I would say generally speaking only if it's because generally the piston is trashed. But if the piston is in spec., then what would be the problem? OTOH if you want max everything then use new everything, obviously.
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Scratch in Cylinder - Rebore?
- Thread starter XSRocket
- Start date
XSRocket
XS650 Member
Thanks Pete.
To be clear, is this the right order to do things?
1. Bring the cylinders to a machine shop with the stock specs (75mm +/- <tolerance from clymer>)
2. Ask them to bore out to increments of +0.25mm to match oversize pistons
3. Get pistons based on how far out they needed to bore
Is there a step 4 that involves bringing the pistons and rings back to the machine shop with the cylinders to check tolerances? I've read in other threads that cruzinimage rings might need to be ground down to spec.
Apologies if these are silly questions - this is as deep as I've ever gotten into an engine and I want to make sure I get this right.
Is think a good machine shop should be able to tell you what size over bore parts you'll need before they start boring.
A good machine shop should be able to tell you if it's salvageable, or a paperweight. If you're not comfortable either doing it yourself, or giving it to a shop, then by all means start looking for a new sleeve (if the whole cylinder is cheaper, cool. One side will be better than the other...), just know you have more options than going 2nd or 3rd over right out of the box, just to make it smooth...
XSRocket. You can measure them yourself to get a rough idea if you have a caliper, or with feeler gauges, or more accurately with a telescoping gauge.
See JimD54's definitive Top End Build Up Thread.....here. You'll want to study this thread in great detail. Everything you need is there to do this job.
Info you need is in the manuals.
If you don't have the measuring tools and even if you do here is what I would suggest having done this this spring......
1) Take your cylinders to a trusted machine shop so they can assess and measure them and tell you what can be done and what you need to buy in terms of pistons and rings size.
2) Then order your new pistons and rings based on their recommendations.
3) Then take your new pistons and rings and cylinders to them to machine as required. I would suggest you take your head as well so they can deck the head and cylinders in addition to the cylinder bore machining and honing.
They will want your new pistons when doing the re-bore. If they are cast pistons they can be fractionally different. Talkin' thou's here.
Good luck with your rebuild and keep asking questions. No such thing as a silly question if you've done some research and you're not sure.
See JimD54's definitive Top End Build Up Thread.....here. You'll want to study this thread in great detail. Everything you need is there to do this job.
Info you need is in the manuals.
If you don't have the measuring tools and even if you do here is what I would suggest having done this this spring......
1) Take your cylinders to a trusted machine shop so they can assess and measure them and tell you what can be done and what you need to buy in terms of pistons and rings size.
2) Then order your new pistons and rings based on their recommendations.
3) Then take your new pistons and rings and cylinders to them to machine as required. I would suggest you take your head as well so they can deck the head and cylinders in addition to the cylinder bore machining and honing.
They will want your new pistons when doing the re-bore. If they are cast pistons they can be fractionally different. Talkin' thou's here.
Good luck with your rebuild and keep asking questions. No such thing as a silly question if you've done some research and you're not sure.
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+1 on the above XSRocket. I’d just take the barrel and your existing pistons and rings to the shop and let them tell you what they think.
In general, you’d like to not bore to more than 1st oversize unless you have to. Once the cylinders are cleaned up to a proper size (ie. 1, 2, 3 or 4th oversize depending on the depth of any gouges or the degree out-of-roundness the shop finds), then you order the pistons and rings - and let the shop check them against the bores.
As Robin says, in the meantime, the shop can deck the head (make sure that the sealing surface is flat) and they can check the valves and valve seats to make sure they are clean and smooth. They’ll also install new valve guide seals (very important to prevent oil consumption) and check the valve springs.
After all the machining and othe specialty work is done, assembling and re-installing the engine is not too daunting.
If you’re going to do this, you might as well do it properly so that your engine runs well, is reliable and lasts.
In general, you’d like to not bore to more than 1st oversize unless you have to. Once the cylinders are cleaned up to a proper size (ie. 1, 2, 3 or 4th oversize depending on the depth of any gouges or the degree out-of-roundness the shop finds), then you order the pistons and rings - and let the shop check them against the bores.
As Robin says, in the meantime, the shop can deck the head (make sure that the sealing surface is flat) and they can check the valves and valve seats to make sure they are clean and smooth. They’ll also install new valve guide seals (very important to prevent oil consumption) and check the valve springs.
After all the machining and othe specialty work is done, assembling and re-installing the engine is not too daunting.
If you’re going to do this, you might as well do it properly so that your engine runs well, is reliable and lasts.
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These budget piston sets have been getting good reviews.
http://www.xs650.com/threads/cheap-piston-sets-on-ebay.26971/
However, advise the machine shop that they're only available in 2nd and 4th over.
http://www.xs650.com/threads/cheap-piston-sets-on-ebay.26971/
However, advise the machine shop that they're only available in 2nd and 4th over.
