local guys says CRM cylinders cant be rebored?

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fishtail
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local guys says CRM cylinders cant be rebored?

Post by fishtail » 27 Jul 2012, 12:47

Might be a HK thing?

but I think my bike is actually a Jap import,, ( 96 mk3 )

havent taken the head of yet - just pricing it all up

but he reckons that CRM heads cant be rebored?

is this true of some models?

( if you read my other woes - I might just be after a whole new engine at this rate! )

anyone got any comments?

cheers!
1996 CRM 250 "Mk 3" FMF pipe .... - the other 'un is a 98 hornet 600 - Sai Kung Hong Kong

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Re: local guys says CRM cylinders cant be rebored?

Post by SkidMark » 27 Jul 2012, 16:36

AR's have a nicosil coating that has to be redone if rebored but I don't think MK3's have that.
AR's rock!!!
TwinAir filter, Braided Brake Hoses, Swingarm/Shock bearings done!, Rear Shock overhauled and customised by G-Force, 14-44 Gearing, Exhaust decoked (fun with Caustic Soda!), DEP silencer.

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Re: local guys says CRM cylinders cant be rebored?

Post by knackeredMk1 » 27 Jul 2012, 17:42

Mk1, 2 & 3 can be rebored as have iron liners. AR is as Skidmark says.

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Re: local guys says CRM cylinders cant be rebored?

Post by fishtail » 30 Jul 2012, 16:32

thanks for the confirmations!

is there any benefit to taking the bore up the max? - ( was it 67 or 68 mm? ) ( more power? )

I'm going to have a month of doing this I think/hope starting in about 2-3 weeks...

I'm also planning to pop back to the UK in september 8-) probably for 10 days -2 weeks..

( anywhere I can hire a CRM? - would love to do some greenlanes when I'm back!!! - I'll be staying near Donnington ;) )
1996 CRM 250 "Mk 3" FMF pipe .... - the other 'un is a 98 hornet 600 - Sai Kung Hong Kong

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Re: local guys says CRM cylinders cant be rebored?

Post by knackeredMk1 » 30 Jul 2012, 18:53

You can get a bit more power by boring out to 68mm but is it worth loosing the ability to rebore if you have a problem :?: .

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Re: local guys says CRM cylinders cant be rebored?

Post by Jeram » 20 Dec 2012, 21:18

Just for the record, the AR can be rebored. you send it to a specialist such as Millenium with your new piston.

for 200 dollars plus they will bore it and plate it for you.
For a little extra, eric gore (whom is now part of millenium) will port it for you while its there.


Also for those of you wanting to overbore a steel liner to the maximum but are worried about not being able to overbore further in the future?
There is a very simple fix for this, you simply send your cylinder to millenium again as ask them to bore our your steel cylinder and nikasil it.
In the event of a seizure your bore will be perfectly fine if you run cast pistons, but in the event of a catastrophic failure where the nikasil is chipped or damaged you just box it up and send it straight back to millenium and they will take the nikasil off and reapply it.

Just make sure you get a set of Nikasil friendly rings to put in your piston.


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