XS650 Triple Tree / Steering stem swap query

[acebars]

I know this has been in threads I've looked at and written in.

But I found some conflicting information and just wanted to get 100% confirmation:

Is the XS750 36mm triple tree / steering stem a direct swap for the early pre-74 steering stem / triple tree (minus bearings of course)?

 

[Okie]

I have one and they are not the same. It's slightly shorter than the '74 tree I have.

 

[gggGary]

74 is new style "long" neck, I believe the early "short neck" 70-73 frames will accept the XS750 stem with no problems. Fork stops, fork lock ignition lock, gauge mounts, etc will be different.
Those forks have the caliper mounts to fit the smaller XS750 rotors. (at least in the USA....) So brake calipers, rotors, etc. from the XS750 need to come along unless you are going all custom.

 

[nj1639]

The xs750 had a standard style fork and a leading axle fork, the standard style will accept the xs650's caliper but you'll need the smaller diameter rotor.

 

[gggGary]

XS750 standard will accept XS650 calipers, late style 77-83.

 

[acebars]

The xs750 had a standard style fork and a leading axle fork, the standard style will accept the xs650's caliper but you'll need the smaller diameter rotor.

I'm using different forks all together, I'd just like to confirm that the XS750 steering stem / triple tree is a bolt on swap with the earlier pre-74 XS650s.

I do not have the welding skills to be able to swap out the stems and would rather not outsource it.

 

[nj1639]

"We" believe that it's a direct swap.......you may just be the one to finally confirm it.
I pressed out a stem on a standard "77 xs750 and welded the stem from an xs650 in its stead. Not sure if I have the old stem laying around here but if you could get a measurement from a '73 or earlier 650 stem I could look to see if that old 750 stem is still around.
GGGary? Got a stem laying around from your swap?

 

[gggGary]

I have both early an early triple and an XS750 fork complete. I have to go look for a few things in the shed anyways I'll add this to the list. See you in a bit.

 

[weaselbeak]

There is a difference between the XS750 I have and the 1978 XS650. Maybe an early 650 is different.

 

[gggGary]

Here's the pics. As before it looks like a "straight swap" That's a pretty beefy triple compared to the "whippy" early 650 frame neck..............

 

[gggGary]

Here blown up together

View attachment 37901

View attachment 37900

 

[acebars]

gggGary, you are a star thank you very much. I have one final niggling question. Have you any idea whether or not the adjustable steering damper knob is transferable from the early XS650 to the XS750, I've always liked one that could be adjusted by hand.

 

[expercat]

I know this has been in threads I've looked at and written in.

But I found some conflicting information and just wanted to get 100% confirmation:

Is the XS750 36mm triple tree / steering stem a direct swap for the early pre-74 steering stem / triple tree (minus bearings of course)?

Hi!
I am glad to give you some informations about this swap becouse I finished this job with success.
However it'isnt an easy job becouse you can use the lower and upper braces from Yamaha XS 750 triple tree but NOT the stem. The stem is shorter.
You have to pull out the Yamaha XS 650 stem (using a lathe for cutting the original welding) and to put it on Yamaha XS 750 lower brace. The hole is the same.
Before making this operation it's better to control the two stoppers on Yamaha XS 750 lower brace. Their position is too large for Yamaha XS 650 frame stop, so you have to weld a little iron slice on both.
I changed the original bearings and I installed All Balls tapered bearings.
Using these bearings the better compromise when you force the stem on lower brace is 227,90 mm (this measure is from original bearing seat on lower brace and the stem top).
Now you can weld brace and stem together. See another my thread about this operation.
A last very important thing to do: you have to put under the new lower tapered bearing a ring spacer: height spacer 3.85/3.90 mm (in my opinion this is the better compromise among different parts of this "new" triple tree)
If you don't put this spacer the lower brace touches the frame. The lower braces structures are lightly different.
Best regards.
Mike

 

[acebars]

Thanks expercat, what XS650 do you have? The earlier ones have a shorter stem than the later ones so maybe perfect for the XS750 steering stem.

I went with XJ650 seca turbo 37mm steering stem so won't be doing it this way, have yet to start doing the mod and seeing what fits and what needs swapping.

I'm sure this will be good info for someone though.

 

[expercat]

Hi!
my XS 650 (two bikes) are both 1974 model (TX 650 A). Original stem diameter (where lower bearing is installed) is 30 mm.
I want to give you another information. Before doing this quite complicate job, I tried to install on my XS 650 frame a triple tree from another Yamaha model TX 750 (fork tubes 36mm).
This triple tree is really perfect and it is not necessary any modification (no cut, no welding) BUT it changes the original bike offset. I mean that this triple tree and its upper and lower braces moves the 36 mm fork tubes 10 mm forward.
I live near Aprilia factory so I know the former chief engineer for 250 race bike frame (Loris Reggiani etc). I asked him for an opinion.
He said this modification was too radical.
So I used the TX 750 stem for swap only.
Best regards.
Mike

 

[acebars]

Appreciate the pointers expercat, some great info there

I too was thinking about offset and preferring less than more!

I got NC24 and turbo seca XJ650 steering stems 37mm to play around with so will see which is the best suited/easiest.

 

[arcticXS]

Interesting,
What is the main reason for swapping to XS750 or TX750 forks? Slightly stiffer fork tubes, 36 vs 35 mm? Looks, or fork length?
I am looking at using a 38 mm fork from a FZR600 or FZR 400, mostly for weight savings. According to Richard Pollock, each leg is 3.3 pounds lighter than the stock XS 35 mm forks. That gives a weight reduction of 3 kilos just from the fork, and being 38 mm, it should be at least as stiff as the 35 mm, even if it is thinner wall tubes.
Looking at the pictures, it looks like the lower tree is cast steel both for the 650 and 750, is this correct?
Are there any all alloy trees for a 38 mm fork that have close to the same offset as the XS?

 

[XSLeo]

expercat, The 74 TX 650 A has the longer neck as mentioned earlier. The 70-73 use a shorter neck.
On the 74 up XS650's the XJ 650 Seca is a straight up bolt on swap. I have an 82 XJ650 Seca Turbo. I put the forks on my 75 XS650 B. Fit fine. Where the air line fill cap on the right side will dent your stock tank.
I have a set of forks from an XS1100 Standard. They won't fit the 74 up XS650 but should fit the earlier 70-73 frames. They both use a shorter neck.
arcticXS. Using the XS or TX 750 forks with a larger diameter tube will stiffen the front end. That's the main reason to use them.
The XS1100 forks measure 31.125 inches from axle center to top of the tube. The XS650 measures 29.625. A difference of 1.5 inches. The top tree of the Xs650 has a drop from where the stem goes through to where the fork tube go through. This drop is, Well I seem to have misplaced my 75 top tree. So I can't post the drop.
On the XS1100 top tree there is no drop. It's flat. So the XS1100 forks may be longer but with the flat top tree the effect on the ride height won't be as much as you would think.
Leo