running problems!

[zx4rburn]

hi im new 2 this!! got a zxr400 l5 and i hav a problem wen its runing! fine on tick ova and its fine up 2 8000 rpm! then it dies! had 2 a garage had differnt coils and leads on it had my carbs balenced but no difference! had a new fuel pump and stil the same?? any idea`s? could it b the shims?? cheers steve

[zimm]

blocked main jets .. or your cdi is playing silly buggers ..

has it been "de-restricted" ?

does it have a kph or mph speedo ?

if its been converted to mph clocks or had the kph speedo disconnected for whatever reason (not the bit that makes it read, another plug on the back) the CDI will limit it to 10,000rpm (which can read as 8,000rpm on the clock)..

answer is a Mmax box, reconnect the speedo, put the kph clocks back on ..

could also be water in the carbs ..

[zx4rburn]

yea it is de-restricted and the speedo is in mph! havnt yet tryd the cdi so wil take 1 off my m8`s bike and try that??
cheers wil let u no wot happens!!

[RedexRobB]

my bet is on the CDI.

If it is blocked jets try Redex mate before you strip it all

[zx4rburn]

had a different cdi on it 2day and stil the same!!

reving gud upto 8000 then missing til 14000!

on half throttle tho there is no missfire??

think it cud b over fueling!!

any answers??

[RedexRobB]

Possibly running rich then. How has it been starting with the cold weather? Do you need the choke?

[zx4rburn]

starts fine 1st time everytime!!

normally dont use the choke if i do jst 2 warm it up!!

???

[RedexRobB]

Reason i ask is becuase if a bike starts in the freezing cold (like its been lately) it can be a sign if it running on the rich side. Have you taken the plugs out and had a look at them, they are a good indicator of whats happening with the air and fuel mixture.

After that its prob time to have a look at the carbs.

[zx4rburn]

yeah already had the plugs out they r all the same gud colour all still with white ends??

only jst had the carbs balenced aswel??

[rover220]

can pretty much rule out overfulling if the plugs are white, if running spot on the should be a brown/tan colour ideally, white can be a sign of running lean.

[zx4rburn]

but wen its running smells very much like 2 much fuel and wen reving hard on the spot back fires at top revs??

[rover220]

but wen its running smells very much like 2 much fuel and wen reving hard on the spot back fires at top revs??

back firing could be overfuelling or possibly cam timing being out.

if it was overfuelling enough to stop it revving cleanly id expect to see blackened plugs but this is by no means a definitive symptom

[RedexRobB]

When did you get the bike? Did it have this problem when you bought it or only since you had the carbs balanced?

Im thinking whoever balanced them might have left a balancing pipe off.

If cam timing was out wouldnt it run crap all over the rev range?

[rover220]

If cam timing was out wouldnt it run crap all over the rev range?

it should do yes, it was just another possible for the back firing.

[zx4rburn]

had the bike ova a year nw has been fine up 2 nw!! started of with a small missfire then got worse!!

now the missfire has stayd the same tho btween 8 - 14??

how hard is it 2 do cam timming?