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Fitting USD forks to a TTR250
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Just a tester, anyone fitted any usd forks or know of any that are a straight swap? Don't want to mess about too much wink



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front end - changing the front forks to USD
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i was thinking about upgrading my front end of my 2006 ttr us model.  i am thinking forks, triples, wheels, brakes. is this what i need to do.  Will a yz 250 or 125 front work?



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RE: front end
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Good question, Brett. confuse

It looks like you may well be in a position, soon, to let us all know? smile

There has been some past discussion on what clamps and forks from which model can be utilised BUT I don't thing a definitive answer has been found.

Maybe now it will be?

Martyn



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It has been done at least once by Mingle, see THIS THREAD.

I have been looking into this myself & I think the stems are longer on the YZ's. Mingle added a spacer & there is a thread out there somewhere where they welded on a bit extra to the top of the frame tube, another where the stem is swapped (didn't bookmark them at the time).

It also seems the 2006 or newer are the prefered YZ forks due to better internals.



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Rober Denison fitted a pair of Showa USD forks on his TTR that came off a 2006 Kawasaki KX250F. He said that they took a little work to fit, ie special modified KX yoke spindle, special modified TTR wheel spindle, and front caliper mount modified to take TTR calliper. He then took the forks apart and fitted softer springs.

He also said "To be honest the original forks were great but these offer a bit more in the way of setting up and adjustment. It’s a fair bit of work to do this mod – not one for the faint hearted (I manage a machine shop!). They do look the business though!

Pics below:

RH fork leg.jpg

LH fork leg.jpg

TTR 002.jpg

TTR 010.jpg



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RE: front end - changing the front forks
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Although I have no problem with my TTR325's front end, I am thinking about fitting USD forks just for the sake of it  smile

It seems to make sense to go for the whole front end from a post-2000 YZ125 to include fork legs, triple clamps, caliper, wheel, disc and axle thus reducing compatibilty issues and minimising any machining costs.

Having scoured eBay, I couldn't find such a complete front end for sale cry

However, it would seem possible to pick up a complete YZ for sensible money and then maybe recoup a good proportion of the investment by selling off the parts.

Any thoughts or better ideas please?

Brian

 

 



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I have been watching parts on ebay for a while, don't recall seeing a whole front end but once. Parting out a whole bike may be a good way to get everything at once, seems like there is a whole industry of parting stuff out & selling online.

I have a set of YZ triple clamps I bought in a moment of weakness for this same project. Haven't fooled with them yet on the bike but I can measure the stem, etc. if you need any info. I believe they were off an '09.

From my research regarding the wheel, a WR/YZ has a 20x37x9 front wheel bearing (so I assume 20mm axle, don't know what the actual mounting point diameter is).

Could the TTR axle be used with end sleeves, if it's long enough?



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Any reason to go for the YZ125 rather than YZ250 please? Is to do with the diameter of the yoke stem perhaps?

Brian



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YZ v TTR250 fork information
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I have done some preliminary Googling etc and findings are detailed below. If anyone can fill in any of the blanks or improve on the data then please contribute.

YZ v TTR250 fork information

Fork Dimensions & Stroke

There are two fork diameters for the YZ Forks 46mm and 48mm (Standard TTR is 42mm)

Fork Lengths are TTR = ?" and the YZ = 37"

Need comparative figure for the TTR250

YZ Forks

Length - Top of upper yoke to axle centre 825 mm 890 mm 925 mm

Length – Bottom of steering Head to axle centre 615 mm 678 mm

Fork Travel or Stroke 170 mm 210 mm 280 mm

Need comparative figures for the TTR250

YZ Yoke Post Lengths

There are different lengths of fork yoke posts between the different year models of the YZ, this has meant the need for spacers of different lengths above the upper Steering Head Bearings (SHB) on some conversions.

 "Short" - 98-08 YZ125 & YZ250F & 98-05 WR250F           Length 195 mm ?

“Mid” - 2008 YZ450F                                                       7 mm longer

"Long" - 98-07 YZ250 & YZ400F thru 450F & WR450F      12 mm longer

 

Steering Head Bearings

Yamaha use 2 bearing sizes, Top – 28x52mm, Bottom - 30x52mm

 Need comparative figures for the TTR250

 

YZ SHB Suppliers

Need comparative figures for the TTR250

Pivot Works Kit Part Number PWSSK-Y05-421

Part Number      Qty       Component Description

Y-BE-105          1          Bearing - 28.00 x 52.00 x 16.40 Cone

Y-BE-106          1          Bearing - 29.98 x 52.00 x 15.95 Cone

Y-SE-105          1          Seal - 28.50 x 60.50 x 4.15

For Models:

2001-2009 Yamaha WR 250F, 2000 Yamaha WR 400F, 2001-2002 Yamaha WR 426F

2003-2009 Yamaha WR 450F, 2000-2009 Yamaha YZ 125, 2000-2009 Yamaha YZ 250

2001-2009 Yamaha YZ 250F, 2000-2002 Yamaha YZ 426F, 2003-2009 Yamaha YZ 450F

 

All Balls Kit 22-1001 Bearings 1 x 28x52x16 1 x 30x52x16

All Balls have a choice on bearing height for the lower bearing

99-3513             28 mm 52 mm 16 mm

99-3521             30 mm 52 mm 16 mm

99-3504             30 mm 52 mm 17 mm

The fork post is a press fit in the yoke so it should be easy enough to replace the YZ post with it except that the YZ posts appear to be either 28mm or 30mm in diameter confuse 

yoke post.jpg



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RE: front end - changing the front forks
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You HAVE been busy!

