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Shim replacement.

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Stevex View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stevex Quote  Post ReplyReply Direct Link To This Post Topic: Shim replacement.
    Posted: 01 Jan 2019 at 20:34
Checked my valve gaps; 1 under lower limits, 3 on lower limit, 4 are 0.01mm above min limit.
Time to replace some shims, in fact going to replace / relocate them all to put the gaps at the high limit.
So far I've got the rear cylinder cams out, which is more of a pain than the front pot due to the balancer mechanism built into the cam cap housing.
A question for anyone who's done this before...I'm changing shims for the next size down Thumbs Up (0.05mm increments), but on the 4 gaps that are 0.01mm above minimum the shims will take the gaps 0.01mm above maximum. 
So only talking 1/100th of a mm...did you have the same problem?
Or, anyone found their gaps just over the upper limit?
It's not going to bother me much, interested in others perspectives.


People say I don't know Jack Sh1t; but I do, he lives next door.
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legend88 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legend88 Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jan 2019 at 21:06
If the gaps are tight then you need thinner shims not thicker ones so that should put you just right. Also measure all the shims that come out with a micrometer as you can often mix and match the existing ones in different locations and save the cost of new ones. They aren't always nominal size either so an accurate measurement is important.

To answer your question though, I wouldn't worry about a marginally oversize gap as that just reduces valve lift a little but too small a gap reduces valve to piston clearance (Not good). So better too big a gap than too small.

Out of interest Steve, how many miles on the bike?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stevex Quote  Post ReplyReply Direct Link To This Post Posted: 01 Jan 2019 at 21:25
Originally posted by legend88 legend88 wrote:

If the gaps are tight then you need thinner shims not thicker ones so that should put you just right. Also measure all the shims that come out with a micrometer as you can often mix and match the existing ones in different locations and save the cost of new ones. They aren't always nominal size either so an accurate measurement is important.

To answer your question though, I wouldn't worry about a marginally oversize gap as that just reduces valve lift a little but too small a gap reduces valve to piston clearance (Not good). So better too big a gap than too small.

Out of interest Steve, how many miles on the bike?

LOL, missed that, meant to say going down in size, edited, thx.
Yep, on the rear cylinder I can re locate 2 shims so just need 2 more; found a KTM dealer on ebay selling 'em for £3 each, but I'll give my local Ape dealer a call tomorrow, see what they've got.
My Tuono's done about 15,000 miles, I checked the gaps last winter, so knew this was coming. I've read some V2 engines have done 10s of thousands of miles without going out of limits, I'm one of the not so lucky ones.
Funny you should mention that they're not all nominal size; I've measured mine with a digital vernier caliper and get thicknesses of 2.73, 2.75, 2.69 and 2.66. All the shim ident measurements have worn off, but the one I measured at 2.66 still has a last digit of 5 on it.
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IanG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanG Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jan 2019 at 14:06
Digital vernier calipers are crap for accurate measurement,never trust them for better than 0.02

We use them as a quick and easy indicator,micrometers are used for accurate measuringWink
www.apriliaperformance.co.uk
www.apriliaforum.co.uk
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Looking forward to the next track day
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legend88 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jan 2019 at 15:02
Originally posted by IanG IanG wrote:

Digital vernier calipers are crap for accurate measurement,never trust them for better than 0.02

We use them as a quick and easy indicator,micrometers are used for accurate measuringWink


We always called verniers Guesstimeters! As you say only a mic will do for shims.



I see you are having a catch up on here Ian, it seems almost every post today is yours!
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IanG View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanG Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jan 2019 at 16:59
LOL

Been catching up on the 4 pages of whatever I've missed since the 23rd Wink

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Post Options Post Options   Thanks (0) Thanks(0)   Quote legend88 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jan 2019 at 17:25
Been in Austria?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanG Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jan 2019 at 17:29
Yup,got back around 1;00 this morning so catching up with things today
www.apriliaperformance.co.uk
www.apriliaforum.co.uk
www.apriliaownersclub.co.uk

Looking forward to the next track day
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