DT125R FORUM

Hello Guys,

Currently trying to tune my carb on my 4BL

It seems like it’s the ?small? Version because of the 22.5 pilot jet

However, if I try the 210 or even the 220 jet it runs lean and bogs down

A 250 was a bit too rich and I wouldn’t rev out right

Setup is stock new cylinder and piston, stock exhaust with Athena silencer and the snorkel removed
De-restricted

I still don’t quite understand how some carbs came stock with a 240 main and some with a 210
And don’t quite know where to fish for the right main jet now

Found the problem

Turns out you can mix up the base gasket and put it on the wrong way, blocking the coolant passage.

Luckily no damage to cylinder or piston

On the richer side
Since im still breaking in the new cylinder and piston
Overheating helps seating those rings better

Ive checked the coolant, drained it, flushed it etc
Even with a co tester for blown headgasket and nothing came up.

At first i tought the headgasket is restricting flow, since its got a new cylinder and piston
But i checked this too and flow seemed sufficient

Hello all and greetings from Germany,

i have a weird problem with my 4BL.

The stock temp gauge broke off in the head and would have to be drilled out, thats why i installed a Temp Gauge on the upper Radiator Hose (the T fitting Type) and am reading temps up to 115 celcsius after 5min run time.

Things i checked:

Water pump impeller looks fine and spins with the engine
All hoses flushed
Radiator flushed and cleared
Thermostat removed
Hose from thermostat removed and started the engine to confirm the flow of water.
Jetting on the richer side

When i put 2 temp probes in the upper and lower radiator fins i get a temp difference from upto 40 degrees, so the rad is functioning
But the water coming into the rad is getting too hot

When i start it and take off the temp is stuck at around 30-35 degress for a while and then suddenly skyrockets

No exhaust fumes in the coolant
No overflowing expansion tank

I am lost at this point

Does anybody maybe had the same problem and can help me here ?
I would really appreciate it

Hello Guys and greetings from Germany

i am currently in the process of rebuilding my 4BL and cant find the correct Setting for the Oil Pump.

Some say the Lines should match up on closed throttle, some say they should match up on WOT.

Sadly i cant find the Haynes manual in Germany anywhere.

Maybe someone can help me here