Final drive swap

[Bonz]

James England,

Good of you to have taken the leap to the Final Drive conversion (or as I have called it on occasion, the "Franken Drive" conversion). Congrats, and that is a very fair and reasonable price to have paid.

I said in an earlier post today that the negative aspects simply don't exist as they are being stated, and it's only those who haven't done the swap or ridden a swapped bike that are sharing their $.02 worth without practical knowledge or experience to speak to the subject objectively.

Be that what it may, it's a totally different bike with the FD swap, and with a fair windscreen on it (I recently put a PlexiFairing 3 from National Cycle on my 80 Special) it is already getting equal or more riding time than my 2001 ZRX 1200 (see signature line). I love the ZRX, as it goes like the wind, with the bar risers and lowered footpegs it's comfy, and it returns nice gas mileage (46 mpg) for the beast that it is, but there is just something extra that the XS provides.

[skids]

Well, I have three running xs11's and one of them with the swap. I will tell you that riding double, up hills in sluggish traffic, with stop-n-go is murder on the clutch. Once you get going and into the torque band, the swap is real nice. Dropping the rpms at highway speed is a real plus.

[3Phase]

Hey, Bones, you've got a Special with the 16" rear wheel and it's not quite the same as a Standard with the 17" wheel.

The 750 FD is a hair too tall in some situations for my '80G but it's a fantastic on the highway. In some situations it reversed the, "I need another gear!" problem and I try to downshift when I'm already in 1st gear. Fuel economy pretty much depends on how I ride, not the gearing, but it did gain a few MPG.

I do like the 750 mod on my Standard but the ring, pinion and input shaft are physically smaller than the ones used in the 1100 so I did not trust it for a long time. Now that I've tried to destroy the thing for over two years and 35K miles and it just won't break I decided to build another XS instead of going back to the stock FD: one for touring, one for fun.

[James England]

[QUOTE=3Phase;320497
Now that I've tried to destroy the thing for over two years and 35K miles and it just won't break I decided to build another XS instead of going back to the stock FD: one for touring, one for fun. [/QUOTE]Sounds good to me.......

[Shacknasty]

I'm wondering if I swap the FD between my 750 and 1100, will the 750 be quicker off the line? The 750 is a bit of a slug (it looks faster than it is!) and I wouldn't mind a little extra go in the old triple. I only use it for short hops so it won't see much freeway time.

Now the FD swap on the 1100 is what I really look forward to trying out. The idea of a more relaxed motor at SoCal velocities is very appealing to me. Besides I would do more distance riding on it but it has always seemed a wee bit busy at speed for any length of time.

If the swap is good for both bikes, then I am golden! If it is not recommended for the 750, then I'm gonna have an excuse to visit my favorite motorsickle boneyard. WooHoo!

[3Phase]

Shack, I haven't actually done the 1100 --> 750 swap but it should work. I think I read about someone considering it but I don't recall how it turned out.

Off the top of my head:

If the shaft will fit, you'd have to take the oil seal off of the 750 drive shaft because there is no machined space in the 1100 FD input coupler splines for the 750 shaft seal and the shaft won't fit into the coupler.

You'd have to remember to add fresh moly paste and grease to the input coupler splines just like the 1100 when you change tires on the 750 because the 1100 FD doesn't have any oil passages from the pumpkin to lube the coupler splines like the 750 FD.

Have fun and take pictures so we can see how it's done or why it won't work!

[Eveready1100]

Hey Shack, what model 750 have you got? Yamaha changed the middle gear ratio on the late model ones to up their performance image so it might pay to check what you have before getting any new bits.

[DGXSER]

Scott basically pointed this out already. The only thing I can see as a problem, would be the length of the 750 drive shaft. Since we have to more or less extend the drive shaft on the 1100 for it to fit the 750 FD (add spacer at middle drive end), it seems you might need to shorten the 750 shaft to fit the 1100 FD.

[Eveready1100]

This bit worries me.

it seems you might need to shorten the 750 shaft to fit the 1100 FD.

Meaning surgery.
I was thinking more along the lines of just looking for the later XS 750 Middle drive which would lower the overall gearing like a final drive change without cutting shafts etc.

