MZ rt 125 issue

[givusago]

Hello,

I have an MZ rt125. I use it as a commuter and do about 70 miles a day. Initially I noticed the fuel hose had corroded slightly causing a small hole in the line just after the fuel filter and before the carb. So I thought I would replace all the fuel hose and fuel filter. soon after this the bike started to play up randomly breaking down. it was as if it was running out of petrol. Jerking a bit then conking out. I checked the forum and looked for potential problems:

Fuel cap is secure and no signs of a vacuum.
Fuel filter is full of fuel so the petlock seems ok.
New spark plug fitted - old one was quite sooty.
Air intake is not blocked and filer ok.
Checked and secured side stand connector.

I spoke to a garage and had the carb ultra sound cleaned as they said it could have been bits of old fuel hose in the there knocking about. The bike was fine for one day - then it got worse. The next step advised to me was checking the valve clearance .
Bike still dies on me at low speed and high speed. Maybe to do with temperature?

Looking for advice if any one can offer me some please?

Many thanks

[DAVID THOMPSON]

I have problems with mine if l use fuel that contain ethonol

Remove seat and check all the conectors to the electrical
System

And what is your country

My carb has always been very fussy about the fuel

Dave

[givusago]

I live in the UK.
Before I changed the fuel filter and hose the bike ran fine. I use normal unleaded which has been fine. I have checked all fuses and connectors - they seem secure and in good condition. I am going to clean out the fuel tank this weekend in case there is any bits float about that randomly stop the fuel going through. A longshot but good to find out. Not sure what else to try?

[DAVID THOMPSON]

with mine it goes nuts if i run low enough to go on reserve or run very low and fill up

seems to correct its self if i lean the right side against the shed and use a phillips screw driver
to open the float bowl drain on the left bottom of the carb

book says 1800 to 1900 on the idle and did the air screw get reset proper

also check that the choke/enrichment valve is working proper with it open and closed function

i have almost 21,000 miles on mine and have found the carb can cause problems but considering how much fuel i have ran through it it does well
estimated 350 to maybe 380 gal in 12 years
dave

[givusago]

When it goes nuts do you mean jerky jerky. As if it is going to run out of petrol? If the carb has been cleaned would I need to drain the float bowl?
the bike idles at 1900/2000 and idles great to be honest. This morning on the way to work it broke down on me after 5 miles. I put it in neutral, pull clutch, as soon as I change gear the engine dies... I have checked the kick stand sensor - could I just disconnect it?

thank you

[DAVID THOMPSON]

read about the relay 19 problem
ever thing on the bike runs through it and may be making you cut out
and here is a drawing of it

click on drawing to make bigger

if its going bad it can be buger

drawing by tony idle

[givusago]

Read through them. Thank you. There was a thread before and you suggested a halfords part that would be a suitable replacement relay. Could i have the link please. Maybe replacing this part will help. The side stand switchlooks good but if the relay is old could be faulty.bikes done 22000 miles so a spruce up may be in order.

Thank you very much

Mark

[DAVID THOMPSON]

i cant find it either

its the relay they use to switch extra lights

the one with 5 pins

dave

[givusago]

Thanks for your help Dave.

It seemed to be the kick stand switch. I disconnected the wires from the stand and tied them together. Its been working fine ever since.

Thanks again.

[DAVID THOMPSON]

that side stand switch is easy to break

do be careful with it disconnected

and you may need to sort out something to replace it to pass MOT

friend of mine ..dealer made him put side switch back on his bike..

but he keeps A "RAT" BIKE and i think they do not want to inspect it

because he always has some thing jimmed up on it .because he treats bikes like a dirty shop rag...