Final drive Solution

[xswilly]

hey chop
I have a 83 XJ750RK it is a seca with the fairing setup
is that the correct rear drive setup?
the pumpkin aligns with the xs rear wheel but i need to rip it apart to check the rest

also the seca has an 18" tire where the 78E has a 17" tire

[xschop]

remove and check it

If it is the same ratio as the seca turbo, You could drag race that one. If it is 2.9 ratio, then go with that one....chop

[red bandit]

Hey chop. Great find. Just wondering... You say the 750 has a 2.9/1 ratio...ok. What does the 1100 have? What kind of rpm decrease are you expecting/guessing at 60 or 70 or whatever? It would be great to have one of each. One for performance and one for gas mileage. Thanks again Red Bandit

[xschop]

xs11 ratio

xs1100 FD ratio is 3.3:1

[xschop]

Gas Mileage

Just reporting back to this thread. My gas mileage is now right at 50mpg with the new final drive. I put in 4 gallons to a near empty tank (reserve) about 10 days ago and went 208 miles to near empty....chop

[knewsom]

WICKED.


This is exactly the mod that I've been looking for! I wonder if we could have a tech tip of this one made, so it's all laid out as far as which 750 final drives are 2.9/1, and exactly what the solution is as per the drive shaft.

What RPM are you at when you hit 80?

Cheers,

[xschop]

RPM

At 70mph, I am doing 3950, and that is with my 16in. special on my chopper. I can easily go from 70 to 100mph with plenty of pull...chop....oh yes, the solution is spelled out exactly in the post begining under the schematic....just need a 5/8in. collar. I made mine from copper tubing!

[knewsom]

nice! I'll bet that with my 17" rear I'd be at about 3.6K RPM @70, and 4k @80, which'd be a whole 1K drop from where I'm currently at.

That'd be awesome. As it is, I can go from 75 or 80 to over 100 in less than two seconds, so I don't think I need any extra pull in that range.

You made the 5/8ths in. collar from copper pipe? You wouldn't happen to have a pic of it would ya? I guess I'm just not 100% clear on what the collar is for - to stop the oil from leaking out? what - of the final drive? or do you mean the grease from the driveshaft?

It also dawned on my on my ride home from work tonight at 80mph on hwy 80, that this might actually help improve the XS's time on the 1/4 mi, by reducing the number of times one needs to actually shift.

I have to wonder if they made the XS with it's final drive with a 3.3/1 ratio due to the 55mph US speed limit at the time.

[xschop]

I'm Glad someone else said it!

I kept quiet about that aspect of the change. I can now launch in 1st gear to 45mph in no time. I'm not a drag racer, but that's the first thing that came to my mind when I started getting on it hard to test the driveshaft mod.... 1st gear to 2nd and you're already 1/4 mile. I don't have a picture, But you can make the collar from cutting 5/8" off the end of a 90 degree 3/4'' copper fitting from lowes/home depot. It is a perfect fit. All it does is keep the xs11 shaft fitted into the recessed 750 splines by pushing it backwards 5/8" and still give plenty off bite at the shaft and u-joint splines....chop

[mro]

copper???

Is it turning against steel or stationary relative to parts it comes in to contact with?


mro

[xschop]

no

No, it locks onto the 21 splines of the xs11 shaft and keeps it from moving forward into the u-joint splines, there is no friction, contact....believe me I wouldn't be riding this bike if I thought it was unsafe....MDRNF

[knewsom]

hmmm...

...we may be looking at a new fastest XS11????

[xschop]

I didn't say it

I'm not one to brag, but I do believe I am the fastest on top end...I can't wait for someone to do the mod and post their results. I believe the fastest 1/4 mile would be from someone who does this mod and has the big bore kit. But don't be fooled into thinking this new ratio with a stock engine is slow, The xs11 has plenty of torque to push around....chop

[Brian_D]

Re: FD

Originally posted by xschop
just make sure you rotate the pinion drive ensuring you have the 2.9:1......before you open your wallet

so, how much $$ should one expect to drop for the final drive .... and other than local boneyards, are there other reliable sources (like an Andreas equivalent) for the XS750 FD?

[xschop]

750 FD

I have a few of them. You can snag one off e-bay for as low as $25. If you're in OKC, A&A cycle has a couple left, they got $40 from me before I knew that it was a 750 FD. I originally thought I stumbled across a rare xs11 FD, But I posted the number marked on the FD is 1J7YO . Someone asked if it was "D" or "E" model and the number references "D" model. So just look for 1J7 then turn it to check for 2.9:1