DT125R FORUM

Forum patched and updated. Fixed some database corruption issues which was having a knock-on effect with emojis so hopefully they're working now.

@HOTSHOT-III Hopefully the issue gets resolved as I don't want to lose the data they're hosting. The important stuff I ought to host here to guarantee it isn't lost.

@Vuteng No worries. You may be right about the pink seat, it's hard to keep track sometimes lol. The oil light should illuminate with the neutral light, it might just be a bulb. The air filter holder can be repaired with new foam. Get some 5mm air filter foam off eBay, clean the holder thoroughly and glue it on using Seal-All, a petrol and oil resistant glue. This is very important, if you run the bike without this the engine will suck dirt. It's also worth applying a dribble of foam filter oil right around it before sliding it back into the airbox with a fresh filter installed. https://www.ebay.co.uk/itm/365607220379?_skw=air+filter+foam+sheet+5mm&itmmeta=01KXEHQNAYY94YVPA0ZCWEDJWT&hash=item551fe3749b:g:bw0AAOSwvgZoJ56X&itmprp=enc%3AAQALAAABAGfYFPkwiKCW4ZNSs2u11xBJIt2fFtFYVz7npvy9%2FdRi6S7mEgUJZasERX59eCBKfXenkOvpapeRTvdBtNGUKUfiPY4fEK4pf%2B9FZEvfYbBUON3xdL3tnhWs58zVRQNZ7pceGI5BgLatkYMECyxPveg5pYDIaV21EePCl7Cqfvwvk3ioK5viwwH2Yz8sIBO23aXzUAkNNyDVUNCXMZc3LzjGdqxuqVXOAKppI%2BXdoEEGNlsakeXqsPKIdfDmz%2BI2T5pOUti5Eev1OACioI8km0yJRYiIVkU2JROBBc1g6SRJx%2FMTcKF3eHF9UzWNeU7y5%2BvMJ4u3qBNGNE1dBrHcjSI%3D|tkp%3ABk9SR-DV3tHrZw https://www.repairproducts.co.uk/product/seal-all-gas-oil-resistant-adhesive/

It sounds to me like the relay. So the starter motor button isn't wired directly to the starter motor as the starter motor requires a lot of current. Instead the wire is connected to the relay and the relay activates the starter. So I'd look in that general vicinity, sounds like it's starting to go faulty, which isn't bad considering it's age and the high amperage that it is subjected to.

@HannesDTX Check all the things @calum said, plus are you sure you've done a FULL carb clean? A lot of people just put them in an ultrasonic cleaner for half an hour and expect to bolt them back on. Doing this doesn't sort the blocked emulsion tube which is a leading cause of DTRs refusing to rev out beyond 6000rpm, precisely the symptoms your bike has. Do a full carb clean including the emulsion tube (the brass tube the main jet screws into). A lot of people (including bike shops) miss this and don't realise it comes out because you have to screw the main jet back in without the brass washer and tap it gently to remove it from the carb body. The space between this and the carb body gets blocked with moisture, dirt etc and blocks more and more holes in the tube (which is how the air atomises the fuel) until it just starts fourstroking and won't rev out one day as this controls the mid-throttle fuelling. Just chucking it in an ultrasonic cleaner usually isn’t enough; you have to actually remove everything from the carb body, physically make sure all the jets and air passages are clear, then reassemble. Make sure the air supply to the emulsion tube is clear as well, it's the small brass tube on the right of the carb body just in front of the carb-to-airbox rubber. You should be able to blow through it, but only just.

Some overheating issues this weekend. I have checked the thermostat, water pump and head gasket. The head was a bit warped (like bulging towards the middle of the sealing surface). However the head is not stock, it has been welded and a new combustion chamber shape was machined, so can't blame the manufacturer. I did not see any signs of head gasket leaks, so I doubt that was it. I resurfaced the head and put it back together. I'm running a bit tight squish at 1mm, so i might have to try lifting the cylinder with a thicker base gasket to increase squish a bit and decrease compression slightly. Should be 11:1 as is which has been ok on other bikes. I'm running double radiators, so cooling should be similar to the DT230. The first two tanks I did not experience any temp issues, so it's a bit strange. Outside temp was about the same as before. Only thing changed that I know of was (continuous) changes with the carb and filling it with 95 octane, since my 98oct fuel can was empty and there is no 98 where I live.

Also don't forget to change bulb in light cluster for an led Kind regards