DT125R FORUM

Reposting images as Imgur not longer viable in the UK.

Reposting images as Imgur no longer viable in the UK.

Reposting images as Imgur longer viable in the UK.

Reposting images as Imgur is no longer viable in the UK.

Reposting images as Imgur no longer viable in the UK.

Reposting images as Imgur is no longer viable in the UK.

Reposting images as Imgur is no long viable for the UK.

Still got this though, haven't done anything to it for a very long time.

Have you earthed the green/black wire?

Sounds like a restriction.

Where is this PWK from? Is it a good quality carb?

Although not the source of your problem here, as the demand/load on the engine increases, the reliability of the fueling also becomes more important. What might be fine in lower gears, presents problems further afield.

Removing the Snorkel will adversely affect the performance. Removing the snorkel will result in turbulence adversely affecting performance.

So put the snorkel back in.

You'd be better focusing on getting a DT230 Lanza Snorkel as it's slightly larger flow.

https://www.cmsnl.com/products/duct_4tp1443700/

Or a cheaper easier solution is to 3D print a larger snorkel.

Well, you need to figure out whether this is indeed the problem. Obviously I can't be certain having never seen the bike, you'd need to take some measurements.

You don't need to get a new top end, correcting the squish is standard practice on two strokes.

This is most likely the squish.

If someone built that top end for you, they probably used too thick a base gasket reducing the compression ratio. The cylinder head could sit be marginally higher than what it was before, meaning the squish is off.

I am not saying this definitely the case, but would explain why you'd lose bottom end. I am not sure about the heavier piston, sounds like a cop out, but if a different dome was used, different profile, then same answer. The squish is affected.

A vast majority of power on a two stroke is made in the head, so it could be that the squish band isn't correct. This is a very simple and easy thing to fix and measure. All that is needed is a set of vernier calipers and some 1.2mm thick solder wire, with a dab of grease to stop it falling into the bottom end.

Could be this, especially as you say, it was fine before the top end rebuild, noticeable after.

I once went from the stock 3MB00 cylinder, to the TZR R Belgarda 3MB00P which has a raised exhaust port by 1mm and as a result, greater over-rev (ideal for the TZR) loss of bottom end (less ideal for the DTR).

I went from lifting that front end up with ease (no small feat on my heavier setup) to having to work for it.

Now I run a ported Athena 170cc kit and I love it for the low-rev grunt. I have my RS125 which is lightening fast so I enjoy both aspects now :)

I am by no means an expert and please someone else chime in and correct me, but based on what you've just articulated, this could explain it.

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?