DRZ400 ATC build using '86 ATC 250R parts

[HK1837]

Hi all

New member here but had Honda trikes since I was a kid. I'm in Australia.

Currently doing some head scratching with a DRZ400E conversion. I have a full 1986 ATC250R front end just need a wheel. Plan to modify the triple clamps to put the DRZ post in it. Will see how the DRZ tank goes with the triple clamps - might have to adapt an ATC250R tank to the frame.

I also have the swingarm and rear axle setup off the same '86. I was originally planning on modifying the '86 ATC250R swingarm to replicate the front of the DRZ and use the DRZ shock and linkage. But I'm wondering if I'm better off using a TRX450 rear carrier, axle etc? In either case, does anyone know who can sell me an already fabricated steel or moly rear axle hub carrier (for either '86 ATC250R or TRX450) that I can then weld onto the rest of the fabricated swing arm? I plan to make the rest. I know there are shops that can sell me swingarms ready to go but I doubt they'd have a jig for a DRZ400.

I'm also in a quandary with the seat and rear plastics. I can see that I can buy new Maier plastic for ATC350X or ATC250R, and the seat cover and foam is readily available. Plus, the seat latches are also around. However, the seat pans are non-existent. I do have a good 1982 ATC250R complete rear seat (off an incomplete bike), but the seat pan is fairly rusty - I was going to use it until I found I cannot buy a seat pan anywhere. Given I have to make mods to the DRZ400E alloy subframe to accept an ATC seat, I don't have to use an '86 seat, does anyone have any suggestions what I might be able to use that would work? I asked BV Trikes what they used on their CRF conversions but haven't heard back yet.

Edit - I was just looking at a 2006 Suzuki LT-R450 quad swingarm. The pivot bearings and bolt are the same size. Unlikely it'd fit straight into a DRZ frame but it might be a good start. It looks to be steel, can anyone confirm? If it is steel, I could cut off the Suzuki rear hub carrier and weld a Honda one on plus modify it to accept the DRZ shock and linkage.

[Dirtcrasher]

You're swapping the 250R stuff onto the DRZ, not the other way around??

I thought you meant into the 250R frame, the TRX450R rear swingarm/axle/brakes can all be used in that case.

It sounds like a cool conversion, we see lots that are done really well and many, not so great.

Usually with dirtbikes they end up sitting too high, if you lower it they rake out too much. The LTZ quad would be better, but then there's the neck to position and all that fun stuff.

So, allot of these end up with a high seat height and they handle poorly. And the footpegs are positioned about 2"s off from where a trikes pegs sit.

It seems like quite a few dirt bike conversions have been built but they seem to get sold pretty quick.

That's why guys started making inverted front end kits for the 250R and 350X, even the 200X; that use either CR 125/250 or CRF250/450 forks. It keeps the geometry in a better position.

[HK1837]

Yes 250R stuff onto the DRZ.

I've always wanted to build an ATC500R or ATC600R. I built a few fully suspended trikes when I was a teenager out of XL185S and another out of an ATC185S using an XL250S engine. Always wanted a big 4 stroke trike.

As years moved on ATC350X are almost impossible to buy in Australia, and they are also getting long in the tooth. As are the donor XR500 and XR600 and they are both kick start, which I always had trouble with in the past conversions. I have a DR650SE as a road bike but that is way too heavy for a trike conversion, but have been looking at the DRZ400E. They are a decent modern-ish bike, they are cheap as chips and they are electric start.

I appreciate that they sit high, my XL185S sat high. But I'm also 6'5" and 110kg an I was 6'4" as a teenager and 95kg. So a high Trike aways suited me better. Footpegs aren't a drama, I'll make up adapters and fit trike footpegs in the right place.

So in the last few days I've done some measuring and drawing. Also research on what is available.

I have sitting on my shed floor a 2022 DR400E frame and triple clamps. Plus its swingarm and rear linkage/shock.

The front end, the initial build will just be the ATC250R front end with the DRZ400 steering stalk in the ATC lower triple clamp. LAter on I might play with making a new set and running DRZ400E or even DRZ400SM front (inverted) forks. But for now the ATC250R will do. The only thing I'm missing is a front wheel.

