I've been having this problem from day 1, the bike is utter skunk under 4000rpm. The problem is at exactly 3500rpm, all the bike does is burble, pop, fart etc... I've checked the spark plugs and...
#1= black
#2= white
#3= black
#4= white
On the coils, does it matter which wire goes on which spade connector? on mine both red wires are connected to the green coloured spade on the coil.
Regards
Rich
MillaMeter's ZXR400 Restoration Click HERE!
ZXR400s 4eva! I miss mine already
As far as i know it shouldnt really matter what way the wires go round on the coils as at the end of the day its just a coil of wire wich has no particular polarity. Have you got he same CDI from day 1? Cant think of much else that would give you those problems considering what you have been through to try and get it sorted. What jets are you running, and are they all the same?
RedexRobB wrote:As far as i know it shouldnt really matter what way the wires go round on the coils as at the end of the day its just a coil of wire wich has no particular polarity. Have you got he same CDI from day 1? Cant think of much else that would give you those problems considering what you have been through to try and get it sorted. What jets are you running, and are they all the same?
Hi
All the main jets are 92s and the CDI has been the same since day 1 yes (BLUE L) I've swapped the coil cables over and not really that much diffrence. I've sprayed the ignition and all plugs with WD40, seems a lil smoother but spark plugs still the same
I've even tried leaning out the rich plugs but still no improvment.
Regards
Rich
MillaMeter's ZXR400 Restoration Click HERE!
ZXR400s 4eva! I miss mine already
Try another CDI perhaps and see how that goes i reckon, thats if you can borrow one anyway. Wild idea but maybe a compression test too, dunno if that might have something to do with it?
RedexRobB wrote:Try another CDI perhaps and see how that goes i reckon, thats if you can borrow one anyway. Wild idea but maybe a compression test too, dunno if that might have something to do with it?
Hi,
Coming to think of it, the CDI that came with the bike was a blue M, that blew up due to the twat hooking up a cheap egay jobbie alarm. I bought another 1 from egay and it's been like that ever since. I can only think it's an electrical fault somewere as the bike has it's moments, 1 day it will run really smooth (no vibrations etc...) then the next day it feels like crap and the bike pops alot at steady throttle and on the down run. I've checked the inlet manifolds for air leaks and they're tightly sealed. The bike does have 1 of them black box thingys under the clocks that derestricts the 110mph limiter. I have replaced the clock to a UK mph 1 but that'll make no difference as the cable originally coming off the import clock is plugged into that box thing.
It's very hard to set up my engine as it's from a ZX400 and I don't really know if stadard jets, needles etc... would run perfect with it? When I had my old L2 engine and got that dynoed, it seemed alright untill. Then I chanced the engine because it was cheaper then paying someone to do the valve clearences. When I put my dynoed carbs on the new engine and then took it on a rolling road, the bike had lost 13bhp!! was running at 53bhp! then he chopped the snorkel up a bit and managed to get it to almost 67bhp at the rear wheel which I must say I was impressed.
Please ..... someone throw some ideas at me before I sell the flaming thing.
Also, has anyone got a import and UK CDI deck I could borrow for a couple of days to see if that helps the problem
Regards
Rich
MillaMeter's ZXR400 Restoration Click HERE!
ZXR400s 4eva! I miss mine already
at 4000 Rpm, isnt the bike still running off the idle jets and not the main jet? Just an idea if someone can quote me right or wrong. Its going to a be a fueling issue. When you had it dyno'd did it have this problem at low revs?
chopping the snorkel up is no substitute for fitting the right jets and needles,
the zx4 engine is no more or less than a zxr-h engine with no oil cooler and sp cams and should be no more or less difficult than any other bike if the operator can be bothered to do it properly.
oh, and plug chops mean nothing unless you're using new plugs each time.. dyno's work out cheaper.
Last edited by zimm on Wed May 06, 2009 4:56 pm, edited 1 time in total.
Scott221 wrote:at 4000 Rpm, isnt the bike still running off the idle jets and not the main jet? Just an idea if someone can quote me right or wrong. Its going to a be a fueling issue. When you had it dyno'd did it have this problem at low revs?
