lucky3underworld

I bought a f20c that dropped a valve and caused minor scratches to the cylinders. I know the cylinder walls are made of some silicone alloy carbon something. I just got the .25 pistons from honda for $115 and ring set for $35 Is it ok to overbore them to .25 and will it work. I mean will the diamond cut this, because when i touch the sleeves they dont feel like cast iron. Also does anybody have a link or info on all the torque specs to rebuild this motor. For example main, rod bearings valve lash timing marks tourque specs stuff like that. Any problems i might encounter. Ahy help will be greatly appreciated. Oh this will be a complete stock motor im not looking to boost or anything. Oh will i have to get the pistons pressed into the rods or are they the floating pin kind that have locking c clips.

Wildncrazy

They are fiber reinforced cylinders. I don't believe you can over bore them, but I may be wrong. I know that many of the boosted motors use traditional steel sleeves.

AusS2000

You can bore them .25 over. That's why Honda provide oversized pistons.

They are FRM (Fibre Reinforced Metal) cylinders. Basically carbon fibre sleeves are placed into the mold and molten aluminium poured around it. Yes, normal boring heads will bored it. You need a 600 grit stone to hone after boring but any machine shop should have this.

I would strongly suggest you invest in a Helms manual. All the specs and procedures are in there.

And the piston pins are floating. Just pop out the C-clips.

kial007

especially about the manual. I was able to download to factory manual with a simply google search. And about the pin clips, make sure you don't try to compress them like a snap ring. You will want to get it started (in or out) and then work it the rest of the way.

lucky3underworld

Thanks for all the info. So i should be able to bore it to .25. and about the pistons they should come right off or do i have to press them out with a shop press?

AusS2000

You said:
I said:
Surely that covers it?

lucky3underworld

Ok i stopped by the machine shop and talked to the guy he told me that it wont work because thre is a scrtch too deep on one of the cylinders. So i cant use .25 over. So my only option is to use sleeves and reuse the stock pistons. Does anybody know where i can get some for cheap they are pretty pricey from 700- 1,200. Also he said it wouldnt work because the FRM would come off and leave aluminum w/auminum and it would seize the motor.

street_ruler

i thought the factory OS pistons are to be used with a fresh hone...not boring out the motor. i may be wrong but like i said...i thought stock bore

lucky3underworld

yeah thats what im going to do just hone it out till it reaches its service limit and put it back together see what it does

AusS2000

What size are the oversized pistons. 0.25? What? MM? or 025 thou of an inch.

I'm guessing mm as Japan like the rest of the civilised world uses metric.

I doubt you can hone 0.25 of a mm. You'd have to use a reamer then hone surely.

And if your scratch is deeper than 0.127mm then you've over the service limit and sleeving is the only option.

I certainly wouldn't be just putting it together and see what it does. THis is not untrodden ground and it ain't cheap.