04-01-2012, 05:37 AM #1
CP pistons 8.4:1 + 0.25mm,what size do i need to hone the cylinder?
Is it as easy as just hone the cylinder to + 0.25 mm oversize and you are done?
Is a 400 grit finish the way to go?
I know the piston to wall clearance is important,but i just want some extra info,before i get my cylinders honed.
Cylinders look just fine after 136 hrs,but due to a engine failure my engine is apart right now,and rehoning the cylinder and go first oversize seems the way to go.
Was thinking just putting new rings in the stock pistons but i'm running 3Rude at around 8600- 8700 rpm,the cp are the way to go i think.
04-01-2012, 08:09 AM #2
Just go with the clearence specified in the instructions
04-01-2012, 08:13 AM #3
- Join Date
- Nov 2011
- Melbourne - Australia
you wont be able to hone your bores to the correct oversize youll be there for ever. a cylinder hone is just to clean the bores up and give the new rings something to bed into
you want the block to be bored to suit the oversize of the pistons and then finished with a hone.
04-01-2012, 08:19 AM #4
at .25mm, most machine shops will hone the material out with a 180 stone, then finish up with a 240, 380 or 400, depends on what you tell him what the manufacture says, i would ask for a plateau finish hone if it was my motor, better ring break in and long term wear and tear IMO
04-01-2012, 09:12 AM #5
Ok thanks for all the help guys.
I'wont be honing myself,i will go to the machineshop for this.
Cp pistons first oversize is +0.25 ,this isn't something you can do yourself.
I will order oversize pistons,my idea was to bring the cylinders to the machineshop to be honed,when the pistons arrive i can install them at once.
Maybe i better first wait until the pistons arrive,and go with pistons and engine to the machineshop and have it honed,so they will be able to measure the clearance between piston and wall.
It's my first total rebuild,done the head and valves before,but this is a new one for me.
04-01-2012, 09:20 AM #6
04-01-2012, 09:25 AM #7
Thanks ,i will first order the pistons and then go to the machine shop.
I was thinking of taking the cp pistons in stock size,because after 136 hrs,my stock pistons look like new,and the cylinder walls are fine also.
Maybe stock size and a very slight hone would do the job also,that's the only thing i'm doubting about.
04-01-2012, 05:37 PM #8
With the stock size replacement piston you can mostlikely hone and install, with an oversize you will need to have the cylinders bored first!!!!!
04-02-2012, 02:07 AM #9
04-04-2012, 04:26 PM #10
- Join Date
- Apr 2005
the CP needs more clearance then stock pistons , + the CPs are slightly bigger compared to stock , measure the pistons and go for 0.075- 0.08 mm clearance
you can hone a stock bore if you go with stock seize CP
if you go with .25 over seize you need new bore, then hone, then polishing
check ring clearance as well after the bore is rrady
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