OK so I have bought some 916 cylinders in good condition apparently. I have sent them to my dad in the UK for the moment. What I am now looking for is a supplier in the UK for pistons to suit the 748/853 conversion. Anybody any recommendations of suppliers? Also I will likely be getting the cylinders replated ,I was looking at poeton in Gloucestershire as its near my parents. Anybody any experience of them or somewhere better?
I always use pistal pistons mate there top draw. had two 853 engines built now great engines Chris at louigi moto built the first one so it might be worth giving them a ring to get the machining work done.
Just looking at buying the pistons etc to get the barrels plated to suit as I will be shipping the parts out to Australia and getting the engine built by an expert.
This may be an easier alternative. No modification required unlike going the 916 barrel route. https://www.speedycom.co.uk/shop/home.php?cat=640
My understanding is if I use 916 pistons with 916 barrels then the barrels will require approx 2mm machined off due to the shorter stroke. But if I use 853 pistons designed for them the gudgeon pin hole has been moved to account for the shorter stroke and no machining is required.
I fitted an EVR 853 conversion kit but still needed to machine about a millimetre off the flange to get the correct "squish". Fortunately I had an experienced engine builder put the engine together. Andy
That is my understanding too. As the 748 stroke is shorter the piston is 'higher' to keep the same overall cylinder length (and use the same belts) so using a 916 piston sits too low and whilst you can machine the bottom of the cylinder, you may then have problems tensioning the belts - I had 1mm skimmed off the heads of my 916 to up the compression and needed larger fixed pulleys to take up the slack but 2mm might be too much?
OK. Who is my most likely option to get the pistons from for the 853 in the UK as I understand I will get charged import now for anything sent from outside the UK .
There were a lot of threads a few years ago about the conversions. One other thing is that 916 pistons are heavier and their use may require the crank to be balanced again whereas after market Pistons weigh about the same as standard 748 pistons
I'm thinking aftermarket (853)and not 916 pistons so as to avoid machining the cylinder height and from what I have read they are mostly lighter than standard 748 ones also.
So a quick search on the internet only throws up the EVR conversion kit. Sigma don't seem to do one and I can't remember when I bought my kit 2 years ago if there were any other options to the EVR kit. Andy
The only people I have found that supply the pistons is FBF(fast by feracci) and these are approx $400 US and obviously shipped out from USA.
Sorry this may be of no help, I have just had a look at my 853 build sheet from JHP and it states ( JHP big bore 94mm barrels for 748R-853 ) these were used with high compression 853 pistons, just my thoughts but if standard 916 barrels were ok with 853 pistons wouldn't it say that on the invoice. Steve PS It might be worth ringing JHP to see if they can still supply the pistons.
I'm lead to believe the 748r barrels have the stud holes in a different position to the standard 748 and also the r has the fancy conrods which I think are slightly wider at the small end also . But every bit of info helps for sure. I can buy a kit here for approx $2000 ish but seems a bit OTT for 2 barrels and 2 pistons ??
