5 replies to this topic

[Kramit]

Sherco USA Website shows the 125 Piston to Cyl Clearance at .0175mm to .0225mm.
Multiplying by .3937 ( 1mm), I come up with .006 to .008 clearance. The well used top end clearance now measures under .003"
Am I doing this right?

[Nigel Dabster]

Kramit, on Feb 24 2009, 04:11 AM, said:

Sherco USA Website shows the 125 Piston to Cyl Clearance at .0175mm to .0225mm.
Multiplying by .3937 ( 1mm), I come up with .006 to .008 clearance. The well used top end clearance now measures under .003"
Am I doing this right?

Millimetres are metric, inches is something different.

[copemech]

These clearance specs seem very tight! Yet at .003 is very loose! As I think it should be much closer to about .001 range!

Do a lookup on the metric conversions. At any length, seems things are out of spec and a new piston may be in order as you can always go a bit over using the ABC spec for sizing which is just a bit!

[mcman56]

You are off by one decimal point. 1 mm = 0.03937

[Kramit]

.0006 to .0008 sounds possible.......I guess

[copemech]

Kramit, on Feb 25 2009, 01:35 AM, said:

.0006 to .0008 sounds possible.......I guess

Yes, I think this is more realistic, yet also probably "new limit" spec.

Typacally the "service limit" may be up too more than twice that amount, although I do not believe it is listed. As yours was at .003 and probably quite noisey. The majority of the wear should be on the piston itself and not the bore.

So basically, if the cylender has no major gouges, you might want to do a light hone job on it and fit a B or C piston and get the clearances in line, and hopefully back to the range of .001 or possibly less.

Honing in istelf can be critical, and unless properly done, i would almost rather see you just try to fit the B or C yourself!