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The Leviathan Project (DT125RE)


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For the past 7 odd months I've been trying to rebuild my Yamaha DT125RE into a truly unique bike.

Paid, bought and then cleaned for £1400 back in 2010


First big think I did was install a Kickstart onto it






Then Sorted out a tail tidy for it.

Acerbis Enduro Tailtidy


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Then I bought some spanking alloy wheels that I was going to attempt to fit


^^^^^Front Wheel^^^^^


^^^^Rear Wheel^^^^

Bought some Upside down Forks for the front end




Four pot front caliper to fit


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Made up a bearing cup in order to maintain the original height of the USD forks. I.e. use the YZ stem




Insert the taper bearings instead of using the original DT bearings


Sprayed to match the frame


Put it all back together (Not WORKING IN THIS PHOTO)


Mock template for the front brake



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How to get the rear wheel done.


Front end on the Aprilia with the front end of the DT


Sprayed the rear arm black


Finished the front brake off


Use the Rs125 front master


Socks to protect the seals on the USD's


This is a photo of the rear brake bracket. Because the wheel is fatter than the standard DTR one I cannot just attach the brake and say happy days. The front AND the rear wheel MUST be in line. And then to complicate things further the front AND the rear sprockets must ALSO be inline


So I have to machine down the rear brake carrier


So now the rear wheel is in the correct position. All I have to do is make sure that the brake sits fully on the disc. To do this we made an adapter plate to fix the brake onto the spacer.


I must say that rear brake is SO MUCH BETTER than the standard brakes LMAO!


Adapter plate.



Uhh sprocket ratios are now my next big concern....


This is the biggest rear sprocket I can find for theses wheels. The original is being held up next to it. And even here it is still TOO SMALL!

Lack of power in the engine just struggles to pull the sprockets.

I've got 13 teeth on the front and 46 on the rear. Also used a 520 pitch conversion on it.

Because the wheel is a different thickness I've had to space out the rear sprocket in order for it to be in line with the front.


I don't think I can go any bigger on the rear anyway!

It's this close to touching the swing arm!



A spanking new full DEP system and everything all wired up and power on after six months!


I have missed off a few things in this post that I also did. But the jist is there

Few pics around the bike




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  • 4 weeks later...

That's really nice mate, some nifty machining!

You got all the kit at home? I can do small jobs at work but have to be in secret haha.

How did you get round the sprocket ratio problem in the end?

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  • 4 weeks later...

Unfortunately I don't have a lathe or a CNC machine lol. So Had to do the trickier stuff round a mates.

Sprocket ratio worked out perfect!

12 Tooth on the front and 46 on the rear. Has dropped 5 MPH to 80 but will get there pretty quick. I've got a TZR125 R barrel. The 4FU00 Nicosil plated barrel. Porting on it looks better than the 3MB and like said is nicosil so will dissapate the heat better. I Put a nicosil barrel on my RS125 and noticed a 10 degrees Celsius temperature drop. Pretty good IMO.

But it's badly scored and needs a replate.

I'm think of boring it out to 134cc then sending it off along with the head and bottom end to a specialist two stroke tuning company to gas flowed and polished. See if I can get about 20+ BHP out of it. Then I can maybe put a 14 tooth sprocket on the front.

To give you some sort of idea of the cylinder an its cost



Hopefully will be worth it in the end though. Despite the $$$

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Given the time and effort you've put in I'm guessing you wouldn't sell it so why not go for the new barrel!

That's a seriously nice bike though, tempted to try something similar to my dt when I get another bike.

Your should definitely get it dyno'd when you've finished it!

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I've just dropped £350 on a TZR Belgarda Engine. This engine comes with a 3MB P 00 stamped cylinder. The dogs bollox when it comes to the 3MB. I'm going to examine it fully though. The bottom end i will definitely use but the cylinder i may shelf. I want to run that nicosil barrel and if i send that off to be tuned in theory it should be no different from 3MB cylinder. Very excited about this. Will get some piccys up soon once i've got the engine back. Got a few more pics of some mods of done as well that i ought to post. So real improvements made to the bike since my last post.

Yeah maybe. I'm not going for speed really. More looks. At the end of the day if i want speed i'll buy an R6 or summit. I might take it to my local dyno once it's finished. Be interesting to see how much it will be running. Think i'll get about 20+ after i'm finished. May not sound a lot but it's only a dt125. That has claimed 15. I reckon mines on 11 so thats quite good

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This is impressive work Callum!!

You do a lot of machining, then? Are you open to private comissions?

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Some nice and lovely new Fatbars installed


Nice speedo bracket made up






A beautiful Aprilia RSV Mille Master cylinder installed. Stops those wheels faster than a fat bird eating a big mac!



It's lovely. Fully adjustable to suit your hands!





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Got some nice stickers for the rims.

Sorry I know this is Yamaha Owners Club but...


Managed to get this knocked up, a lovely piece of anodised aluminium


It's basically where the headlight mounts into on the new yokes. The bit that folds back has a 45 degree angle and I drilled a hole into it. Pucker job done on that. very pleased.

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Some photos of the old girl as she stands now out and about. Passed MOT No advisories! WELL CHUFFED! Tax'd and MOT's ready to be abused this summer until next winter when the new engine goes in and the frame gets stripped and powdercoated. Can't wait to do that part. I'm going to seriously take my time on it and get it effin perfect!



Notice the fork guards. After popular demand I got round to buying some. Also notice I haven't found a space for my speedo.


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  • 2 weeks later...

So some more updates.

Been riding the bike now for about a month or so. And just starting to get a bit annoyed with the poor performance. I mean sure it's alright for a 125 but it just lacks the power that the setup demands. I mean it looks faster than it is. Which is disappointing.

So what engine will be a straight fit and will definitely give it more power? What engine will match the uniqueness of this project. It's got to be something rare, expensive and fast.

I've decided to go with the Yamaha TZR 125 R Belgarda 4DL engine.

So after a bit of eBay searching and £300 later I managed to get myself a complete 4DL engine in A RIGHT OLD STATE!

It's all there it's just messy as hell!

Sold to me as a running engine closer inspection reveals that this IS NOT the case. And that I may have been ripped off a little. Nevertheless I'm determined and bored so whilst the slow engine will remain in the bike for then next 6 months I'll work on rebuilding this 4DL engine and tuning it.

Have a look at these photos and let us know what you think...



It's got all the right markings so It's definitely what I was looking for which is a plus!






And now for the bad bits :(




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Quick clean up, head and barrel skimmed as suspect it has warped what with the head gasket BEING ON UPSIDE DOWN! Dumb mothers!

I mean it was seriously like 2cm of sediment between the head and the cylinder WTF!




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So what are my thoughts.

Well a couple of months ago i spent £120 on a scored 4FU barrel which is nicosil plated. And NOW i've acquired a 3MB00P cylinder. I've examined the porting work done to the 3MB00P and to be fair I don't think it's anything special. It's definitely bigger than the 4FU00 but I think it's definitely achieveable on the 4FU.

So I'll going to run a tuned and ported 4FU on the belgarda bottom end.

Examine the photos and let us know what you think.








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So that's where I'm at at the moment. Money has run dry and I don't want to be without a bike for the summer. So I'm probably going to be working on that 4DL for the moment. Cleaning it up. Powdercoating the cases. Rebuilding the engine and then by the end of the year fitting it into the DTRE and setting it all up for the next year. Hopefully this time next year my DT will be running 24+ bhp at the rear wheel.

As you can probably tell money isn't really an issue. If i've got it i'll spend it so expect dyno results as proof once i'm happy it's complete.

As usual any questions don't hesitate to ask!



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