big meats

[stumpy]

Good morning all!!!! Just a quick question....I want to put a big fat donut on the back of my ' 79 XS11 Special. Right now I have a 140/90 on there, its not quite touching the swingarm. Any body have any tricks to get wider? Chain drive conversion or space the drive shaft out. Any ideas? Thanks. Stumpy




' 79 XS1100 Special K&N FIlter Dyna Coils Jardine 4-1 Accel Wires Vented Rotors

[Dennyz]

In my opinion, the 140x90x16 is the largest tire/wheel combo that will bolt on. Some XSs can't even take the 140.

A 150x90x16 might fit if the wheel was shimmed to the right enough at the drive unit and the swing arm was adjusted as far left as possible. The down side (if it worked) would be that the shocks would be out of line.

I am looking at putting a 160x80x15 VMax wheel and tire under my "F". It is going to require extensive modification and fabrication.

Obviously something only a Mod-o-nut would take on.

[strom]

I have a 130/90/17 on the back of my 78E, but I don't think anything wider could go in there without some bending/grinding/cutting...

LP

[chopper]

i run a 140/80 with a bare shaft( dunno if it would rub on a swing arm bike)

[stumpy]

I want my big tire!! I was afraid that might be the answer. How thick is the tube surrounding the drive shaft, anyone ever take a peek inside? Could the tube be cut on the inside and strengthened on the outside. Does the drive tube seal up the whole assembly or are there seals front and back for the rear end and front tranny. Are V-Maxes shaft drive, you may be on to something.......hmmm. Well please let us know how your mods go,I can't wait to read.! Thanks all in advance. Stumpy



' 79 XS1100 Special, Dyna Coils, K & N, 4-1 Jardine, Accel Wires, Drilled Rotors

[Dennyz]

stumpy wrote:

Are V-Maxes shaft drive.........

Yes, the drive spline and axle diameter are the same as the XS. The VMax wheel attaches very nicely to the XS Drive unit. I also plan on using the VMax rear break assembly for simplification.

The bummer is the narrow swingarm and drive location of the XS. To do it right, the follow issues need to be addressed:

1- Swingarm widened by 30mm.
2- Middle drive unit needs to be spaced out 15mm, requiring a longer middle drive unit shaft.
3- Move the left swingarm pivot bearing out 15mm.
4- Relocate lower shock mounts on both sides in 15mm.

1 is easy, 2 is half easy. The longer middle drive shaft will be an expensive thing to fabricate, but possible. 3 could be the most complicated problem to resolve. 4 is also easy.

The end result would make it possible to get a 160 to comfortably fit on the back of an XS (and maybe a 170 would squeeze in).

If I am able to pull this off, you can bet this list will be the first to know.

[xs11jack]

Rear Tire relocation

Is it possible to cut a notch in the inside of the drive shaft tube and weld a plate over the the notch opening? How much clearance is there between the shaft and the tube? If the notch were long enough, a fairly large tire should fit.

[Dennyz]

The shaft is only about 5mm from the inside of the tube, plus this area is already the weakest part of the swing arm. I cut one apart to see. By the time I reinforced the swing arm. I was back to only a couple of mm gained.

The second problem is the 16" Special rim is only 3.5" wide. That limits the size of tire that should be installed on it. Check with the manufacture of a particular tire for the RRW (recommended rim width). I think most recommend no larger than a 140.

My local shop would not install a 150 on my 16" rim. I could have done it myself, but I am not into killing myself to get a bigger tire. I like to go fast on my XS and want to be comfortable with my rear tire configuration.

Some have been able to get a larger rear tire by going to chain drive. I personally like the shaft drive and want my cake and eat it too.

I am not trying to dampen your vision. If you find a way to safely upgrade your XS to a large tire, please let us know how. I am sure there are others with "rear tire envy" out there.

I am current working on a sport fairing/wind screen for my XS. Once it is complete, the rear tire project is next. I will keep you all posted.

[chopper]

140 is the biggest tyre to fit an xs rim and swing arm.fact. you can space out the drive like you say and use a 900 diversion rear three spoke fzr style wheel (17"),this takes a 160 tyre. if you are going to go as far as spacing the drive use a split rim and billet centre that is the easiest way,or a billet hub and car wheel i did this on a virago 1100 (215 rear tyre) not easy or cheap but very trick as the brake was inside the wheel

[stumpy]

Well Dennyz i'm glad your a few steps ahead of me. Is the V-Max rear wheel a 16" or 17", does it matter? if it fits on the rear drive like you say. I like how you say #1 is easy, 2 not as easy and so on...you are right....I hope. I have built and fabed many things, but never a rear swingarm I'm like you Dennyz, I want to go fast and live to tell about it. By the way, how much are V-Max rear wheels going for?? Anybody have a clue. Chopper....what is a Diversion, i've caused a few an used a few but never heard of what ur speaking. I take it that its a bike. Available only in Scottland maybe? Well now i'm really into getting this fat tire on there...one way on another. Dennyz keep us all posted, and Chopper and anybody else who has any ideas.

stumpy


1979 XS1100 Special Dyna Coils, K & N, Jardine 4-1, Accel Wires, Drilled rotors

[Dennyz]

Stumpy wrote:

how much are V-Max rear wheels going for??

I picked up the rim (15x4) with tire ( Dunlop K491 - MV85HB15, like new), rotor, caliper, axle and caliper mount for $150 on eBay.

MV = 150mm

This rim/tire combo is about an inch shorter, so it will lower my effective rear drive ratio. I am thinking easier wheelies

[uk1.1s]

....what is a Diversion, i've caused a few an used a few but never heard of what ur speaking. I take it that its a bike

Stumpy - Not a US model then? - maybe under the Seca name or XJ900 ? It's a '90's 900cc tourer - shaft drive naturally.



Bit of info here if it really is alien to you guys

http://www.motorcycle.com/mo/mcyam/diversion9.html

[Dennyz]

more VMax/XS match up

The renewed interest in a wider tire on the XS inspired me to do some research.

I was able to put the Vmax rim and tire (150mm) on my "F", with no brakes hooked up. The VMax rim has less offset than the XS rim, which puts it 20mm to the right of center in the XS swing arm (with XS final drive). There is also 20mm of clearance between the tire and drive shaft side of the swing arm.

Ignoring the offset, it looks awesome. All I need to do is figure out how to move the final drive unit to the left 20mm and keep the driveshaft connected. I would like to find a solution that most anyone could take advantage of, like a custom swing arm. Several options come to mind that I will experiment with over the next couple of months.

Then riding season will be upon me and R&D season will be over.

Stay tuned.

[chopper]

if your back brake will fit the v max wheel you can offset the front wheel to match easily.wider trees and spindle,might look weird tho? depends how desperate you are to have the fat tyre

[Sid Clarke]

Doctor Dennys xs rear drive "fix"

Gentlemen, you are all after the same "fox", but DZ has more hounds! You go Guy, you go!! Can I get on to your first "buy in " list? WOW, a "FAT TIRE", on the back of the Std! Like water to a Buffalo! Just gazing, watching the herd, with myopic eyes!
SQUID