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Piston Kit


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I need to get a piston kit for the Bultaco Sherpa T 250 1976. (Engine number 19000***)

Including postage costs these are the prices I have found so far for the kit:

In Motion = £180

Feked = £185

KBR = £168

And from the USA at around = £130

But before I go ahead and buy one, probably from the USA Bultaco spares people, can any of you guys recommend somewhere?

Or a piston that will fit, not necessarily a Bultaco badged piston kit, just the right sizes? There may be a common piston that people fit, that I don't know about?


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Model 80 makes a good point,I recently bought a piston off Ebay from a seller in Texas, I had to pay £66 to Parcelfarce for handling and customs costs. Same deal when I buy parts from the US for my Chevy pickup, it can almost double the cost of the parts...

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I’d use (and have used) the reputable dealers as mentioned above..... but when possible always purchase an original mahle piston if available through these dealers.  They may cost more but are worth every penny.  

Without opening a huge debate; simply stated the wiseco brand pistons are very finicky to use.  Because they are a forged piston they expand very quickly causing cold seize issues.  When the cylinder is bored to fit the cold clearance needs to be in the neighbourhood of .004”.  You can drive a truck through that !!! A stock mahle piston when new is .0015-.002 when cold.  Much tighter clearance.  Wiseco has a reputation of “making more power “ or being high quality.   In 25 years of working as professional motorcycle mechanic I’ve never seen a wiseco 2 stroke piston that hasn’t seized.  No matter the set up they will always scrape a little bit.  But due to their lightness they probably would make more power (less reciprocating mass) 

 If you’ve been lucky enough to use one of these pistons without issue then you are the exception and not the rule.  As the NOS pistons become more and more scarce we are all looking for decent alternatives.  And the use of wiseco pistons in the bultaco is becoming more and more prevalent as they are the only source we have for new parts.  Just be very very careful with initial set up.  And always warm the engine fully before riding to prevent cold seizures.  

Import duty and tax would play a role for me.  If you have to spend more to buy local then do that.


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The Italpart pistons that In Motion stock have the advantage of using stock Mahle/Bultaco rings so that is great. I have a Wiseco in one of my Sherpas and it has been in there for about 3 years now and it is still going fine with no hassles. I have changed the rings once in that time and they were less worn than the wear limit. Graham.

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Dinamin became GPM, and both are now no longer available, as far as I know.

I have no personal experience of  Wiseco , but read lots of bad reports from users Stateside.

The original Mahle pistons always were and probably still are, the ones to go for, but are now almost totally unobtainium.

Most, if not all currently available new pistons are Italkit , I believe (but I also have no personal,etc.....) 

yamanx - the first question any supplier will want answered is "what size ?"  ( "Bultaco Sherpa 250T" could be 71mm. - 73.5mm. depending on year and 


Other opinions are available........


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