Is my bike bent?

[GS500FNoob]

I bought a 2004 GS500F cheap.  A college kid had thrashed the hell out of it and apparently didn't own a wrench or screwdriver.  It had been dumped & slid at least twice, maybe more.  The top frame bolts were jiggling in place when I got it.  It was amazing it hadn't fallen apart.

I've been trying to give some of the TLC it's been missing.  One problem I haven't been able to solve is shown in the pic.
The rear frame plate keeps working loose. I can only guess the bike is bent.
Please tell me I'm wrong.

What else could cause this?

Thank you,
GS500FNoob

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[BockinBboy]

That plate adjusts the rear wheel and chain alignment.  There are many ways that can come loose, and know that locktite is a must on nearly all bolts for bikes, especially twins.  Judging by the lack of care you mention, you are probably due for new sprockets and chain... I'll let others chime in on reasons why that could come loose (bad threads, excessive chain vibration/really bad alignment, etc..) I don't really know... but I think you need loctite regardless.

- Bboy

[gsJack]

I've put 175,000 miles on 2 GS500s without ever putting locktite on anything.  Properly tightened bolts, nuts, etc don't come loose without a reason.  That screw/nut shouldn't ever be locktighted since it's an adjustment screw.  It's used to properly align the rear wheel and to adjust chain freeplay.  Likely Bboy is right on in the need for a new chain and sprockets particularly based on your descrirtion of PO care of the bike, you didn't mention how many miles on the bike.

Start by properly aligning the wheel and adjusting the chain with about an inch of chain freeplay and then tightening the axle nut tight and putting a cotterpin in to keep it tight.  If you then have the rear axle still moving there is something wrong like a bad wheel bearing for example that would allow the axle to keep loosening.  If you find the chain loose in some spots and tight in others you need a new chain, likewise if the axle is getting back towards the ends the slots in the swing arm the chain is worn out.  Looking at the rust on the rear brake disc it's likely you also have a kinky chain..

[BockinBboy]

I've put 175,000 miles on 2 GS500s without ever putting locktite on anything.

You are a lucky man!  ... You are probably right about this specific area on the bike, as I really have nothing objective to go by for the adjustment bolts.. and what you mention definately makes sense... so I will bow to your experience 
But I do think loctite is an important safety that is necessary on most bolts.  Many bolts come from the factory with loctite (or whatever brand suzuki uses), and the repair and maintenance manuals suggest its use on many maintenance tasks or repairs.  I can't argue that properly tightened bolts don't come loose without reason, because I agree.  But time will give reason for things to come loose (vibration and regular wear over time), and loctite is a commonly suggested and widely accepted safety... and as any rider knows, you want as much in your favor as possible when on two wheels.   

- Bboy

[gsJack]

There are probably more members here that would agree with you than with me on using Locktite Bboy but I've been wrenching for a long time now.  I never use a torque wrench on anything either except engine work just go by feel on the rest of the bike.

[GS500FNoob]

Some great suggestions, everyone.  Now I can't wait to sit down with a wrench.

By the way, I have a (slight) background in aircraft construction & engines.  (Not an A&P though.)  I have LOTS of locktite.

Another thing I have might be of use in the motorcycle world.  It's "torque seal", better known as indicator paint.
When you're done wrenching, put a spot across your bolt & nut.  The slightest nut/bolt movement will crack the paint.
It's great when you're giving your bike it's 'annual.'

http://www.aircraftspruce.com/catalog/cspages/f900.php?clickkey=143786

Thank you all,
GS500FNoob

[project94]

One possibility that the nut is working itself loose might be because it was over-torqued at some point. Maybe the threads either on the bolt or nut were damaged before. How do the threads look on the bolt?

A cheap check would be to swap out that nut (with same type nut) and tighten it with a torque wrench. No loctite necessary.

What other indicators do you have for your bent-bike theory?

[piresito]

The adjuster plate that the axle nut holds, looks really bent, like if at some point the whole spindle/wheel went out of alignament by brute force (crash).
See part 23: http://www.cmsnl.com/suzuki-gs500-f-usa_model16026/partslist/434156.html#results
You might have to replace/repair that part in order to proper adjust the alignament...

[adidasguy]

Adjuster plates on the side get bent when they're pit on positioned wrong. They bend over the bottom just to keep them straight. Easy to loosen the axle then the plate turns and bends when axle retightened.

Take it off and flatten with a hammer or don't worry about it.

The nut is a self locking nut. I forget the name, but the kind that are squished a little so they fit tight. That nut probably is worn out.

After you alighn the chain and tighten down the axle, give that nut an extra 1/4 turn to really lock it there.

[Bluesmudge]

Another thing I have might be of use in the motorcycle world.  It's "torque seal", better known as indicator paint.
When you're done wrenching, put a spot across your bolt & nut.  The slightest nut/bolt movement will crack the paint.
It's great when you're giving your bike it's 'annual.'

http://www.aircraftspruce.com/catalog/cspages/f900.php?clickkey=143786

Nail polish works great for this when you are done painting your cat's claws! I didn't know there was a product designed for the job. Good to know.