DT125R FORUM

@westy7070 will update this thread in full tomorrow lads sorry for the delay, had a crazy couple of weeks!

Well my parts have finally arrived in full from PJ Engineering and ebay.

Time to get busy with the DT and get her all nice, rebuilt, and ready for the summer! (And her MOT thats coming up.)

This is my DT125R build story!

Full picture updates and part porn to follow in the morning!

New parts & kit / work list to be fitted:
Haynes manual (88 to 03)
Mitaka piston kit 57.00mm.
Yamaha genuine small end bearing.
Athena full gasket set.
Rebore 1mm from standard and honing to be done monday. (Got away with sanding the scores at the edge of exhaust port with this first top end rebuild hehe so time to do it properly.)
Still running great but got other things i need to tackle now i'm preparing for the mot.
EBC racing full drc series clutch kit.
(Clutch is slipping slightly but also need the right transmission oil instead of 4 stroke heheh)
Yamaha genuine clutch tab washer.
Genuine yamaha oil seal kit. (gear peg seal is seeping slightly so gonna be a wise idea to do all of them.)
Front and rear sprockets (std).
Yamaha genuine sprocket tab washer.
IRIS heavy duty racing chain.
Apico chain roller.
Yamaha genuine chain guide.
Rock oil chain wax.
Yamaha genuine front & rear wheel bearings and seals.
Pyramid parts headset bearings.
EBC front & rear brake pads and full brake bleed.

Then i also have some little trick bits and stickers and stuff to tart her up until next year when i paint the whole bike.

Full updates and photos tomorrow!

@calum Sorry about that dude haven't had to link images in years, used to be into bits of coding and stuff aswell would you believe xD

I'll work it out on the next post, been posting from my pc.

Monday i'm going to revamp her fullly so will do a build thread

Hope everyone is safe and well!

ooooops forum is saying the pictures from my phone are too big.

EDIT: how do you get your photos on here lads? cheers

@stevie-wonder Thanks for the kind welcome dude sounds perfect, i lurked around different forums for a while after purchasing the bike trying to find the best place for me to settle down and get chatting to some other DT / 2 Stroke enthusiasts, got some help here, done some reading then decided this is the place! nice to meet you all!

The bike is a 97 all round originally black but with a shit custom blue paint job a, full DEP exhaust and different engine in.....3bn. (don't know if thats the same as the original not looked yet) Aftermarket digital speedo. I did fit one of those led lights from Portugal off ebay but it soon knackered up so replaced it with an acerbis xled. I haven't got the original rear light unfortunately.

To be honest, there is quite a story behind this god damn bike already xD

Had a pulse adrenaline for the last 3 years while i was levelling back up from a bad break up with a girl heheh. bag of shit but it done its job and time. got it through the mot myself every year.
Always been into bikes, had several silly road legal monkey bikes, pit bikes, mopeds (the yamaha slider was fun at the time of being young i gotta admit haha) and then a cr85, rx50, cg125, and then the pulse. always done all the maitenance myself even a sandblaster conversion on one of the pitbikes but never any engine internal stuff & minimal electrical knowledge. (I do understand how the electrics and all the stators / coils etc work but no pro) learned different bits of electrics and how to fix them messing with pitbikes)

I'm a 90s kid so the DT125 was the bike i dreamed of getting when i was young, although my parents couldn't afford it at the time. ended up with a piaggio moped at first like most young chavvy idiots do xD

Recently came into a bit of money and always wanted one so went for it. only had a certain budget so it was a risky buy and the only one even anywhere near the area for that price...looked great on the advert.....ended up being an absoloute bodged nightmare!
But I've learned so much where do i start?

get my mum to take me in the car...(good old mumsy eh) go get the bike after a little looking around it and checking it runs....knowing full well theres probably gonna be some stuff that needs sorting at the price....sealed the deal...insured it...got my mum to follow me back as the thing had dodgy lights.....get round the corner got excited opened her up, the throttle stuck on in 5th shit my pants and had to reach for the key xD had to pull over on a dual carrigeway and bodge the throttle best i could, then i noticed the power valve servo was hanging off and cables were bodged open...bike bogged and spluttered its way all the way home about 20 mile with my mum tailing to make sure i was ok from there....lol...fun times....

Got home after a long and dodgy ride whipped the tank and plastics off changed the spark plug....cleaned the carb.....looked at all the wiring loom to realize it was a bodged bag of shit xD
followed the wiring loom down and found the battery wires earthing out all over the frame, got a shock off it lol.sealed them all up with electrical tape (temporary fix for now), fixed the power valve servo back into its place with some nuts on the back of the bolts (bolt threads were rounded) and tightened the ypvs cables up properly. put the keys back in turn keys, power valve servo goes on and off, Success!
Rear light was still dodgy, flickers on and off. replaced with one from portugal, was still the same, leds flickering or failing, brake lights sometimes working sometimes not. took me ages to work it out. rusty crimp connectors abit further up the circuit. fitted acerbis x led and cleaned up all the connections....it all came on properly, success!
the only minor lighting problem which i still have is when you give it loads of beans all the lights dim. it seems to be alot better than it was though, was very bad at first. quite minor now after all the playing. i have put a new battery on. and tidied up electrics best i can for now with care.
then it ran great for a few days, then i had a few weeks battle with the pilot jet keep randomly blocking up before it eventually dropped the rings, managed to bump it and limp home from work clutching it and revving in a horrible fashion before it died a couple of streets away from my house. (lucky considering i do a ride down some busy lanes to get to work)

