get a small file or knife and scrape the rust off the connectors, spray contact cleaner in to each con, wait for it to dry then pack the female end with Vaseline which seals and lubes the con for future access.

Had a similar problem with mine (which I somehow never noticed while I was test-riding it), it runs smooth to about 4,000RPM and then suddenly starts to sound rough, but once I go over about 5,000RPM it stays sounding that way even if the revs drop down below that.

I'm a bit confused about the whole derestricting issue though, how can fitting a speedo convertor override an engine lag issue that appears to be related to the revs?

if your speedo still reads in kph, the restriction sits at 180kph. fit the converter and it changes it to mph.
there is NO WAY your bike will ever get to 180mph where the restriction still sits!

the restriction sensor is in the speedo. when the sensor is set off. it enforces the restriction in to the CDI>sparkplugs.
when the sensor does not get power it automatically goes in to restriction mode at 5K rpm, i believe its the same safety mechanism when you get in to the red line. it stops you blowing up the engine. i have hit that once since i have owned my bike and after a few seconds i realised what it was and upped a gear, revs dropped and all was fine.

i didnt design the bike/CDI so i dont know why it does it, just that it does and how to by-pass it!

I've noticed another odd thing as well though, when I get to 5,000 RPM and the engine starts running out of power, it tends to make an odd crackly sound as I'm going along, it only does it when I'm revving and only when I'm in gear. Now presumably if that noise was symptomatic of some major engine issue it'd be doing it all the time rather than just when the revs are high, but it's still a bit concerning.

Spudiator wrote:I've noticed another odd thing as well though, when I get to 5,000 RPM and the engine starts running out of power, it tends to make an odd crackly sound as I'm going along, it only does it when I'm revving and only when I'm in gear. Now presumably if that noise was symptomatic of some major engine issue it'd be doing it all the time rather than just when the revs are high, but it's still a bit concerning.

They all tend to do that - that's why God invented the Dyno & tuners!

To pass noise regs - the power is dropped a little at about 5000 rpm - where the noise testing is done. This means we all get a little problem in this zone.
If you have tweeked your bike any, or it is a little out of tune in any way - it could exagerate this reluctance.

5000rpm coinsides with the carburation switching from being controlled by needles to the main jets - which needs delicate tuning to get it right.

Prime example - when I first fitted my ram air, K&N, bell mouths etc - my power drommed from 58bhp to 23bhp - it would not pull past 5000!

Go back to basics - good plugs, well set carbs, valves set, no leaks etc, etc... (you know the drill) .......If it's still bad - dyno time

sorry for the long post

Well the speedo converter didn't work, which kinda figures. There's no logical reason it should, or even could, have worked really, because the engine goes funny at 5,000RPM irrespective of the speed I'm doing, speed doesn't even come into the equation. I'm just glad I only wasted 15 quid on a second-hand speedo converter rather than 30 quid if I'd bought one new. I am gonna do an oil and filter change and replace the plugs soon enough anyway just as a point of maintenance (let's face it, buying a bike you never know how long it's been since they were last changed), and if that makes no difference (as expected) I'm gonna have to get it looked at, because this is starting to cause me a problem, especially when I'm trying to overtake someone and finding I've barely got enough grunt to do it at all, let alone safely. I've only had the bike a week, I wasn't expecting to be worrying about it going wrong on me just yet.

running down the road yesterday and my bike started to judder again and not go over 3 thousand revs.. it just kills the revs and dies off untill 2.5thousand revs. so i grabbed the Starter Relay and was moving it around to see if the wiring was loose to get a connection to be able to carry on with my journey. eventually got it going again and off i went. just up the road i thought it was ok and it started doing it again but this time i couldn't get it going so tryed to get somewhere i could look at it but then after a while of 5mph with the revs on and off the bike died! Compleatly dead. i have no ignition or power anywhere!
so there i was sitting on the side of the road (luckly had my haynes manual in my backpack) :) looking at the wiring diagrams with no tools!
Eventually i got one of my mates to pick me up in one of my works Vans and got it to work....
Traced the fault to the Starter Relay. and have one on order! but may be a other problem somewhere....
Just thought i will share my story haha!
Dave

"I only wasted 15 quid on a second-hand speedo converter rather than 30 quid"
lol they saw you coming then! i sell my resistor mod kits for £7 that do the same thing..

speed doesnt come in to the equation WHEN the sensor is not getting power (fuse or wire broken).
when the signal does not get to the CDI unit the REVS is what the CDI unit goes from.. 5krpm...
get a wiring diagram and trace the sensor wiring back through the bike to CDI unit, check for shorts, rust/corrosion, broken dodgy looking wires....

dave.. last xmas my bike started dyeing on me.. turned out to be a knackered fuel pump. replaced it and all was well, our pumps have points like the old alternators. they ware/burn out over time/use.

oh really.... that is interesting! cos when i first got my bike it didn't start! tryed everything! tested everything but all was well! so bit the bullet and booked it into a bike garage. they got it started and it was the fuel pump! it worked when i tested it but they did something to it to get it going but wouldn't tell me what! thats Deff in need of a replacement! Thanks! bu will get this Starter Relay on and see it i get ignition back. and take it from there!
All the help is well appritiated! Thanks guys!
Dave

the shop told me that i could get almost any bikes fuel pump just so long as the pipe in/out lets lined up with the old one.
i bought a pump off a younger, less mileage NC29