high speed running

[RAYZ1]

Ny z1b hasnt been used as nuch as it should and I know he pilots were a bit blocked and a good 100 mile run has low speed running spot on. problem I have at about 5-6k rpm - giving a decent handfull of throttle the engines lurches before it picks up. This can also be the case if you work it hard through the gears then ease off and reopen the the throttle, it feels like starvation

The carbs wer cleaned, stripped , new jets etc, std air box , std 4-4, the needles were set to middle position on the slides

I think its suffering from fuel starvation, in which case I was going to try raising the needle a notch, as this problem doesnt appear till about 75-80mph on full bore

Any other ideas before I do this ?, could it be ignition or would I see the problem through the rev range?

Ray

[Pigford]

I think its suffering from fuel starvation, in which case I was going to try raising the needle a notch, as this problem doesnt appear till about 75-80mph on full bore

Any other ideas before I do this ?, could it be ignition or would I see the problem through the rev range?

Ray

Ray: you say "suffering from fuel starvation" ..... if thats the case raising the needle won't help You need to check flow from the tap.... also make sure the filler cap is venting well. Try running a good gallon or so thru the tank into a container & time it... then you can eliminate that side of it.

The ignition is unlikely, but not impossible that its the culprit

Do a "plug-chop"...... Go for a hard run at the "problem" speed with fresh plugs fitted..... then cut the ignition, clutch in and coast to a stop and check the plug colour.

[RAYZ1]

Ray[/quote]

Ray: you say "suffering from fuel starvation" ..... if thats the case raising the needle won't help You need to check flow from the tap.... also make sure the filler cap i.[/quote]

yes I had a gpz9 which had a blocked cap and it was like running out of fuel if you were giving it a lot of throttle at high speed, it even ground the bike to a halt with a massive vacum release whe I opened the cap

So it does feel like that, except its a new cap, with an nos petcock and the tank was cleaned and sealed before fitting the tap, it looks like new inside, the carbs were meticoulsly built and all jet ways cleared and it didnt do this 2 years ago after the rebuild

i thought raising the needle a notch would low more fuel at higher rpm but maybe not, it could be one of the mains blocked or I supose a faulty plug or coil breaking down under load?

maybe a new set of plugs 1st, thats the easy option, the other thing Im considering is a new elec. igntn, the back plate thats on struggles for range as its a pattern one, although I may have the original somewhere

Ray

[Pigford]

i thought raising the needle a notch would low more fuel at higher rpm but maybe not, it could be one of the mains blocked or I supose a faulty plug or coil breaking down under load?

Raising the needles will help from approx 1/4 to 3/4 throttle opening.

You stated "this problem doesnt appear till about 75-80mph on full bore" which is when its down to the main jets - the needles should be out of the equation by then

Always a pig (sic) to eliminate these running problems. Just gotta keep at it, one thing at a time. My GSX1100 Effer was running a tad off the money - so yesterday stripped the carbs (again) went back up a size on mains & re-set pilots in half a turn, then re-balance carbs statically....... Bike runs much smoother now

[RAYZ1]

i thought raising the needle a notch would low more fuel at higher rpm but maybe not, it could be one of the mains blocked or I supose a faulty plug or coil breaking down under load?

Raising the needles will help from approx 1/4 to 3/4 throttl..

, i would say 3/4 to full throttle, as if you try and accellerate form 70-80 with either 3/4 or full throttle say in 4th its lurching before it picks up and I dont think its making the power. I will strip the carbs off and check them out as sitting about seems to be the main cause

thanks

Ray

[tricky]

have you checked your service fuel level? just a thought.

[RAYZ1]

have you checked your service fuel level? just a thought.

I did at the time , but I will check as I have the right adapter