4000rpm is roughly where the carbs are transitioning from the pilot jets to the needle, .. mains come in from 7ish (depending on the rottle position)
Last edited by zimm on Wed May 06, 2009 7:15 pm, edited 1 time in total.
when tuning cv carbs you get the main jet right first, then the needle, then set the idle mix ..
if the snorkel has been chopped about (what's been done to it) and that resulted in a jump from mid 50's to mid 60's, then my guess is that it was running rich, cutting the snorkel allowed more air in thereby correcting the mixture and giving more power, but at the expense of screwing up the harmonic resonance's in the airbox.. What should have been done, is leave the airbox alone and fit smaller jets.. once the main jet size is right experiment with whatever different needles you have available untill the midrange is spot on.. then set the idle mix till its just rich enough to stop the revs hanging
to correct it without re-fitting a stock airbox you'll be looking at trying different pilot jets and needle profiles\heights to minimise the difference between them, but i have my doubts you'll get it perfect this way, and changing pilot jets is uncommon and normally unnecesary
zimm, I've also noticed that when the airbox and tank is off after a run, the airbox to carb bracket (the 1 with the trumpets on) is swimming in unburnt fuel. I've also noticed that if I start the bike with no airbox on it and blip the throttle, fuel spits out of the trumpets, the harder I blip it the more that spits out. Anyone else had this when balancing carbs etc...?
Oh, and can someone tell me if this is right.
Left coil has a red and green wire, and the right coil has the red and black wire. Lead for cylinder 3 is the closest to the top of the coil and lead for cylinder 2 is the closest to the engine. Lead for cylinder 4 is closest to the engine and lead for cylinder 1 is nearest the top?
I have a feeling I may have an electrical fault somewere or my shims need doing.
Just cant seem to get my head around the misfiring on 1 and 3.
Regards
Rich
MillaMeter's ZXR400 Restoration Click HERE!
ZXR400s 4eva! I miss mine already
there shouldnt be fuel pissing out of the carbs like you describe, but it does fit with the symptoms you're having ..
my guess is either;
float heights wrong (fuel level too high, which equates to the "float height" being too low, as the carbs are inverted when the measurement is taken, i find 12mm works well with keihin jets, and 13mm with Dynojet jets which are longer, and consequently pick up fuel from lower in the float bowl)
float valve's leaking (so the carbs are continuously filling with fuel)
float valve holder o-rings perished (same as above, and very common, ive had to replace them on every zxr ive had)
does your fuel pump run lots .. like more than just the occasional "tic tic tic tic" that would also corroborate any of the above
I'd really stop worrying about the electric's and get the carbs thoroughly rebuilt and setup, at the end of the day you've got tiny jets, a cut up airbox and its still running rich..
as a point of reference..
my L4 with full micron, dynojet kitted carbs and knN filter was running #105's and the needles on the 2nd or 3rd clip from top
my H1 with full beet, dynojet needles, pipercross filter and SP cams is running #105's and the needles either 3rd or 4th clip from top
our ZX4 with delkevic headers + open can, 32mm carbs, ZX4 needles and stock airbox is running #100's
and im pretty sure steve's H1 (which is still with me despite being sold over a year ago) is stock save for a full scorpion system and #102 mains
all of these run fine, my racebike showed as marginally rich across the range with the #105's last time it was dynoed, but i'll blame that on the dusty pipercross filter, wasnt enough to warrant a jet change at any rate.
btw, it doesnt matter one bit which way round things are connected to the coils, each one is a single coil, the HT leads both go to the same place internally, and the LT side isnt polarity sensitive... well, it might be in theory, but trust me it makes cock all difference if you swap the leads round
I've replaced the float needles with new 1s, i'm not 100% sure on the O-rings in the seats... I may just get another set of carbs and check the new set over as I use the bike for work. I've also noticed that the valve seat is stamped with a number, 1.6 i think it was. I was told by Cradleys that the original is meant to be 2.4 or something. On idle the pump doesn't workout like crazy, just the normal tic......tic......tic......tic and gets faster as I rev.
If I was to put the bike in 6th then boot it from 2000rpm, the revs with climb.... struggling then as soon as it gets to 3500 the bike just stumbles and burbles untill I ease off the throttle then open her up slowly. That's telling me it's running rich? The mid range doesn't feel as sharp as it used to be, it used to be really snappy and responsive when you really give it a handfull. The inlet manifolds are very tightly sealed (checked them the other day with a can of carb clean)
If this helps I'll tell you the specs.
ZX400 engine
snorkel rubber inplace just not the plastic insert.... well, only the very top bit where the dyno man chopped it up.
11mm float heights
92 mains
dyno needles on top groove with both washers on top.
mixtures turnt to 2 1/2 out
slides drilled.
micron headers with a custom jobbie carbon can (sounds mint btw )
new float valves
valve seat size 1.6
CR9IEX plugs
Regards
Rich
MillaMeter's ZXR400 Restoration Click HERE!
ZXR400s 4eva! I miss mine already
i no this is a really old thread but im still having trouble setting my L1 up i was just wondering if you had got yours all set up and if so what settings your using such as float height, jet size, needle height etc and help would be great thanks.
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