Valve clearance, how tight before you start replacing shims?

[Watevaman]

  First off, I know the clearance is supposed to be within the .03-.08 mm range and apparently some people open their exhaust to up to .10 mm, that's not what I'm asking. What I'm asking is how close to the .03 do you guys let your clearances get before you replace the shim? Both of my intakes are very close to the .03x feeler gauge I stuck in them, so those are going to be replaced, but one of my exhaust was able to get a .05x gauge under it and the other was fine at .076. The bike's got about 15k miles on it with 7k of those being me riding more aggressively than the average owner, so I wonder if it's ok to leave that exhaust shim in?

[adidasguy]

My preference would be to open them up.
Intakes we like in West Seattle to be 0.05 to 0.08 and exhausts 0.05 to 0.1. Generally anything under 0.04 we change out.
But we do try to get left and right sides close. 0.05 and 0.10 on exhausts is too different so we'd probably try get the 0.05 closer to 0.08 or 0.09. and/or maybe tighten up the 0.10 to more like 0.08 at the same time.

[twocool]

Leave 'em........

if .03 goes under intakes, that's just fine.

.05 exhaust is just fine too...but keep an eye on...don't let exhaust get down to .03...

yes, running the exhausts to the larger gap is wise, but as long as you're in  spec, don't worry

if you try to change out the .05 exhaust, you're gonna get up to .10...ok but a bit big IMHO..

yes some guys collect shims, and find that some are a few points more or less than what they are labeled at...so you can drive yourself crazy trying to measure and fit "in between" sized shims to get to the exact ten-thousandths of a mm....

Just stay within Suzuki spec and be happy!

if it ain't broke, don't try to fix it!

Cookie

  First off, I know the clearance is supposed to be within the .03-.08 mm range and apparently some people open their exhaust to up to .10 mm, that's not what I'm asking. What I'm asking is how close to the .03 do you guys let your clearances get before you replace the shim? Both of my intakes are very close to the .03x feeler gauge I stuck in them, so those are going to be replaced, but one of my exhaust was able to get a .05x gauge under it and the other was fine at .076. The bike's got about 15k miles on it with 7k of those being me riding more aggressively than the average owner, so I wonder if it's ok to leave that exhaust shim in?

[gsJack]

I set exhaust valve clearances at .003-.005" (.08-.13mm) and leave the intakes at .001-.003" factory spec.  You're OK for now but if you want to get 100k miles from the valves get the exhaust valve clearances wider soon.

http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs_zpscvcef42y.jpg

[burning1]

I keep the exhaust between .08 and .12. If it's tighter than .08, the shim is replaced. Wear increases dramatically as the clearance shrinks. A big benefit of the .08-.12 clearance is extended valve adjustment intervals. You lose those benefits if you let the clearance get too low.

I'd probably also adjust the tight intake shim. Replacing a shim isn't much work compared to pulling the bike apart.

[Watevaman]

 3 of the clearances are now able to get the .051 feeler under them, so I'm in spec for those. The remaining intake (the one that was previously too tight) can only fit the .038 feeler under it. I still have the cover off so I can replace it if needed but I'm in spec so it's really apathy right now that's causing me to second guess just throwing it back together.

On a related noted, measuring these shims is a PITA. I had to take them to the dealer to have them use their calipers (mine aren't digital and aren't metric) and the shim that I swapped into the other intake was reading from 2.54 to 2.58 depending on how it was rotated.

[Atesz792]

Do these loose specs affect your highest safe rev range? Like at 0.12, doesn't valve float occur before the 11K redline?

[gsJack]

I so far so good    I ran my 97 GS bought new for 80k miles at Suzuki specs and the tighter of the 2 exhaust valves required a 1st shim change at around 40k miles and a change of 1-2 shim sizes ever check after that, it was down to a minimum 2.15 shim before 80k miles.

When my current 02 GS started requiring shim changes at around 30k miles on the tighter exhaust valve I went to the larger .03-.05" clearances.  I based the choice on the .02-.05" spec for the 82 GS750k I had put 80k miles on.  After a couple changes to the wider gaps it went 40-50k miles without a further change and has over 100k miles on it now.

Both of my GS were run stock all the way and with a 8500 rpm red line there was nothing to be gained by going much over 9k rpm.  I used to warn when posting about the larger gap that if you redline it all day maybe you should keep it a bit tighter.  But when burning1 posted about running his track bike with the wider clearances I dropped the warning so if you throw a shim blame burning1.   

[twocool]

Why does wear increase with slightly less clearance?

How much can you extend the adjust intervals?

Don't you still have to check them to be sure, at regular intervals?

I check mine every year, during winter, which works out to be every 10,000 miles or so....more interval then the book says.....I have changed out shims (intake 1x and exhaust 2x) over 40,000 miles....

I keep the exhaust between .08 and .12. If it's tighter than .08, the shim is replaced. Wear increases dramatically as the clearance shrinks. A big benefit of the .08-.12 clearance is extended valve adjustment intervals. You lose those benefits if you let the clearance get too low.

I'd probably also adjust the tight intake shim. Replacing a shim isn't much work compared to pulling the bike apart.

[gsJack]

Greater clearance gives more cooling seat time for the hot running exhaust valves.  Exhaust valves recede into the seats if run too hot.  I last checked my valves at 86k miles and I'm over 100k miles now and don't plan on checking them again.

[burning1]

Do these loose specs affect your highest safe rev range? Like at 0.12, doesn't valve float occur before the 11K redline?

Nope. No issues on my race bike, and these are the clearances Megacycles recommends for their race cams.

Why does wear increase with slightly less clearance?

How much can you extend the adjust intervals?

Don't you still have to check them to be sure, at regular intervals?

I check mine every year, during winter, which works out to be every 10,000 miles or so....more interval then the book says.....I have changed out shims (intake 1x and exhaust 2x) over 40,000 miles....

Stock interval is about every 4K miles. Based on what I've seen, 10K miles is a bit too for stock clearances. 10-15 is probably okay with the wider gaps. I'd advise you to inspect every 10K or once a year with wider gaps. You can extend that interval if the clearance is stable.

AddidasGuy tracked his inspections, comparing wide clearances to OEM clearances. The results are amazing.

[Badot]

AddidasGuy tracked his inspections, comparing wide clearances to OEM clearances. The results are amazing.

So... could we see those results, by chance?

[adidasguy]

AddidasGuy tracked his inspections, comparing wide clearances to OEM clearances. The results are amazing.

So... could we see those results, by chance?

I don't recall doingthat. Someone else perhaps? Or just was I mentioning what I did to the valves and the change in performance?

[radodrill]

Sounds like something GsJack would have done

[gsJack]

I kept a log of all the valve checks on my 97 and 02 GSs for 14 years and 180k miles that shows where I increased the exhaust valve clearances at about 30-40k miles on the second bike.  It's linked in my first post above, could be what burning1 was referring to.

[burning1]

Yep, GsJack, not AddidasGuy. My mistake.

[Atesz792]

Well, greater clearance it is, then. I mean, like next time they require checking
Thanks for the input!