I have machined .05mm/.002" off my OEM valve shims more than once, it works great and its quick and cheap. But don't go under 2.15mm which is suzuki spec as the thinnest shim thickness.
I just take mine to the local header place and he does them while i wait. Anyone else done this?
Why are the clearances so close on the gs? Its only a hair thickness.
Johno
Spec calls for 0.03 to 0.08mm cold
Its small value but the maximum is almost x3 the minimum and in engineering terms that's a massive tolerance.
Grinding shims is not good practice, you can't say how it affects the finish and hardness.
It doesnt affect the finish, well it does but only on the bottom side where suzuki already machined it.
I had 3 shims ground 8000km's ago and just the other day i checked them again (i check every 2000km) and one was out of spec. I pulled it out, inspected the top surface and it looked perfect to me. I took it to the head guy and he took a hair off it (.002") and now its all back in spec, its all good and it doesnt affect the shim at all.
Johno
Your bike, your choice :dunno_black:
They mill the bottom sledge, it doesn't create any more heat than the operating temp of the engine. Infact it would be way way less. It's good and saves the planet :thumb:
Are the top and bottom faces still parallel?
Yes the are, its done by a professional on an industrial milling machine.
I've measured with my very good quality verniers and i couldn't see any variances, remember we are talking about a hairs width here.
To be honest i cant see all the OEM shims being "perfect". They would just set the machine, pump out out a few thousand and check tolerances every now and then.
Are the shims case hardened from the factory ?
Or just surface ?
Or neither ?
I have heard all 3 ...
Bottom face had the numbers right ? It takes up oil and that oil can make it wear slower, that could help.
Cool.
Buddha.
Quote from: The Buddha on June 03, 2017, 06:38:09 AM
Are the shims case hardened from the factory ?
Or just surface ?
Or neither ?
I have heard all 3 ...
Bottom face had the numbers right ? It takes up oil and that oil can make it wear slower, that could help.
Cool.
Buddha.
I couldn't tell you Budda what happens at the factory and what doesn't.
Yes the bottom face has the numbers.
As for the bottom of the shim taking up oil, i couldn't say. They only gets spray from the cam journals and cam chain. I have never seen any wear between the bottom face of the shim and the bucket. But I only have 2 1/2 years 15 thousand km's experience with the GS. In My experience the tolerances always get smaller, i have never have one go larger. So either the valves stretch or the valves chew into the valve seats or both.
Johno
I've never detected any wear in valve shims in 80k miles on my 97 and 100k miles on my 02 GSs and I measured them all over with a quality micrometer. The wear is between the exhaust valves and the valve seats. Both my GSs had the same intake shims in them that they came from the factory with.
The Suzuki .001-.003" spec is on the tight side and exhaust valves left at or near the min .001" setting will recede into the seats with wear and one that I left at .001" on my 97 was down to a min 215 shim at 80k miles.
When the 02 GS started the same pattern I went to a .003-.005" setting for exhaust and the exhaust valves then went tens of thousands of miles without shim changes. Here's the whole record:
http://oimg.photobucket.com/albums/v443/jcp8832/GSvalvelogs_zpscvcef42y.jpg
Quote from: crackin on June 03, 2017, 06:06:32 AM
I've measured with my very good quality verniers and i couldn't see any variances, remember we are talking about a hairs width here.
So you can measure 0.002" with a vernier accurately and repeatedly? .......Sorry but I simply don't believe you.
If you had said with a micrometer I might have. If you had said on a surface table with a DTI I wouldn't have even doubted you :dunno_black:
I find that interesting. If the local guy was using a surface grinder on the shim I think you'd find the finished surface was quite nice (depending on the wheel used you can get a mirror finish).
I find my verniers aren't too bad for measuring shims - they at least put you in the ball park although I don't use them for final measurements. I just replaced an exhaust shim on my 54,000km bike and after that long, a factory '282' shim measured at 2.816mm with a set of micrometers. I'm not sure if it is wear on the shim or how close it was at factory to 2.82mm but I'm confident about my micrometers.
I had to go thicker and thicker. From 8k to ~48k that one bike definitely needed thicker. Especially after 35k or so, definitely had to get thicker.
But that bike used oil from day 1 of my ownership and before.
I used to daily commute on it in the bay area from 8K to ~42-43k when I moved to NC, and commuter bikes are sorta beat to hell inspite of my best efforts and I was definitely pretty stupid on it.
I also ran 20w50 all its life and near that 35k mark was using straight 60 wt. And likely after the NC move it never got even warm enough to flow being 60wt.
I don't have data on any other bikes. cos I never owned them for any real mileage.
Anyway that bike lived a hard life but it stayed alive even after I sold it. I actually saw the guy riding it 3-4 months later.
Cool.
Buddha.
Quote from: sledge on June 03, 2017, 07:41:55 AMSo you can measure 0.002" with a vernier accurately and repeatedly? .......Sorry but I simply don't believe you.
My vernier has a small dial on it showing increments of 1 thou. But yeah "what ever".
Errrr......that means nothing.
Really.....you are wasting your time trying to convince me personaly that your methods are correct and accurate.
Professional machinists do not rely on uncalibrated verniers to measure as low as 0.002".
Firstly I wouldn't grind the shim, I would lap it
Then I would use.....
A micrometer, ideally ball ended to measure the thickness
A surface table and DTI to compare the parallelism between faces
....and if I wanted to be really thorough, an optical flat to gauge the flatness and finish.
But hey.....if you are happy......go for it, like I said, your bike, your choice.
Fair enough, we'll leave it at that then shall we.
Although i will say your opinion means absolutely nothing to me because as you have alluded to, you have zero experience machining valve shims.
Johno
Quote from: gsJack on June 03, 2017, 07:29:41 AM
I've never detected any wear in valve shims in 80k miles on my 97 and 100k miles on my 02 GSs and I measured them all over with a quality micrometer. The wear is between the exhaust valves and the valve seats. Both my GSs had the same intake shims in them that they came from the factory with.
The Suzuki .001-.003" spec is on the tight side and exhaust valves left at or near the min .001" setting will recede into the seats with wear and one that I left at .001" on my 97 was down to a min 215 shim at 80k miles.
When the 02 GS started the same pattern I went to a .003-.005" setting for exhaust and the exhaust valves then went tens of thousands of miles without shim changes. Here's the whole record:
http://oimg.photobucket.com/albums/v443/jcp8832/GSvalvelogs_zpscvcef42y.jpg
Thank you for your input gs jack, I always learn something from your posts.