XS Adventure

[osteoderm]

Great thread! Some solid work here, and I totally appreciate the effort that goes into documenting/photographing things as they move along.

One question/observation: Is this the set of triples that you ended up using?

The reason I'm asking is because that looks like a radical change (subtraction) in offset from stock. I'm using less-than-stock-offset triple clamps (TT500), and I always figured that the decreased offset would somewhat compensate for the steeper rake caused by my aggressive fork-lowering, resulting in a near-stock trail figure. Long story short, my forks are better than stock, but less than desired.
Have you worked out the changes to your trail numbers yet?

Keep up the awesome work!

 

[SOSXS]

Great thread! Some solid work here, and I totally appreciate the effort that goes into documenting/photographing things as they move along.

One question/observation: Is this the set of triples that you ended up using?

The reason I'm asking is because that looks like a radical change (subtraction) in offset from stock. I'm using less-than-stock-offset triple clamps (TT500), and I always figured that the decreased offset would somewhat compensate for the steeper rake caused by my aggressive fork-lowering, resulting in a near-stock trail figure. Long story short, my forks are better than stock, but less than desired.
Have you worked out the changes to your trail numbers yet?

Keep up the awesome work!

Thanks! It's my defense for the cabin fever I am prone too I have not checked the trail, at least that I can remeber what it is. I'll check it as soon as I pull it off the rack. I believe that you are right and the rake is less than stock. The triple trees are a combination of a 1987 YZ125 lower machined for the stock XS stem and a 1989 YZ490 upper. The YZ125 and YZ490 upper trees have the same off-set, but the 490 tree has rubber mounted bars and fits the XS stem without mods. We actually have a YZ125 upper tree that we modified to fit the XS stem, but once we got a hold of the 490 tree we realized we did not need to modify it

Correct me if I am wrong, but I believe lowering the front end will decrease your trail; making quicker steering, but losing straight line stability. For my project there will be 2 different trails, one with the 21" front wheel that is mounted now and a smaller trail with the 18" motard wheels that will be replaceable.

Honestly, I do not know exactly how it will handle with all the mods. I am certain that once it hits the road we will have to play with the front and rear spring rates, dampening and rebound.

How does yours handle? I know you said better than stock, but less than desired, but is it the steering or the suspension side?

 

[osteoderm]

Correct me if I am wrong, but I believe lowering the front end will decrease your trail; making quicker steering, but losing straight line stability.

Agreed. Triple clamp offset has always been a way to tune this effect one way or the other. I've always counted on less offset = more trail for a given rake.

How does yours handle? I know you said better than stock, but less than desired, but is it the steering or the suspension side?

I need stiffer springs (pre-load maxed, Gold Valves nearing the upper end of reasonable adjustment), but otherwise suspension-wise the forks are a huge improvement:better large-bump/high-speed compliance, controlled dive under braking, well-damped on the small stuff.
Handling-wise, the bike has a little better turn-in, but still needs a firm hand; less "spooky" than stock, but mid-corner corrections are still... not appreciated. The steeper front-end effect I was expected was largely diminished by a similarly-lowered rear (the rake angle being less-changed overall)

 

[SOSXS]

Agreed. Triple clamp offset has always been a way to tune this effect one way or the other. I've always counted on less offset = more trail for a given rake.



I need stiffer springs (pre-load maxed, Gold Valves nearing the upper end of reasonable adjustment), but otherwise suspension-wise the forks are a huge improvement:better large-bump/high-speed compliance, controlled dive under braking, well-damped on the small stuff.
Handling-wise, the bike has a little better turn-in, but still needs a firm hand; less "spooky" than stock, but mid-corner corrections are still... not appreciated. The steeper front-end effect I was expected was largely diminished by a similarly-lowered rear (the rake angle being less-changed overall)

I'll have several spring options for the forks and at least 1 for the rear. I have a set of YZ490 forks and rear shock that came with the rolling chasis. The rear spring is nearly 1mm thicker in the coil. I don't know if that will be enough, but statically the bike sits well with the 125 suspension. I assume that the 490 fork springs have a higher rate than the 125 springs and the forks are about an inch longer so they may preload if I install them. The other fork option for me is a set of Progressive springs for a DR650. The OD of the spring is the same, they are about 12mm longer and have a much higher spring rate than the YZ125 springs.

Dampening and rebound are a different story. I will have to start riding it to figure those out. Plus this bike is intended for trails as well as the street so I'll have to find a happy medium

 

[SOSXS]

Hard to find time to work on the 650, but I did get some of the mounts done.

The upper motor mount had to be redone in order to fit the MX125 tank. The original mount was a funky 3 piece per side deal Not sure why Yamaha did that, but here is the making of the new mounts.

The other issues were the rear brake stay and the mounting for the muffler onto the frame. I originally had the brake stay mounted to one of the main bolts for the pivoting dogbone on the suspension linkage, but I was affraid it would fail after some fatigue. Also, it was getting pretting crowded in that section of the frame with the rear brake pivot, brake stay, suspension linkage mounts and then a muffler mount.

In the end I was able to weld a single mount to the frame that would serve both as the brake stay mount on one side and the mounting point for the muffler on the other side. It took some planning to get the mounts to work while still being able to remove all the hardware (i.e. not welding in a frame piece so I couldn't take the suspension apart).

Here is the muffler in roughly the position I wanted it in.

And making a bracket to hold it there.

And the 2 mounted together

I think that is the last piece that I need the motor mounted in the frame for. There are a few odds and ends to work on, but I think it is time to tear everything down for final welding and then rebuilding everything. It's been a long time to get to this point and I'm glad to be moving on to another phase

 

[mick71b]

Nice work, Mr Problem Solver! I really like the concept of the DS XS. Hopefully it won't shake it's head too much.