DT125R FORUM

Oh how annoying! I've seen this before when people have incorrectly set up the YPVS servo and stripped the teeth on the gears. It's probably easier to just buy another YPVS servo sadly than trying to find the individual cog. https://www.ebay.co.uk/itm/307114030022?_skw=Yamaha+DT+125+R+YPVS+servo&itmmeta=01M0T0CTAKVKYBVERW4KK9HKJQ&hash=item47816c33c6:g:QqIAAeSwkVdqdvO2&itmprp=enc%3AAQALAAABAGfYFPkwiKCW4ZNSs2u11xDV5F88zNLFmQlOj5cc4%2FxlPVfMrS0CX9zdgmCMx0exrIiMBYEnl2C70gEhZcvwr3BYq%2BewLJHyMjxf%2BATBLTUnAq5B4Os%2FAuVyeOUNpVSRYxblUNuwL%2BjqWn0F95mbpkEWkXEDU%2F4blrRDuajNXDPVd8py1aTbWsSecsyFqwFQqqWjrgMG65s52PTjh2LPZ%2FOmWbQsy4dMVcVkq6VX2lCX6cdUUBN6SMPZHm3xNkDwYsJXuOa1TCyyOEaSwcuLKfJrQwb9YP1PtVMNdQS0UqCxAXfBI4hQNMZjPJwu4V6qdKAjffzCnESPO3DSoS0%2FsfE%3D|tkp%3ABk9SR9als8CGaA If you have access to the a 3D printer, or are capable on CAD, you might be able to 3D print a new set of teeth, setting the TPU to 100% fill should be strong enough to cope with the demand. My 3D printer is pretty darn accurate so it would probably do a fair go at it to be fair.

@Carl-Kennedy hello, I had the same problem. Found out that someone ripped out the mechanical gears out of it, you can try that. And if you happenned to have them, could you please tell me the dimentions of the gears? Thanks

@elan-n Too much to list. [image: 342%20-%20xp34p3D.jpg] I've done basically most things to it, the thing that's impressed me the most is specifically the Zeeltronic ignition system. I have like 5 of those CDI units now as they're excellent! I fit them to all of my bikes. Single biggest bang for buck. I've done everything to it: https://www.youtube.com/watch?v=jZ1C_xCmqWg&pp=ygUbVGhlIGxldmlhdGhhbiBQcmplY3QgZHQgMTI1 (build video). I've ran TZR R 4DL Belgarda setup, to ported Athena 170 kit. I'd say, if you dampen your expectations, then the Athena kit is next inline (after exhaust setup). This is because, whilst it's not rip roaring tear your arms off performance, it gives you more low-end grunt and that suits my setup better. I have my RS for all out smoker power.

Thx mate I’ll have a look

It should rev to the redline. Depends on where you get your Zeel from, I paid £200 for mine, but that was like 12+ years ago.

It sems to have potential, even if I still have a bad carb, and PV and ignition are just based on butt dyno. Riding with a friend today I realized how slow his bike seemed, he was keeping up fairly well before, but now I felt like I was puttering around for him to keep up I have had a creeping feeling that maybe the reeds were damaged, and not the carb, so I pulled them out and checked them today, but they were fine. (VF4 clone for CR125 with DIY Polini 0.35mm petals). Can't wait to try another carb on it, feels like I have done a million mods and adjustments on that POS carb by now.. I was not so familiar with the PWK's before, but by now I know them in and out BTW, temp was perfect during the ride.

@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.

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.

These bikes are getting to an age where the clutch cush drive rubbers will start to wear out. It's possible that this is where the rattling is coming from. Whip the clutch cover off and try and rotate the clutch basket by hand. There should be no discernible play in it. These rubbers sit behind the clutch basket [image: PXL_20260527_183632013.jpg] Sandwiched between the primary gear. [image: PXL_20260519_091204926~2.jpg]

@DTGREENLANER Nice job, that looks ace!!

I’m having the same problem, did you manage to find some ?

Update: it now works, adjusted the timing a bit. Helped and do not know why it worked now since ive tried before and upto no progress then. It idles decent but it only runs nice with the choke on. Without choke on it runs like ass. Ive just fixed all the intake manifold gaskets and made it way better so no airleak. Changed the crankshaft seal and that also should be very very minimal. Not sure where else it could leak air

Fair play that's mint.

Hello Welcome to the forum Yes, photo uploading is disabled as I host all of this myself and imagine hosting is expensive. Imgur was the preference, but is now blocked in the UK and therefore cannot be viewed here But yes a build thread would be awesome.

@Calum It has a 24mm round slide carburator to meet the requirements of the a1 lisence in sweden, downtuned to about 15hp, im just wondering if a TM28SS will fit, they are very hard to find.

Hi there, Pretty sure the RPMs as far as the CDI are concerned are determined by the pick-up/magneto. So when you switch the ignition on and off, the powervalve does a cleaning cycle. Once this cycle is complete and the engine is running the valve should return into its closed state. If it is not, then it's possible that the powervalve wires have been inverted and the powervalve hasn't been adjusted properly. I feintly recall this being a common problem back in the day.

@Calum so i got it together it ran well when i started it in the garage but when i went for a ride when riding it doesnt have power and doesnt rev over 7k rpm when in neutral doesnt go over 9k but powervalve is working and no weird noises from the engine im completly clueless