Fat Rear Tyre, XJ900 Frame

I'd like to get a fatter rear tyre for my XJ750 (with a 900 frame) at the moment I've a 120/90-18 on there, and it's a bit skinny for my liking, I'm looking to do a few mods to make it more streetfighter, sports bike, perhaps with a bit old school Norton stylee thrown in for good measure, I don't know, but I want to take it from looking like a commuter bike to something a bit more stylish and mean..

Any recommendations for the rear tyre? If necessary I'll get a new rear wheel if I can find one that fits, but I'd prefer just to stick the fattest tyre on the rear wheel that I can find that will fit the standard wheel, because then the wheels will match.

While we're at it, I'd like to jack the rear end up a bit and lower the front end. On my XJR, I've dropped the forks through the yokes by 30mm, I'll see if I can do something similar, and I might change the rear shocks for something slightly longer, unless a jackup kit is available (a cheaper option! )

 

is that going to be a shafty or chain driven?

 

Hmmmm, sounds like you want everything on one bike, Streetfighter, Sport bike and Cafe all rolled into one> Pick one and go with it. Tires....look at the tire that's on the bike now, how close to the frame and chain/ shaft is it now? Pictures??
Fat may look cool, but can adversely affect the handling of the bike, so can lowering the triples on the forks and jacking up the back. If you do both you may end up with something unrideable.
Get some pics and give us a bit of background on your abilities to do this build, it'll help us help you.

 

It sounds like he's really looking to fighter it more than anything. Go and check out customfighters.com for some ideas....

 

ive raised the forks on lots of bikes as long as you dont raise more then an inch your fine adleast on all the bikes ive done. i think the tires you run have alout to do with it. ive never done an xj so if you do just raise them slowly and make sure everything clears and keep it under an inch you should be fine

 

I've been riding a XJR1300 for some time now.. Love the look of the wobbly old beast and really wouldn't mind something that looks close to its baby brother. I'm not one to pick a theme, more of a "stick this bit here and see how it looks." I haven't really seen anything on the roads I really like.. So I'm just going to go with the flow.. Yeah, part Cafe Racer, Part Street Fighter, and maybe a bit of Rat thown in for good measure... Like I said.. I've a black 2004 XJR1300, it looks and sounds mean, and pulls like something has bitten it in the ass.. I want something that I can put on the stand next to it and have it hold its own, at least in the looks.

I bought this bike cos I needed something to commute to work on.. My XJR is a bit nice to leave on its own in town and I'm doing 200km a day on it, so wanted something cheap and reliable, so I bought this for next to nothing, the engine is good, and she handles ok, so I figured I'd leave it as a knock around.. Only I can't leave well enough alone.. At the price I paid for her, I can do virtually anything I want, and if I mess it up, I'll sell the parts and probably come out evens.

Experience is just doing up my XJR really, I rebuilt a single cylinder 125 from bits I found in various junk yards, but that's not so difficult, just get a spanner and a Haynes manual.. I stuck some stage 1's in the Carbs on the XJR and fiddled with the handling set up, and done all my own servicing on it.. Nothing major, but since I can't really lose on the XJ, I'll try it and see what happens.. I need something that can get in and out of traffic easily, and is comfortable on the motorway.. I've my tractor for messing about at weekends, this is just to get me back and forth..

I'm willing to try most things, depending on price, it's got to be cheap, my welding is sh*t and I don't have access to a professional workshop, so I wouldn't want to cut and weld anything that can be seen or that's going to have my life depending on it, but I'm quite handy with a spanner and screwdriver, and happy to get stuck in with pretty much anything.. You tell me what, and I'll have a go.. If it goes wrong.. So what..

I'll sort some pictures out later.. I've got the fairings off to respray them at the moment, and the tank is going to be attacked with some tank sealer and then have a bath in paint remover followed by filling the dents and respraying... I've no idea how this is going to end up, but it's fun doing it! Nothing quite like sitting on the settee stinking of grease and petrol and getting shouted at by the Mrs..

 

Oh yeah.. I'll jack up the back only if it can take it.. The idea was that if I was going to drop the front, then raising the back would improve the handling.. If it doesn't, then I won't.. I'm happy to drop the forks throug the yokes about an inch, that's about where I ended up on the XJR, it improved the cornering no end.. If it has the opposite effect, I'll just lift them up again!

 

OK- - here goes,
For the widest rear tire fitment, you need to get a machinist to make a 10 MM thick spacer to go between the rim and the hub drive thing, then trim 10 MM from the axle spacer. This lets you run a 150 size tire.

Cut a clearance notch in the swingarm, having a patch welded in, and maybe a gusset on the bottom, and you may be able to fit a 170.
You will be tracking slightly out of true.

Watch out for a possible high speed instability or wobble with your other mods, you're really quickening the handling.

 

Thanks TtR.. I tried to add a photo, but it wouldn't let me..

I don't think I'm going to do anything that throws the tracking off, that's going to make the handling really wierd.

By the looks of things, there's about 20mm on the right and a 10mm gap on the left (I take it the brake yoke moves with the wheel, there's about 10mm on that) Damn.. Oh well, limitations of the bike I spose.. Is it safe to go up to a 135 with no mods or is that cutting it too close? I suppose a 130 is prolly the safe bet, giving me 5mm on the swing arm and the brake yoke. LoL.. Learned more about tyres today than I ever knew before. 8O

I know the other mods will quicken the handling, that's the plan I'm planning to drop the front by 5mm at a time and live with it for a while, and drop it again, and keep going like that, if I get to 30mm without a problem, I'll jack the back up by 30mm and reset the front yokes and then start again.. I do 200km a day, mainly on motorway, if I get a wobble, I'll know about it soon enough.

Thanks for your advice lads.. Much appreciated.. Any more suggestions on mods, I'm all ears.