GN250 6000rpm miss

[alistair1]

wwe have a 1983 gn250 that fells like hits a revlimiter at 6krpm when on the road (in anygear) but it will free rev right up to 8krpm when in neutral?

we have tried a new sparkplug,and cleaned the carb jets,any other surggestons?

thanks alistair

[raftn]

Get a new bike..............

[alistair1]

you know not all of us a made of money.
and we couldnt see the point of spending lots on a bike only needed for our learner/restricted.

[xwhatsit]

Get a new bike..............

You're a dick.


Anyway, does it come on very suddenly at 6,000rpm? Or not? Playing with a Nifty 50 that had the float level too low and a blocked fuel line, wouldn't rev out as it couldn't get enough fuel, so there was a lean misfire at higher RPMs.

I dunno, just an idea.

[Hamish Carlson]

when the fuel valve in the carb was sticking it missed around the 5krpm mark, but anything over or under would either have enough fuel or take the level in the carb to null and the valve would unstick, letting it rev at areas from 6k - 9krpm. worth a look maybe...

[MacD]

My SRX had a similar symptom. It turned out to be an air leak at the rubber manifold between the carb and head, where the rubber bonding to the mounting plate had broken down.

[alistair1]

thanks, we will look into it.yes it is a sudden thing,not a gentle proggresion.

[The Stranger:Me]

If testing for a fuel restriction, take it up to the point it stuffs around and back the throttle off a touch. If the motor picks up a little in response to the closing of the throttle you know it is lean.

Closing the throttle a touch corrects the lean mixture and thus causes a slight surge in power.

[Laava]

Just a thought, mine had an old spark plug lead and it had begun to deteriorate to the point it was causing erratic idling and misfiring. Check it at night to see if there are sparks jumping around. I put some 2" heat shrink around the cap and that was it!

[Paul in NZ]

wwe have a 1983 gn250 that fells like hits a revlimiter at 6krpm when on the road (in anygear) but it will free rev right up to 8krpm when in neutral?

we have tried a new sparkplug,and cleaned the carb jets,any other surggestons?

thanks alistair

Sigh - how many kms, whats the general condition of the bike, has it been serviced?

What I'm getting at is that I could think of 5 things that might cause this fault but really its impossible with this much info and over the net.

83 is pretty ancient - chances are the carb needs a going through and all the rubber bits are perished to buggery, fuel filters clogged, clag in the tank stopping the fuel flowing enough, water in the petrol cos it lives out side, obstructed vent to the gas tank, ignition breaking down, dodgy plug, mal adjusted ignition, valves, low compression, dodgy battery.....

Best bet is to complete a full service, adjust the valves, set the ignition, new plug, new air filter, change the oil n filter, clean out the fuel system, inspect the carb and go from there....

[alistair1]

alright.thanks

[ferrari_chris]

Hey alistair1, did you fix this problem with you GN?

Mine is having the same problem as yours right now, and I was wondering if you found a fix for it?