Right this ongoing rpoblem is getting right on my tits.
1.8 zetec zx9rb carbs and megajolt.
Right iv got it revving ok when standing. When i drive it its ok up to 2k then between that and 4k is crap. if i really ease it past 4k it revs ok up
to 5.5k then drops off. If i boot or drive eagerly it it boggs down like anything at 2.5 to 3k and will actually die if i keep it trying to pull. So
much so it is undriveable and the smell of petrol is bad.
Plugs are greyish brownish. Not black as you would expect if its running rich.
Now iv cleaned the carbs sealed the diaphragms etc. Changed the fuel pump. Pressure is 2.2psi. Carbs balanced. Rewired the ignition system and
checked the timing. All is well. Still it is an arse!!
The fuel its going through is unbelievable.
Any ideas?
What bikes have carbs that arnt cv's?
I would take it to Boggs to sort out but they are too far away, so if anyone knows anywhere in suffolk or surrounding where i can take it.....
i have two zetecs running bike carbs and megajolt one blackbird set and one r6 set they both have a air hole inline with the needle blancked off bogg brothers did the blackbird set and i did the r6 set otherwise they did the exact same thing you are describeing its got somthing to do with leaning bike engines off high up the rev range
They have that done.
what size mains have you got
155's.
thats dosnt seem a million miles away ive a 1.8 with 165 mains and the 2.0 with blackbird carbs has 170 mains
I've never used him but have often heard good things about Peter Baldwin at Wilshers Garage in Wimpole (next to Cambridge), apparantly a wizard
at setting up Crossflows on his rolling road, Zetecs arn't so different, might be worth a look perhaps.
Kev
Edit: http://www.wilshers-garages.com/
[Edited on 15/2/09 by flibble]
Any rolling road is better than none, whether or not the operator has experience of your particular set up.
He will be able to see if the timing or mixture is wrong, and that's what you need to know
John
Not valves is it, seems youve tried everything else. I had a similar problem with a Pinto & webers it was a sticking valve, try a compression test
sometimes you can be blinded by the obvious.
Cheers,
Bob
I have used Peter Baldwin in the past , he set up my x flow when it was on carb and clockwork ignition. Found another 10 BHP and 1000 more usable RPM . Don't know if he would be interested in megajolt and bike carbs but worth a phone call
What have you done with the choke?
its not flopping about is it ?
What ignition are you using ?
dizzy or mega-spark
I have megajolt, the choke is connected to the sierra bonnet pull so doesnt move anywhere.
Can you post a full list of your set up please IE
main jet size
how the needle is set
air holes blocked
air screws set
etc etc
Graham
Errrm
Air screws 1.5 turns out
standard non adjustable needles but iv tried slightly longer non adjustable needles which made it worse.
155 mains
air holes blocked inline with needles
38 pilots
zx9rb carbs.
[Edited on 15/2/09 by Danozeman]
[Edited on 15/2/09 by Danozeman]
Have you fitted a lambda sensor boss into your exhaust system yet?
Just a thought...
Not yet mate no. Im working on it.
Have you checked that the timing is actually advancing when the engine speed rises? Sounds a bit like retarded ignition timing.
quote:
Originally posted by rusty nuts
Have you checked that the timing is actually advancing when the engine speed rises? Sounds a bit like retarded ignition timing.