I have 3 x rear ends to pay with, swingram, axle, brakes etc, will have them all side by side in the next few weeks:

1986 ATC250R.
2008 TRX450R.
2006 TLR450R.

I already think I've ruled out the ATC250R stuff as parts are hard to get and its the least likely to work. So I'll probably onsell it.

So far the TLR450R looks promising. The swingarm is the same across the pivot at the engine (103-104mm), but the pivot parts are about 6-7mm wider each side than the DRZ400E. I can machine that off, and run the DRZ bearings and seals, however the OD of the pivot may be too small to machine the internal lip for the DRZ outer seal/cap. This can probably be overcome by machining up a pair of rings to go over the OD of the pivot and weld on, so it replicates the DRZ. The other option is to machine an additional 3mm per side off the LTR swingarm pivots so it'll take the full LTR bearing and seal kit, but in this case I'd have to machine the same amount (10mm overall) off the inner pivot spacers (1 per side). These run 2 x 29mm x 22mm bearings that are 20mm wide on the 2006-2007 models and 29mm x 22mm x 15mm wide on the 2008-2010 models. So I'll just have to work that out when I strip it all - the 2 x 15mm wide ones might be OK. The other thing this does is moves the rear sprocket 6-7mm away to the left of the DRZ400E engine as funnily enough the chain offset is the same between the DRZ and the LTR, but machining that 6-7mm off the outside of the swingarm pivot pushes it away. I can deal with this with a spacer ring at the sprocket as the sprocket sits on the inside of the carrier towards the rear axle bearing carrier (away from the LH tyre). It also means the LTR chain buffers/protectors are in the wrong spot. However it will be easy to adapt the DRZ one. In this scenario I have to cut out the curved gusset at the front of the LTR swingarm and fabricate another one that replicates the DRZ mount so I can run the DRZ shock and linkage.

I'll do some measuring and playing with the TRX450R rear end when it arrives, but it would be a lot harder as it is an alloy swingarm and I'd probably have to fabricate a new one. Unless the planets align with it.

There is another possibility too. The RMZ450 MX bike uses the same bottom end, and I'm told its swing arm is a direct match with the LTR450. So I could use a RMZ to build this out of. The downside of this is these are a high performance engine, I just want a thumper.

[BOB MARLIN]

I've done the dirt bike to 3 wheeler thing. They have the potential to turn out very good, but as dirtcrasher pointed out, there is definitely some geometry issues that need to be addressed or it will turn out to be useless.
The 250R front end, while perfect for the 250R, is a poor choice for a conversion because of the built in "rake" that they have. The dirt bike frame already has way more rake than a 3 wheeler, adding more in the triples is a big step in the wrong direction. Also the 250r forks will be too short for the dirt bike frame geometry and results in very limited ground clearance. As for the swing arm, its best to make a custom one, but if you find something from a quad (or ATC) that fits you can make it work, but it needs to be extended a bit to make the frame geometry work. You will need to play with the shock length and/or the shock mount position to "push" the rear axle down (seat up) to pivot the frame forward over the front axle to take out some of the rake in the front end.
The list goes on and on. But done right, the make awesome rides !.

[HK1837]

Awesome advice guys. I'll get the rear end sorted and still use the 1986 ATC front end as I have it already, but will look to build a better front arrangement later, maybe even using the DRZ400E front forks. I can pretty easily CAD up a set of triple clamp upper and lower with 0deg rake and get them laser cut out of 32mm aluminium, then press the DRZ stalk in. But I'd rather do this once I have the whole front clearances and geometry sorted. Not sure how hard it'd be to get the DRZ400E front caliper to work with the 250R front disc? I guess that is just a matter of an adapter bracket done correctly.

[Dirtcrasher]

Sounds like you have the machines, skills and lots of parts, you'll get something together that works. It has to be tough for guys in other countries that can't get the exact parts they want. Canada has it hard enough, Australia is even worse. If you have to build a swingarm, I'm sure you can.

We've watched people build things for decades and you get a general idea of what works and what doesn't.

I'd tell you to look for a Tri-Z because the frame seems to fit taller riders better, but those are probably very hard to come by for you as well.

Gotta be self sufficient in Australia...

