Yamaha front ends work too!

Questions and comments about converting to beefier forks..
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EdC
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Yamaha front ends work too!

Post by EdC »

I know that KX fronts seem to be the choice for conversion , just wanted to pass along my Yamaha WR conversion experience.

I used a 2001 WR 426 triple/forks/wheel/axle/brake caliper hanger to make it simple. All went fairly easy, I did have to knurl the stem, tapped the stops on the WR lower to install bolts as the triple hit the tank without them. I haven't had the forks shortened yet, but probably will next service, for now I have them raised 3/4" in the triples. Haven't put a lot of time on them yet but they feel great compared to stock.

After looking around for parts at the start I thought that starting with a front end that is pretty plush to begin with would be a head start over using a moto front end.
Rwd4evr
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Yamaha front ends work too!

Post by Rwd4evr »

I have a yzf426 front end I was thinking of using on my 1990 e2 since my fork seals are leaking and I just wrecked the caliper seals with foamy engine bright(woops). Why did you need to knurl the stem? Are the h and e head tubes different ? What bearings did you use?
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kawagumby
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Yamaha front ends work too!

Post by kawagumby »

I've used both YZ125 and YZ250F forks, for 3 bikes in total. Work great - more tune-able than the KX stacks in my opinion. The YZ125 forks come with .41 springs, which is perfect for me.
Don't use the pre-2001 yamaha triples though, the bar position is too far back, IMO, which affects the handling/turning.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
Rwd4evr
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Yamaha front ends work too!

Post by Rwd4evr »

How did you deal with the upper bearing? Stock is 25-47-15, yzf is 28-52-16.
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kawagumby
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Yamaha front ends work too!

Post by kawagumby »

you don't use the stem or bearings from most donor bikes you use the KDX stem and kdx bearings.
1994 KDX200, Beta 200rr, yz125, yz250, kx100 modded for adult, gasgas contact 250.
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6 Riders
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Yamaha front ends work too!

Post by 6 Riders »

Rwd4evr wrote:How did you deal with the upper bearing? Stock is 25-47-15, yzf is 28-52-16.
So, if you don't do a stem swap (I'd think you would need to) then you'd go to a bearing shop and buy a 25-52-15 bearing. Then the bearing will fit the KDX tube, and the YZF stem.
I'm doing an RM swap (using a KDX stem) and will be using the KDX front wheel with RM bearings (same idea, different part). This leaves me able to swap hubs out easily IF I need to.
newbbewb wrote:^what he said.
masterblaster wrote:Man 6 riders you rock.
*side note...I'm drunk, so try to read what I'm trying to say, instead of what I actually type
Rwd4evr
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Yamaha front ends work too!

Post by Rwd4evr »

It's the other way around. Need a 28 Id 47 od with yzf stem. That bieng said, I hadn't looked at my parts in awhile and was thinking that the upper tree hole was the same size as the upper bearing(duh). Yzf stem is 32 mm at the bottom(pretty sure,i cant find my digital caliper right now)and 25mm through the upper tree. Does anyone have the Kdx stem( the press fit part) and upper tree hole measurements? Mine is a 90 .I know the forks are different 91-92.
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6 Riders
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Re: Yamaha front ends work too!

Post by 6 Riders »

The steering heads are all the same size, even on the H series. You nee to find out if the yz stem is long enough/to long. If the length is good, then a bearing swap is all you need to do. If not then a stem swap will be necessary.
With my RM swap there was a bit of machine work that needed to be done. I will try to pick up my parts tonight tomorrow and get measurements.
newbbewb wrote:^what he said.
masterblaster wrote:Man 6 riders you rock.
*side note...I'm drunk, so try to read what I'm trying to say, instead of what I actually type
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Yamaha front ends work too!

Post by Rwd4evr »

Great thanks! And I was wrong, 93-94 are inverted, different trees.
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Yamaha front ends work too!

Post by Rwd4evr »

The stems look to be identical in length, or at least very close. Can't quite tell cause the bike is still together. I think I'm going to use a piece of 30mm od 28mm Id stainles tube pressed on the yzf stem with a 30-47-12 upper bearing and put a 3mm shim under It to get everything in the right place. Other wise I need to have the stems swapped and the Kdx stem knurled, plus have a bushing made to go from the 23mm upper tree stem part to the 25mm upper tree hole. I can't find anything 23mm Id that I can turn down on my lathe, and I don't have a boring bar.
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