with synergy 8000 tomorrow morning) and took her for a quick lap....

bugger me! its 50 times better with the advancer than without it... even if its a bit rough down low, it just makes soooooo much difference!


if you have a 9R, get an advancer. 4 degrees rocks but you can get 6 degrees too... would need some fairly specialised tuning for that tho possilby...and definately 98 octane

[MadKaw]

fiddled a little with the pilots and needles with no real success... put everything back as it was ... and stuck the advancer back in (gonna fill her up with synergy 8000 tomorrow morning) and took her for a quick lap....

bugger me! its 50 times better with the advancer than without it... even if its a bit rough down low, it just makes soooooo much difference!


if you have a 9R, get an advancer. 4 degrees rocks but you can get 6 degrees too... would need some fairly specialised tuning for that tho possilby...and definately 98 octane

Yep, I think I mentioned that on page one..
although I wouldn't bother on a stocker but with a full system and jet kit the advancer really does help....
Surely your sick of mucking around with it by now and just wanna ride it... ?
How did it come up after the crash, the last pic I saw it had a rather insightly ding in the frame...

[SocialSecurity]

supprisingly it still rides as well as it ever did while i owned it...

yes im definately sick of taking the carbs off but i ride it plenty any way


im gonna have to pretty it up, everybody at work gives me heaps when they see me get on it i look out the window during the day and see people walk past it, stop, walk back and stare at the damage for a few minutes and poking it

still, of the 6 or so bikes parked at my work, im the only one with no chicken strips

[SocialSecurity]

filled up with synergy 8000 today (98 octane) ... it took about 15L, so there must have been about 3 or 4 litres of ULP in there still, and fuck me, its running like a dog! seems like its running seriously rich... its a bit smoother down low where it might have been pinging on ULP, but has about half the grunt...


this might explain why the bike had 142 mains in it when i got it, and yellow fuel in the tank.... tho i only ever put ULP in it till now i might make the next tank ULP, then try some normal premium (95-96 octane) ... it seems 98 is just way too dense, and i cant be arsed rejetting all over again

[SocialSecurity]

OK its official! i am FINISHED tuning this biotch!


well, i think its as good as i can get it that is...


back to 4 x 155 main jets, staggered needles with 1 & 4 on 1.5 clips from the top and 2 & 3 on 2.5 clips from the top ... floats on 13.5mm, and pilots set to 2.25 screws out


power is now nicely usable from a bit above 3k, depending on the gear.... if its in top gear it will just stumble if you crack the throttle open at anything slower than about 80kph... but it pulls reasonably from 90 in top gear now... midrange is pretty damn violent and top end is nicely crazy

i think i desperately need a balance too... not sure if that will help the low down fluffyness, but its not running very cleanly on light cruise, lot of popping/stumbling... hopefully a balance will help that.... now whos got a manometer nearby?


hopefully hit the 1/4 mile sometime soon and maybe a dyno