916 Pistons in a 748....
 

Has anyone ever put 916bp pistons into a 748 Bp. Can it be done...?

it can be done but you need 916 barrels too, if its done right you'll get something like 853/855cc, John Hackett does a chip too. If you really want it doing well have a chat with Nelly (Cornerspeed) as he's just doing his second 855cc big bore this time on his own 748.

Or try Neil at Sigma Performance. There's probably something about it on his website - I haven't looked - or give him a ring.

If you just stick 916 barrels and pistons on a 748 bottom end you will end up with a comp ratio of abut 4:1 as the piston is too short.

To make it work with 916 cylinders you will need the specific 853 piston which are longer to accomodate the 748 shorter stroke.

As Dukerob says speak to Nelly, he has had his own pistons made up and he also bores out and replates the 748 barrels. Nelly's kit is 855cc.

You can use 916 barrels and pistons but you need to deck the barrels by 2mm and then the bottom end will need balancing due to the pistons being significantly heavier.

Sigma's, and my own solution is to use bespoke pistons that weigh the same as stock so the bottom end is left well alone.

Or simply buy a 916!!!:D:D:D:D

but how many 916's rev to 12000 :devil: :smug:

Ratler

Your being sensible, now stop it!

Allo,

I had my 748 turned into a 853. Neil at Sigma completed the work. The 853 pistons weigh the same as standard 748 ones so no need to re balance the bottom end. My bike still revs to 11500 and makes the same power as a 916. So best of both worlds:roll: Its a hoot to ride too!!!;) Hits 160 no problem. On private roads of course!!

I thought that if the 916 pistons were fitted then the crank cases would have to be opened out??

DC:cool:;)

[Edited on 12-8-2004 by DC]

[Edited on 13-8-2004 by DC]

nelly ,
ive got a 2001 748 and a box in the celler with 916 sp heads barrels and pistons in is it realy that easy? willl it fitt!!! as i was thinking of selling the 748 and buying a 916-996 , this sounds like a better solution to me ............. nat

Yep. Pretty much is that "simple" ;)

DC, the cases don't need any work. 916 pistons are the same diameter as the ones Sigma fitted in your motor. They're heavier though hence the bottom end'd need balancing, and you'd more than likely inherit the 916's rev limit.

Nat..........you've got all the ingredients to do the job, basically you'd just need the balancing done on the bottom end and the barrels machining to compensate for the differing piston heights. Ducati Kamna are in Germany and have the info/parts on their site. Look like they know the game. Maybe worth a call??

thanks Nelly,
would i be better off with the different pistons and leave the bottom end,
only asking as the standing cylinder base gasket has started to leak and needs the lot taking off and re sealing ......a nice swop and power increace would take the pain out of it. if you know what i mean.

IMO yes. I'd go for lighter pistons and get the barrels decked.
It would definately take the pain out of having to do the job :devil:

I thought Ducati did an "official" kit. Is this not the case?

allo Nelly,


"DC, the cases don't need any work. 916 pistons are the same diameter as the ones Sigma fitted in your motor. They're heavier though hence the bottom end'd need balancing, and you'd more than likely inherit the 916's rev limit."



Perhaps I am getting confused with 955 pistons and the size etc.
;)

What about the idea of fitting some hotter cams from the 748R or SP. Also, I have always fancied putting 916 injectors on if they would supply more go juice!!:devil:

DC.

DC, it is the 955 kit you're thinking about..........unless you have a 916SP.
The SPS or R cams would go in OK. You may/may not need to machine the piston pokets, but you'd fuel it OK with an eprom change. I'm 95% sure the injectors are the same.
No need to swap them for the 855 motor I'm building, even with big valves and a gas flow :smug:
The 916 throttle bodies are 50mm whereas the 748 are 45mm downstream of the butterflys. I'm thinking of taking those out to 50mm or swapping for 916 items :puzzled:

problem with fitting SP pistons is they have 21mm gudgeon pins and also barrell have 100mm skirt into crankcases because if you fit a 955 kit to a SP you dont have to machine crankcases out unlike 916BP

Nelly,

I must make the trip up to see one day.:devil: I feel a winter engine mods list coming on!!!!;):devil:

DC