DT125R FORUM

Due to Imgur being blocked in the UK, I've had to rehost these images. Maybe I'll reorganise it at some point, but need to do this for all my projects :(

I'm sure someone here will be able to point you in the right direction.

What we've been seeing in recent times are a lot of DTRs being imported from Europe, these can come with subtle differences, this may be the case here.

This is the 3NC wiring diagram.

I only have a Haynes manual so can't speak for what other diagrams look like.

I have also hosted the workshop manuals here: https://dt125r.co.uk/topic/3258/yamaha-dt125r-200r-workshop-manual
https://training.dt125r.co.uk/files/Yamaha_DT125_Workshop_Manual.pdf

This may be useful.

I'd expect there would be a few issues, the bike wouldn't handle particularly well if the front and rear wheels were misaligned. The bike would have a tendency to crab.

 |     <-- Front wheel
[  ]   <-- Frame
  |    <-- Rear wheel

Figure: Exaggerated misalignment

I'd be inclined to measure/check and if necessary locate and reinstall the speedo drive.

Aww nice! I've just received another Zeel for my RD yesterday. I've got to wire the plugs myself mind you as it's going into a Cagiva Mito.

HHhmm, that's annoying!

A common one is if you accidentally got water in your exhaust! I've seen this before, if the expansion chamber has water in it (if you washed it, left it outside, rode it in the rain) then this can cause it to bog.

You've said you put a new pipe on it, but just worth taking the exhaust off and tipping it upside down.

Poor fuel can also cause these types of problems. What does the colour of your spark plug tell you?

So just go with the stock settings. You can't go too far wrong.

The easiest way go get started with learning is by having a play with the powervalve timings. You won't run the risk of detination and damaging your engine, so it's a safe place to start

I love mine, I have about 5 Zeeltronic ignition systems and just this week bought another one.

I'd say, bang for buck, the Zeeltronic made the single biggest impact on my DTRE, over exhaust/Porting/carb the ignition system made the biggest jump in performance.

Hi @barron-1989,

Great little project you have there. Looks as though it's coming together nicely now.

Haven't seen anything on the For Sale section for years. These days it seems like FaceAche is your best friend here. The sale sections are not visible to members below a certain post count mind you, although I haven't looked at the settings since I set this website up over 10 years ago.

These are cracking little machines, it won't take you long to get her ticking over nicely that's for sure.

What bits are you after just out of interest?

Shouldn't be too difficult.

You see the little dot on the balancer shaft cog, that should align with the corresponding dot on the crank gear. On the DTR, it's like the piston is at TDC for the dot to align.

But should be simple enough.

Slow slow progress on this.

Made a bit of a push on this the last couple of weeks.

New Renthal chain fitted. Bought some nice Apico foot rests and refitted/bled the front brake system.

No surprises, but the original brake caliper was shot, completely seized solid.I managed to source another one, but one of the pistons was stuck. Once I addressed that, I found I was unable to pressurise the system, the master cylinder was shot.

These bikes share the same master cylinder as the Cagiva Planet, but I was unable to source one of those for a reasonable price. I ended up getting a KTM Duke 390 front master cylinder as the closest match I could find.

Front brake now bled and working. Bought lovely Hel lines front and back. The rear master cylinder's wiring loom was shot to buggery. The banjo switch was all snapped and the wires were merely soldered onto the bolt.

A new genuine bolt, wire harness restored, then I designed and 3D printed the cover to secure it all into place.

Need to reattach the rear brake master cylinder fluid reservoir and see what surprises are in store for me for the rear :o

Hoping to continue to make progress on this as it's basically done. Just need to find original panels (or refurbish my ones for now).

@kepirok I haven't ridden it in years! I do really want to though, it's a great bike :)

@kepirok Probably lost to time now due to Photobucket and Imgur. But everything is documented on my build thread and I made a YouTube video of the build, so you can piece the two together there.

https://dt125r.co.uk/topic/15/the-leviathan-project?_=1776597285894

https://youtu.be/jZ1C_xCmqWg

That's so cool!

It's been ages since I have been on my DT. I ought to sort the bits out on it and get it up and running again.

My ETX is close to being done as well and that thing will rip when it's finished

Hello and welcome to the forum!

Tidy looking TDR you have there =)

@hotshot-iii Always heard good things about the TDR250. @scrimsmustang Used to rate them as well.

Oh awesome! Congrats on the bike. I've had mine now 16 odd years now!

Some great advice here, but I'll just chime in with some alternative idea for food for thought, but it doesn't negate the great advice we have here.

Many years ago, I went down the TZR Belgarda route, which effectively ran a DT125RE engine, just modified porting. As a result, I ended up using the carb from that bike, which was a Dellorto VHSA 32mm carb. These are probably easier to find as they're used heavily in the scooter community.

I've never had problems with that setup, but I am not convinced that the bike is that rapid (despite all the mods I've done), but maybe I just got used to it.

I just run an NGK cap for mine.
https://www.pjme.co.uk/acatalog/NGK-Spark-Plug-Cap-Racing-Red-1550.html

Pretty sure I run an NGK lead as well to be fair.

So I don't align the powervalve with the hole (partly because my exhaust/valve have been ported so it probably isn't right anyway. You did right by aligning flush with the exhaust port. I'd just focus on that, take the exhaust off and align it with the exhaust port. Flick the ignition on and off a few times to make sure the cables don't realign.

If you want a quick way to diagnose your problem to get you a steer in the right direction then I'd do this.

1. Align the powervalve flush with the exhaust port
2. Disconnect the powervalve servo
3. Remove the carb air filter boot (eliminating the airbox)
4. Run the bike with no air filter

What this should do.

Remove the powervalve will stifle bottom end, but 6k+ should shoot off like a rocket.

Eliminating the airfilter removes any restrictions that might be present in the air intake tract. Whilst not ideal running without a filter, it will be fine for a short space of time. Unless a stone flicks into the inlet you'll be fine.

You should now be running the bike quite lean (so avoid prolonged wide open throttle). The bike should run better now than ever.

If it runs worse, it tells you your jetting is too rich. If it runs better then you know that you need more fuel. If it runs the same, then you know the problem lies elsewhere.

I am expecting it to be the latter, I'm expecting the problem to lie else where, but ruling these items out first, means we can then start to go more technical knowing that we've addressed the simple things first.

The OEM ones are apparently made by GPR or Tourmax.

One manufactured by Mitsubishi should be of sufficient quality, Mitsubishi supply into Yamaha for a lot of other parts these days.

Can you link the one you're looking to buy?

Presumably it's this one:
https://yambits.co.uk/dt125re-ignition-coil-mitsubishi-japan-p-222065.html

Yambits is a quality website, so should be reliable and Mitsubishi is not going to mess about with subpar coils.

Hi John,

Sounds like a lovely little time machine you've got there.

Cracking bike and very very reliable, if it's not working, then it'll be something very simple and I am sure we'll be on hand to answer any questions you may have in an attempt to get you on the road again.

Definitely go the OEM route for sure.