DT125R FORUM

Biggest update yet had a friend come over which has way more knowledge then me, original main yet is somehow too big for the bike so 240 is actually 1.3mm when we put main yet drilled to 1.2mm bike ran great but was missing a little notch we will have 1.25mm jet by eveninng and that should work properly will see still has small issues idling

@calum the more i think about it the more it makes sense to me, foubd couple of pictures online and all of them have brass ball fitted, im just not sure if its fixed or its with spring, also found that the part is ventilation channel to the main nozzle/mixing tube, closed by a pressed-in ball, on here:
https://dtpedia.de/mediawiki/index.php/Vergaser:_Mikuni_TM28SS

No wonder it would bog and not idle, air going strait to main nozzle and airscrew having little to no effect..

@Calum https://imgur.com/a/jK2SHIF

@calum would you know? If it needs to be plugged there could be my huge air issue..

I may have stumbled across something and i need your help, new geniune coil, snorkel, reed valves, everything nice and seal same issue runs bit longer but nothing bogs down as soon as i touch gas that being said should there be a brass ball in the middle hole of the carburator? From the intake side picture uploaded in file? If so what is its purpose, can i plug it in?

https://gofile.io/d/a3c76865-740e-41b5-bc6d-3f4b5cf8934b

Another update, seems like it was fitted with powervalve servo from tzr125, hence why cables are crossed but still follow 1-1 2-2 arrangment i need to wait for battery to come in order to see if thats what setup should be in order to open properly

@Calum well i have an update, im not expert electrician by no means but i know some stuff, started taking everything off and tested bunch of stuff, first of all coil is gone, it test OL on every combination of terminals possible, so good i ordered genuine one, i just dont get why it still sparks. Power valve on servo has been messed with the cables are way too long and look like they have been wraped around te servo rotor or whatever but i cannot get bottom part out near engine as one screw is stripped and i didnt have time to deal with that, so i will be ordering new cables probably when i open bottom part as its possible its been pinned. I have one question and im not sure if thats normal or what, i have 7ohm resistance on battery terminals, when key is ON and if on beeper it beeps, when key is off it doesnt beep and resistance is OL..

@hannahharris ordered bunch of original parts for original carb as i didnt know i was missing rubber gasket at airscrew, plus original coil assy and some other bits and drops including battery while im waiting for that i will do some cleaning and sorting out

@joshuaseward yeah thats what i will be doing next couple of days, it looks really worse then it actually is. Just needs some proper cleaning and sorting out,engine is bone dry it was rebuilt like year ago and wasnt driven much. When coil arrives if it doesn't start with harness sorted and carb rebuilt i will probably swap out carb for tmx30 or something like that. But i think problem is going to be coil as it was bugging a little (like hitting rev limiter at random) while it was still working and when i put gas directly in cylinder it doesnt start.

Also i dont know if it matters i dont have battery inside of it

@Calum where should i look for earth? Bikes was bought from 15yr that used zipties for everything from coil to servo of valve... so i woudnt be suprised if it was earth even.. here the link where am at now https://gofile.io/d/HHUZA4pa i don't think its carb issue cause at every setting on needle and on air screw result is pretty much the same, if it was carb i would expect it to run poorly or rev high or something but thats not the case here..

@Calum bought replacment coil as there wasnt any original, currently orange one is in, rebuild carb changed everything other then air mixture screw as it didnt come in kit. Starts runs poorly on idle same as before but little better and when touching throtle it dies i tried turning the screw milimiter by milimiter no luck, needle was at 3rd point from bottom i moved it to 2nd one same thing, throtle valve is a little worn on the idle screw where it touches the screw like a small dent but i dont think that should be causing this much of an issues, compression is at 130psi so that should be all right if anyone has any idea feel free to suggest im going crazy here

@Calum i bought psi gauge today but i wont be near bike till saturday, so i guess thats when i will update on numbers regarding compression, bought also new coil just incase, and have spare cdi on hand so we will see thanks for info!

Forgot to mention reed valves are also good no cracks sit nice and tight, bought repair kit for carb waiting for that to come and also bought some cheap carb link down below, as far as i can tell everything in carb is original, has athene aftermarket exhaust.. https://www.motor-x.com/p/carburetor-moretti-parts-yamaha-dt-125

Here is link to couple fo videos how it runs/doesn't..
https://gofile.io/d/NdQhLVbX

Bought DT125R 2002 couple of days ago bike wouldn't idle and required choke to start, came home started playing with idle on carb its Mikuni 28SS as soon as i touched idle screw it wont start i kicked it probably couple hundred of times trying to get it right, cleaned carb cannot see anything wrong, sparks is short but blue guess thats fine, filter is clean and oiled, fuel geta into carb, looked at side stand switch its also okay. While playing with
screw i would get it to run on like 200rpms per minute for 3 secs could it be coil? Cdi? Im going crazy here. Keep in mind it ran fine before i bought it only sus thing was it hitting rev limiter as its limited to 7k? And 80kmh..