Went to do the valve clearance check on my 1994 Suzuki Katana 600 and was dismayed to find that I have zero clearance on any of the valves... Even my thinnest feeler gauge won't slip between and it visibly looks like hard contact. 16,000 miles on it and as far as I know this has never been checked.

Is this engine a lost cause? Or, can I attempt thinner shims and see if I can get some clearance?

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    You can possibly mix/match shims to get the right clearance ... still going to require you to get some more shims. Bike is not a lost cause, though. I would think it would just be down on power as you might be getting some leakage past the valves at worst. Maybe do a leakdown test to see if there's anything happening there. Not bad on the intake, but leakage on the exhaust side could cause a burnt valve. Commented Nov 8, 2020 at 19:44
  • Is there a performance problem ? Commented Nov 8, 2020 at 22:06
  • @blacksmith37 It's got some wonky idle issues that didn't go away after carb overhaul and balancing. Seems to run well at speed though. I really expected to measure and find it still in spec After talking to some other people I'm now concerned that it's going to need valves and seats. I'm not equipped to do that job and would likely scrap the bike and buy a new one in that situation. Commented Nov 8, 2020 at 23:23
  • So does it have a shim in place as standard? If you remove it whats the measurement then? Commented Nov 9, 2020 at 3:09
  • @BrianKnoblauch i dont know your circumstances but scrapping the bike over a valve job seems excessive. Hang in there. This might be something simple to resolve without major expense Commented Nov 9, 2020 at 3:12

1 Answer 1


Based on memory of similar bucket shims the process was to remove all shims then measure the gap and do a bit of subtraction to get the required shim thickness.

And also needed is a big supply of shims - last time I did that I was at the main dealer so I had access to the full range... But if you have to order and wait that is not so much fun.

  • On this one it's measure existing gap, if in range, do nothing. If out of range, remove the shim, measure it, do the math for new shim, replace. Then measure again when done to confirm. Commented Nov 8, 2020 at 23:20

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