stripped the head to find just as i suspected dropped rings...although not that bad luckily...a little bit shattered but mostly just snapped....few shards had got to the top....few tiny scores in the barrel, nothing you could rub with your finger nail. although it did have some chipping round the edge of the exhaust port. but being a welder / fabrciator i took the head to work and sorted it out with some wet & dry then blew it all out with the airline and polished / cleaned all of the head / barrel. may need a rebore next time, original bore.
also ever since i had brought it there was a seeping of black shite from under the cylinder gasket by the exhaust port, when i rebuilt it and took the old gaskets off it had just been bodged with 2 gaskets because the gasket base on the bottom end there is a scratch where ive mentioned. I did have a go at doing it properly with the single gasket it was ok for abit but is seeping again slighlty now. the head and barrel i've managed to sort nicely.
After a top end rebuild, clearing the petrol tank out and carb several times, polisport fuel filter, new spark plug and cap, new jets after breaking a brittle one, and new throttle cable later...I have nice running bike...

few bits of anger and pushing it places, but it was so worth it, now i've finally worked it all out bit by bit. xD
Next week its payday and i plan on really tarting her up with lots of fresh parts, paint job, graphics and a fresh rebuildas the first one was a learning curve very much...will get on a build thread to show soon...pic incoming in a sec!

sorry if that post is longgggg guys

@dtr-nsr thats cool to hear, definately up for that in the summer
will post some pictures shortly! shes a work in progress and is being used as a daily but shes my pride and joy!

Hey guys! posted a couple questions previously regarding my 97 DT125. thought it was time to pop up and say hi! really loving my new 2 smoker, and keen to meet some like minded guys! I'm from a little town called Nuneaton in the West Midlands, UK.

Will post some pictures of my bike tomorrow

Hope everyone is all good during this crazy time!

Sorry for the mega late reply on this lads, sacrificed internet for the rebuild at the time and just wanted to say (now i remembered :P) Thanks so much for all your help. got it sorted with the loctite in the end and it all worked out! really grateful for the replies. will post some bike porn soon and start getting active!

Hello there guys, my 1997 dt125 started dying the other day... (started loosing compression, wouldn't kick start, managed to get it bump started.) got halfway to work and it really started dying and went limp if that makes sense.) I got to work got through the day came out, after a few hard attempts i managed to get it bump started again and limped it home. (I know this isn't the best, didn't have no other choice ) got the head off, fried piston rings with minor scoring on the edge of the exhaust port and piston, managed to get rid of the score on the barrel as it was right on the edge of the exhaust bridge, (used wet and dry) got hold of brand new gaskets (hendler brand, made in italy) and piston kit and attempted my first rebuild. cleaned the barrel and where the gaskets join meticulously and attempted to put it all back together torqing everything up to the correct specs and lubing all the parts with 2 stroke after cleaning a load of carbon off the power valves, barrel and head. got some coolant in her and a fresh tank of fuel with castrol power1 racing 2 stroke at around 35:1 (usually run 30:1 but read that it will want it more rich for rebuild) got it all together and tried kicking her up, i now have water seeping from the top head gasket. i have purchased some instant gasket and im going to strip it again shortly. just wondered if you guys had any advice before i go at this again, its my first rebuild on the bike and i have tried my hardest to get it right... there is no leaking from the bottom gasket on the barrel just seeping from the top head gasket, and when you try kick it over there is water coming from near under the swing arm (which i've also read is head gasket failure). should i strip it clean it out again and apply instant gasket to the failed head gasket? thanks in advance for any advice on this guys....

Really struggling with the back light, can't get no power to it at all! It's one of those aftermarket led ones if that makes any difference I've got a multimeter coming today. Do I just check for continuity from the tail, brake, and earth?
Thanks in advance for any more help on this guys, frustrating not being able to ride it at night

Thanks so much for your help spookdog. I've just about cracked it, got the rear indicators working again! just gonna go through the process of elimination on the back light now.
Rear left indicator was brown / green & black.
Rear right indicator was red/ blue & yellow

Leaves me with black & white, light blue, yellow for the rear light.

Just gonna eat my dinner then get back to it! Finally some success

EDIT: Just realised that works out to exactly what you've said for the back light too so should be easy now

Hi everyone, many thanks for the replies. I now have the haynes manual with the wiring diagrams on it. just trying to work out which model my dt125 is. its a 1997 dt125r i'm thinking its the 3db1, can I tell this by my frame and engine numbers? engine and frame are saying 4bl/ 3bn? thanks in advance racked my brains over this all day and need to get it done

Hello there guys, first post! brought an old 1997 dt125r in really good condition and so far I'm loving it but need some advice.
I have replaced the rear light and cowl for the reg plate as the light wasn't working and like a numpty when I disconnected the light and indicators i wasn't paying attention to what goes where. (The indicators were working). I have looked for the right wiring diagram but it's abit confusing.
The wires I have coming out at the back are: white, light blue, brown (chocolate?), black and white, blue and yellow, green and black, and red.
If anyone could tell me what goes where or has links to the right wiring diagram and could help me it would be so so appreciated as it's the last thing that needs fixing. I won't make that mistake again!
Thanks in advance!
From Lewis:)