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Author Topic: Piston to cylinder clearance  (Read 341 times)

olebmw

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Piston to cylinder clearance
« on: January 04, 2018, 10:00:59 pm »
I am ready to fit a new piston and need to know what the factory recommended piston to cylinder clearance is. 
I have a reprint of the "Istruzioni Per Le Riparazioni E La Revisioni Generale'' in Italian which does me little good.
Is there a reprint of this manual in English,anywhere on the net that I can print?   
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randall

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Re: Piston to cylinder clearance
« Reply #1 on: January 05, 2018, 03:01:23 pm »
« Last Edit: January 05, 2018, 03:12:18 pm by randall »
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olebmw

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Re: Piston to cylinder clearance
« Reply #2 on: January 05, 2018, 09:57:24 pm »
no speak or read the Deutsch either.
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cloggy

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Re: Piston to cylinder clearance
« Reply #3 on: January 17, 2018, 09:50:25 pm »
XT500s have a similar sized piston and the safe clearance on those is 3.5 thou
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olebmw

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Re: Piston to cylinder clearance
« Reply #4 on: January 18, 2018, 07:08:40 pm »
Wow, I was thinking 1.5 thousands.  If I did the conversion math correctly from the German manual, I came up with around 1.5
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banquo

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Re: Piston to cylinder clearance
« Reply #5 on: January 23, 2018, 09:43:25 am »
I've translated the inspection section of the workshop manual using Bing Translator, which states:
The mounting clearance between piston and cylinder must be 0.395-0.440 mm. Ovality 0.13 - 0.17 mm.
Ring gaps: 0.3 - 0.4mm.
I've just had mine bored and honed to that spec. so better hope it's right... ;D
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olebmw

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Re: Piston to cylinder clearance
« Reply #6 on: January 23, 2018, 09:59:36 pm »
The 0.395 mm converts to just over 1.5 thousands [ .01555] of an INCH, correct?
Cloggy, I thought your measurement was in inches, my mistake.
Thanks for both of your help.
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banquo

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Re: Piston to cylinder clearance
« Reply #7 on: January 23, 2018, 11:08:14 pm »
0.395 x 1000 / 25.4 = 15.5 thou NOT 1.5 thou, which is the route to very expensive pain....
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olebmw

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Re: Piston to cylinder clearance
« Reply #8 on: January 26, 2018, 05:16:48 pm »
I can assure you I wasn't going to have the cylinder bored .o15 inches.
Does .00155" -.00173'' sound  better?
I don't understand how to convert .395 mm to  inches and get .00155.
Shouldn't the measurement in the repair book be .0395- .0440 ?
What am I missing?
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banquo

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Re: Piston to cylinder clearance
« Reply #9 on: January 26, 2018, 05:38:42 pm »
The calculation's in the previous post....
25.4mm in an inch, so to convert mm to inches, divide by 25.4.
0.395mm/25.4 = 0.015551"
x 1000 to convert to thou = 15.55 thousandths of an inch.
Sounds a lot, but that's what the book says....
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olebmw

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Re: Piston to cylinder clearance
« Reply #10 on: January 26, 2018, 06:16:42 pm »
As my Dad use to say, "Clear As Mud".
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