DT125R FORUM

Hi, thanks again for the detailed reply and for all the information.
I had already heard about the larger snorkel from the DT200/DT230, but I’ve seen that they are very difficult to find. Designing one in CAD could be possible, but I don’t have any experience with CAD programs and I also don’t have access to a 3D printer.
Regarding the carbon reeds, I had heard about them before but I’m not sure which ones would be a good option at a reasonable price.
I’ve also read that some people install a VForce4 reed block for the Yamaha Blaster on the DT125 with small modifications. However, it’s quite expensive. I did find a cheap copy on AliExpress, but I’m worried that the lower quality materials could damage the engine or even perform worse than the original reed block.
The air filter was replaced a few months ago with a TwinAir filter, and the exhaust was also cleaned a few months ago.
If I eventually decide to modify those spigots in the inlet port, do you know where I could find a good guide or tutorial to follow?

Hi everyone, sorry for the late reply, I’ve only just had time to check a few things on my DT.

I checked the YPVS and it is working correctly.

I had noticed that the bike had a strange and unstable idle, so I removed the carburetor and cleaned the jets. After cleaning it, the bike feels more responsive and I managed to reach around 80 mph.

I also reinstalled the bottle on the air boot, restoring it to stock.

However, I noticed a problem with the carburetor: the air screw won’t unscrew completely. After about 3 or 4 turns it gets stuck. I tried using some lubricant but it’s still stuck, and I didn’t want to force it and risk damaging it. Does anyone have any advice on this?

I also noticed that the bike still seems unable to fully pull the last gear. Do you have any simple and inexpensive suggestions to slightly improve performance? I was thinking about opening up the airbox a bit and rejetting, but I’m not sure if it’s worth it.

Regarding the advice about removing the reed block and checking the inlet port: if I decide to remove the reed block and work on those protruding spigots, what kind of tools would you recommend to safely remove or smooth those edges?

Thanks to anyone who can help!

Hi, thank you very much for your advice and for taking the time to explain everything.
I’ll check the YPVS as soon as possible following your suggestions.

Just to clarify, the valve is not physically installed backwards. It is only set slightly more open than the position where it is flush with the exhaust port.

As far as I know, I think the Italian models have the same restrictions as the UK ones.

Unfortunately, I don’t have the knowledge or the proper tools to do serious work inside the engine, so I won’t be able to attempt modifications like port matching or working on the crankcases myself.

Thanks again!

Hello everyone,
I’m new to this forum, I’m from Italy and I own a Yamaha DT 125 RE. I need some help because I feel that my bike is not performing as it should.
The bike is fully derestricted: it has the ground wire connected, a full Giannelli exhaust, and I also blocked the small bottle near the air filter (not the one on the intake manifold). After doing this, it seemed to give slightly better performance.
Regarding the carburetor, the idle is a bit unstable: sometimes it’s lower, sometimes higher. The air screw is almost completely closed, even though the air filter is completely stock and unmodified. I’m not sure if this could be related to the performance issues.
Another thing I noticed is that the YPVS valve is not aligned with the exhaust port. It is actually “reversed”, meaning it stays more open than the fully open position. When the valve is correctly aligned with the exhaust port, the bike becomes very slow, especially in acceleration (I don’t know why). With the valve set as it is now, the bike reaches about 122–123 km/h (around 77 mph).
For reference, the engine has been fully rebuilt and has about 5,000 km on it.
Even so, when I compare my DT 125 with others I’ve seen on YouTube, mine seems slower, especially in acceleration.
Do you think there is something wrong with my bike, or is there anything else I can do to make it more powerful without spending too much money?
Thanks to anyone who can help.

Hi everyone, my name is Mattia, I’m 17 years old and I’m from Italy. I recently got a Yamaha DT 125 RE and I’m really excited to share my passion for motorcycles.
Since I don’t have much experience yet, I’m looking forward to learning from you and getting your advice to improve both myself and my bike. At the same time, I hope I can help others by sharing solutions to problems I’ve already encountered with my DT 125. I’m really happy to be part of this community and can’t wait to learn and contribute!