I've got a late 90's CR500 thats at .080 over and probably needs to be overhauled. The problem is, I've got a killer port job on this cylinder, and dont really feel like throwing it in the junk pile (just cause its on its last bore), buying a new one, and starting again from scratch. New cylinders are around $400 these days, not to mention the top end kit at about $200, and then the added cost of porting and head work $3-400.
The last time I looked inside my cylinder it appered to have quite a bit of sleave left. Why dont they make a .090 or a .100 oversized piston? I understand the heat problems with a thin cylinder but, geez there still seems like a lot of sleave is still left in there.
If a .080 piston will last in the trails and mud, surely a .090 - .100 will last on a mx track or hillclimbing.
CR 500 piston sizes
A riding buddy of mine had a cylinder "big bored" and replated by Millennium. After 2 hours a big chunk of the cylinder "web" fell off and trashed the motor. They told him "that sucks"...and "sorry, no warranty"..."have a nice day"...not my idea of good business. 
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2002 CR80
1999 Cr500
2003 CR250R
2005 CRF250R
2006 YZ450F
2005 CBR1000RR
1997 Banshee
2002 CR80
1999 Cr500
2003 CR250R
2005 CRF250R
2006 YZ450F
2005 CBR1000RR
1997 Banshee
powerseal usa did mine. they do have a warrantee and did nice work with a torque plate. I had to provide the plate. I tested the work by running the motor without coolant on 927. scuffed things up a bit but she still was running the same compression after I realized the coolant was gone.
They bored out around .004" and put back about .008 of nikasil. then hone to the clearance I specified, .003 using a vertex piston with a swaintech pc-9 coated skirt. The PC-9 wore off a bit from all the heat but she never melted anything.
Pretty glad I switched to the 927.
They bored out around .004" and put back about .008 of nikasil. then hone to the clearance I specified, .003 using a vertex piston with a swaintech pc-9 coated skirt. The PC-9 wore off a bit from all the heat but she never melted anything.
Pretty glad I switched to the 927.
plated cylinder,have i misread this?
is that what your suggesting some sort of nickel process to our iron bores like the modern cylinders??i didnt think this was possible with iron liners,i always thought modern nickel cylinders didnt have a liner/sleeve it was just a process the alloy went thru to surface harden/coat the cylinder..but it did have me thinking if there was a process to super toughen our iron cylinder bores but i guess we would have to sacrifice being able to rebore it.
Question,,with a modern nickel cylinder rebuild,do they bore out the cylinder to remove any grooves etc than re chrome it which leaves a bigger bore,or does the chroming process add material which is later bored /honed back to original size, otherwise if its bored i guess it can only have the process done so many times like a liner...ive never owned a chrome/nickel cylinder so i wouldnt know.
ill have a look at bobs link he put up for millenium tech
Question,,with a modern nickel cylinder rebuild,do they bore out the cylinder to remove any grooves etc than re chrome it which leaves a bigger bore,or does the chroming process add material which is later bored /honed back to original size, otherwise if its bored i guess it can only have the process done so many times like a liner...ive never owned a chrome/nickel cylinder so i wouldnt know.
ill have a look at bobs link he put up for millenium tech
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