Valve shim size guidance

[k-roc]

Hi, I measured the valve clearance on my 1995 BMW K75RT and got the following numbers in the attached jpg file. 

There are four rows for each valve and values for the measured clearance, the existing shim size, the sum of clearance and shim size, the ideal clearance (top end of range, 0.15 to 0.20 mm for the intake valves, and 0.25 to 0.30 mm for the exhaust), and the ideal shim size (existing total  minus ideal clearance).  The calculations was found at https://www.venturerider.org/forum/forums/topic/55336-easy-peazy-valve-shim-calculator/.

The middle (#2 exhaust) was quite tight so it was a good thing I checked.  Got my K75 in spring of 2024 and have been going through it.  Most recently the valve clearance check and lubrication of all splines including the clutch spline.  I was just wanting confirmation or correction of the new shim (ideal) sizes to be ordered for all 3 intake and 3 exhaust valves.

Thanks, Kelly

[milq]

Your calculations seem correct to me. But you'll have to pick your poison on that one shim that works out to 2.23mm. (also, keep an eye on that guy, quite a difference vs the other two...not to be a jerk but did you double check the clearance?)

2.25 or 2.20 are available but not a 2.23 to my knowledge. You might get a machine shop with surface grinder & magnetic plate to grind a 2.25 down (if they have some free time). I've never tested one but I'm sure the shims are through hardened rather than case hardened, wouldn't be worth the effort to case harden something that thin.

[Laitch]

The intake clearances are okay. The ideal clearance for intake valves is 0.15mm. Intake valves clearances tend to grow, not shrink. Leave the current intake valve clearances alone. 

Exhaust valves get hot and their clearances tend to shrink. Your choice of 2.35 for exhaust #1 and #3 are good. Like milq suggests, double-check your measurement for exhaust #2. If it's correct, your choice for exhaust #2 would be 2.25; adding 0.20mm of space for a clearance of 0.276—approximately 0.001mm from the middle of spec. When you're in spec, you're in spec. This is no thoroughbred racing machine being flogged to the max on every outing.

Use your money and time for riding, not obsessing.

[k-roc]

The intake clearances are okay. The ideal clearance for intake valves is 0.15mm. Intake valves clearances tend to grow, not shrink. Leave the current intake valve clearances alone. 

Exhaust valves get hot and their clearances tend to shrink. Your choice of 2.35 for exhaust #1 and #3 are good. Like milq suggests, double-check your measurement for exhaust #2. If it's correct, your choice for exhaust #2 would be 2.25; adding 0.20mm of space for a clearance of 0.276—approximately 0.001mm from the middle of spec. When you're in spec, you're in spec. This is no thoroughbred racing machine being flogged to the max on every outing.

Use your money and time for riding, not obsessing.

No worries at all.  I had measured all valves both intake and exhaust and did so twice with the resulting existing clearance numbers but only with feeler gauges that were 0.15 and 0.20 mm for the intakes and 0.20, 0.25 and 0.3 mm for the exhaust.  I also measured the existing shim sizes with a digital caliper.  I then went and rechecked the clearance numbers and used some smaller feeler gauges to get the clearance on the #2 (middle) exhaust valve.  As per the first go around I couldn't fit the 0.25, 0.20 mm feeler gauge, while the 0.15, 0.127 and 0.10 mm feeler gauges didn't fit.  Only the 0.076 mm one fit.  Will keep an eye on the #2 (middle) exhaust valve.

I will recheck one last time (I tend to be a bit OCD). 

Assuming the numbers are the same I will go for the 2.35, 2.25 and 2.35 for exhaust valves #1 (front), #2 (middle) and #3 (rear).  As suggested by Laitch I will leave the intakes alone.  I was waffling on the intakes as they were all 0.15, but as Laitch also indicates the intake clearances tend to grow rather than tighten.  My first bike was a 1994 KLR650 (purchased by me in 2012, sold in 2016 when I got a 2015 Yamaha FJ-09 in April 2016, but sold in spring 2022) and I did some valve adjustments and noted similar comments related to intake valves.  Also did the same with an 1981 KZ650 (purchased in 2013, but sold in 2015 as I was only supposed to have one bike...).

I appreciate the advice and comments!

I used the valve adjusting tools from Kenneth Lively (Polepenhollow Machine and Tool, polepenhollow@yahoo.com) to get at the shims to measure them (http://www.flickr.com/photos/41449418@N08/sets/72157632081388219/, http://www.flickr.com/photos/41449418@N08/sets/72157632085640060/).  They worked great.

I was looking at Motorworks UK for the shims as they don't seem to be too pricey (https://www.motorworks.co.uk/parts/engine/valves.html).  I noted either on this forum or some other ones that a Kawasaki dealer may have 29 mm diameter shims that would work.  Will call them as they are only about a half an hour away in Red Deer, AB.  Any other suggestions regarding a shim supplier? 

Thanks again.

Kelly

[Laitch]

You're looking for 29mm shims. Try these guys. Determine if they'll ship if you have difficulty finding what you need.

[Past-my-Prime]

I stopped in a local motorbike garage and asked if they had some old shims from their stock. They have a huge box of various sizes of the Kawasaki 29 mm shims. I didn't care new or used and bought them quite inexpensively. I tested sizes with caliper and rechecked valve clearances after reassembly.