XJ Bobber project, general questions

Hi,
I am in Aus, this was a stock standard early 80's XJ650 that belonged to a friend. He no longer wanted it as it had been vandalized. I decided to do a bobber project. I got a 650 maxim tank, custom bars and seat pan. I am now at the point I am ready to weld the new mounts for the seat and tank (top of tank raised about 7"). I will raise the bar about 4 to 6" using extender pieces from the factory mount position.
The rear shock on one side is removed, but I will be retaining the standard shocks.

I have a few questions:
1. Can I go a slightly wider rear wheel & tyre. Is there anything that will bolt straight on.
2. What is the difference between XS650 and XJ650
3. Can anyone see any issues or have suggestions for what I am doing.

Cheers

 

1. Yes you can go to a 140 wide tire with the stock wheel with not much modification. But your wheel options are limited. I would keep it stock.

2. im pretty sure the xs is a 2 cyl.

3. I don't think your going to be happy with your tank.. don't take this the wrong way, but It doesn't look right. Either leave the stock tank in its regular place, or get a different one. If you like if when your all done, that's all that matters though.

The front fender needs to go, too.

ON A POSITIVE NOTE your seat pan looks daaaaamn good. seriously.

 

Hey mate. Really appreciate your advice and feedback. I will just go the standard rim then and put a 140 on. On the tank, I agree it wont be to everyone's taste. However I hate the stock tank, plus its damaged. My problem is if I fit the this tank in its stock position it all looks wrong due to where I need the seat and bars. I am 6 foot but really long arms and legs, so I need to stretch out the seat and bars, and it just looks alot better (to me) with the tank jacked up at the top. Gives an illusion that it has an increased rake on it. Cheers

 

Yeah I agree, I like the tank & bars personally (maybe it's a tall guy thing, I'm 6'2" lol)

Think if I was going to do that myself I might have the front of the tank an inch or two lower so it's level with the top yoke though, looks a bit high from the front view & kinda reminds me of a Beluga's head :?

And yeah the front fender needs the front portion shortening at least IMO. plus don't forget the brake linings/hoses in my links (just saying, in case lol)

 

All else I would've said having been covered thus far, what I have left to say is make sure you're getting full clearance on the handlebars including the controls.

For example, when I went to a lower bar, the throttle cable J-hook thing would hit my tank on the right side, and the bottom of the choke lever hit the tank on the left. So watch for that. I had to tweak the positioning of the bar and controls to clear (with an 1/8th inch to spare!).

 

I agree with 750E-II_29Rbloke about the tank...

Unless you have some pretty tall gauges to block the view a bit, I just think being able to see down the tunnel of the tank over the handlebars makes it look a bit out of place. I do like the look of the raised tank, just maybe a little less raised IMHO...

That being said, to each their own, so if you like it go for it!

 

Don't think your going to get a 140 tire on the back without rubbing. I've got a 130 on my 700 and there is 3/16ths inch clearance between the tire and shaft housing.
Virago's could handle a 140, but not the XJ unless you cut away some shaft housing material.

 

You can swap the Virago swing arm to use a 140 tire, but you do have to use the Virago shaft cause the swing arm is longer. The Virago rear wheel is 15 inch,but I think you can use your XJ wheel (16 for Maxim 18 for Seca). Someone made this swap awhile back, I'm thinking it was MICarl.
The XS650 is a vertical twin chain drive bike and your XJ is a Transverse inline 4 shaftie. To answer your earlier question.

 

O&B, don't forget though that standard tyre on the 16" max rear wheel is already 130, so its only adding 5mm either side. As long as there's at least 5mm clearance at the closest point it may take a 140. :?

What size wheel is on your 700 by the way, 16 or 18?

 

love all the feedback and info, thanks heaps guys.

Last night I had a play and lowered the tank between 1 & 2" and I agree it looked better. With the handlebars I intend to lift them up about 3 to 4" from where it currently sits.

Regarding the rear wheel & tyre. At the moment the tire has around 15mm clearance on the shaft side, so I think it should be no issue taking a 140. But will double check.

cheers guys

 

My 700 with a 130 is damn close to the shaft cover as well. The 700 has a 16" rear. I guarantee I don't have the extra 5mm of clearance necessary to run a 140.

