Caution do not rebore the cylinder?
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Caution do not rebore the cylinder?
G'day all,I was just thumbing through the manual ('91 TY 250 R) of my bike reading bits and pieces when I came across this warning with regards to the cylinder.It staes 'Score marks-repair or replace,use #600-800 wet sand paper' and then the caution.So,if one needs to rebuild at some stage what do you do with regards to a new piston etc?
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brt650
- A grade participant
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- Joined: Sat Oct 04, 2008 5:28 pm
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- Bike: Bultaco 350 Sherpa T
- Location: Newcastle NSW
Re: Caution do not rebore the cylinder?
Hello Banshee,
Sounds like the engine has a "chrome" bore or Nicasil. Not cast iron as is usual in older engines. It's very hard and virtually non wearing. It can get damaged on a major engine failure.Like big end /main bearings metal going up and getting between the piston and bore. But generally it's fine.Just needs to be cleaned before fitting a new ring and/or piston kit. Because it doesn't wear much, a standard size piston is all you would need.I don't know for sure in this case, but specialist piston manufacturers make piston's in very small increases from standard to take up this minimal wear. Check for instance a 2002 Suzuki RM250 . It has about 4 different sizes for the same bore size from ProX pistons. Std + .001mm increases . I copied this from the Pro X website;
ProX pistons for Nicasil/plated cylinders
The latest cylinders are plated by a Nicasil plating. Therefore we offer a wide range of PROX pistons in standard size, as well as in A, B, C, D+ oversizes.
A-D sizes are the variances in size from the manufacturer.
I hope this helps.
Cheers
brt650
For more reading you can check out there website http://www.pro-x.com/pistonkits.asp#pistonkits
Sounds like the engine has a "chrome" bore or Nicasil. Not cast iron as is usual in older engines. It's very hard and virtually non wearing. It can get damaged on a major engine failure.Like big end /main bearings metal going up and getting between the piston and bore. But generally it's fine.Just needs to be cleaned before fitting a new ring and/or piston kit. Because it doesn't wear much, a standard size piston is all you would need.I don't know for sure in this case, but specialist piston manufacturers make piston's in very small increases from standard to take up this minimal wear. Check for instance a 2002 Suzuki RM250 . It has about 4 different sizes for the same bore size from ProX pistons. Std + .001mm increases . I copied this from the Pro X website;
ProX pistons for Nicasil/plated cylinders
The latest cylinders are plated by a Nicasil plating. Therefore we offer a wide range of PROX pistons in standard size, as well as in A, B, C, D+ oversizes.
A-D sizes are the variances in size from the manufacturer.
I hope this helps.
Cheers
brt650
For more reading you can check out there website http://www.pro-x.com/pistonkits.asp#pistonkits
Re: Caution do not rebore the cylinder?
Thanks Mate,that helps a lot.Mine is a little bit rattly but sounds like I shouldn't have to sell the first born into slavery to afford a fix when I decide to go ahead (famous last words),which should be sooner rather than later I'm guessing.Again thanks for the input.