nsr 125 overheating problem

[robbie21mcn]

ive had my nsr 125 90-r for a week and its been running fine goin 60 mile return journeys until dun dun dun!!!!!!
i noticed water coolant is backing out thru the overflow under the seat and now the gauge is moving higher and higher to the red when i try to run the bike. this doesn't happen right away but over a period of say 10 mins gets hotter and hotter. im a total newbie to the world of biking and any help is much appreciated. i also noticed im losing very slight gearbox oil but cant spot where its escaping.
____________________
fzr 600 its yellow but its no banana!!!!!!

[alains]

i think your thermostat is worn . take it out (it's inside the pipe going out on top of the cyl head) , have a run and see it that continues. about your oil leak it's probably going out off the little plastic pipe near the stand (as your oil is a bit hotter)
____________________
the worst day fishing is better than the best day working

[robbie21mcn]

but if i take the thermostat out how will i know if the bike is running at the correct temperature? i had only just spotted the green fluid coming out the overflow pipe and realised im losing coolant and hence the engine running hotter to me would suggest theres something more sinister going on?
____________________
fzr 600 its yellow but its no banana!!!!!!

[alains]

it happens sometimes with the thermostat . look your clock temp , after 10-15 mn running , the needle will overtake the first zone (mine is in blue) by 1/4" . if that's correct , your thermostat is worn . as it is quite expensive , you can run without . but if the temp goes over and more , that means you have a problem (radiator fured up or cyl head gasket leaking)
____________________
the worst day fishing is better than the best day working

[jesus_tricky]

hey i don't know if it helps but i to am kinda new to the riding and ride a 125 nsr too....
i had a new head and piston in mine and a new thermo
i was doing a trip much like yours and being a two stroke the only thing you can do is carry some tools and hope for the best.
all the same it over heated and all i could do was let it piss out water and leave it to cool down, fill the water back up and away you go
so i'm pretty sure its not a problem
p.s. remember its a 2 stroke not a 4

[alains]

just a precision , i was not talking about the temp detection N°8 but about the calorstat (or thermostat) N°7 . here is the picture
____________________
the worst day fishing is better than the best day working

[robbie21mcn]

tursn out there was no water in the radiator and that an airlock had stopped the water circulating. but what confuses me is why the fluid leaked from my coolant bottle underneath my seat to allow air into the system and furthermore is it likely to happen again?
____________________
fzr 600 its yellow but its no banana!!!!!!

[alains]

yes , if a dust block the thermostat it can happen again . to avoid that you may use a descaling powder ( the same as you use for washing machines) . take the thermostat off , refit the pipe . dissolve 1 dose in 1L of warm water , fill your engine . let it warming for 1/2 H or more , make the circuit empty , rince it 2 or 3 times . during you warming brush the thermostat and rince it , prepare a saucepan full of water , when it begins to make small bubles , put the thermostat in and observe if it opens correctly (it suppose to be fully open at around 72-75°celcius 157-163°F) . if not , trow it away , buy a new one or not (you may warm a bit longer in the winter)
____________________
the worst day fishing is better than the best day working

[robbie21mcn]

well now the bike seems to sit at halfway on the thermostat but if i open her up full throttle she goes towards the red and sits just about 3/4 and i dont think this is right could it be that the thermostat is constantly closed now?? it will go back to halfway if i slow down but im worried should i just take the thermostat out?
____________________
fzr 600 its yellow but its no banana!!!!!!

[alains]

of course , then you will see the difference !
____________________
the worst day fishing is better than the best day working

[robbie21mcn]

its none of these alains its as you originally hinted at.
HEAD GASKET!!!! AHHHHHHHHH
got a new gasket and skimmed the head now running fine. it seems the gasket being bad was allowing air pressuried into the water system causing so much pressure it had nowhere to go but put the back of the expansion bottle
____________________
fzr 600 its yellow but its no banana!!!!!!

[alains]

that was a sign of bad head mounting . i had 3 NSR since 1991 , i've done rings or piston or cylinder several times , on my forum every mates have done de-coking or same as me . never the head gasket has gone , so it's a sign of bad DIY or from a awfull garage !
____________________
the worst day fishing is better than the best day working

[robbie21mcn]

alains any other ideas on the des restriction guide.
i know the bike is restricted but cant seem to fathom where. the exhaust has been taken off as shown in the pic and although it is a standard exhaust has no sign of a restrictor. someone told me the restriction in the can maybe in the middle but how do i know. someone else told me it will be restricted at the di unit and another person said it will be in the carb which i cannot see either. looked at these on www.nsr125.com but cannot see any of these things on mine. aaaaaaaaaaaaaaaarrrrrrrrrrrgggggggggggggggggggggggghhhhhhhhhhhhhhhhhh
____________________
fzr 600 its yellow but its no banana!!!!!!

[alains]

the french bikes (and swiss or german) have the restrictor down in the pipe (about 8") . to check that : take a piece of steel or cupper wire , make a small loop (2-3 mm avoid scraps) introduce it by the entry and look if you are stopped after 6 to 8" . if you are restricted it's here . so you may cut the pipe (by reporting the length outside and making marks) vertically . take the restrictor off with pliers) then solder the 2 bits as they were separated . precaution : use steel hand saw blade (not a machine) , make good marking , use only oxyacethylen torch . the other way is to buy a uk specs exhaust or a race model .
____________________
the worst day fishing is better than the best day working

[NSR150RR]

[alains]

the slice that burning oil lay on every surface of the head , exhaust chamber . every 7500 miles the top engine needs to be open for cleaning otherwise you loose power , your valves get stocked and your engine overheath . this is why when you do it you change at least the rings .
____________________
the worst day fishing is better than the best day working

[robbie21mcn]

i see on www.nsr125.com that it says the de restriciton on these bikes are not in the cdi unit can this be true? i dont want to replace an exhaust if its not that which is ristricting the bike.
____________________
fzr 600 its yellow but its no banana!!!!!!

[robbie21mcn]

in fact i noticed that my bike is an italian import so is there a possibility that the restrictor is on the cdi unit??? is this technically the same as the rc valve im so confused i just want a bit of leway when im driving about sitting at 70 with the rev counter thru the roof is not what i want. and before anyone says it i dont want a bigger damn bike my own is the business.
____________________
fzr 600 its yellow but its no banana!!!!!!

[alains]

download my file https://www.geneva-racing.com/~alains/NSRtips.doc
french import are restricted on both CDI & RC valves control unit , but they have not the same barrel , RC valves , exhaust as UK & IT models .
it appears that if you serial number begins by ZDCJC22B or ZDCJC22E your bike is fully restricted .
____________________
the worst day fishing is better than the best day working

[knockout_bar]