engine piston check
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Just a quick dumb question: when you order pistons they have a size listed such as ø56.5 mm.
Is that the diameter of the piston, or the cylinder hole it is supposed to go in?
If it is the diameter of the piston as I suspect, how much larger should the cylinder diameter be?
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Just a quick dumb question: when you order pistons they have a size listed such as ø56.5 mm.
Is that the diameter of the piston, or the cylinder hole it is supposed to go in?
If it is the diameter of the piston as I suspect, how much larger should the cylinder diameter be?
@Hark_Ptooie yeah its the diameter of the piston, the standard is 56.00mm if you get a bigger one you need to rebore the cylinder so that piston can fit
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@Hark_Ptooie yeah its the diameter of the piston, the standard is 56.00mm if you get a bigger one you need to rebore the cylinder so that piston can fit
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@erion1 i ordered a piston now but im concerned about my rod bearing or crank bearings so im thinking about spliting the cases, so i want to know if the mid case gasket is reusable or do i need a replacement
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Doesn’t have one. It’s just sealant.
The clutch casing gasket? always good to get new ones.
If I’m stuck. I reuse them if they’re in really good shape.. -
Most people recommend Yamabond. It’s a silicon RTV type sealant I believe. I have used Hermatite red without any leaks or problems. I prefer it just because it doesn’t shed ‘worms’ of sealant into the gearbox. Not so important on a 2/ but can be death to a 4/ if it clogs an oilway…
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@Hark_Ptooie yeah its the diameter of the piston, the standard is 56.00mm if you get a bigger one you need to rebore the cylinder so that piston can fit
@erion1 said in engine piston check:
@Hark_Ptooie yeah its the diameter of the piston, the standard is 56.00mm if you get a bigger one you need to rebore the cylinder so that piston can fit
OK, thanks - and what would the appropriate size of the bore be? +0.1 mm? +0.5 mm? +50 µm?
I may need to swap piston in the not too distant future, and motorcycle workshops are few and far between where I live. So it may be that I will need to turn to some car shop and tell them how it should be, because they are not used to this type of engine.
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@erion1 said in engine piston check:
@Hark_Ptooie yeah its the diameter of the piston, the standard is 56.00mm if you get a bigger one you need to rebore the cylinder so that piston can fit
OK, thanks - and what would the appropriate size of the bore be? +0.1 mm? +0.5 mm? +50 µm?
I may need to swap piston in the not too distant future, and motorcycle workshops are few and far between where I live. So it may be that I will need to turn to some car shop and tell them how it should be, because they are not used to this type of engine.
I don’t have my Haynes manual at hand, but the max recommended clearance is in there…
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Okies, thanks!
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Found it! 45-50 µm on the diameter. Wear limit 100 µm
25 µm per side is hella tight.
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Found it! 45-50 µm on the diameter. Wear limit 100 µm
25 µm per side is hella tight.
Kinda pisses you off when your recently ‘rebored’ piston used to rattle back and forwards in the barrel, doesn’t it?! I had the same experience buying a REBORED barrel & piston.
I’m very particular about who does my rebores now…
