Hi Guys, I have sent my barrel off to be rechromed/ nicasiled and the company are asking what the piston to bore clearance I want , can anyone help me with this information, cheers Dean.
Ps It is off of a Coguaro.
501 piston to bore clearance.
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morini_tom
- Posts: 928
- Joined: 05 May 2006 13:47
- Location: Northampton
Re: 501 piston to bore clearance.
Hi Dean,
You may find the following information useful (this is from the 'red book' -The Cagiva published workshop manual) and applies to nikasil linered 350 and 501 engines...
Cylinder:
Check that the walls are perfectly smooth and without any signs of localized wear. Measure the cylinder diamtere at three different heights and in two directions at 90 degrees to eachother to obtain teper and ovalization vaues. Max ovalisation (wear limit) = 0.00118in (0.03mm) Max taper (wear limit) = 0.00118in (0.03mm). In presence of damage or excessive wear the cylinder must be replaced as it has a special silicone carbide inner coating (giving exceptional antifriction and antiwear properties to cylinder walls) hence it cannot be ground. The cylinders are marked by a letter indicating the class they belong to, and then cylinder-piston coupling must always be performed with parts of the same class.
Piston:
Diameter of the piston is measured at the gudgeon pin, perpendicular to the pin axis.
Cylinder-piston coupling clearance 0.00-0.00071in (0.00-0.018mm). Max clearance 0.00138in (0.035mm)
Piston rings
They must never show signs of shrinking or scoring.
Insert the piston ring in the lower section of cylinder (where wear is min) being careful to position it well (in square) and measure the distance between the two ring ends: 0.0078-0.0118in (0.2-0.3mm). Wear limit 0.0177in (0.45mm)
Piston ring grooves
End play of piston ring in piston groove mx wear limit 0.0023in (0.06mm)
Hope that's of use, and good luck getting the coguaro back together,
Tom
You may find the following information useful (this is from the 'red book' -The Cagiva published workshop manual) and applies to nikasil linered 350 and 501 engines...
Cylinder:
Check that the walls are perfectly smooth and without any signs of localized wear. Measure the cylinder diamtere at three different heights and in two directions at 90 degrees to eachother to obtain teper and ovalization vaues. Max ovalisation (wear limit) = 0.00118in (0.03mm) Max taper (wear limit) = 0.00118in (0.03mm). In presence of damage or excessive wear the cylinder must be replaced as it has a special silicone carbide inner coating (giving exceptional antifriction and antiwear properties to cylinder walls) hence it cannot be ground. The cylinders are marked by a letter indicating the class they belong to, and then cylinder-piston coupling must always be performed with parts of the same class.
Piston:
Diameter of the piston is measured at the gudgeon pin, perpendicular to the pin axis.
Cylinder-piston coupling clearance 0.00-0.00071in (0.00-0.018mm). Max clearance 0.00138in (0.035mm)
Piston rings
They must never show signs of shrinking or scoring.
Insert the piston ring in the lower section of cylinder (where wear is min) being careful to position it well (in square) and measure the distance between the two ring ends: 0.0078-0.0118in (0.2-0.3mm). Wear limit 0.0177in (0.45mm)
Piston ring grooves
End play of piston ring in piston groove mx wear limit 0.0023in (0.06mm)
Hope that's of use, and good luck getting the coguaro back together,
Tom
Re: 501 piston to bore clearance.
Hi Tom, very useful information, thank you very much. Dean