Somebody did run a virago wire wheel with a 150 with no shaft mods... You'd have to search for the thread.

 

Now there's a thought, if you were more for the "fat ass" look than you were for handling then you could adjust the offset of a spoked wheel to even the gap both sides & run a bigger tyre that way... Not sure how much it'd affect the handling, but having ridden some pretty bent & battered machines in my time I'd say a few mm of wheel offset from centre wouldn't be hugely noticeable.

 

16inch wheel on mine and the 3/16ths clearance may have been generous on my part. I can't think of anybody that has been able to get a 140 on the XJ without mods. Good luck, hope your able. Remember that every model tire has different crown tread so you might find one that will work.

 

Good point, a 140 isn't always 140mm across. I know Avon tyres over here are wider than "rated" so worth checking...

O&B, what's stock size for a 700 I meant to ask at same time as wheel size? Stock width on the 650 is already 130 so maybe the shaft tube's slightly different?

 

Not sure of the stock size, my bike had a 120 on it when I got it. Wanted to go wider and did a search on this forum and was told that a 130 was the largest size I could get to fit. Haven't seen a larger one yet without a swing arm change.

 

someone mentioned to you to get rid of the front fender. I wouldnt , as is acts as a brace/support for the fork tubes. Just my opinion.

 

my plan was just to cut the front back on it

cheers

 

No worries then. Have fun with the build.

 

No, the 700 should have a metal brace already. If you ride in the rainy season, I would recommend having one. But if it sees mostly sunshine, you should be just fine. You can even tie a bandana around your forks (have it touching the tire, even) and it will act as a fender.
It wont look like a true bobber if it has a front fender IMO. That being said, its just my opinion lol

As for the tire. I have a 140 with no modification. As someone else mentioned, it depends on the tire.. Even if it does rub, you can grind the shaft down a bit. I barely consider that a modification.

EDIT: Just saw it was a 650. No metal brace. But thee shouldn't be a problem with having no fender. lots of people run it that way. up to you though.

 

That could be the issue then, maybe the 700 arm is different since the 650 runs 130 stock? Either way, if I was after maximum width for looks personally I'd measure how much clearance you currently have, how wide the current tyre is, and then go measure up replacements to find the widest "140" that will fit without rubbing...

 

The problem isn't whether or not you want to spray crap all over the front of your bike or not; that's a matter of choice. At issue is the loss of the fork brace. Not something to recommend.

Yamaha has installed a fork brace on their street bikes forever; sometimes they hid it (like on the early XJs) sometimes it was right out there in the open, like on the 700 and other later XJs and most of their current crop of sportbikes. Believe me, if it weren't necessary they wouldn't have gone to the trouble.

Even if the fender is removed, a fork brace is still a good idea.

 

I like the bike. Cant wait to see more pics as the project goes on. I'm planning to raise the tank on my 750. How are you going to mount the tank? I've never done a tank lift before.

 

Sorry for the delay mate. To raise the tank I just welded an exact replica of the stock tank mount on the top tube of the frame (backbone ??)

I will get a photo and post it on.

 

I need some feedback please. I have now welded all the new mounts for seat, tank and handlebar risers. When I did it in the workshop I liked the look, when I looked at the pictures later I did not like it and felt the tank is way to steep. Please give some opinions / ideas.

I am thinking to either put it back to its original mount or halve the current height increase.

Also, will the tank actually function properly like this ??

The seat pan you may notice is back a fair way, but I am 6 ft+ and long legs, so it has to be there.

 

xj

 

similar set-up, but tank in stock position

 

The front of the tank really needs to drop. The raised idea is cool, just needs to come down 3 or 4 inches. Make the tunnel even or a tad bit lower than the top fork clamp.

XJ 700 wheels will work. You will need the entire rear brake set up. On the fron you will only be able to run a single brake (the 700's have duals) and you have to use the rotor from the 700, but can use the caliper from the 650. You will also need to make or buy an additional spacer for the front axle. I used XJ 700 wheels on one I built awhile back. Have been too lazy to post pics.