748 4V Monster?

[Roscoe]

Is it possible to fit a 748 motor into an early Monster frame? I know the rad mounts would need to be fitted, and of course the obvious such as the electronics and FI. But will the motor physically fit? The 916 is in the S4, but I recently read that the SBK 916 motor is different. I imagine the difference is where the swingarm mounts.

Any input on this would be great. I'm thinking 853 powered monster...

[Pedro-bot]

Is it possible to fit a 748 motor into an early Monster frame? I know the rad mounts would need to be fitted, and of course the obvious such as the electronics and FI. But will the motor physically fit? The 916 is in the S4, but I recently read that the SBK 916 motor is different. I imagine the difference is where the swingarm mounts.

Any input on this would be great. I'm thinking 853 powered monster...

Anything is possible with some work. However, my understanding is that the S4 heads are shorter than the that of the SBK it shares the same engine with. The horizontal head may give you the most clearance problems. If you were able to fit that engine without the clearance issues I would imagine you could simply use the S4 or S4R monster radiator.

The other issue is the swingarm. I imagine you would have to use a '02 or newer frame to easily bolt the suspension shock linkage/pivot, but you would need a set of rearsets that could brace the swingarm and the frame somehow.

You can't use the Monster SSS since the engine casing is trimmed on the 748 and 9*6 motors.  The case is  too narrow at the point where the swingarm bolts. It would have to be a SSS from a SBK.

The easiest solution in my opinion is this:
Buy an S4 or S4R (not Testa) engine and have the 748 853 kit installed. With some sleeves in the engine you could down size the displacement to the 853 your' looking for. You would actually be taking performance away from the motor but hey, you get what you're after; A 748 4V Monster. 

[Roscoe]

The other issue is the swingarm. I imagine you would have to use a '02 or newer frame to easily bolt the suspension shock linkage/pivot, but you would need a set of rearsets that could brace the swingarm and the frame somehow.

You can't use the Monster SSS since the engine casing is trimmed on the 748 and 9*6 motors.  The case is  too narrow at the point where the swingarm bolts. It would have to be a SSS from a SBK.

The easiest solution in my opinion is this:
Buy an S4 or S4R (not Testa) engine and have the 748 853 kit installed. With some sleeves in the engine you could down size the displacement to the 853 your' looking for. You would actually be taking performance away from the motor but hey, you get what you're after; A 748 4V Monster. 

I see the conflict of the sss on the older frame. But do you NEED to brace the swingarm to the frame with rearsets? The dss doesn't have anything. Anyone here done a SSS on the early frame?

And as far as sleeving down an S4 motor, that would defeat the purpose of the 853. Remember, it's not just smaller bore, it's shorter stroke, meaning quicker rev's. Some people say the 853 kitted 748 is an ideal setup, better than the 996.

Maybe the shorter stroke means the cyl./head combo is shorter, in turn more room around the vertical cyl under the tank?

Or maybe I'm just chasing my tail... I should just buy a wrecked 748 and "Monsterize" it, but thats too easy.

[Speeddog]

SBK SSS linkage is in a different spot compared to ST-style Monster frames, so you would have to modify the rocker mount.
Different from early-model frames as well.

748 engine does not have the low-cam heads, AFAIK, so it will be very tight clearance to the front tire on full bump on ST-style frames, likely worse for early model frames.

You're on your own for mounting the battery, ECU, and airbox.

You would need a SBK wiring harness to start from, and be prepared to mod it significantly.

Unless you're fitting it to an S4 frame, there will be issues with frame crossmembers interfering with the throttle bodies.

Probably about 10 other things as well.....

[ghostface]

Just buy a 4 valve monster.

[MotoCreations]

I'm a big proponent of custom built Ducati's.  But putting a 4V 748/853 into a 2V/4V Monster chassis gets you nothing uniquely different for all the work involved -- Ducati has already built it and built many of them.