As a disclaimer, I am no expert & have just been gathering information online myself so....

Wish I was better organized with information, but I found this quote informative:

"The first WR450 had the same fork that the YZ450 had, a 46mm KYB single chamber unit similar to the earlier forks going back to '99 or so.  The '04 YZ got a new 48mm SC fork, but the '04 WR kept the 46 for another year.  
Then, in '05, when the YZ stepped up to the twin chamber AOSS fork, the WR inherited the 48mm single chamber from the '04.  The WR has had that same fork ever since, and pardon me, but, it's inexcusable, IMO.
But, the 48mm Single Chamber is not a bad fork, and you can make it work pretty well, especially if you send it someplace like Enzo and have it gone over.  The problem with that is that it's about the same money as you could spend on a used set of the new SSS forks and a pair of springs, and that setup is better out of the box than most reworked SC's are."

In '06 the YZ's went to the SSS (Speed Senitive Suspension) dual-chamber fork which by all accounts are really good. I think the WR only got the SSS forks last year (2012) so there were alot of WR guys swapping over to the YZ units.

Also read this thread:   http://www.thumpertalk.com/topic/937656-fork-swap-from-yz-to-wr/       , a bit of info about valve types, sizing, etc.

I think that the 125s were just sprung lighter which may work better for the trail.

There are also a number of threads on Thumpertalk about the Smart Performance "Phase 4" valve kit which was for the earlier WR/YZ design (which the WR kept using) that is also well thought of. I think the kit is around $200 for us DIYer's. Emailed DaveJ once but didn't hear back.

But an earlier fork with his kit may be a less expensive route to a good front end.

 

 

 



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This thread is also interesting, a bit old but but relates to the earlier design, pre-SSS:    http://www.thumpertalk.com/topic/363979-introducing-the-kyb-phase-4-fork/

I think it is the same kit for more late-model WR's

 

This video (there are 2 parts) also gives you a good idea of the newer stlye:  http://www.rockymountainatvmc.com/Video/91

 

 

 



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RE: front end - changing the front forks to USD
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Brian, Here are the YZ clamps & stem measured out fairly close. They are supposedly from a 2010 YZ250.

Best that I can tell with dial calipers is that the pressed-in section of the stem is 31.5mm

 

YZtriple-labeled2_zps84407d69.jpg

YZtriple2labeled_zps0fddc64a.jpg

 

 



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That's brilliant Ted - very many thanks!

It seems to me that the best way forward would be to open up the hole in the YZ lower fork clamp to 33mm to accept the TTR post which will need to be pressed in.

If I am right then the TTR steering head bearings are all going to fit and the YZ top clamp will also fit straight on as it has the same diameter.

Have I missed something or is it that simple confuse

Brian



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It just may be that simple. I can't imagine it would be too difficult to re-machine the lower clamp. I rechecked the hole diameter in the upper clamp & it is indeed 25mm.



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One other consideration in swapping to the TTR stem spacing (distance between upper & lower clamps) is that the upper fork tubes taper to a smaller diameter between the areas where they are clamped by the triples. You can see it in the second photo you posted of the Showas & also in the linked pic of some YZ forks.  There is likely enough mounting surface for the smaller spacing but is probably worth checking.

050117514_img0185.jpg



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I see what you mean about the fork legs Ted but I will try and check it out as a good buddy who is into Yams for enduros and has had YZs and WRs reckons the tubes themselves are parallel where they go through the yokes.

The lower fork tube has a wide section, all parallel, so it could be raised upto 30mm without clamping issues. He doesn't think the TTR stem will pose a problem due to being 19mm shorter.

 




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Just to futher confuse things, I came across this:

The Aussies here probably already know about this, but Geoff Ballard (who you Brits may know more about than I do) runs TTR forks on his WR.

Check out the reducers to hold the much smaller upper tubes.



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Makes you think doesn't it!

A great vid and a lovely man.

I found a quote from him and like him even more now:

For the adventure stuff, I'll stick with my favourite tools. And for the big stuff, it's the GS1200 Adventure; I still think it's the king! On the smaller, and more go anywhere side of things, I think I'll forever have a Yamaha TTR250 in the shed! For the 'all round' and tighter stuff, you can't kill or beat that thing. Last month I did my sixth straight New Zealand Safari, where I rode a TTR. I love them – and that ride in NZ – so much that I've bought one that I leave over there at a mates place. That bike is definitely under rated!



