I’ve had similar temperamental problems with this (& a 100 other things!!)
The only thing it can be is the needle valve that is operated by the floats (or the floats themselves!)old fuel varnish or dirt is the usual suspect...
You can get a replacement kit I think. The needle and the brass insert it fits into...
A good inspection and clean is usually good enough...
P.S. the ‘weight’ of fuel can exasperate the situation, or it has in my experience (which isn’t much!)...

@SpookDog
Have drained the carb multiple times,
No water and stuff

@SpookDog meant to quote Declan there pal.

With the athena kit it's a complete unknown quantity. Only issue I've experienced with running a colder plug ( a10 range on nsr125) was it would foul and cause a missfire when the weather turned cooler.

@Calum yeah

3bn 1988 model.

Cheers bud, that’s something to work with. I’ve got a good 3bn, my reworked 3mb and another 3mb (that I forgot about till now) that is battle~scarred but otherwise original.

@jonne123 I bought the usb/laptop lead when I bought my zeel. Very easy to use once you have it installed.

Yamaha just refer to both of them as Air Chamber on the parts diagram's - I still say its not a performance item and its just a bolt on for emissions / silencing etc.

Thanks for all the respons.
I did skim the head, but i will try to tighten the bolts👍

I was told, time spent fine tuning powervalve timings is worth its weight in gold.

In my opinion, this all depends on the usage.

For road racing, a finely tuned opening wouldn't net huge gains. Since once you are fully opened, you are likely to stay that way. I.E. does the Honda RS125 even have a powervalve? Or is it just chocked wide open.

MX a working powervalve is important, but there is always the gear below? I know people faff around with springs to get that powervalve open earlier/later but often it's just about shifting the timing.

I was told by a local technician at Yamaha that tuning the valves timing will net you decent gains. I was always too lazy to actually do any of this.

@jackreece show a picture with your tm32 installed. The float bowl needs to be pretty level. Because of how the DT engine and intake is, some carbs will sit at a angle

@Challenger yeah I really wanted it to either be the graphite colour or just the standard silver but it’s all the paint I had or could get during lockdown so is what it is

Yamaha TZR125 DTR TDR 125 Wiseco Piston Stock 56mm Bore 679M05600
on ebay aint bad at all either they range .5mm and have 8 stages u have to have a rehone though to be sure u aint blowing your funds

Also, does the block breather pipe connect to the carb just behind the fuel in pipe? Cheers peeps!...

Hey! You weren’t wrong, there is a paper gasket. I was wrong about the oring though. It’s to big for the coolant pipe🙄

What one are you on about?

https://www.fowlersparts.co.uk/parts/4189513/dt125re-1d02-2005-030-a/clutch

alt text

Can you not just use something like this?

https://www.toolstation.com/spring-washer/p83526

Just done the one on my 3SH - when you put the new one in make sure that you cover the gear lever shaft with tape so it does not damage the seal when you push it through. Budget for a new clutch cover gasket and oil as well.

BTW do not lose the clutch ball bearing!

I did my mains recently and one of the seals was tight. I had to clean it up a bit with some really fine wet and dry, just to kinda deglaze it. Lite smear of grease on the seal and it went in easy. Don’t forget the right seal is one sided. It should have outer wrote on one side. Also it doesn’t go all the way in. It sits flush with the outer edge (or it does on mine 1988 3bn). It shouldn’t be a bear to fit cause it’s only the outer that’s touching anything, unless you left the spacer in the crank. You just need a longer tube to drift it...

You really need to check the back of the piston that isn’t exposed to exaust gas at the manifold. The piston skirt is exposed to the ex manifold on the upstroke.