My engine is probably around 20k right now, cbr600rr. I read all over the net people don't even bother checking valves or check them at 30k+ and they don't even need adjusting at that mileage. Have any of you guys actually had to adjust your valves? Especially on sport bikes? It sounds intimididating to self check and really expensive for a shop to do it.

I have a 2006 Yamaha FZ6 with over 115,000 miles. The valves have never been checked. No engine problems, doesn't use old and it still gets about 45mpg. It it ain't broke, I'm not going to fix it.

My 2006 F4i has 53,000 mi and the engine has only had oil and filter changes and that's even just using regular old Pennzoil 10w40 since the first oil change.  

Still on the original spark plugs too.  I have a new set of NGK plugs for it that I bought along with a new air filter a few years ago.  Changing the air filter at around 40k seemed to wake the engine up again.  Been thinking about changing the plugs but I'm not getting any misses or anything so I keep putting it off and just keep riding it.

A common sign of the valves being out of adjustment is the bike will be harder to start.

impressive!

Damn near 100k on my first CBRXX and it never needed any adjustment back in the day. Current XX was fine at the 16k service.  BMW GSA was fine at 6k.

Even my old CMRA 600SS endurance CBR600 never needed any adjustment.

My CBR that I had from 6000 miles to almost 40,000 I adjusted once and that was only because I was getting close to the minimum clearance and had it apart anyways.

My DRZ I have in pieces in the garage at 15000 miles readjusting them now.

That bike will likely never need it while you have it

None of mine ever needed adjustment.

My brothers Vulcan did once at around 20k.

Its not difficult to check just a little time consuming depending on what all you have to take off the bike.

I run my valves every couple thousand miles.

But I have an air Cooled Vw in a dune buggy so it's like a 10 minute job

Nome of my street bikes have needed adjustment, dirt bikes are a different story...

3 beemers in my stable old airhead and 2 oilheads only the RT has ever needed adjusting and that was @6k the others remain spot on

Beemers are a PITA to adjust and sync....not hard just time consuming

I've done it twice but on a simple one-cylinder KLR650) with shims in buckets.
I would send you over to the Fire Blade forums for bike specific advice on your bike. Over there you'll get a bunch of input specific for the bike and what folks are seeing valve wise.

2001 Kawasaki Ninja 250 - Needed adjustment once at roughly 13,000 miles (screw and locknut adjusters)
1997 Triumph Speed Triple - Never checked
1993 Yamaha Seca II - Need adjustment once at about 15,000 miles (shim-over-bucket)
1980 Suzuki GS550E - Needed adjustment once at roughly 16,000 miles (shim-over-bucket IIRC)
1996 Kawasaki GPz1100 - Needed adjustment once at about 22,000 miles (direct-actuated shim on valve stem)
2000 Triumph TT600 - Checked but never needed (shim-under-bucket)
2003 Moto Guzzi V11 LeMans - Checked, needed adjustments twice (screw and locknut)
2005 Kawasaki Z750S - Checked, never needed through about 42,000 miles (shim-under-bucket)
2001 Aprilia Falco - Checked once, and needed adjustment , roughly 22,000 miles (shim-under-bucket and a massive pain in the ass)
2008 Yamaha WR250X - Never checked, didn't get to first adjustment interval before sale
2011 Kawasaki ZX-6R - Same as above
2006 Yamaha FZ6 - Same as above
2014 Yamaha V-Star 1300 - Same as above
2013 Yamaha Super Tenere - Same as above

My early bikes were purchased used, so doing a valve check was something I did on nearly all of them at some point.  Looking at the record, the shim-under-bucket types seemed to rarely need adjustment.  The other two types did, particularly if screws and locknuts were involved.

Every bike I've owned that had bucket/shim valves has needed an adjustment at one time or another. But, admittedly, I put a lot of miles on my bikes.

The only one that was questionable was a TTR250, that was on the tight side of the spec, so I budged it back to the looser end but I could have let it go.

It's not hard to do, never had any issues checking/changing.

I have an 05 VStar 1100, did a valve adjustment at 41k miles, there was a night and day difference.

Also have an 06 R6, 04 F4i, 00 R6, and a 97 GSX600F Katana. The 06 R6 had 26k miles, the others all had less than 5k. When I went to check them, they were all within spec, so it was  HUGE waste of time.

I have an 08 R6 with 800 miles on it. It's never been registered and I pretty much only ride it around the storage unit parking lot a few times a year to keep the gas from going bad and the valve seals from drying out. Anyway, I rode it down to the Yamaha dealer for new tires because they were weather cracked and the guys there said I'm 200 miles overdue for my first service which will include a valve adjustment, oil change, carb synchronizing (it's fuel injected), and thorough check of the electrical system. All for a low cost of about $500. I think I'll get that done in probably about 30 years.

As an old engine guy. I would say if it's mechanical adj. Do it at recommended intervals to avoid burnt valves. The old Toyota V6 3.0 was famous for burning exhaust valves if they didn't get adjusted.

I've got a garage full of bikes, all ridden hard, but the only two that have needed adjustment are my Husky 510 supermoto and my R1 race bike. As they are almost always WFO, that is the difference I'd imagine.