DT125R FORUM

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

Oh wow, well you'll be pleased to know not much has changed in the last 20 years for two strokes. Port tuning is as it's always been and fuel injection came a few years ago on nothing but the most elite machines. These bikes are a doddle to get running, so throw up any questions you may have and we'll point you in the right direction.

Sorry for late reply Thank you We carefully took it apart and greased it back up and running nice now, the bike is so much more responsive and acceleration is a lot better

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

Hi @yennie , That's cool and I am glad you've managed to get something working for your setup. I am working on something similar to just add a slight angle to the inlet manifold so pod filters don't foul the shock absorber.

They say it's mechanical but the description sounds electrical and they're adamant it's not I still maintain it's electrical related, ignition timing, static angle, etc. But I am not familiar with the ignition system they're running and/or how it's been wired together

Where is the Dyno result with power changes?

Okay, a few more NOS parts ordered and now the primary drive gear, clutch basket and generator nut all torqued to spec! [image: clutchAssembly01.jpg] All 6 TZ750 clutch springs fitted with brand new clutch plates and NOS OEM damper rings installed. I also replaced the factory pressure plate with a gorgeous billet RDLC Crazy pressure plate. [image: clutchAssembly02.jpg] It's said to have better oil flow and looks to have a fair amount machined out of it, but I was surprised to see it's slightly heavier than the factory setup. [image: clutchAssembly03.jpg] This milestone marks the completion of the bottom end There's just the matter of the water pump to install, I was really hoping to get a Chariot Performance uprated one, but they're no longer manufacturing them. And then there is a company that makes a stunning carbon fibre generator cover/chain guard. I did have my eye on a Chariot Performance one, but again they seem to no longer be making them sadly. The cylinders are booked in with Mick Abbey for some mild porting work, then the heads need to be sent off for machining. But once that's done it will mark the engine work completed for this project and I will turn my attention to the frame. The frame has now been moved into the garage and I'm just trying to figure out how/where the steering damper should be fitted!

I do need to get back out on this bike! The front brake disc failed (annoyingly as this wasn't cheap) and the battery died over winter, even though it was on trickle charge, again very annoying. I did manage to get some nice bits for this bike, but I've only manage to get around to fitting one of the parts as the bike is in a storage unit and I don't have all the tools there to do all the bits. Firstly I have this beautiful VHM gold skull cap. [image: vhmSkullCap.jpg] I look forward to getting this fitted. I also have a pair of these beautiful carbon infills for the side panels (if I can remember where I've put them). I will fit these when I do the skull cap as it requires taking the fairings off. This week a special parcel arrived from Italy, which was a beautiful carbon fibre rear seat infill to replace the FRP one I had there originally. [image: carbonRearSeat01.jpg] It almost looks plastic dipped in that photo, but I can assure you it's the real deal. [image: carbonRearSeat02.jpg] Very happy with the fit and finish (although the seat wasn't placed down properly in this photo, hence the gap). [image: carbonRearSeat03.jpg] Just buzzing to get out back on it now that summer is here! [image: carbonRearSeat04.jpg]

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