madrevs Posted November 21, 2013 Share Posted November 21, 2013 Hi my 2003 dtr125 project I have now noticed yet another fault lol the rad radiator pipes and coolant in the rad and around the head is nice and warm and a blue colour but I noticed the expansion bottle under rear panel was empty after filling it and riding it for a couple of days the bottle doesnt get warm and the water I put in there isnt mixing with the antifreeze in the rad and head etc any thoughts on what the fault could be dont seem to bw losing any coolant now so dont no why it was empty and level hasnt changed doesnt seem to overheat but temp gauge sender is currently faulty and needs replacing as always reads hot even when bike is not running and ignition is sqitched on Link to comment Share on other sites More sharing options...
slice Posted November 22, 2013 Share Posted November 22, 2013 Sounds like your thermostat is not opening, you could take the thermostat out and see if it warms the bottle that would tell you if that is your trouble, otherwise take the thermostat out and dip it in some boiling water to see if it opens if not then replace it, should be an easy fix. PS you do have to get the bike up to normal running temp before the water will mix, it may be that as it's your project your not running it for long enough to get the system hot? Sorry just reread your post and you say your riding it, thought it was a project that just sat in the garage while you were working on it (DOH!!) Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 would the thermostat not stop the coolant in the rad from heating up though as thats getting nice and warm and bike doesnt seem to be overheating.yeh its a ongoing project lol its on the road but seems like things have been bodged on it for the last 10 years.just needs tidying up really and a few bits here and there Link to comment Share on other sites More sharing options...
slice Posted November 22, 2013 Share Posted November 22, 2013 Not really as the thermostat only allows the water through when it's warm enough to open so the water in the rad and the pipes will still get warm it might just not be circulating which is why your over flow / header tank is not getting hot, my thoughts on it anyway, it would be the first thing I checked. Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 ok tahnks sorry am used to working on cars lol will get the thermostat out tomoro and if faulty probably just leave it out as i doubt i need it on a 125 .thanks Link to comment Share on other sites More sharing options...
slice Posted November 22, 2013 Share Posted November 22, 2013 Should be ok in the winter but summer time you might need to think about replacing it, bikes run hotter than cars even with water cooling and also if you leave the thermo out it will run cool all the time and that has it's own set of problems, I would replace it rather than leave it out myself but obviously up to you. Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 Surley if water is circulating round the rad though will it not still cool it in the summer what does expansion tank actually do.its only got a bottle cap on it from a evian water bottle as a cap which isnt a great fit so maybe its stopling it from pressurising Link to comment Share on other sites More sharing options...
2 Wheels Posted November 22, 2013 Share Posted November 22, 2013 Thermostat is no1 suspect,,,,,,,,not opening,,,so coolant isn't going round the engine. the system only takes water from the expansion bottle if it needs it. Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 Oh right I see well am off work tomorrow afternoon so will take it out then and have a look canbu recommend any good sites for yamaha spares as so far been using the dealer which tgey stipid amounts of money for bits mixture screw I had off them was 13.50 ouch Link to comment Share on other sites More sharing options...
2 Wheels Posted November 22, 2013 Share Posted November 22, 2013 http://www.wemoto.com/bikes/yamaha/dt_125_r/01-03/ Give em a bell and they prob get you what you want Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 Just emoved thermostat and using a kettle tested it and its working opening as it should could it be a blockage somewhere am unsure what it could be the thermostat is bottled to the top of the head theres a pipe going from thermostat to rad and a smaller warmer pipe going to carb and both are warm after running for a short while.theres two pipes comingboff expansion one overflow and one on the bottom this dissapears through the rear mudguard somewhere.am at a bit of a loss now as to what the cause could be Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 Ta for the link Link to comment Share on other sites More sharing options...
