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Can someone tell me if you need to make any alterations if you replace the standard rotor with the kit rotor?

Cheers

It depends on what the rest of the ignition on your bike is, and whether its a "kit" rotor from a J or an M

if its from a J, the lobe spacing is the same as a normal zxr, but it'll advance the timing 6 degree's

if from an M, the lobe spacing will only work with an M cdi and loom.


the same amount of advance can be had by modding the pickup mounting plate anyway.

Hi Zimm. I have always used the kit rotor, however I recently rebuilt another engine with Kent cams, porting skimming etc and swapped the standard rotor for a kit rotor, but when the bike hits 9000 revs it then runs so lean that it goes of the gauge and pops like an electrical issue rather than fuelling!!
All the electrics are as they were before other than the fact I have moved the coils. I binned the standard rotor so I cannot even try swapping, but just could not see why it would make any difference.

hi, sorry .. busy editing first post while you were replying ..

the kit rotor gives more static advance than a stock one, could be your issue ?

(i know when i got the curve wrong on my programmable setup the bike wouldnt rev out at all, felt like a 2-stroke about to "nip-up" at ~12k)

what cdi are you running ?

H/L/J/M/aftermarket ?

i'm sure ive got some stock rotors kicking about, but they'll be off H's.. pm me if you want one to try on it.


course, it could be a blocked main jet ?

It is the standard L model I think, but I am not sure. Was on it when I started racing the bike 4 years ago!! I have tried larger jets to get more fuel in, but all this did was affect things at lower revs with no change at the problem point.

weirdness !

did you ever run the new engine with the stock rotor ? or has it always done this ?

cam timing springs to mind.. they will run a tooth out without bending stuff .. just VERY badly.

you could try slotting the ignition pickup so you can advance/retard the timing a few degree's to see if it improves things..

fwiw, the "kit" cdi backs off the advance at 9000rpm, then picks it up again after 10,000rpm whilst the stock cdi maintains a constant advance from 7000rpm upwards.

The combination of stock cdi and kit rotor would (should?) mean that from 9k - 10.5k (and from 12.5k up.. but thats a good thing ) you are running more advance than you would be with a matching setup.

however.. ive run a stock cdi with a modded rotor/pickup that would be essentially the same setup, and whilst it wasnt as good (clean) as with the proper curve, it didnt have the symptoms you are describing.

maybe your new engine is just in a higher state of tune and therefore more sensitive to the ignition timing.

hope this makes sense.. sorry for wiffling .. you've got me thinking now.

Hi Zimm. The motor run sweetly on the bike I removed it from and I have left the timing as is and all I have done since is fit Ramair, move coils, fit kit rotor, change plugs and remove flywheel. I am going to block the air correctors tonight as this has not been done. It is driving me mad!!

Hi again Zimm!! I am presuming an H model engine would run with an L model CDI? Just throwing around ideas!! My old engine was from an L5, but not too sure about this one.

zimm wrote:hi, sorry .. busy editing first post while you were replying ..

the kit rotor gives more static advance than a stock one, could be your issue ?

(i know when i got the curve wrong on my programmable setup the bike wouldnt rev out at all, felt like a 2-stroke about to "nip-up" at ~12k)

what cdi are you running ?

H/L/J/M/aftermarket ?

i'm sure ive got some stock rotors kicking about, but they'll be off H's.. pm me if you want one to try on it.


course, it could be a blocked main jet ?

Just checked and it is an SP CDI according to another link on here. Blue label with a letter M.

interesting..

whats the full part number on the cdi ?

"Blue label with a letter M" sounds like a uk spec L cdi to me. The sp units are completely different to the "normal" units both physically and internally.

L/H engines are interchangeable, so its not that..

the incompatibility between H and L models is in the loom which must match the cdi being used as the pins are arranged differently even though the plugs are the same.

thinking on about this..

does the bike rev out at all ? or is anything over 9k just shite ?

i think my suspicions would be centered around the ram-air installation.. as your electrical system is a known and unchanged quantity.

i know folks have had issues getting consistent fuelling without the air-correctors blocked. Theory being that with them open you need such HUGE jets to stop the topend running wildly lean that the midrange gets screwed as the needles cant meter the fuel correctly.

what jet's/needles are installed ?

is it being run up on a fan assisted dyno ?

Struggles to get over 9k almost as if hitting limiter although it does climb through but only just and is shite!! I have dynojet needles in and tried lifting and lowering all to no avail. The dyno does not have a fan other than for cooling.

I blocked the air correctors tonight, but not sure if that will make any odds due to the fact that there was no air getting forced into the ramair. I will need to try a wee blast on the road.

I am trying to get my head around the fact that the kit rotor advance the timing by 6 degrees and as to what effect this would have if the cam timing was set up using the standard rotor, however I cant think how this would make any odds.

I think my brain is broken!!!

Fatspanner #44 wrote:Struggles to get over 9k almost as if hitting limiter although it does climb through but only just and is shite!! I have dynojet needles in and tried lifting and lowering all to no avail. The dyno does not have a fan other than for cooling.

sounds like mains/air-correctors rather than needles as you should be largely off the needle by 9k on WOT.. but i've no real experience setting up ram-air systems... suppose bunging a stock airbox on for a quick trial would decisively point at either carbs or ignition ?

Fatspanner #44 wrote: I am trying to get my head around the fact that the kit rotor advance the timing by 6 degrees and as to what effect this would have if the cam timing was set up using the standard rotor, however I cant think how this would make any odds.

it wouldnt matter .. was just pondering as you said it was a rebuilt motor.. but if it ran like that before, then it should now, +- a couple of degree's on cams makes little difference .. certainly not the difference between sweet and shite.

Fatspanner #44 wrote: I think my brain is broken!!!

i know that feeling !

Cheers for all your help. Nice to borrow someone elses brain power!!!