Wisely or not I just got in a bunch of piston sets from cruzinimage. I want to have my local engine guy bore a bunch of cylinders to match. Nothing is simple, looking for some opinions experiences on cylinder boring. He has bored three sets already for pistons I bought last year and one set is in an engine and running (rephase and I got to ride it!)
That motor had "some machinists" bore and Mikes pistons for about 500 miles and it didn't go well, there was a lot of scuffing, metal swapping, those bores had distinct wear lined up with the where the studs are ie the 4 stud corners show the scuffing, they got one of my sets and put it in.
OK the questions.
Is it a big deal to do a full cylinder clamp down torque jig set up before boring? Or is "standard boring machine clamping fine? I don't know if anyone is has done a jig build. Building an XS specific jig is not trivial and the exact jig set up may raise more questions than answers.
Cylinder to bore clearance. stock is .002" inch I am planning on staying with that but anyone got any "other" clearance suggestions? Does use matter, say street vs race? I will be doing several 706 78mm big bores and also some 2nd over sets.
the specs I supplied my machinist with last time;
XS650 Cylinder boring and honing
Stock bore 75mm
Wear limits 75.1mm, taper .05mm (.002")
Supplied pistons 75.5mm nominal dimension
Cylinder to piston clearance
.050mm to .055mm
.002" to .0022"
Ring end gaps
1st and 2nd rings .2mm to .4mm limit .8mm
.008" to .016" .030
Oil control rails.
.3mm to .9mm
.012" to .035"
Basically copied from the Yamaha manual.
OK what'da think?
That motor had "some machinists" bore and Mikes pistons for about 500 miles and it didn't go well, there was a lot of scuffing, metal swapping, those bores had distinct wear lined up with the where the studs are ie the 4 stud corners show the scuffing, they got one of my sets and put it in.
OK the questions.
Is it a big deal to do a full cylinder clamp down torque jig set up before boring? Or is "standard boring machine clamping fine? I don't know if anyone is has done a jig build. Building an XS specific jig is not trivial and the exact jig set up may raise more questions than answers.
Cylinder to bore clearance. stock is .002" inch I am planning on staying with that but anyone got any "other" clearance suggestions? Does use matter, say street vs race? I will be doing several 706 78mm big bores and also some 2nd over sets.
the specs I supplied my machinist with last time;
XS650 Cylinder boring and honing
Stock bore 75mm
Wear limits 75.1mm, taper .05mm (.002")
Supplied pistons 75.5mm nominal dimension
Cylinder to piston clearance
.050mm to .055mm
.002" to .0022"
Ring end gaps
1st and 2nd rings .2mm to .4mm limit .8mm
.008" to .016" .030
Oil control rails.
.3mm to .9mm
.012" to .035"
Basically copied from the Yamaha manual.
OK what'da think?