One of those days, I think I'm going to be sick...

[hotrdd]

Took the bike out for a short ride yesterday and except for a few minor issue I wasn't too concerned. Today I thought I would head out and adjust the chain and check over a few things before I took the bike to work tomorrow. What I found was a huge groove carved in the middle of the rear tire and chunks missing out of the tire on the right hand side.

After walking around the frame a bunch of times I think the tire is hitting the battery box area when the suspension is compressed. I also think the rear tire was expanding at HWY speed. NOW I think my only option is to get a new rear tire and start cutting the powcoated frame. The thought is making me sick. Someone shoot me now.

One thing that seems weird though is how little room is on either side of the tire and between the tire and swing arm. How much space do you have. Also if I cut out the battery box area how much room do I need to leave for the tire to expand at HWY speed

 

[650Skull]

your tire is obviously hitting the bike where it has been modified and clearances haven't been taken into account. I see the chain guard has a piece missing to allow for the travel of the, whatever that is that is hitting it.

Is this an XS650, in the last pic the frame looks nothing like it

The swing arm is not an XS650 one either.??????????

 

[XSLeo]

You can try an longer shock. That might lift the bike off the tire enough to not hit.
I can't say how much a tire grows. I think with proper pressure it won't grow much at all. Maybe 1/8 to 1/4 inch.
Things like this is why I often suggest once you get a bike mocked up and ready for paint you should ride it to be sure everything is all right. I know that don't help.much now. Might want to remember that for the next one.
You might try lengthening the swing arm and inch, that would mean just repowdering the swing arm.
Leo

 

[gggGary]

I think I'm with skull here, aren't those maxim 550 bits?

 

[650Skull]

found some pics of your bike........whatever has been done to the back of the frame is causing your problems. the swing arm is not from the 74-79 roadster, in fact all i can see that is XS650 is the motor and frame from the foot-pegs forward.

 

[1974jh5]

Maybe a shorter/wider rear tire? Tire size chart:

http://www.kgmotorcycletires.com/size_conversion_charts.htm

The aspect ratio will tell you how tall the tire is. A 90 aspect ratio means the measurement from the rim to the outside of the tread is 90% of the width. As in, a 130/90 is 117mm from the rim to the top of the tread (130 x .9 = 117), double that (to account for both sides of the tire) = 234 mm, divide that by 25.4 to get inches = 9.212, add that to your rim diameter (we will go with 18) gives you 27.212 overall tire height. With this you can get a rough idea of what tire may fix your clearance problem.

 

[gggGary]

What size is the tire and how old is it? The maxim rim came stock with a 110/90-18 rear.

Just thinking out loud but a tire that's too wide for the rim it's on may very well have some unusual expansion characteristics at speed.

 

[hotrdd]

I’m still trying to sort out what the bike is exactly. I was told by my mechanic that the front forks and rear may be XJ 650. I’m assuming that the frame is XS650 but who knows. The frame was modified by the PO.

I think the rear tire was old, though it passed the safety inspection no problem. I don’t mind getting a new rear tire I just want to prevent this from happening again. Next time I may not be so lucky.

Rear Rim - J 16XMT2.50 DOT
Tire - Cheng shin tire 5.10 – 16 4 ply rating

 

[Shovelheadsd]

I don't think your tire is expanding, but rather like you stated, your bike is just compressed when you are on it causing the tire to rub on the battery box. Have a buddy sit on the bike and see how close the tire gets to the area it is rubbing on (might have them bounce a little to simulate bumps) . Maybe a longer shock (like XSLeo said) or a little stiffer setting whould take care of the issue? And to me the swing arm looks alot like mine on my 1975 XS650?

 

[650Skull]

certainly is an interesting contraption, do you have some more pics of the whole bike

 

[hotrdd]

This is how it sits right now. Sorry this is the only current pictures I have on my computer.

 

[gggGary]

I would be looking up inside that fender for a bolt or bracket that is contacting the tire under load. For a frame mounted fender it looks rather close to the rear tire. Seems like you would HEAR that much mayhem going on?????

 

[pregrid]

Whoa!....................

 

[1974jh5]

After seeing the whole bike (pretty interesting BTW) I think I'd have the swingarm stretched or get a longer one. I'm going to SWAG that that is an early XS S/A. Does anyone know if there were different lengths available over the years?

As a quick dirty 'see if it works', add a couple of links to the chain so you can run the wheel further back on the swingarm. There's what is known as a 'half link' available which might help.

 

[hotrdd]

I'm going to rip into the rear of the bike later this week and see what can be done. Adding a 1/2 link might be workable. As far as the fender goes it may look close in the picture but there is over 4" of space all the way around the tire. I'll know once I pull the fender off if there was any contact issues up inside. Thanks for the help so far.

This may be a case of fix it now and then tear the frame apart again this winter and do "Take two", or fix it by cutting out that section and riding it that way for a few seasons until I decide on a better direction.

 

[hotrdd]

Well last night I grabbed a beer and took the rear wheel off of the XS. Then I started to measure for the clearance again by dropping the shocks all the way down. Before I knew it I had the grinder out and was cutting the frame. I thought about trying to find another way to make this work but in the end that little “battery” box that was hanging down was just being worked around in too many ways. Even the mechanic who safetied the bike cut the chain guard to get more clearance.

I’m going to get a new tire later this week and see how much more I need to cut out. I’ll get everything back together and get some miles on the bike before I do anything else but now that the frame needs to be re-coated it has me thinking about changing the rear of the bike all together. Thanks for the ideas and help.

 

[XSLeo]

On aging tires, there is a DOT number on it some where. The number is a series of numbers and maybe letters. The last numbers are in an elongated oval. If there are three numbers in the oval, the first two are the week of manufacture, the last digit is the year of manufacture. With just a single digit the first three are 199. So if your three digits are 237, the 23 means the 23rd week of 1997. That's a very old tire.
Starting in 2000 they put four digits in the oval, the first the same as before, the week, the last two are the year. As in a 4508 is a tire made in the 45th week of 2008.
Most tire makers recommend NOT running a tire over 6 years old.
They start to deteriorate, the glue holding the tire together starts to break down, the belts start to seperate.
Not fun things to have happen at 65 mph.
Leo

 

[racerdave]

Leo, that's some good info. Do you know if it applies to car,trailer,truck tires?

 

[XSLeo]

As far as I know, if the tire is round and black, it applies.
Leo

 

[gggGary]

One thing, there are tires that are too old to have any DOT markings. I have found pre DOT tires on XS650s and shame of shame I have ridden on them . Not fast or far but I have gone "around the block" on ancient rubber a time or two. Oddly some of that really old rubber has survived the decades rather well without the cracking/separation that tires now exhibit after only a few years. They tend to be about as soft and pliable as a concrete block. Getting those old donuts off the rim can be a serious chore.