March 31, 200917 yr This may have been coved before but I can't find the thread. What's my chances of having a 125 cylinder bored out and using a 200cc piston? Best of balance. Neo
March 31, 200917 yr i thought that these barrels were nicasil lined? if that is the case i would have thought it would be cheaper ( and better) to buy a 200 barrel and head. you could always sell your 125 stuff on ebay to ofset the cost.
March 31, 200917 yr They are nicasil lined, well some kind of coating anyway. I wouldn't have thought that would matter the biggest problem will be if the ports are the correct size and shape, there is defiantly enough material there, the 125 barrels are very thick and surprisingly heavy too.
March 31, 200917 yr You have to de-nicacil first, then bore and re-nicosil as you cannot bore plated liners as its too hard Dave
March 31, 200917 yr Author Thanks for the info gents....did realise that nicasil stuff was so tuff. Looks like I'll postpone this idea for now and buy a 200 cylinder at a later time. Hi Cope....did you say in a past post that you'd fitted a 250 cylinder to a 125 gearbox? Best of balance. Neo
April 1, 200917 yr Thanks for the info gents....did realise that nicasil stuff was so tuff. Looks like I'll postpone this idea for now and buy a 200 cylinder at a later time. Hi Cope....did you say in a past post that you'd fitted a 250 cylinder to a 125 gearbox? Best of balance. Neo Not me, not possible as I know. The Beta is the only one I know of that shares a common stroke with the 200 and 250 and may interchange. The problems mentioned would prohibit a rebore.
April 1, 200917 yr Thanks for the info gents....did realise that nicasil stuff was so tuff.fitted a 250 cylinder to a 125 gearbox? It is hard but it could be ground out or I bet there is some chemical that will dissolve it away but leave the aluminium intact, I've got a feeling the replaters have to remove some (if not all) of the coating before they replate. The new Gasgas 225 is just a cut down 250 barrel on a 125 bottom end.
April 2, 200917 yr Neo, From what I have read on line it is pretty common to recondition coated cylinders that have been damaged, in the MX world. It is also possible to increase the displacement of many 2 and 4-strokes by removing plating, boring oversize, re-plating, and fitting a larger piston. A few years back I had the displacement of my Yamaha YZ125 upped to 144cc by Eric Gorr. If I remember correctly the bore was increased from 54mm to 58mm using the stock cylinder, and a commonly available aftermarket piston. This engine also has variable exhaust port timing (complicating the modification) so the power valves needed to be cut to fit the new cylinder size. This wouldn
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