Honda-SOHC

SOHC.co.uk Forums => CB350/400 => Topic started by: royhall on August 18, 2017, 07:42:10 AM

Title: CB350f bore size
Post by: royhall on August 18, 2017, 07:42:10 AM: Can anyone confirm the piston to bore clearance for a CB350F. I have found so many differing sizes, but it appears to be 0.0008" (eight tenths of a thou) but I have seen as little as 0.0005" specified by Hondaman but that does seem very tight and risking seizure. What clearance have you guys used with good results. Cheers.
Title: Re: CB350f bore size
Post by: kevski on August 18, 2017, 08:35:38 AM: I have two figures and it equates to 9.8 thou or 250 microns which is what I work to.
Title: Re: CB350f bore size
Post by: Tomb on August 18, 2017, 10:14:05 AM: Quote from: kevski on August 18, 2017, 08:35:38 AM
I have two figures and it equates to 9.8 thou or 250 microns which is what I work to.

Wow that's HUGE, are you sure that's not the wear limit? even if it were its still big.
Title: Re: CB350f bore size
Post by: Nurse Julie on August 18, 2017, 10:52:00 AM: Gosh, with that clearance I thought you were talking about Brit bikes all of a sudden, even then it would be too much.......Dick and bucket come to mind ;D ;D ;D
Title: Re: CB350f bore size
Post by: royhall on August 18, 2017, 03:22:45 PM: Quote from: kevski on August 18, 2017, 08:35:38 AM
I have two figures and it equates to 9.8 thou or 250 microns which is what I work to.
Shouldn't that be 25 microns?
Title: Re: CB350f bore size
Post by: Tomb on August 18, 2017, 03:41:38 PM: 10 thou is 1/4 of a mm so 9.8 thou is about 250 microns
Title: Re: CB350f bore size
Post by: royhall on August 18, 2017, 04:23:16 PM: Quote from: Tomb on August 18, 2017, 03:41:38 PM
10 thou is 1/4 of a mm so 9.8 thou is about 250 microns
Exactly, it should read 25 microns or 0.00098" not 250 microns thats way too much?
Title: Re: CB350f bore size
Post by: kevski on August 18, 2017, 04:53:41 PM: I cocked up my sums there and am now looking for more info on it now.
Title: Re: CB350f bore size
Post by: Trigger on August 18, 2017, 09:39:37 PM: All depends on the piston manufacture ( Different grades of alloy ) 0.0005"to 0.0008" is ok for OEM Honda.
Title: Re: CB350f bore size
Post by: royhall on August 19, 2017, 08:13:46 AM: Quote from: Trigger on August 18, 2017, 09:39:37 PM
All depends on the piston manufacture ( Different grades of alloy ) 0.0005"to 0.0008" is ok for OEM Honda.
Good point about the piston make. In this case I'm talking about the Cruzinimage pistons and rings.
Title: Re: CB350f bore size
Post by: royhall on August 19, 2017, 08:39:52 AM: Quote from: royhall on August 19, 2017, 08:13:46 AM
Quote from: Trigger on August 18, 2017, 09:39:37 PM
All depends on the piston manufacture ( Different grades of alloy ) 0.0005"to 0.0008" is ok for OEM Honda.
Good point about the piston make. In this case I'm talking about the Cruzinimage pistons and rings.
Just for info of anybody watching this thread, the correct clearance for a 350F with Cruzinimage pistons is 0.0009" to 1 thou. Cheers.