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 +1 for keeping this bike original, it looks great and the motor sounds good to me. I'd definitely enjoy riding it for the rest of the summer before taking on any serious work. In one of the vids it does sound like the rubber snorkel could be missing from the airbox intake, if you're somewhere in the EU the easiest way to get one is probably to just get a complete airbox from a French or German breaker which have plenty of DTRs. This model also shares the CDI unit and YPVS servo (both marked 3MB) with the KTM LC2 125 which sold well in Europe so if you want a spare CDI unit/servo that might be the best way to find these. Looks like you have an OEM clutch cable, this and (especially) the throttle cable are best kept original as the throttle cable splitter has a mechanism that balances the carb and Autolube at all throttle openings. These are still available new and worth every penny. This model I think had a dark blue seat when new (same colour as the frame/fork gaiters), probably available from bikerpartshop in Portugal: https://www.bikerpartshop.com/en/166-dtr-50-125-200 Definitely retain the Autolube, and get a Haynes or Yamaha manual which explains how to bleed and adjust the oil pump. It's also well worth reconditioning it with a kit from Yambits. They used to sell a clear oil line kit but I can't find it, car windscreen washer hose works just as well. Here's a list of other bits to order at the same time, air filter elements are as good as OEM but half the price (get 3 or 4 so you can keep cleaning and re-oiling them and store them ready to change in a plastic bag, this is the easiest way to look after your engine), cable oiler (essential): https://yambits.co.uk/dt125re-air-filter-p-9241.html https://yambits.co.uk/dt125re-airbox-snorkel-genuine-p-230082.html https://yambits.co.uk/dt125re-oil-pump-repair-kit-1989-1995-p-218588.html https://yambits.co.uk/dt125re-oil-pump-oil-line-elbow-p-65302.html https://yambits.co.uk/dt125re-cable-lubricating-tool-p-46571.html Also here are a couple of things I like to do to any DTR; a full suspension linkage strip including making sure the troublesome relay arm bolt never seizes again, and making your own YPVS cables from MTB gear cables: https://dt125r.co.uk/post/28245 https://dt125r.co.uk/post/28693

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.

The 230 is up and running! I have run about two tanks through it, but the chinese pwk carb I'm using is bad (had it in a box of junk carbs), so it drinks more than it should. Its stutters and putters on low throttle openings, and nothing I've done helps the issue completely (jets, needle and even filing the cutaway on the throttle slide). Runs well on more throttle though, and pulls pretty well. I have another clone pwk on the way, and hope that will work better (had good reviews). Internal gearing is higher, so 5th on the 230 is about the same as 6th on the 125. Went from 17 to 16 on the front sprocket, and now I'm doing just abt 5k at 80kph. It goes better than my sligtly modified 170-engine. I still have stuff to do with tuning the carb when I get it, tuning the zeeltronic, fixing the starter cicuit etc. I have not figured out how to integrate a starter button close to the throttle handle yet. Not a lot of space to add a switch next to the stop switch (that I'm using as a map switch now). Engine seems fine, no problems with vibrations, shifts are good, and clutch is holding up. Some small drag from the clutch at standstill that can make it a bit hard to shift when standing still, even if the engagement point is fairly early on the travel of the lever. Using a DT LC clutch cable, because the DTR cable did not fit the engine, DT LC cable was a perfect fit. I guess that's it for this update.

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