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That you may learn from my mistakes...

I hadn't checked my valve clearance in a while, and finally got around to it this week.

Very early in the bike's life (after about a month), I had to make a minor adjustment to one of the exhaust valves, but hadn't checked them since.

Both my exhaust valves were fine this time, but both intake valves were just over the max allowable clearance. Better loose than tight, though.

I had created an Excel worksheet to help me calculate the thickness of the shims I needed, so I plugged in the numbers. Then went to a KTM parts fiche to see what thicknesses were available. KTM said I needed 10mm diameter shims, which were available in 0.05 increments. With that info, I knew I needed a 2.30 and 2.40 shim to bring the intake valves back into spec.

I didn't think to measure the diameter of my shims before driving 30 minutes to my closest KTM dealer, nor did it occur to me to take an old one with me. I did bring my digital calipers, and remembered to measure the thickness of the ones the parts guy pulled out of the box.

When I got home after this 1.5 hour errand and went to install the new shims, I discovered that the diameters were wrong. Not only that, they had given me a 2.35 instead of a 2.30 shim (they got the 2.40 shim right, though). That was my bad, though, since I (supposedly) measured them while I was there.

Yes, I know the thickness is also printed on the shims, but I had left my reading glasses at home.

Checked the diameter of my old shims, only to find out they were 8.9mm rather than 10mm. Double-checked the KTM parts fiche and the Hot Cams web site (supplier of shims), both of which insisted that my 2014 bike uses 10mm shims. Called Hot Cams and learned that someone there owns a 2015 500 EXC, and it uses 8.9mm shims.

So, between 2014 and 2015, KTM must have switched from 10mm to 8.9mm diameter shims in the 500 engine. So, I must have a late-2014 or early-2015 engine in my 2014 bike.

Another 1.5 hour errand to the KTM dealer first thing this morning. Only to be thrown by the discovery that the 8.9mm shims come in 0.04 increment thicknesses rather than 0.05, so while the 2.40 shim was available, the 2.30 shim was not. Had to settle for 2.28mm, which turned out the be a blessing in disguise. For one side, at least.

Got home and installed the shims, and found that the 2.40 shim resulted in a smidge too little clearance. Should have opted for the 2.36 shims.

Not being up to another 90 minute run to the dealer, I broke down and ordered a complete set of shims from Amazon.com. They'll be here tomorrow, and I will (hopefully) be done with this task, and be fully ready for the next valve adjustment.

Provided, that is, I don't misplace the box of shims in the meantime.

Dang James. Loving my two stroke.

Talk about a kick to the nuts Rick!
I calculated my shims assbackwards when I was rebuilding the topend on my KTM so I ended up opening it up a few times to get it right. It was stressful at the time but now I'm pretty decent at retiming cams.
I wonder why they changed sizes? Cutting weight everywhere they can?

I neglected to mention the part where two of my feeler gauge blades had stuck together, and couldn't figure out why all of a sudden there was even less than the minimum clearance (.1mm). Thought maybe I had re-installed the rocker arm incorrectly.

I've got to say, though, that getting to the valves, and R&R'ing the rocker arms is extremely easy to do. KTM did a great job of engineering in this area.

As for the two-stroke comment...

I have yet to ride a two-stroke that made me want to go out and buy one.

Rick, I love the concept behind your Freeride, but wish they made a bigger one. It felt way too small for my 6'3" frame.

I like Randy's new Beta X-Trainer, too (especially the oil-injection feature), but I'm sure it will feel to small as well (I haven't gotten the chance to ride it yet).

The last two-stroke I owned was the 1982 Yamaha IT465 pictured in my avatar on the left. That bike replaced a 1976 Honda MR250 Elsinore that was never big or powerful enough for me. Had I not gotten married and given up dirt biking for a (long) while, I'm sure I would have traded the 465 for the 490 that replaced it. I loved that 465, and it was perfect for the open-desert that I was primarily riding at the time in So Cal. I probably wouldn't enjoy kick-starting a 456cc thumper at this point in my life, though. Don't remember it being a big deal when I was in my mid-20s.

KTM doesn't make anything bigger than a 300. Yamaha's YZ450F and Suzuki's RM-Z450 weigh as much as my 500EXC, so what's the the advantage?

If KTM, Husky, or Beta would produce a 400cc+ two-stroke, I would seriously consider switching.

Looking forward to riding with you next month James.

Ditto

Didn't know the shims were changed from 10 to 8.9. I will watch for that. Getting the right size with calipers should be straight forward, as it has been in all previous bikes, Brit, Japanese or Austrian. The smaller size might be better since it gives you finer gradations for thickness.

Stu

Wish I would of seen this earlier I had a full shim kit that i sent back to amazon cuz didn't need it...

But also have something you might really like or anyone else with a newer ktm 4 stroke. Have a brand new dirt tricks timing chain tensioner that will take that ticking sound away that makes it sound like u need to check your valves all the time and the sounds bad at startup. It's unopened I'll give it a few days before sending back it was $85, I'd sell for 70 to someone here

Unfortunately, neither of the Dirt Trick timing chain tensioners fit my 2014 KTM 500 EXC.