Hi all, I am planning to change my base gaskets on my '97 748 bip over the winter and thought it might be an idea to upgrade to a 853 while I am in there. After searching for 916 barrels and pistons, can anyone confirm what the differences are as I have found a set that are called '916/748SP', what is the difference between my 748 ones, I assumed its the piston diameter? And will I need to consider any other parts, can I use my 748 heads etc? I know there are kits available but I am on a very limited budget so they will have to be second hand barrels with new head and base gaskets. So to summarise, are the 916 pistons/barrels the right parts and what else would I need for the job? Having tried an 853 recently, I love the revvy nature and beefed up midrange, rather than swapping the entire lump for a 916. And yes, I am making more work for myself but it will be a little bit special! Cheers for any guidance
Barrels are ok from 916 but pistons are specials , the height from the little end to the top of the piston is different to compensate for the different throw in the cranks. Heads should be ok. Steve And don't forget it will need a different chip for the ecu. Just ordered one for mine from JHP.
Or you machine the 916 barrels.... Trouble using 916 pistons is the weight. It really needs a crank balance. Drop in kits usually match 748 piston weight using better quality pistons. That's the route I went with my kits a few years back and the way many others have. tbh, if your doing the labour yourself, there's not a lot in it between using decent pistons and getting 748 barrels bored out vs. used 916 parts and getting them to work. Factor a crank balance in and there's no contest.
Hasnt Mike aka cranker v2 got a whole kit for sale? edit; http://ducatiforum.co.uk/f20/748r-853r-bigbore-kit-5183/
I have a feeling that this will still be too much £££££ but only one way to find out I guess.... Thanks for the guidance though chaps, greatly appreciated
When I did mine I picked up a set of used 916 bores for £100. I then acquired a set of DP 853 pistons for £450 as they are apparently a straight drop in........ However whilst it would have run, the squish was way out. Had to machine 1mm ish of the base of each cylinder to get the squish correct (1.0mm squish). This of course messes up the valve timing and the desmo doesn't have adjustable cam pulleys so setting it correct becomes a pain messing about with offset keys. The bike runs well, however I wish I had had the crank balanced. Maybe a job for the winter. Good luck.
This is worth a read. 748R We did an 853 conversion to a 748R late in 2008 – the first 853 kit I’d been involved with. Funny how it’s a popular mod in lots of places, but not Melbourne, Australia. We used Pistal pistons, the specific 748R ones as the 748R uses small end located Titanium rods. If you fit normal 748 style pistons meant for big end located rods the rods are not held at either end and can move sideways on the crank up to just over 2mm. Chris @ CJS said he pulled apart a 748SPS (Ti rods) that someone else had fitted with std 748/916 big end located rod pistons and although it had good compression, it had a heap of blowby when running and was a bit of a dud. Correct small end located pistons fixed it. The big end located rod pistons have quite a bit of side clearance between the piston and rod at the small end – usually 1 to 3mm depending on the piston manufacturer. Whereas small end located rod pistons have about 0.40mm side clearance. Full report here, BikeBoy.org - Ducati 853, R and Stuff Steve.
I've got a pair of 748 cylinders in my workshop if you want some to bore. I got them when I had my 748 as I decided to go down the pistal piston route instead of messing about with 916 stuff. I never got around to it though! Pm me if you want them, they've even got stock pistons not that you'll need them!
