DT125R FORUM

While I check if that is indeed the issue, allow me to share the "before and after" of my troubled rebuild (tried uploading but it seems all my images are too large to compute, sorry): Before: https://drive.google.com/file/d/10vFChB0EYgA4KcdGXxD0ADUuBkG3_3L1/view?usp=drive_link After: https://drive.google.com/file/d/1-vahreq0O_fcCLm1wl73cvFQxRDeTEqF/view?usp=drive_link

Finally! Actually found some time to go out on this thing! [image: L5TZajj.jpeg] The original gearing I bought for this was a no-go and I ended up chucking it in the bin. Instead, I found a Trail Tech crankset made for an E-bike, had to swap out the bottom bracket, but the result is something which gives me the ability to go up a few teeth on the front (currently rocking 24t), blitzes up moderate inclines, but lacks real top end. [image: faXVi2L.jpeg] I managed my usual route easier than the 26er, both up and down hill. It just felt like it handled the rocky sections better than the 26er, the lower gearing made it easier to climb some of the hills I had to get off and push, overall I'm very pleased about how this one has turned out, hopefully get a lot of use out of this over the coming years.

@BalnAndCantGetUp Update! The site was legit i was just overthinking it I fitted on my bike about a week ago and i did my first ride after 4 hole months yesterday. Needless to say it is a trustworthy site

@fishy-fish I'll put money it's that then.

Piecing it together bit by bit. [image: 3AEcKCy.jpeg] Got some Ferodo brake pads for the rear caliper. [image: Fy3yXKn.jpeg] Wiring loom gently fitted, I think this is where it goes. [image: OmUYdh6.jpeg] The original ignition barrel was ropey as f. Clearly non-genuine and been replaced before. This gem came up new old stock genuine, so snapped at the chance to get it. [image: GZoJj4q.jpeg] Just focusing on the front end at the moment. Got some genuine wing mirrors from Italy winging their way to me. [image: H2VD1je.jpeg]

Here are the differences in the 3BN Cylinder head [image: 1483566896896-dt125rheads-diffrences.jpg] It'll be marked on the cylinder head. [image: 1663628447669-874e98a1-e604-4e06-9310-d20f77cae655-image.png] The 3BN head is interoparable with the 3MB head, but has a combustion ring which is said to adversely affect performance. Here is a video of the difference between a 4FU cylinder and a Belgarda 3MB00P cylinder. https://www.youtube.com/watch?v=P8okvTxe-Bs Here is a 3MB cylinder. [image: cylinder-1_medium3MB1131100-02_4baa.jpg] [image: 1663628477295-8e899a28-4514-4881-89ec-bfcc824ade10-image.png] You'll see the crankcases are stamped 3BN [image: 1663628512647-b054f520-0af7-4920-948f-cc532b8bbd25-image.png] For the most part you don't need to worry about it, it'll be rare that you'll find a DTR with a 3BN crank/cylinder and most of them will be 3MB cylinders. But it's just worth bearing in mind. There are variations in CDIs and Exhausts which affect the performance, but these are less important as there are aftermarket support that recitfies any loss in performance

Hello, Im in the very same spot as you, did you manage to get something done?

[image: 020dvoy.jpg]

Yeah, I hear that the bargains at Lidl get great reviews.

@HOTSHOT-III Would definitely like to see that. Would make for an interesting build for sure. I was surprised to see cast pistons in this kit, but apparently I have to junk them anyway to go with the stroker kit I bought as the wrist pin offset is different. So I've got a few more things to buy before this is called done.

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@Calum I remember you having a Li-ion bonfire but the thing I’m most interested in is the old AC/DC bikes that have three coils on the stator. The ignition coil is horizontal on the top of the stator. The lighting and charging coils are at a V at the bottom of the stator. I don’t claim to understand it but the lighting & charging coils are both numbered the same in the Haynes manual and seem to be connected, unlike the ignition coil which seems to be more isolated. It would seem to have something to do with my investigation into why my headlight dims badly (when I have a FUBAR battery) when I use the brake lights, horn or indicators. I’m hoping that the short life of my battery’s is down to the Reg/Rec being of the oriental OEM variety that’s always been on the bike since I got it. Like the lighting coil being burnt out. It’s the last gremlin on the bike since I got it as a basket case back when the pandemic started. Unfortunately my multi metre chose this time to die, just when I want to check the coils…. The later DC only bikes (anything with more than 3coils) don’t apply to me, unfortunately ….

https://www.devmoto.com/devmoto-solutions-electriques/materiel-electrique/boitiers-dallumage-cdi-ou-tci/boitiers-prets-a-brancher/yamaha-dtr-125/

@facundo-duarte There are loads of unused block connectors all over my 1988. Just cause it’s there doesn’t mean it HAS to be used… Your jetting is perfect for a late model Mikuni 28mm flatslide… I’d try removing the side of the air box yourself (don’t take somebody else’s word on it) and remove the the foam element. They fall apart over time, especially the aftermarket ones…. They need cleaning with solvent, or petrol but make sure it’s proper dry. Then you have to wet it with oil and squeeze out all the excess…

@detsinomistaja He also could modify them YPVS flanges to work with boost ports.

Well are you sure it's beyond repair? I mean it has to be pretty bad for that to be the case?

@gazza76 the neutral switch is part of the side stand curcuit. its when you take it out of neutral and put it into gear that it cuts out the engine, i think. someone who has one fitted would be more 100% more definite than me who doesnt have one fitted... its probly best to follow the wires from the side stand switch and see what they leed to...

Sad times You still doing this on your sisters drive?