fitted jet kit to 98 zx9r + dyno graph

SocialSecurity · Post by **SocialSecurity** » Fri Nov 25, 2005 7:59 pm

Hi

I had a factory jet kit fitted to my 1998 ZX9R that runs a full akrapovic system, stock air filter, stock everything else...

the mechanic fitted 150 mains on cylinders 1 & 4 and 152 mains on cylinders 2 & 3, and changed over the needles and springs for the ones in the kit

below are links to pics of the dyno print outs (sorry for the quality):

http://www.members.optushome.com.au/nin ... /dyno1.jpg

http://www.members.optushome.com.au/nin ... /dyno2.jpg

the red line being before jet kit, and the blue line being after jet kit. The carbs had factory 142 mains in all 4 cylinders (stock is 155 i think?), but did not appear to have the same needles or springs etc as the jet kit.

this dyno reads a bit lower than most others in the area (for comparisons sake he had a 2000 R1 make 118hp on it) but im not so much concerned about the peak power, but just that its running as good as it should be.

I keep hearing about ZX9R's that want to lift the wheel at 4000rpm in first gear, certainly not something my bike will do in any hurry. Any suggestions on ideal main jet selection, needle height settings, float height etc etc?

Thanks

Post by **MadKaw** » Fri Nov 25, 2005 8:40 pm

My 98 zx9 had a factory pro jet kit which also came with 142 mains. Now with stock being 155's you'd think this was a bit lean bit with the other components it worked fine, at first.
My 9 had a full Akro, ignition advancer (4 deg), some head work, intitially the stock filter with the mesh removed then a BMC race filter. It also had straight through air ducts and the exhaust air injection (kleen) system removed so it breathed pretty well... It was running lean so I had it on a dyno to check it out, the clown put a set of stock 155's in it and ran shit.
I then put a set of 158 mains in it and ran like a dream.. last time it was on a Dyno it put out 149.? hp.... on most dyno's it was generally about 143 +....
http://www.factorypro.com/Prod_Pages/prodk67.html

SocialSecurity · Post by **SocialSecurity** » Fri Nov 25, 2005 8:44 pm

just noticed the instructions suggest running 155's on the outside carbs and 158's on the inside carbs if you have a 'competition exhaust system' where it recommends 150's on the outsides and 152's on the inside if you have a stock pipe or slip on, and thats whats in there now ...

think i might try the 155's and 158's along with a +4 degree advancer

might leave the air filter for now, i hear its not a huge advantage any way

but looking at my current A/F ratios, is there anything to gain?

SocialSecurity · Post by **SocialSecurity** » Fri Nov 25, 2005 8:56 pm

hey looks like a letter from you down the bottom of that page

btw, what height were your needles and floats set to?

cheers

Post by **MadKaw** » Fri Nov 25, 2005 9:03 pm

Can't remember the needles but floats were about 13 to 14mm pretty stock I think.
The easiest mod is to take the mesh out of the std filter its worth a couple of HP on its own and doesn't have any ill effects...

SocialSecurity · Post by **SocialSecurity** » Fri Nov 25, 2005 9:10 pm

i think mine already has it taken out, its just a brown foam that looks like a door mat with a white plastic frame around it?

might give it a clean tho

MadFab · Post by **MadFab** » Fri Nov 25, 2005 11:52 pm

my nine goes like fuck

fab

SocialSecurity · Post by **SocialSecurity** » Sat Nov 26, 2005 12:01 am

top stuff there

Post by **MadKaw** » Sat Nov 26, 2005 7:28 am

MadFab wrote:my nine goes like fuck

fab

Yeh, I did a good job with it didn't I...

stevew_zzr · Post by **stevew_zzr** » Sat Nov 26, 2005 1:15 pm

I'm no motorbike tuning expert, but i would say that the A/F ratio is probably still a little bit high where you are making peak power. Slightly larger jets may help, but also now that you are running a slightly rich mixutre (looks like about 13.5:1) you really need to advance the timing a fraction to take advantage of the slower flame-front. You'll probably see quite a big gain once you get the timing right (not going to quote numbers).

SocialSecurity · Post by **SocialSecurity** » Sat Nov 26, 2005 2:15 pm

yeah im definately keen to get an advancer in place, probably +4 degrees

gonna throw in 155 (outside) and 158 (inside) staggered jets and what ever needle and float height factory suggest

SocialSecurity · Post by **SocialSecurity** » Sat Nov 26, 2005 7:34 pm

ok i fitted 158/160 mains (there were no 155's in my jetkit!), set float height to 16mm (from 13mm), left the needles on the leanest setting, left the pilot screws on 2 turns out... also got rid of the exhaust air injection setup

what can i say... the dunlop D208 on the rear will happily wheelspin in first when cold!

it feels a lot snappier around 5k, the front is pretty light now, i can feel the forks stretching out all the way under WOT

however it still feels a little strangled in the top end

Aussie Ninja · Post by **Aussie Ninja** » Sat Nov 26, 2005 7:42 pm

Nice one. I know it costs money but you need to get her back on a dyno to get it exactly right. Not that I can talk 'cause I haven't, but I'm sticking with the excuse that the nearest one is currently 7 hours away.

SocialSecurity · Post by **SocialSecurity** » Sat Nov 26, 2005 8:41 pm

i might have a little bit more of a fiddle still, and stick on a +4 degrees advancer... i rang up brighton kawasaki and they had one in stock for about $120

SocialSecurity · Post by **SocialSecurity** » Sat Nov 26, 2005 8:54 pm

MadKaw wrote:Can't remember the needles but floats were about 13 to 14mm pretty stock I think.
The easiest mod is to take the mesh out of the std filter its worth a couple of HP on its own and doesn't have any ill effects...

i was wrong, my filter still has its mesh on it

so ya dont think it'll require any changes to the float levels or anything if i take the mesh out?

raising the float levels (as in less fuel in the bowls) seemed to help quite a bit, the choke never used to help at all when starting cold, made it worse if anything... now it runs like shit till its warm unless you use the choke

a good sign im sure.