[sschering]

Does anyone know if there are any 35 or 36mm Tripple trees that will fit a XS400 frame without doing a stem swap?

I know the XS400 shared headstock bearings with a bunch of other Yamahas
RZ-350 35mm and YX600 36mm are ones I've been looking into.

 

[ZouLou]

The XS650 after 78 i think has 35mm triple trees

 

[sschering]

Yeah but it uses a different head stock bearing set so then I'm either looking at finding a set of bearings that will work or swapping the stem..

Just so it's out there the bearing dimensions for the XS-400 and most of the RD's plus the RZ-350 are
Tapered Roller Bearings(STEERING) Upper = 25 x 48 x 13mm Lower = 30 x 48 x 13mm PARTS PLUS part # SSY125

 

[Mr Fischer]

Just because the steering bearings are the same for 1 model and another model doesnt mean it will fit.Some models use a longer steering stem than others and this wont be reflected in the bearing kits. Just because the bearings are differnt sizes, doesn't mean they can't be made to fit also.

The steering bearings are sized like this (XS 400 top bearing used for an example) = 25(inner hole dia/stem dia) X 48(outer dia/frame hole) X 13(bearing height). Your post list the XS 400 bearings, here are the XS 650 bearings = 25 X 48 X 15.2 and 30 X 48 X 15 (SSY500).

If the steering stems are the same length (I beleive they are, but you need to check to be sure), you would use the XS 400 bearing kit to install the XS 650 steering stem into the 400 frame. The stem diameter is the same for the 400 and 650(as shown in the 1st measurements in the bearing sizes), the difference is the outer sizes of the bearings and bearing heights and the size of the mounts in the frame.
DG

 

[ZouLou]

And Mr. Fischer comes in for the save and the win haha. Nice answer and perfect information. Trust him with XS stuff the man knows all there is about the machines haha.

 

[sschering]

Hey great.. thanks for the info..

I haven't found the XS-650 bearing sizes before..

Any idea on the XS-650 stem length or the neck length on the frame?
I found 1 place that stated 171mm don't know if that was the frame or stem.

 

[Mr Fischer]

The XS 650 stem length is 225mm (the later 35mm forks - top of stem to bottom of bottom bearing). I don't have a later frame to measure.
The top triple tree is 23mm thick at the stem and there are 2 X 7mm locknuts between the bearing and the top triple tree. If you subtract the top tree and nuts thickness (total 37mm) from the overall length of the stem ,it gives you 188mm between the top of the top bearing and the bottom of the bottom bearing. Measure your stuff(stem,top clamp thickness and locknuts) and compare it to this info.(or put your 400 stem, locknuts, and top tree together and measure the distance between, bare, with out any bearings on it)
I tried to measure the early (1976) 34mm XS 650 stem and the measurements seem to be about 5mm longer (230 instead of 225) than the later 35mm measurements. It was hard to get an accurate measurement because the bike is together and not easy to get to, so it may actually be the same size as the later forks.
DG

 

[crazypj]

You can shorten steering head on XS650 to get clearance.
Don't remember on 400 as I haven't done one for about 25 yrs
XS650 steering head is 190mm long stock, just used a tape measure on spare frame (1979 frame)
Yamaha use the same bearings on XS models over 250cc, RD DT, YZ etc for a least a 10 yr period and from what I've seen, still use same sizes today on smaller cruiser style bikes.
The taper bearings are taller than stock in every case and for every manufacturer(Honda, Suzuki,Kawasaki, Yamaha)
It only makes a difference if your running stock headlight 'ears' you need a 4~6mm spacer on fork tubes to stop them flopping about
Ball bearing just have a lower stack height.
(I've been fitting 41mm Suzuki Katana forks into XS frames)
GS500 has 37mm tubes, max dia for vintage I believe?
BTW, Hello everyone, I'm new here
PJ