[HK1837]

Yes. I have picked up the following locally:

LTR450 rear swingarm and bearing carrier plus hubs.
LTR450 spocket carrier, disc carrier and rear caliper arm. Just have to import the nut and the snap rings. Seals I can get new here.
LTZ400 rear subframe.
KFX (green) rear fender. Seat I can but new relatively cheaply in blue or black for a KFX or an LTZ.

I have a 2022 DRZ400 frame, swingarm and rear linkage for mockup.

I also just bought a new 2024 DRZ400E to replace my 2012 DR650SE that was simply getting too long in the tooth. So I have a good reference to look at and copy.

Given I have the green rear fender I'll have to use a black DRZ fuel tank and a white front fender I guess, with white or black radiator plastics. I was going to get a new '86 ATC250R front fender for the triple clamps but I guess I can use anything of I'm going to make up a set of triple clamps. So I could buy anything even a Tecate front fender KTX Pro sell a green front fender for a 1983-4 but not louvered. Will see what I can get.

[HK1837]

Found an old photo of my ATC built from an XL185S in the early 80's. I have others but can't find them.

How do I add photos here? I don't use photo hosting.

Edit - found it.

271370

[Footy]

You need to use the "Go Advanced" tab beside of the reply tab. It will lead you through adding a photo.

[oldskool83]

DC plastic reproduced 2nd gen Tecate front fenders for me years ago and sells both generations now because I supplied good oem fenders. You can pick them up from him for $70 a fender. Not bad quality.

[HK1837]

DC plastic reproduced 2nd gen Tecate front fenders for me years ago and sells both generations now because I supplied good oem fenders. You can pick them up from him for $70 a fender. Not bad quality.

They look pretty good and he does them in yellow too if I happened to find an original yellow LTZ or LTR rear fender. Otherwise the green would work with the green KFX rear fender and black DRZ400 tank. Would just have to find tank shrouds for it in green, black or white. Acerbis do them in black and I have seen white as well but the KLX400R is the same bike as the DRZ400 so the tank shoulds for it will fit. Basically this colour theme other than the white sides (image pinched off the 'web):

271371

And buy a green headlight surround - I have a red 1985 with light and the rubbers but it has a crack so I was going to buy a new one anyway.

[atcmatt]

How are you getting on with this project mate?

[HK1837]

Slowly mate. Still collecting necessary bits, but currently flat out with work, 2 x bathroom renovations and a Holden HK Monaro GTS to finish. The trike is something to play with when I get time.

Been doing some planning though:

First step will be to machine the LTR450 swing arm on the outside of the pivots to make them the same overall width as the DRZ400E. They are the same inside (across the engine), same ID and same pivot bolt diameter. And I'll make up a mount in steel to replicate the DRZ400E swingarm shock mount as a combination brace and mount, cut the brace out of the LTR450 swingarm and weld the brace into the LTR swingarm. I'll try and move the mount about 5-6mm forward which will raise the back end to account for the smaller tyres. Also have to make a slight mod to fit the DRZ chain guard to the LTR swingarm. And I need to make up a spacer ring for the sprocket as its about 5-6mm offset on the DRZ400 back towards the centre compared to the LTR450. That should sort out the back end other than adapting the DRZ brake master to the LTR caliper and making a handbrake setup.

I've had a look at the LTZ400 (actually a KFX400 but same thing) rear subframe against the DRZ frame. Going to be a bit of work to adapt these together but will leave that until late in the piece, will get the back end sorted as per above and make up some triple clamps.

[atcmatt]

Sounds like you’re all over it like a rash. Keen too see the final product as I don’t think I have ever seen one done.

[HK1837]

I saw one somewhere where they had used an LTR250 swingarm and rear fender. The swingarm was a straight bolt with sprockets aligning (similar engine so makes sense), just had shock sorting to do. Fender sat OK with the DRZ400 tank, which is what gave me the idea. I chose the LTR450 swingarm though as it is a far superior rear bearing housing and rear axle arrangement. Here is the thread on it:

https://www.thumpertalk.com/forums/topic/704136-street-legal-drz400-3-wheeler-build/#comments

I have a brand new 2024 DRZ400E here with 40kM on it. I'm not using it for the conversion but it's a good reference. I'll mock it up with the 2022 frame I have and then buy a good running DRZ400E or KLX400 as a donor and swap everything over onto that bike.