nc23 rrk running rough above 5000rpm

[gmc400rr]

having major probs with this thing!, engine is running mega rough especially after 5000, have took it to bits and found the rectifier was pumping out nearly 18 volts at 4000rpm!, this has been replaced with no change to the running, could this have damaged my cdi?. also compression tested it and results were cylinder 1-140psi, 2-150psi, 3-150psi and 4-165psi, not sure if these should be more even, any ideas would be much appreciated, cheers, Gaz.

[tanuki]

have you removed the speedo?

check all of the wiring aroung the clocks as it sounds like the restrictor kicking in.

[gmc400rr]

Hav not checked that, cheers, will have a look at the clocks tomorrow and will hopefully get somewhere!

[leopard_pagan]

"sounds like the restrictor kicking in."
> it is.
1st place to look at is the fuse box. check the fuse for the dash, indicators, headlight, horn etc.
2nd thing to look for:
loose connection behind the dash, plug anything back in.
dirty wires
corroded wires plugging in to the dash
cut wires or wires pulled out.

at the CDI/ECU end check all the above again.

this is whats happening...
see thread: http://www.400greybike.info/newforum/vi ... 26&t=12381" onclick="window.open(this.href);return false;
"inside the speedo is a lig/beam trap switch. a disk attached to the needle inside the speedo cuts the beam at 112mph.
what then happens is a signal is lost/stopped to the bikes CDI unit telling it to cut power to two spark plugs. this signal will continue to be cut all the while you try to go over 112mph. once you drop under it, the signal resumes and the CDI powers all 4 plugs again.
Some times bikes have hic-ups with the limiter. this is often caused by bad by-pass wiring, loose wires or more commonly the fuse for the *dash*, indicators, lights has blown.
when this happens the CDI no longer receives the "i'm here doing my job" signal and automatically shuts down two spark plugs as soon as the bike revs over 5,500 RPM."

[gmc400rr]

good news!, took the front end to bits and disconnected all the wiring, cleaned the connectors up and sprayed them with wd40, fired it up and it burst into life again:P , many thanks for the advice. next step will be a good service and get the carbs balanced to get it spot on

[leopard_pagan]