900A4 Carburation question
Posted: Tue Dec 04, 2018 1:32 pm
Chaps
I'm 95% there with my A4 project; she's been running 10 times better since a good friend re-did the ignition, and I've loved riding it around and feeling that joy! Carburation seemed absolutely fine, no fluffing, clean-revving throughout the range, etc, however, one issue is still the mixture; she's a KZ recently imported and had a reproduction full 4-4 system fitted, post-import and the plugs tell me she's running rich. Very sooty plugs on all 4 pots.
My logic went along the lines of "Well, it's probably had a 4-1 on it at some point in it's life, so has probably been upjetted to suit. Maybe she's running rich because it's got too bigger jets in, so I'll go back to standard".
Hoiking the carbs off for what seems the 5th time in as many months, yes, there are 120 jets in there, whereas Z-Power say they should be 115's. I am for the moment assuming she has Mikuni 26's on there as I can't work out how to identify them properly. I should also say, she has a Z1A/B Airbox too, making things more difficult to diagnose.
So - I fitted the 115's last night, thinking she'd fire up and run sweetly - however, as sod's law so accurately states, quite the opposite happened. She's running as rough as an old dog, will only run on choke (full choke gives around 3,500 RPM, half-choke gives 2,000, and no choke, it won't run.) On any of these choke settings, even gently moving the throttle causes it to bog down and die. She's suddenly smoking like hell - something she's never done before!
So dear knowledgable friends - what on earth have I done wrong? I suppose I cold have checked the needle clip settings, but I only want to change one thing at a time.
Thanks all :-)
I'm 95% there with my A4 project; she's been running 10 times better since a good friend re-did the ignition, and I've loved riding it around and feeling that joy! Carburation seemed absolutely fine, no fluffing, clean-revving throughout the range, etc, however, one issue is still the mixture; she's a KZ recently imported and had a reproduction full 4-4 system fitted, post-import and the plugs tell me she's running rich. Very sooty plugs on all 4 pots.
My logic went along the lines of "Well, it's probably had a 4-1 on it at some point in it's life, so has probably been upjetted to suit. Maybe she's running rich because it's got too bigger jets in, so I'll go back to standard".
Hoiking the carbs off for what seems the 5th time in as many months, yes, there are 120 jets in there, whereas Z-Power say they should be 115's. I am for the moment assuming she has Mikuni 26's on there as I can't work out how to identify them properly. I should also say, she has a Z1A/B Airbox too, making things more difficult to diagnose.
So - I fitted the 115's last night, thinking she'd fire up and run sweetly - however, as sod's law so accurately states, quite the opposite happened. She's running as rough as an old dog, will only run on choke (full choke gives around 3,500 RPM, half-choke gives 2,000, and no choke, it won't run.) On any of these choke settings, even gently moving the throttle causes it to bog down and die. She's suddenly smoking like hell - something she's never done before!
So dear knowledgable friends - what on earth have I done wrong? I suppose I cold have checked the needle clip settings, but I only want to change one thing at a time.
Thanks all :-)
I run 3 bikes, a 635d coupe, petrol rav-4, and Toyota hiace swb dturbo, odd one out is coupe it fills up on wrong side 
