Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

kawasaki Zx7r ..aftermarlet muffler/rejetting/mods

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by rayzrider65, Sep 18, 2008.

  1. Hey guys,I have bought a zx7r it's a 1996 model 26k,has a aftermarket muffler.the guy i bought it off said just use a little choke..which I did for the first 10 rides..a couple of days ago I thought I will just use the choke fully and see how it goes..shhhhhhiiiiittttt.half aclick up the road the bike started to miss on 2 cylinders,,it really scared me,thinking I had blown the engine..the choke was off at this point..I thought just keep goin and get to work..luckily 4km later the motor fully kicked in..So I suspect the motor was flooded with choke on,and soaked the plugs
    ..So does a change in back pressure(muffler) really affect the way starting needs to be done,I had a zx6r with standard everything and it needed the choke everytime,anyway in future i am reluctant to use the choke on this bike unless really neccessary..

  2. It's been a common practise for many mechanics over the years to fit slip-on mufflers and then "over-jet" the engine.

    It accomplishes nothing more than poor low speed running and excessive fuel consumption. (Not to mention poisoning my kids planet!)

    You SHOULD need to use the choke on a cold morning to start a correctly tuned 4 cylinder motorcycle.

    I'd start by returning the carburettor settings back to standard. You'll probably find the needles have been raised. Richen the idle/air bleed screws by half a turn and fit some new plugs.

    That should give you a good baseline setting.