new exhaust = jetting = questions

raffiki · Post by **raffiki** » Sat Nov 12, 2005 11:01 am

i've just got a 2nd hand akrapovic evo system for the 7and i'm not sure about the whole jetting issue.

i've spoken to balls, cosways and the local joint down the road. balls and the local guy said stage 2 factory jet kit 450$... but cosways said thats a load of crap, all you'll need is the main jets changed and they'll only cost about 7.50$ each.

i'm going to see brighton and race replica as well but i was wondering what the hell is the difference between getting a 'jet kit' and just getting the main jets done? is the 'jet kit' thing just a load horse shit?

Post by **icebreaker** » Sat Nov 12, 2005 11:32 am

with balls find out if that includes full tuning, dyno and stuff..

I 've heard that they do a pretty good job tuning and getting more power out of your engine. Simmo has his ZX9 done there, and from memory he was pretty happy.

My understanding is that if you go a full system you SHOULD have the jets done, and that you would need to get it completely tuned to prevent lag spots through the rev rainge.. you might not need a complete set of jets replaced but who knows where you bike is at now compared to another zx7 before as well as after the system is fitting.

but having said that.. fit it.. try it out who knows how it will run. and then
next service get it done perhaps? *shrugs*

Stereo · Post by **Stereo** » Sat Nov 12, 2005 11:51 am

My last "Jet Kit" for my CBR600F3 included...... wait for it...... some new needles...

The standard needles arnt adjustable, the jetkit needles were...

They installed them wrong... they were morons...

Once installed properly it gave much better power throughout the rev range..

raffiki · Post by **raffiki** » Sat Nov 12, 2005 12:03 pm

so when i stick on a new system does the jetting need to be done straight away or can i ride it but it will just run like shit? i was under the impression that the jetting needed to be done as the bike would run lean and lead to engine damage or something like that...

Stereo · Post by **Stereo** » Sat Nov 12, 2005 12:22 pm

raffiki wrote:so when i stick on a new system does the jetting need to be done straight away or can i ride it but it will just run like shit? i was under the impression that the jetting needed to be done as the bike would run lean and lead to engine damage or something like that...

not sure about engine damage, but yes, it will run lean and backfire a bit when you back off the throttle...

I ran around for about 8 weeks before getting the needles done...

mike-s · Post by **mike-s** » Sat Nov 12, 2005 12:28 pm

I thought that backfiring was caused by running rich

Speaking of which, anyone know a fairly good tuner in Sydney? im still trying to figure out if/by how much the gpx is running rich.

Barrabob · Post by **Barrabob** » Sat Nov 12, 2005 12:34 pm

could try one of these http://ivansperformanceproducts.com/zr7.htm

is a tried and tested thing but i didnt check out the price.

Aussie Ninja · Post by **Aussie Ninja** » Sat Nov 12, 2005 2:33 pm

A Factory-Pro jet kit comes with main and idle circuit jets, variable height needles and instructions for setting the float levels and idle screws. There aren't any dyno's here in the sticks so I fitted it myself after putting a full yoshi on my '98 6R. The jet kit worked fine "out of the box" and after a little fine tuning I've got it near enough to perfect for me and I'm a picky bastard. Your bike will still run fine with the factory jets, but eventually you'll burn your valves and other fun stuff, escpecially if you do track days. There is also alot more grunt to be had by setting the carbies exactly right. Even from the factory the sizes are a bit jeneric as no two engines are exactly the same. Try http://www.starcycle.com. I paid $180 to my door.

balanse · Post by **balanse** » Sat Nov 12, 2005 3:20 pm

I thought that backfiring was caused by running rich

Yeah, I'm trying to work this out too....mine (ZRX1200R) has a full Muzzy and a Dynojet needle kit. Bought 'em both on the Internet and fitted the Muzzy pipe as soon as I got it, but being a lazy bastard didn't pull the carbies and do the jets. Run it like that for about a month and it ran fine but popped like a bastard on overrun. :cry:

Finally got sick of the sound of it and fitted the jet kit to "stage 1" instructions (Dynojet kits offer stage 1 and stage 2 in the same pack - stage 2 is for if youv'e modified the airbox or running pods etc). Runs a lot stronger I must say (so I guess it needed it) but guess what? Still pops like a bastard on overrun :evil:

I think it must be lean on the pilot jet because it goes away completely when I apply some choke, but not too sure about it all. :?:

Aussie Ninja · Post by **Aussie Ninja** » Sat Nov 12, 2005 4:13 pm

I think its because in a lean situation the exhaust gas would be hotter and when it gets a sniff of fresh oxygen, bang. I think.

Edit: Oh yeah. No over run dramas with the factory kit.

SNR · Post by **SNR** » Sat Nov 12, 2005 4:15 pm

STAGE 1 is all you need. For what you have mate.
'balanse' has it right about STAGE 2, only for air box mods and ignition advancer- racer boy mods for STAGE2. Play safe with STAGE1

snr

Barrabob · Post by **Barrabob** » Sat Nov 12, 2005 4:17 pm

My 636 used to pop like crazy on the over run till i had the clean air system removed, sounded like a motorbike after that.

Dont know if there is one of these on a zrx though but it pumps air into the exhaust on the over run to burn off unused fuel and reduce emissions.

Aussie Ninja · Post by **Aussie Ninja** » Sat Nov 12, 2005 4:24 pm

Perhaps thats why mine hasn't ever done it. Part of the jet kit was giving the arse to the clean air valve.

raffiki · Post by **raffiki** » Sat Nov 12, 2005 4:33 pm

ok fair enough i think i get the picture about jet kits, but here comes the next barrage of dumb questions...

what stage do i get?
has anyone used the ivans jet kits?
has anyone here tried the vacuum mod? http://homepage.ntlworld.com/webzxr/zxr750r/Features/ventbowl.html i was wondering about peoples opinions on that little trick.

i've got a k&n filter, carbon intakes, akrapovic evo system and i'll be getting some new plugs and ignition advancer along with the jets if that has any bearing on what stage jets to get.

thanks for the site aussie ninja

i'll be buying the jets and ignition advancer off those guys since balls wanted 450$ for the jets and 120 for the ignition advancer

i owe you a beer :wink:

*edit* i think i should hit refresh before i post something, i think i get the stage question *edit*

Aussie Ninja · Post by **Aussie Ninja** » Sat Nov 12, 2005 4:47 pm

raffiki wrote:what stage do i get?
has anyone used the ivans jet kits?
has anyone here tried the vacuum mod? http://homepage.ntlworld.com/webzxr/zxr750r/Features/ventbowl.html i was wondering about peoples opinions on that little trick.

I've heard nothing but good things about Ivans kits. I've got nothing but good to say about Factory Pro however. As well as their jet kit I've got a +4 advancer that works a treat. Whenever I've emailed Marc a question he has got back to me really quickly with exactly what I wanted to know. The vacuum mod is part of the Factory Pro kit for my '98 6R and works a treat.