dave dix Posted March 24, 2009 Report Share Posted March 24, 2009 Hi, does anyone know the differences between the two as i am after an o/s piston for a 247 montesa and as bultaco pistons are more common i was hoping they may be interchangeable without too much trouble, Are the small end bearings the same size (piston pin same size ) and the same height. I can always more the ring pins if needed Dave Quote Link to comment Share on other sites More sharing options...
woody Posted March 24, 2009 Report Share Posted March 24, 2009 Don't know about Mont/Bult piston similarities but there is someone selling Mont pistons on ebay UK at the moment, item number 120396701665 for what could be a 72.5mm Cota piston 72.50 may be standard size, can't remember but if it is it may be worth contacting him to see if he has others as he has a lot of Mont stuff to sell which is NOS, although you may need to give him the part number. I got a 247 Wiseco piston from Jared Bates at Southwest Montesa in the US. It takes a different small end from the standard type but he can supply that too. Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted March 24, 2009 Report Share Posted March 24, 2009 I was pretty sure they were different probably both made by mahle though? Quote Link to comment Share on other sites More sharing options...
dave dix Posted March 24, 2009 Author Report Share Posted March 24, 2009 Thanks woody, i have already contacted him but no o/s pistons as of yet, it was a bult piston he has that looks like it may fit but i'm not sure on wrist pin size and pin height etc. O/S doesn't matter as it can be re-bored to size Dave Quote Link to comment Share on other sites More sharing options...
cotacrazy Posted March 25, 2009 Report Share Posted March 25, 2009 Ive put a 238 bult piston in a mont 242(having put a steel liner in the barrel) and the the gudgin pin /little end bearings were the same.as was the skirt height.Just had to drill 2 holes to match the origional for the small transfer grooves in the back of the barrel.Given this i would think that a sherpa piston might fit a 247.might be worth giving the cota piston dimensions to Dave Renham to see if he could match a piston up? Quote Link to comment Share on other sites More sharing options...
wayne_weedon Posted March 26, 2009 Report Share Posted March 26, 2009 Have you tried contacting Kevin Breedon? Seems to have a lot listed, never dealt with them though. http://kevinbreedonracing.co.uk/products_pistons.asp Quote Link to comment Share on other sites More sharing options...
spokerider Posted March 27, 2009 Report Share Posted March 27, 2009 I know it's not what you're asking, but..........perhaps you could locate a standard sized new piston and have the cyl resleeved? Would cost some $$, but'll get you back on the trails...... Just a thought. Quote Link to comment Share on other sites More sharing options...
dave dix Posted June 20, 2009 Author Report Share Posted June 20, 2009 I did get a bultaco o/s piston and bored the barrel to suit and it runs fine Dave Quote Link to comment Share on other sites More sharing options...
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