DT125R FORUM

@Calum maybe i could check the exhaust to be sure indeed, ill try that first. Some time has passed and it suddenly was gone but came back after a short while, very weird haha. The spark plug color is deer brown so a little rich but more for climate purposes because in Belgium the weather is so annoyingly unpredictable. But it would be weird if it was fuel related. Because it drives very well in alle the conditions for the past 300km. A have a bad habit to be a perfectionist so i can break my mind about to find the cause haha.

Hey y'all,

I fixed my dt125x a while ago and had a blast riding it for now around +-300km. But yesterday i came to this problem, drove 30 km's en went for a 15 min break suddenly after that it had problems with starting and bogs out if i give full throttle while idling and dies. Driving was still okay. Jetting should be on spot and a little on the richer side, jetted it for weeks till i got it right (240 main, 27.5 idle) float height properly set according the right manual (16mm if im right), Snorkel still installed and have only a romeu upper exhaust. The sparkplug(br9es, +-300km) still looks fine in my opinion and i also checked the reeds and also nothing to see. For the rest has it a new ignition coil(oem), new intake gaskets, cleaned and properly oiled air filter. Driving temperature is always very stable around +-71 degrees Celcius. Hope someone can help me :)

@hotshot-iii hey, before assembly i adjusted the float height to 16-16.5mm according to the maintenance manual. I went through all ignition related cables and switches but nothing out of the ordinary. No corrosion etc... Also installed a genuine replacement coil and measured the primary and secondary winding just to be sure haha. The plug chop was done at 10k rpm. Did it a lot with mopeds to check if the main jetting was right. Today it was less hesitant to pull through so it went better when i just gave it full throttle from the go. This was after i finished the idle configuration with the screws. Steady +-1.6k rpm like the manual says and the air mixture screw is just about right. Temperature is very stable +-70 degrees celcius and its stay like that after driving almost an hour long. Im suspecting 2 things that are happening, correct me if im wrong haha. 1st thing is my powervalve that is opening a little bit to slow, i feel if they once open up, i can hear it and feel it and i can give them beans without any problem. Tohe other thing is maybe im running too rich in the lower rpms?

Hey @calum @hotshot-iii i already have a blast on de dtx. Currently running in 27.5 pilot, 5j40 needle with clip on the leanest. And a 240 main. It works very wel. Only 50/50 times it sputtert right before the powerband and somethines within. If i go full throttle from the start it stutters more often and if i give half throttle and when it hits powerband to full throttle it pulls al lot better. Other times it pulls straight forward like a beast. Did a plug chop on full throttle and sparkplug is on the brown side but not wet or anything. It has also a little struggle in sixth gear to get higher rpms around 100km/h Any tips?

@hotshot-iii @calum im so angry at my self 😂, the hole time the problem was that i drove without the seat so my butt was too close to the snorkle. Went from 17.5 to 27.5 and 210 to 240 and runs like an angel. The 210 was totally worn out and was bigger than the 240.
Both are genuine mikuni jets btw. Still changed the coil tho. Threw that Chinese orange coil in the bin

@calum @hotshot-iii okay a lott happened in the meantime. Firstly i fixed the servo cables and after cleaning procedure it aligned perfectly with the hole. Looked in the exhaust port and was correct. Removed the spacer but kept the carbon reeds. Still runs like crap en servo moved weirdly, not correct in my opinion. That aside, still stutters right before powerband. With as well the 210 and 17.5 jetting and 240 and 27.5(French setup )but with the higher jets i had a lot better throttle response and idling. With the richer setup i tried it to pin the pv on the open position to see what it does when i hit the powerband. And finally it hits :) but only in first year tho :s the other gears is starts stuttering again.
Checked my deristrictrion and everything was like its supposed to. So yeah im out of ideas now haha, i run a br9es also like im supposed to. Checked for air leaks, no leaks present. Cleaned air filter and oiled it correctly. Also of i compared the original mikuni jet 210 with the new 240(also a real mikuni) the hole on the 210 was bigger??

I searched with an endoscope in the intake an sparkplug hole and damn everything looks mint. How is that even possible haha.

@calum damnnn thats indeed a mayor problem haha, today im gonna remove the reeds and sparkplug and inspect the piston and cilinder walls with an endoscope

@calum @hotshot-iii all right, i contacted the seller of the exhaust and he told me to use 245 main jet. So ill try that first. After some time ill get that zeeltronic. Firstly i want to get safely on the road. Piston replace gotta happen too because my piston has 22k kilometers but stil sounds good tho no ratlling or something but i want to be sure

@calum @hotshot-iii @rallyfinnen All right! But so abaut the jetting, so i should have no restrictions on my 2006 dtx. The only upgrades that i have are the reeds that were switched to carbon ones and a spacer between the intake and the reeds. and also the purtagal pipe from romeuhenriques. Current jetting is: idle 17.5 and main 210. Am i supposed to follow the older model with the 240 jets or what should i start with?

@calum found the problem, servo cable snapped so the powervalve didnt work properly.

@rallyfinnen installed the overhauled carb, tried a whole lot of jets and ended with 210 but now it suddenly runs really bad, cant get past 4k rpm because it stutters really hard, sounds like a rev limiter.

@calum @hotshot-iii yes i did a full carb clean, took everything apart and cleaned it and i dont know, the seller told me it drives good and gave the original exhaust with the bike too. I also ordered an fully overhauled carb to replace it. Came in today and dontacted the seller from the exhaust and told me to use a 245 jet but havent tried it yet. Tomorrow im gonna install everything back

@calum thanks for your reply. Stock jets are indeed present, main is 210 en idle is 17.5. my carb is a mikuni tm28ss. Bike bas bogging(buuhhh sound) if i twisted the throttle while idling when it was warm

Hey, guys im new.
I just got a yamaha dt125x from 2006, with a custom exhaust from romeu Henriquez. My question is wich jets i should buy for this exhaust? The bike is stock except i changed the reed valves to carbon ones en putted a spacer on the intake. Hope you guys can help me out :)