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Fuel Starvation ??
Posted: Sat Apr 28, 2007 8:44 pm
Author: mysticzed
I've got a Z900 with a 1075 conversion (400 miles since rebuild), standard carbs, bell mouths and Pingel tap.
Fuel pipes from Pingel to carbs have air bubbles which seem reluctant to depart. Some 'light' black smoke from Vance and Hines at low revs.
Bike pulls like a train to 5.5-6k then starts to die.
It feels like:
i) Fuek starvation
ii) Or a tight engine
Any suggestions, additional diagnostics would be appreciated.
Any observations re use of standard carbs vs alternatives also welcome.
Thanks.
Posted: Sun Apr 29, 2007 9:57 am
Author: Pigford
Mysticzed, are carbs on std jetting/set-up
The whisps of black smoke means its running RICH. If it runs OK up to 5/6k rpm, is this on a constant run (over some distance) or just acceleration

When you throttle back from6k, does she run OK again, straight way or after a while
Try going at it until it starts to die then slowly wind throttle back & see if she picks up again. Does she clear 6k rpm with part throttle, in other words is it WOT (wide open throttle) that kills her?
Posted: Sun Apr 29, 2007 9:19 pm
Author: mysticzed
Hi Pigford, unfortunately haven't had time today to take it out....I haven't pushed it as I don't want to create any problems....will rev freely in neutral.
Always pulls like a train up to 5.5.-6k revs even if you back off the throttle, doesn't matter if its constant or under acceleration.
Get where you are coming from re throttle opening, unfortunately won't be in a position to try this out until later this week
What is the rich running likley to be from...flooding in a carb ?
Thanks for the help
Posted: Mon Apr 30, 2007 6:20 pm
Author: Pigford
Could be many things
Hows the electrical side, points? std coils? recently timed, plugs etc. This stuff needs to be spot on first.
Posted: Mon Apr 30, 2007 7:54 pm
Author: Garn 1
Myst', when you step up from 900 to 1075, it is usually mandatory that your "standard" carbs are re-jetted, particularly with ram tubes and your V&H 4 into 1. Running on normal setting would conform with your title "starving for fuel".
RegardZ.
Posted: Mon Apr 30, 2007 8:00 pm
Author: Pigford
Yeah, what changes since kast running right, are bell mouths new & 4:1

Posted: Mon Apr 30, 2007 9:37 pm
Author: mysticzed
Guy's bought bike like this, done 75 miles, haven't taken carbs off yet...will do so this w'end, to check jets, if they are standard how much bigger should I go ?
Posted: Tue May 01, 2007 8:14 am
Author: rickman CRR
The bellmouths will be sucking so much air, 130's should do it.
Posted: Tue May 01, 2007 6:09 pm
Author: mysticzed
Thanks Colin