If it develops a misfire that stops it from revving past about 5000 rpm I would suspect the 180kph speed limiter circuit inside the speedometer has failed or it is disconnected for some reason. There are three wires coming out of the speedometer that run back to the ignition control unit

If the ignition control unit does not detect the speed limiter circuit in the speedometer it will stop the ignition to the two rear cylinders when engine speed tries to go above approx. 5000 rpm.

To fix the problem you either replace the speedometer or fit a bypass resistor to the speedometer wiring.

If not fixed before you start off home you will has a slow ride limited to 5000 rpm in any gear.

uhm well i got the bike for £900 with 12 months mot and tax and its in fairly good condition considering age, i just took the sellers word for it , he says it stil works full speed just the tacho wont show anything over 4000rpm and when i revved the bike etc in nuetrul the taco moved quite slowly up to around 2000 then i let off n tried again n same thing so i think he is genuinly telling the truth

magg wrote:If it develops a misfire that stops it from revving past about 5000 rpm I would suspect the 180kph speed limiter circuit inside the speedometer has failed or it is disconnected for some reason.

Even in 'limp home' mode as above the engine will easily rev above 5000 rpm in neutral on only 2 cylinders.

nazzurro_19 wrote:i just took the sellers word for it , he says it stil works full speed just the tacho wont show anything over 4000rpm and when i revved the bike etc in nuetrul the taco moved quite slowly up to around 2000 then i let off n tried again n same thing so i think he is genuinly telling the truth

You might just need to replace the tacho. Check that the earth wire at the back of the tacho is mounted securely first.

ahh cool so , when i next go to pick the bike up i will

1) check earth from tacho
2) check speedo

if neither of these cure the problem ill see if maybe someone local could swap cdi quickly to see if that helps

if not change just the tacho , i take it you dont need the whole cluster and just the tacho?

cheers guys

Can you just clarify if the bike is only reving to 4000 rpm or the tacho is only showing upto 4000 rpm but the engine is reving as normal?

i only revved it too 4000 and it wouldnt go up anymore to which the guy selling said its always had this problem with the tacho not reving right round but he reckons the bike still hits full speed as he has done more then 112 which leads me to believe it has a uk cdi

If the engine wont rev past 4k then its not going to hit 112

he said the bike revs fine and builds up speed fine but the tacho will not go past 4000

so the speedo stil shows the correct speed like 50-60-90 etc but what ever the speed is he is doing apparently the tacho only shows 4000 rpm max

nazzurro_19 wrote:he said the bike revs fine and builds up speed fine but the tacho will not go past 4000

so the speedo stil shows the correct speed like 50-60-90 etc but what ever the speed is he is doing apparently the tacho only shows 4000 rpm max

Ok so thats answered my previous question

Drunkn Munky wrote:Can you just clarify if the bike is only reving to 4000 rpm or the tacho is only showing upto 4000 rpm but the engine is reving as normal?

Right then the problem id say is your tacho and i wouldnt worry about riding it home

ahh right cool , well the guy said he will take it to the garage to get it moted and ask them just to have a check so if it is the tacho i shall just buy a new one and fit it

im also after a double bubble screen , any ideas on cheapest best quality etc ?