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Zetec, bike carbs and megajolt help please.
Danozeman - 28/9/08 at 10:00 AM

Im still having troubles getting my car to rev freely. Its been like this since i put it all together.
When i rev it gently it will rev up ok. but if i try to rev it hardish it bogs down. I have tried loads of maps and various different settings but no different.
The carbs have 1.6 jets and the air by pass thing blocked up. I was playing with it yesterday and got it to rev more free, i thought id sorted it but when i drove it it bogged down again. Its okish over 3-3.5k.

1.8 zetec, megajolt and zx9r carbs.


Any ideas? Its really annoying me now as i cant get it right.

marmot0 - 28/9/08 at 10:07 AM

have you checked the timing

paulf - 28/9/08 at 10:14 AM

Are the needle heights adjustable? You could try adjusting them up or down a notch if so, also are you using a fuel pump giving the correct pressure for bike carbs?. I recently helped someone set up bike carbs and megajolt on a pinto , he was having similiar problems and eventually found one of the air bypass jets to be partially blocked.
Paul

whitestu - 28/9/08 at 02:26 PM

I've got the same setup but ZX6R carbs.

You can have a copy of my MJ map if you want.

I guess I've been lucky as mine has always worked perfectly.

The needle position on mine only makes a very minor difference.

The fuel pressure is worth a check though. I'm using a ZX6R pump as well.

Stu

David Jenkins - 28/9/08 at 03:33 PM

Sounds a lot like my original bike carb problem - OK at low revs, really strangled at higher revs. In the end I connected up my JAW AFR meter and found that I was far too rich at wide open throttle. I originally had 1.6mm main jets on a 1660cc x-flow - now I have 1.3mm.

What colour are your plugs after a run? (not after a period of tickover - hard blast, stop, check plugs). Mine were really sooty before I fixed the problem. This is not a scientific test, but it may give a clue.

Do you have a lambda sensor boss on your exhaust by any chance? If so, I can try my AFR meter on it - if not... well, I don't have any way of holding the sensor up the exhaust!

cheers,
David

Danozeman - 29/9/08 at 08:16 PM

quote:

Are the needle heights adjustable? You could try adjusting them up or down a notch if so, also are you using a fuel pump giving the correct pressure for bike carbs?. I recently helped someone set up bike carbs and megajolt on a pinto , he was having similiar problems and eventually found one of the air bypass jets to be partially blocked.


The needles are fixed and im running a r6 pump so quessing thats ok for pressure. Its seems to be more over fueling than under.

Whitestu a copy of your map would be good if u wouldnt mind. Just to see how different it is to mine.

I changed to smaller jets and it made no difference. They were 190's i took out and 155's i put in.
The carbs were set up by bogg brothers which is the annoying thing.

David thanks for the offer of AFR but i have no boss so would be a bit arkward. Im gonna take it to work and get it on the smoke tester to see what its doing. Then i can drive it aswell.

rusty nuts - 30/9/08 at 05:54 PM

Dan Can you get hold of an old cat from work and remove the boss from that to weld in? May be able to help if you get stuck.

Danozeman - 6/10/08 at 08:58 PM

Rusty good idea but they would be mild not stainless.