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Rubbish rs125


BoB3rt
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Have a previous post about its problems but they have been sorted i think as the bike went into a workshop.


Anyways the backstory is my friend new to biking and doing his licence, blindly bought an RS125 of his long standing boss in work (small company) it appears he has screwed him at charging £1k (paid for) it has so many problems

Clutch not engaging then not disengaging, engine not right, Transmission gasket leaking.


They have been sorted turned out the counter balance on the crankshaft was timed wrong i think monkeys could have done a better job than this.


So now the issue appears to be the bike really struggles to move off in first gear loads of revs are needed but once its gunning for it it can go up the gears fine.


Told him to be having words with his boss but he is a quiet lad and new to it all. just forked out £300 for getting them bits solved.


Ta.

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Have a previous post about its problems but they have been sorted i think as the bike went into a workshop.


Anyways the backstory is my friend new to biking and doing his licence, blindly bought an RS125 of his long standing boss in work (small company) it appears he has screwed him at charging £1k (paid for) it has so many problems

Clutch not engaging then not disengaging, engine not right, Transmission gasket leaking.


They have been sorted turned out the counter balance on the crankshaft was timed wrong i think monkeys could have done a better job than this.


So now the issue appears to be the bike really struggles to move off in first gear loads of revs are needed but once its gunning for it it can go up the gears fine.


Told him to be having words with his boss but he is a quiet lad and new to it all. just forked out £300 for getting them bits solved.


Ta.

 

Could tell the counter balance was out, its fiddly when putting it back together after a rebuild. Sounds like someone has been in there and rushed it back together.

The engines are easy to work on though.


Its bogged down which is quite normal, the bike does do 42mph in first if ragged to the top. What year model is it? The early ones had a CDI that had a port to plug in a power valve. This makes the bike more manageable in the low rpms and then it should make a loud click at idle between 6-8000rpm and it will give it a good top end. I believe there was a power valve on all pre 2003 models. After that due to emmisions they fitted a blanking plate instead and choke the exhaust so it could only make 15BHP.


As joeman said, if it has a blanking plate instead of the powervalve it will have no power down low. It should still go with 4000rpm or more but be quite crap. If it needs to be screamed to even move there is an issue.

Check for the powervalve, as if its there and stuck in full power mode it will kill the bottom end, if its not there and no blanking plate is fitted you will have a very big air leak into the exhaust and it will seize in no time and run badly, sometimes they trick you into thinking everything is fine when they accelerate well up top.


Either way it sounds fuel related as these things are absolute buggers to set up "just right".


Check the carb, give it a proper clean. Set it back to factory specs for your best chance of getting it right. See if this makes a difference and get back to me. Better yet make a video.

When I had these I could tell from noise and the way it revved what the issue was.

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125 two stroke,, going back many a long year (pre jap bike ere) I had a 125 twin port two stroke that suffered from power loss, so much so, I had to walk along side it in first gear to get up some of the steeper hills :oops:


after a lot of faffing around I found out that the exhausts were blocked with the carbon deposit that all two strokes produce, so the engine suffered from back pressure being unable to expel the exhaust gasses,,, A lot of hard work, loads of caustic soda & boiling water cleared them out,, but it was a job well done & the bike ran well,,


it might be worth checking,,,, just a thought :wink:

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I will try get my hands on the bike as soon as possible and thanks for all the help.


There does seem a problem with pressure! with the seat off when the bike is reved i can see the 2 stroke oil backing up in the tank then back down when revs are shut off.

Its a lot of revs needed to move the bike off at a stutter!


The carb is spotless and been cleaned properly and i think it is back to factory with mixture and idle.


I will make a video and get back to u.


Thanks Again!!


Rob

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I will try get my hands on the bike as soon as possible and thanks for all the help.


There does seem a problem with pressure! with the seat off when the bike is reved i can see the 2 stroke oil backing up in the tank then back down when revs are shut off.

Its a lot of revs needed to move the bike off at a stutter!


The carb is spotless and been cleaned properly and i think it is back to factory with mixture and idle.


I will make a video and get back to u.


Thanks Again!!


Rob

 


Now I'm Confused, in my day 125s, worked on an oil mix in the main tank, but that was long ago & I've never bothered with them since, so do modern 125s have two tanks,, one for fuel + one for oil ????? seems cockeyed to me, how do you know if your mix is correct ????

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Blimey Roadtorque....even my RD350 back in '76 had a separate oil tank for the 2 stroke..... :wink: :lol: :lol:

 

Well, there you go :shock: wonderful thing technology ,, My 125 was twenty three years past 1976 & it was five years old when I bought it, first bike I ever had,,, it had a little cup on the inside of the tank filler cap,, one cup of oil to every gallon of fuel ,, so by todays standards primitive,,,, but hey,, it never went wrong :wink: :wink: :wink:

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Blimey Roadtorque....even my RD350 back in '76 had a separate oil tank for the 2 stroke..... :wink: :lol: :lol:

 

Well, there you go :shock: wonderful thing technology ,, My 125 was twenty three years past 1976 & it was five years old when I bought it, first bike I ever had,,, it had a little cup on the inside of the tank filler cap,, one cup of oil to every gallon of fuel ,, so by todays standards primitive,,,, but hey,, it never went wrong :wink: :wink: :wink:

 

Dont worry, some bikes are still pre-mix.. My 2005 KTM300 needs oil adding to the tank as it has no oil pump/tank.

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