A forum for owners of Yamaha TTR250 trail and enduro bikes!

Not sure how you are going to do that considering that the YZ swingarm bolts into the engine. Are you trying to bolt it in as per Yamaha does or place the motor forwards more and use some kind of linkage/or spacer?

The reason I ask is that the TTR250 is roughly 11.5mm at the rear bolt and is not positioned in the right place for the swingarm. The WR engine on the other hand is roughly 7.5mm across and position in the right place for the swingarm.

Jarrah

However, a water cooled TTR would be novel.

In the remote, distant past it was usual to fit engines into engine plates to overcome the discrepancies. 

Triumph engines could then be made to fit Norton, BSA, Ariel and more frames with alternative gearboxes, clutches and equipment to make an acceptable "Special".

There have been instances of Vincent twin engines shoe-horned int Featherbed frames.

I imagine suitable plates could be fashioned to cope with the TTR/YZ differences.

Martyn

If you decide to break the bike for parts, here is a small list of things that fit the TTR250

Front end (using the spacer mod or steering stem mod) 

Rear caliper guard

Rear sprocket

Swingarm caps

Other than that nothing else fits. The rear axle is a different size so good luck fitting that!

Look on the bright side, you'll have a complete YZ front end to install on one of your TTR's.  However, you will either need to fit a WR front wheel from 1999~2013 (using the LH spacer of the year model wheel as there is three types) or a digital speedo if a speedometer is required.

Jarrah

PS. if you want to know what other models the YZ parts will fit onto, let me know.

TTRfan wrote:

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Cheers Jarrah - I need all the encouragement and information I can get 

One more thing that looks like it will fit the TTR - the petrol cap 

Not going to be able to get to it for a while as I am still in the middle of a restoration 

Brian

 

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 No problems Brian

Oh yeah, the cap fits. Been there done that on my WR400 haha.

Just to clear up any confusion, I meant to write-  Look on the bright side, you'll have a complete YZ front end to install on one of your TTR's.  However, you will either need to fit a WR front wheel from 1999~2013 (using the LH spacer of the year model of the bike as there is three types) or a digital speedo if a speedometer is required.

Jarrah

PS. If you make the TTR engine fit into the YZ frame, you're the man, and a persistent one at that  

Cubber wrote:

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In the bike world, especially the "modified" section, there are Those That Can and there are Those That Can't.

To which category do you belong?

Martyn

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 I know it's a nice gesture Martyn but I guess I belong in the ''is it practical'' category. Either that or the ''is it possible'' category

All jokes aside- it would be great to see it done but I think you may find that it is impractical if not impossible.

I would love to be proven wrong though.

Jarrah

boredus wrote:

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It would be better (IMO) to modify a TTR chassis to suite the YZ running gear.

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 Heaps better idea!

The only benefits of using a TTR250 motor in a YZ frame (that comes to mind) would be the YZ suspension and the YZ components. However, the YZ suspension and most components can be fitted to the TTR250 easily enough anyway. I did notice that the 2000 YZ does not have an oil tank but I doubt if it is much lighter (if not heavier) than the TTR250 frame.

The downsides being that there would be a minor loss in performance due to radiator fins that scoop air for basically nothing, the rear fender is not sturdy enough to hold an aftermarket numberplate holder properly as well as being hard to find the original Yamaha WR part (with brackets), you loose the comfy TTR250 seat and are now crouched over the tank due to the larger 19'' rear wheel and the way the YZ sits, the speedometer now has to be the WR unreliable plastic type drive gear or aftermarket, the WR swingarm chain guide will need replacing more regularly, no steering or helmet lock, not many options for a carry rack (if any) and a modification ''blue plate'' would be needed to register it (in AU at least).

The downsides far outweighs the benefits IMO!

I am not trying to discourage you Brian, it's just the reality of it.

Jarrah

TTRfan wrote:

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Thanks for the encouragement guys 

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 I am not saying that it can't be done, just that it is impractical to go through all that work for the same end result as if you just used the TTR frame and made the YZ suspension fit. It would actually be a better end result like this as you would still have the benefit's of  the TTR components.

Anything can be done with enough money, it just depends on how much you are willing to pay and how wisely you want to spend it.

If you don't look at the job realistically Brian, how do expect to do the job at hand?

Jarrah

The only problem that I can see that will be a hard one to overcome is the rear upper engine mount. I am pretty sure that it could be overcome by modifying the YZ frame but would not be easy as the YZ suspension sits further forward than the TTR.

It would be interesting to see how much lighter the YZ frame is compared to the TTR. If there is a big difference it may make this job feasible.

The wheels are both different size diameter axles than the TTR. My WR400 uses the same as below also.

YZ/WR info:

Rear Axle Diameter: 22mm

Front Axle Diameter: 20mm

Bearing info for 97-up front wheels, and 99-08 rear wheels:

Front - 6904-2RS - 20mm ID x 37mm OD x 9mm
Right Rear - 60/22-2RS - 22mm ID x 44mm OD x 12mm
Left Rear - 62/22-2RS - 22mm ID x 50mm OD x 14mm

TTR250 info:

Rear Axle Diameter: 20mm

Front Axle Diameter Left: 15mm

Front Axle Diameter Right:17mm

Taken from the FAQ but edited because it the opposite way around for LH and RH ...

Rear wheel takes 3 x 60/22 2RS size - 22x44x12  and oil seals for wheel 2 x 28x47x7.
Front wheel LEFT  takes 1x6202 2RS - size 15x35x11 and oil seal 20x35x5
Front wheel RIGHT takes 1x 6003 2RS - size 17x35x10 and oil seal is 22x35x7. (digital speedo models only - blue TTRs don't use a seal on the speedo drive side).

Interesting enough, the pre 1998 YZ/WR rear wheels uses an axle with the diameter the same as the TTR: 20mm

I am only trying to help Brian so don't take any of this to heart. If you really want to make this happen, I am pretty sure it will work out for you.

Good luck!

Jarrah

Looks like its going to be a winter project. Sorry to say that I haven't made a great deal of progress but haven't give up on it 

I have accepted that I am not going to get around to working on this project so will be breaking the rolling chassis for spare parts.

The forks, brake caliper and master cylinder complete, and front wheel will be available to any TTR owner looking to upgrade their forks.

PM me if interested.

Brian