[Bonz]

3phase,

I agree with what you say, and I recall reading at one point or another that the FD swap is something that Special owners look at more so than Standard owners, but I can't tell overall what number of Special Vs. Standard bikes have had the swap to get an idea of the ratio.

CaptonZap converted his 80G a couple weeks before me, and he is running about 200 rpm lower than what I am seeing on my converted 80SG based on what he's told me.

I try to make sure and mention in each post that mine is an 80SG (it's in the signature as well) because I do know that the FD swap could/will have a different feel on a Standard vs. a Special, but haven't directly said that.

For the other stuff about changing a 750 to the 1100 FD, since we "extend" the 1100 driveshaft with a spacer to fit the "recessed" splines on the 750 FD, if you used the 750 driveshaft with the 1100 housing, would the splines on the 750 driveshaft end extend too far back into the 1100 housing , or would they just engage the splines further in and leave unused spline on the forward part of the 1100 FD housing splines?

I hope that makes sense...

[cywelchjr]

3phase,

I agree with what you say, and I recall reading at one point or another that the FD swap is something that Special owners look at more so than Standard owners, but I can't tell overall what number of Special Vs. Standard bikes have had the swap to get an idea of the ratio.

CaptonZap converted his 80G a couple weeks before me, and he is running about 200 rpm lower than what I am seeing on my converted 80SG based on what he's told me.

I try to make sure and mention in each post that mine is an 80SG (it's in the signature as well) because I do know that the FD swap could/will have a different feel on a Standard vs. a Special, but haven't directly said that.

For the other stuff about changing a 750 to the 1100 FD, since we "extend" the 1100 driveshaft with a spacer to fit the "recessed" splines on the 750 FD, if you used the 750 driveshaft with the 1100 housing, would the splines on the 750 driveshaft end extend too far back into the 1100 housing , or would they just engage the splines further in and leave unused spline on the forward part of the 1100 FD housing splines?

I hope that makes sense...

I don't have my 1100 FD by me now (being at work at my computer) but you might look at your 1100 FD to see. I don't remember if the splines are machined all the way back or not. If they are, then you might be able to do it without having to deal with shortening the drive shaft, just eliminating the oil seal. I had though about trying to incorporate an oil seal into the 1100 drive shaft and leaving the spooge holes open in the 750 FD. But that would have mean trying to figure that out, and worrying if the gear oil would handle the heavier load that the 1100 shaft carries. It's an unknown and enough miles have been put on the mod as documented that I figured I'd leave well enough alone.

[jetmechmarty]

Special vs standard tire

If you have a standard running a 120/90-17 rear tire, the tire diameter is approximately 25.5 inches.

The Special running 130/90-16 has a tire diameter of approximately 25.2 inches.

How much difference does that make, especially considering the manufacturers don't keep to exact standards when it comes to tire sizes?

Marty (in Seattle)

[crazy steve]

If you have a standard running a 120/90-17 rear tire, the tire diameter is approximately 25.5 inches...

A 120 is too small for the standard; yeah, I know the 'conversion' chart says it's the equivalent size, but it's not. That chart 'converts' by load rating, not size. In fact, none of the tires currently available that will fit the standard are the same actual size as the original OEM 4.50H-17...

[jetmechmarty]

So, I can assume in their original configuration, the standard and Special shared the same or nearly the same tire circumference.

What size rear tire does one put on a standard now, assuming it still wears the 17 inch wheel?

Marty (in Seattle)

[cywelchjr]

No, they're quite different. The closest you can get is a 130/90-17, which is a good bit bigger than the 130/90-16 on the special, and you can tell it in the difference in the sidestand and how it leans.

When I got mine, the PO had a 130/70-17 on the rear, and it was almost vertical on the sidestand , and really hard to get up on the center stand, with LOTS of air under the rear tire. Now with the "close" 130/90-17 on the rear, it's got a nice lean to it, more like I'm used to from other bikes, and on the center stand (which is pretty easy to get it up onto now) I have just couple inches (maybe inch and a half?) of air under the tire now. And just changing the tire make a huge difference in the gearing all by itself. I had actually been considering taking the side and center stands off my special frame and putting on my standard before I changed the rear tire. It also made cornering so much better. However, it's not good for the inseam challenged, cause it does raise it up a bit. However, my seat is not normal height, as it's a custom job that clearly was lowered when it was done and it pretty comfy.