ZXR750 J1 Bike seems to lose RPM

[kwaker750]

HI I am new to this forum,actually I only registered 5 mins ago.
I am hoping that someone here might know what is happening with my ZXR750.
The bike has an intermitent problem.When cruising along after the engine is hot doing say 6000 rpm the motor loses rpm and drops 3 or 4000rpm for a few seconds and then the motor runs fine again for a short distance and it happens again.
Has anyone got any ideas, or know of a BIKE auto elec that might and won't charge the earth?

Thanks Peter.

[robracer]

Hi Peter welcome to the club
What Suburb / State are you in?
Your problem could possibly be is vapour lock in the fuel tank
Check the filler cap & make sure the breather is working I think that model has a one way valve
Thats a statrting place anyway but based off your description I dont think it is electrical

[Mel]

Hi Peter!

I have no idea about your bike's problem, but thought I'd say hi and glad you found this place

Cheers!

[JetPilot]

Gday, curtainly sounds like a fuel problem. Rob is onto something, start with that and check for kinked fuel and breather lines.
It doesn't sound electrical to me. If it was it would stop all together, not drop in rpm.
Does it run rough or hard to start?

O yeah welcome to the Klub

[kwaker750]

Thanks for the replies.
I will try what you guys are suggesting but I still think that it is electrical.
Because the motor drops rpm so suddenly and then picks back up so quickly after a second or two is why I think that it is electrical.
When this happens the motor seems to stutter and backfires as well.
If it was lack of fuel i would n't expect backfiring.
saying this I am keeping my thoughts open to the cause and any ideas are well apreciated.

[kwaker750]

Hi Peter welcome to the club
What Suburb / State are you in?
Your problem could possibly be is vapour lock in the fuel tank
Check the filler cap & make sure the breather is working I think that model has a one way valve
Thats a statrting place anyway but based off your description I dont think it is electrical

Hi Rob
I am located in Sunbury Vic I will update my profile soon as I get a bit of time and work out how to do it.
Thanks for the welcome.

[kwaker750]

Hi Peter!

I have no idea about your bike's problem, but thought I'd say hi and glad you found this place

Cheers!

Hi Mel we will be on the road together again soon.Tintaldra/Bright can't wait.
I bought a 06 zx10 today so I might be a little quicker on the corners this time around.
The problem I am having with the ZXR is why I had to miss the last Bright ride.
I will be happy when I get it sorted.The problem is nothing major but enough to be a real pain.

[JetPilot]

Thanks for the replies.
I will try what you guys are suggesting but I still think that it is electrical.
Because the motor drops rpm so suddenly and then picks back up so quickly after a second or two is why I think that it is electrical.
When this happens the motor seems to stutter and backfires as well.
If it was lack of fuel i would n't expect backfiring.
saying this I am keeping my thoughts open to the cause and any ideas are well apreciated.

Well you really didnt mention the stutter or backfire. Could well be elec. Check coils and cdi ignition.
Im no mechanic and definately not an electrical wiz......
Its hard to evaluate without looking or hearing it...
Sorry....Bike shop mate.

[Rossi]

Sounds like a coil breaking down mate......how long a ride before it breaks down ?
time it between faults as an overheating coil breaking down occurs on a fairly regular pattern

[kwaker750]

Sounds like a coil breaking down mate......how long a ride before it breaks down ?
time it between faults as an overheating coil breaking down occurs on a fairly regular pattern

I have checked all of the electrical connections and I am fairly sure that it is not a fuel problem.
It could well be a coil breaking down Rossi.Does anyone have any suggestions for how I can check the ignition coils and the pulse coil? I have a multimeter but I am not quite sure how to test the coils.

When I do finally fix this problem I will post what the problem was for others to read.
Cheers Peter.

[kwaker750]

The problem doesn't occur until the bike is hot.Especially under high revs.
I have ran the bike until it was out of fuel but the symptoms were different.The tacho did'nt drop sharply and come back up compared to what happens when the fault occurs.Because of this and the fact that the fuel filter is full of fuel when the fault occurs leads me to think that it is not fuel related but spark related possibly pick up coil?

[kwaker750]

Ok I replaced the ignition coil igniter and Hooray I think that the fault is fixed.
So it seems that the problem was the ic igniter all along.

[larrythelathe]

i have this stuttering problem did you change the ecu or the stick coils?