Makita Piston
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I wouldn't assume anything. Checking the ring gap will take you 60 seconds per ring.
It's literally just placing the rings at the top of the bore. Use the piston to push it a few centimetres in and making sure it's square. Then using a feeler guage to measure the gap where the rings butt. It should reside within tolerance.
I find the Wossner ones always supply one ring out of spec. Presumably so you can fine tune it yourself.
Do that for both rings make sure they are tip top. Then whack them in and away you go.
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I wouldn't assume anything. Checking the ring gap will take you 60 seconds per ring.
It's literally just placing the rings at the top of the bore. Use the piston to push it a few centimetres in and making sure it's square. Then using a feeler guage to measure the gap where the rings butt. It should reside within tolerance.
I find the Wossner ones always supply one ring out of spec. Presumably so you can fine tune it yourself.
Do that for both rings make sure they are tip top. Then whack them in and away you go.
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Hey Calum, where can these tolerences be found? I suppose its in the service manual? I dont own a manual but maybe its time i pull the trigger on one
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Yeah. Mitaka. I called it something entirely different in the thread title and edited it to Makita. How embarrassing?!!
The barrel and piston have just come back from PJME so I trust the tolerance, ect. The barrel is a 3MB and it says TZR on the piston box. I’ve never had one like this before but I have seen them online in pics, ect.
The piston that was in before was a wossner. Both the rings looked identical, so I don’t really know what to make of it all. Just want to get it right, what with being the sixteenth ‘registered’ owner. I feel I have a duty of care for the old plodder
@SpookDog ive installed one and left one out can’t remember which bikes but the dt probably has one and I’m sure I tried one with and without on an am6 engine and it appeared to make no difference I don’t actually know what it’s for most people don’t install them.
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@Arild 0.30 - 0.45mm you'll want a decent small file. And only file inwards towards the centre of the ring. I hold the file in a vice and slide the ring along the jaws of the vice to help keep it all square as well.
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Soooo, it’s an expander ring, for bores that have a bit too much clearance. Goes behind the thinner ring, on the bottom of the piston. Not recommended to be fitted if you have a nice tight fresh bore...
Got an email from PJME -
@Calum that was a cold engine aswell! That's with +1mm over bore. Running a mick abbey modded head. Which is quite a few cc's less volume than stock 3mb.
Runing two base gaskets and a spacer plate now. To lower the compression which has also raised the port timing. I miss the heaps of midrange but not the bruised foot from kickstarting it lol. -
@declan
Sorry, didn’t mean to offend. Plus I gave
up a looooong time ago! 
In all seriousness, I’d like to know what the cc of a 3MB head is? Mine had to be reprofiled to get rid of piston ring explosion marks and I’m not sure if it was skimmed to the point that it kept the same compression ratio
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@declan
Sorry, didn’t mean to offend. Plus I gave up a looooong time ago! In all seriousness, I’d like to know what the cc of a 3MB head is? Mine had to be reprofiled to get rid of piston ring explosion marks and I’m not sure if it was skimmed to the point that it kept the same compression ratio
