standard piston question

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kdxquebec
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Post by kdxquebec »

Where I work we have a Quality Inspection Departement where they inspect all the machined aluminium pieces from the machine shop.

They re- measured my cylinder with telescopic guages at 3 places
They re- measured my piston with a calibrated micrometer as stated in the manual.
The measured the end gap of my new rings and the ring groove clearance also.
All is still in the manual shop tolerences.

They said it is not 100% the truth but gives a precise idea.

I will run this setup again next season and after I will see.

Thanks for the info guys.
'89 KDX 198cc '03 Gasgas Ec250 '13 Husaberg Te300
*CANADA* LEADING THE WORLD IN BEING JUST NORTH OF THE UNITED STATES.
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fuzzy
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Post by fuzzy »

66mm = the bore size

This is about the 10th time this crap has been discussed on here.

Also, a teloscoping guage and mic don't even come close the the accuracy needed to measure the bore down to the 'letter' sizes. This is why the factory 'baselines' the cyl by stamping it(after it's measured with mucho-fancy equipment), and installs the corresponding piston. Then you are 'supposed' to go up one letter every piston install. Again, the differences are neglegible. Hardly any engine builder could ever get the piston clearance back to say a B-B configuration. A in a F, F in an A....All within spec clearance. As stated the wiseco is on the larger side, and only comes in one 'std' size. Pro-X ABCDEF are all 'std.' This system eliminates the need to measure clearance between top-ends....That's all.
Last edited by fuzzy on 01:15 pm Dec 02 2005, edited 1 time in total.
'91 KDX 200 Project $300 KDX
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KDX220PHIL
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Post by KDX220PHIL »

"They re- measured my cylinder with telescopic guages at 3 places"

If telescoping guages are used, I see a few problems with this:
They are a means of transfering a measurement, they are not direct reading so they must be measured with another guage afterwards, hopefully not calipers. This results in twice the chance for error.
It may be enough to ensure the features are in spec. but they will not give you an accurate figure of your clearance.

"They re- measured my piston with a calibrated micrometer as stated in the manual.
The measured the end gap of my new rings and the ring groove clearance also.
All is still in the manual shop tolerences. "

Excellent.
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KDX220PHIL
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Post by KDX220PHIL »

"IF that Pro-X is 65.990" and the Wiseco is 66.000"...that is a BIG difference. Ten thousandths' inch (.010") is a gross measurement that any machinist would laugh at. "

I hope you mean 66.000mm????

.01mm = .0003937 inches.

.01mm/25.4mm/inch.
Last edited by KDX220PHIL on 07:01 pm Dec 02 2005, edited 1 time in total.
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kdxquebec
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Post by kdxquebec »

No calipers was used.

ok. they measured the telescopic result with a micrometer.

They also have a 3 pins telescopic gauge...They used it but I do not think this is the right tool.?
'89 KDX 198cc '03 Gasgas Ec250 '13 Husaberg Te300
*CANADA* LEADING THE WORLD IN BEING JUST NORTH OF THE UNITED STATES.
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KDX220PHIL
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Post by KDX220PHIL »

"They also have a 3 pins telescopic gauge...They used it but I do not think this is the right tool.?"

Called 3 point micrometers.

http://www.microtest.ch/_bilder/sondermikrometer/01.jpg

Ideal is CMM, hehehe, next Dial bore.
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RBD
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Post by RBD »

A dial bore gauge as shown by KDX220PHIL is more than adequate to measure cylinder bores and most professional engine builders use them.

Ron
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canyncarvr
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Post by canyncarvr »

Fuzzy is indeed correct about all 'this crap'.

..and I've been guilty of it before.

The sizes listed in the Wiseco pdf are indeed bore sizes...not piston sizes.

Please accept my apologies for all the crap.

Of course I meant inches! I have the 'big bore' kit!! :wink:

Hopefully the **edit** leaves less than a big mess.

Consider the source
Using a perceived level of knowledge to boost my self worth.
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fuzzy
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Post by fuzzy »

LOL! :) It is some confusing crap!
'91 KDX 200 Project $300 KDX
'95 KDX 200 Project $600 KDX
'94 WR 250 Always a project
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