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TTRfan wrote:

Makes you think doesn't it!

A great vid and a lovely man.

I found a quote from him and like him even more now:

For the adventure stuff, I'll stick with my favourite tools. And for the big stuff, it's the GS1200 Adventure; I still think it's the king! On the smaller, and more go anywhere side of things, I think I'll forever have a Yamaha TTR250 in the shed! For the 'all round' and tighter stuff, you can't kill or beat that thing. Last month I did my sixth straight New Zealand Safari, where I rode a TTR. I love them – and that ride in NZ – so much that I've bought one that I leave over there at a mates place. That bike is definitely under rated!


It does indeed make you think.

I thought maybe I'd find mention of what modifications they do to the TTR forks but haven't found anything. Sounds as though they were using the TTR front ends on occasion as recently as a year ago.

Like the quote as well.



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i now own this bike and was wondering if the guy who did the work is on here and has he posted anything about the work that was done???

i have looked and can,t find anything but hoped maybe there,s some history of it somewhere.

 



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the bike with the yellow frame and the usd forks that is !!!!

 



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glynn4623 wrote:

i now own this bike and was wondering if the guy who did the work is on here and has he posted anything about the work that was done???

i have looked and can,t find anything but hoped maybe there,s some history of it somewhere.

 


 All the info I have is in my post of 1 March.



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USD forks....
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I dug the USD forks out & took few numbers for the conversion

into the TTR.... It turns out the 05 YZF250 USD forks use the same

ID bearings as the TTR... 28mm Top / 30mm bottom...

Even the steering stops look to be in about the right place..

The YZF forks are 40mm longer but theres enough un-tapperd

area where the bottom clamp fits to raise them 30mm... top

is no issue as there lonf un-tappered area..

not looked at the wheel & caliper yet... but the YZF dose use a

20mm axle... so spacer sleeves will be need to reduce the

holes in the forks to 17mm....

 

also got a small speedo/tach as I wont be able to use the TTR

speedo drive...

the pics.....

 

 

 

 

 



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steering head bearing conversion chart...

www.allballsracing.com/index.php/forkconversion





..

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I think all that changing forks from other bikes is a huge waste of time, the TTR forks are pretty good and can be made excellent by any good suspension tuner, here in Oz we have for example Teknik Racing, they are suspension experts for less than $500 you get your TTR forks converted into fantastic forks, gold valves, cartridge emulators, new springs, seals etc...

That would be my first option with out a doubt. $1000 get both ends done, no mucking around all in 1 day.

 

 

Cheers, Steve



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TDVT wrote:

Just to futher confuse things, I came across this:

The Aussies here probably already know about this, but Geoff Ballard (who you Brits may know more about than I do) runs TTR forks on his WR.

Check out the reducers to hold the much smaller upper tubes.


 What a great little video, ballards is just down the road from me



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great video, thanks for posting.

Legend of a guy

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I dig the YZF250 front end out from under all the other stuff
think it's about time it went into the bike....

just weighed it... 11kgs ... clamps/forks/wheel/tyre/axle/disc/caliper
be interesting to see what the TTR one weighs....

Got a ride this week end after that it's all go....

 

And 2 new golden tyre GT230 rears arrived yesterday... should keep me up

right for the winter rides..




...



-- Edited by petenz on Thursday 2nd of March 2017 05:05:47 AM

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Go for it Pete! I'm about to embark on a CRF250 front end onto xr400. A good machinist and time well spent measuring and I think anything's possible within reason!
Plenty will be watching with interest...

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this is going to be too easy...
just checked bearing sizes...

06 TTR250...
top bearing - 28/52/16
bottom bearing - 28/52/16

06 YZF250...
top bearing - 28/52/16
bottom bearing - 30/52/16

so the YZF250 bearings will fit straight into the TTR steering head...

then its steering stops & stem length to deal with....






.

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Luck is on your side Pete!

Here is a page of sizes of all thinks fork related -  http://www.clubchopper.com/forums/metric-chopper-talk/77043-jap-bikes-fork-tube-sizes-neck-bearings-axle-diameters.html

Might be useful to someone wink



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TTRfan wrote:

Luck is on your side Pete!

Here is a page of sizes of all thinks fork related -  http://www.clubchopper.com/forums/metric-chopper-talk/77043-jap-bikes-fork-tube-sizes-neck-bearings-axle-diameters.html

Might be useful to someone wink


 Kool thanks...

just measured the steering steem length....

this is going to be a bolt in fit...

TTR stem is 240mm , guess what the YZF stem is 240mm..

Steering stops even look to be in the same place as well...

 

just ordered a set of YZF head bearing on line..

So if it's as easy as it apairs it should be in next week end

then the forks can go into Lintern for a full rebuild , revalve

& sprung for my weight from MX to enduro...

 

 

.



-- Edited by petenz on Saturday 4th of March 2017 03:52:13 AM

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