Topic: 400F bore tolerances

[fmctm1sw]

I took my 400F cylinder to the local machine shop.  What exactly is the cylinder ID assembly standard?  and service limit?  Does it also have an "out of round" limit?

[mattcb350f]

Cylinder ID Standard: 51.00mm to 51.01mm
Cylinder ID service limit: 51.1mm

...From Honda Manual: 350-400 Fours

Not sure about out of round.... but it should be fairly round 

 Matt.

[crazypj]

They should just measure it and give you the results. (then you can post them here to find out if its any good  )
You 'should' have 6 measurements per cylinder, (top, middle, bottom, X-axis, Y-axis)
X-axis usually in line with the pin, Y is thrust face and generally where the wear takes place)
 You need to mic. up the pistons to find out what actual clearance you have. (the pistons are undersized, probably around 50.96~97mm)
I normally set smaller Honda's at 0.0015" total clearance when boring (one and a half thousandths, just under 0.04mm)
 Tend to do everything up to 70mm bore like that, no problems so far.
CB400f is only 100cc per cyl, (51mm) so you could probably go with 0.0012" total.
PJ

[fmctm1sw]

Thanks guys and good news, my bores look good.  I feel pretty confident with the guy.  He said the service limit would be .0012 (before I ever mentioned the specs to him) and none of mine were over .0009.  He said he'd hone them for $6 each.  I should take my pistons to him too I guess, thanks for the advice...