2 Wheels Posted November 22, 2013 Share Posted November 22, 2013 Just emoved thermostat and using a kettle tested it and its working opening as it should could it be a blockage somewhere am unsure what it could be the thermostat is bottled to the top of the head theres a pipe going from thermostat to rad and a smaller warmer pipe going to carb and both are warm after running for a short while.theres two pipes comingboff expansion one overflow and one on the bottom this dissapears through the rear mudguard somewhere.am at a bit of a loss now as to what the cause could be Well mabey you don't have any problem at all. The rad pipes and rad it'self will always get a bit warm. The coolant in the engine is kept in the engine until it gets too hot, then the thermostat opens and lets the hot coolant out of engine into rad, the cooler water from the rad then goes into the engine and the process starts again. Sometimes the thermostat can get stuck,,,,, so by you putting it into a kettle might of freed it up, if your gasket is OK then put the thermostat back in. Anyway you said in your first post that the bike wasn't overheating so again mabey you have no problem at all. The pipe that goes to the carb is supposed to be warm,,,,,,, its a carb warmer pipe to help stop "carb iceing" there is another one that returns aswell. The pipes on the expansion bottle. Yes there are 2,,,, one is an overflow and the other should go to the top of the rad somewhere. The one on the bottom of the bottle should go to the rad,,,,,the overflow one should be the one that disappears back under the bike and tucks into the frame, this one is just open-ended. Mabey some one put your pipes on arseways on the expansion bottle. I haven't got my bike here at the min so am just going from memory but am pretty sure that's the way its all layed out. The expansion bottle will never get warm as its only a feed to top up the rad if it needs it,,,,,, different system to cars and other bigger bikes. Fix your temp guage in the dash and you will have no worries. These bikes run hotter than you think but on my guage it never reached the half way mark. ps, if you smell your bike getting hot or if the bike starts to stumble in anyway stop straight-away and let it cool down. Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 Ok will see how it goes might give it a flush with some radflush just to be on safe side have also ordered a temp sender off ebay as yamaha wanted 35 quid did try soldering the tab on the sender that broke off but it went straight to hot as soob as i turned ignition on might of fried it with the soldering iron next problem now lol neutral switch Link to comment Share on other sites More sharing options...
2 Wheels Posted November 22, 2013 Share Posted November 22, 2013 The pipes on the expansion bottle. Yes there are 2,,,, one is an overflow and the other should go to the top of the rad somewhere. The one on the bottom of the bottle should go to the rad,,,,,the overflow one should be the one that disappears back under the bike and tucks into the frame, this one is just open-ended. Mabey some one put your pipes on arseways on the expansion bottle. I haven't got my bike here at the min so am just going from memory but am pretty sure that's the way its all layed out. Don't forget to check these pipes are the correct way arround Link to comment Share on other sites More sharing options...
madrevs Posted November 22, 2013 Author Share Posted November 22, 2013 Will do trouble I found with the dt is everything s cramned into tiny spaces so makes it a bit awkward to work on.couldnt even work out how to get the airbox off when I took the carb off as it seemed attached to everything Link to comment Share on other sites More sharing options...
2 Wheels Posted November 23, 2013 Share Posted November 23, 2013 Will do trouble I found with the dt is everything s cramned into tiny spaces so makes it a bit awkward to work on.couldnt even work out how to get the airbox off when I took the carb off as it seemed attached to everything It is attached to everything,,,,,, ya have to take all the back plastic off that goes down round the rear wheel. With some messing round ya can get carb off without doing all that. Sometimes ya can just rotate the carb if your just working on the bottom of it,, eg floats or jets Link to comment Share on other sites More sharing options...
madrevs Posted November 28, 2013 Author Share Posted November 28, 2013 after fitting a replacement uses temp switch last night.started up and lefyt ticking over for 20 mins in garage.gauge went up to the middle as it should.however riding it the 13 mile commute this morning it will only warm up at traffic lights and as soon as i start moving again the gauge creeps back down to just above the c.is this normal for this time of year Link to comment Share on other sites More sharing options...
2 Wheels Posted November 29, 2013 Share Posted November 29, 2013 after fitting a replacement uses temp switch last night.started up and lefyt ticking over for 20 mins in garage.gauge went up to the middle as it should.however riding it the 13 mile commute this morning it will only warm up at traffic lights and as soon as i start moving again the gauge creeps back down to just above the c.is this normal for this time of year Perfect,,,,,,, when you start moving the air flows through the rad more cooling down the coolant/water. When you stop at light the temp rises a little. If temp guage ever starts to go above half way mark keep an eye on it and turn engine off if it gets near the top (ie. red hot mark) Link to comment Share on other sites More sharing options...
dt502001 Posted November 29, 2013 Share Posted November 29, 2013 Did you put the thermostat back in? At this time of year you can get a erem aaha reverse seizeur a sudden cooling of the cylinder and it grabs the piston. If the thermostat is working properly then the temp shoud stay fairly consistant as its only measuring the temp of the cylinder not the rad,leaving it out will not be good for the motor the piston will get hot stay hot but if the cylinder temp goes up and down everytime you leav a stop you'll kill it. Link to comment Share on other sites More sharing options...
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