Sunday, July 9, 2017

Valve Clearances

The maintenance interval for valve clearances on the 2016 KLR650 is 15,000 miles. However, prior to taking delivery back in November 2015, I got into a discussion with some owners who indicated that checking the clearances around 6,000-7,000 is a good idea. Apparently, the spec used to be around 6,000 miles and with no changes in engine design the interval was pushed way out to 15K. Indications were that the valves got tight around the lower mileage.

So today I had some time to take a peek at the clearances and see how we were doing at 6,700 miles. I'll spare you the details of the procedures. There are plenty of youtube vids and other instructional materials. I have the Service Manual, so I followed that.

Here's what I found (closest feeler gauge in mm):

Exhaust (spec 0.15mm to 0.25mm)
  • Left 0.152mm
  • Right 0.152mm

Intake (spec 0.10mm to 0.20mm)
  • Left 0.102mm
  • Right 0.127mm

As warned, clearances were tight even at 6,700 miles.


My plan is to open up the clearances to the upper end of the range. To do so I needed to pull the shims. Here's what I had in there in terms of shims. Two 2.40 shims on the Exhaust Valves. One 2.50 and one 2.45 on the Intakes. These were marked numbers that I checked to my micrometer.


It's interesting that the two Intake shims were different (2.50 vs 2.45). That difference actually showed up in the clearances (0.102 vs 0.127). Why on earth would the factory have used two different shims there when the clearances would have been the same with either the 2.50 or the 2.45?

Onward....

Okay, so the way this works out is there's a formula:

Current Shim Size + Current Clearance - Desired Clearance = New Shim Size.
  • I'll run 2.30s on the Exhaust as follows: (2.40 + 0.15 - 0.25 = 2.30). 
  • I'll run 2.40s on Intakes as follows: (L = 250 + 0.10 - 020 = 2.40) and (R = 2.45 + 0.13 - 0.20 = 2.38...rounded to nearest shim size of 2.40). 

The way this will work is I'll only have to buy the two 2.30 shims and move the current 2.40s to the Intake. That will save me about $24 since the shims run about $12 each.

Anyway, I guess the point is that it may make sense to have a look at the clearances sooner than spec. Even though I was technically in spec, my valves were not at the optimum median clearances for proper performance. The KLR will be breathing a little better when I get the new shims installed.


Update...

The shims were $14.75 each. Crikey! The damn things are only the size of like a quarter.

Update...

Having completed the re-shim (after the disaster discussed below) the motorcycle really sounded different; not bad in any way, just different. I took it out for a test ride and it rode fine. However it just seems smoother. Hard to describe and I'll stop here and keep riding to see if I can articulate better what I'm talking about.

Update...

Bad things happen when you're impatient!

When I was reinstalling the cams I lost one of the bolt dowels down the cam chain slot and into the bottom end. It's all open, I had a towel covering it, but it got past. I was able to get a replacement down at my dealer, but I didn't go after the one that I lost hoping it just made its way to the sump.

Well, it didn't make to the sump. The minute I started to turn the crank I could tell something wasn't right. I tried a little harder hoping to knock it out, but it didn't work. So off came the left case, flywheel starter wheel to go find where it was bound in.


Old dowel, new dowel. The dowel is a very thin tube that is used to align the cam clamps, two each for four clamps. So there are eight dowels. Should you take them out? Should you leave them in? Obvious I took them out and then got caught up in the tight working space.


As advice, whether you leave them in or take them out, I think I really should have done a better job covering up the gaps. I just stuffed them with paper towels. The other advice is keep your Eagle Mike doohicky tools!

Fortunately I retained all my Eagle Mike doohickey tools to get back there and fix this.

The good news was that there was no damage. I should have just gone after it in the first place though.

Of course, that threw off the timing so I had to reset all that. What was a couple hours work turned into the better part of a day. Yikes! I was sweatin' it.

2 comments:

  1. Good info. If you're confident in the process, it's fairly quick and easy. And one less thing to worry about.

    ReplyDelete
  2. Awesome post! I am extremely impressed by your quality of writing! I will definitely need to share your blog with my friends, thanks for the share!
    Gregg

    ReplyDelete