I think a nakid 748/853 w/SBK frame would be more unique and easier to build as well.  Nobody has done a really cool one to date so far with a radiator assembly and the bodywork removed. (there is the 2V aircooled into SBK frame that was unique on www.DucCutters.com)

One thing to think about is given your watercooled engine is to use a smaller than stock radiator.  Just use two better quality fans and run constantly with shrouding to move the air.  The factory radiator is designed for passive airflow while riding and supplemented by fans at lower speeds.  Do an underengine exhaust ala my BoomTubes style and then package the radiator / fan assembly beneath the SBK seat area itself?  (there isn't enough room on a Monster frameset to put there properly)

[brad black]

i don't buy the short stroke revs faster thing, but then i don't think the bore/stroke ratio for a given capacity makes much difference either.  any 916 will be faster than an 853 with the same attention to detail spent on cam timing, squish, tuning, etc.  and a 996 faster again.  but the bigger the capacity the lower the peak power rpm and i think it's this that many mistake for a feel of slow revving.  it's just about greater capacity under similar heads giving a flatter torque curve peaking earlier and the feeling that gives at your arse.  i've made a few 748 feel rather boring at higher rpm with cam timing changes because the torque peaks earlier, but they're faster.  and the 1026 i did revved like crazy.

some people just like to rev things i think, and that's where it comes from.

back to the question - yes you can do it, but it's a heap of work.

[weemonster]

folks built 916 monsters long before ducati made the S4. I talked to a guy about 10 years ago who had made one and he said it wasn't that difficult and that he didnt to anything that wasnt reversible.
A sbk engine is narrower than a 2v.  you need to machine the casing of the 2v to fit a sbk swing arm.

Therefore you'd need to shim a double side monster swing arm to fit a sbk engine.

[Roscoe]

Thanks for the replies. Although I dont have any immediate plans for a major build, my gears are turning. I just thought an 748/853 monster might be a little different than all the S4/S4R/S4Rs bikes I see.
Brad, I see your point on engine size, bigger is usually better. But then again, why not? And if that were the case, why was the 748 made in the first place? Oh, and I like your website, Lots of useful info.

I think for the work involved though, esp. with the airbox/battery box/ECU/FI/wiring, etc, etc, I might as well find an S4 with a blown motor and do the easy swap, or just make a naked 748.

MotoCreations, you have some very creative bikes utilizing the SBK motor, and the air cooled as well. Maybe sometime soon I'll have to swing down and check you out. I'm just north of Seattle so it's not that far.

In another direction, I do like the idea of an air cooled motor in a SBK chassis. Maybe a 1000DS or even the 1100DS. My friends Hyper is a hoot to ride...  (DucCutters bikes are SICK!!)

[brad black]

the 748 was built as a supersport race base, plus it mean they could sell a cheaper (less profitable?) version of the 916 to increase sales of what is basically the same thing.  the original 4v desmoquattro motor was a 748 too, but by the time they got to production they were racing 2v motors at 851cc in the F1 chassis so they made the 4v 851cc.  then they stroked the 2v to 68mm to create the 904cc 906 motor.

my main point was - you can buy a 748 or a 916, but to make an 853 you need a 748 then you buy 853 pistons and get cylinders bored and it's not cheap.  and you can buy a 916 already in a monster.  they all respond the mods the same way and they're all undervalved.  like the 748 motors the s4 has the close ratio gearbox too, which also changes the way the motor feels.

but if you want to fiddle, go for it.  as always, someone's simple is someone else's make the beast with two backsing nightmare - there was a guy on the old list who gave up and parted out a 750 to 916 monster when he just couldn't sort running issues that may have been nothing to do with the application per se.  so it depends on you more than the task at hand.

the main 2v - 4v issue is the cross member that runs across the top front of the vertical cylinder.  2v bikes are straight and the inlet goes under it, 4v bikes are bent in a v and the inlet goes over it.  the only chassis without stuff in there is the ss, but the section over the vertical head is far too narrow and low to fit a 4v in.

all the 748 and 916 engine cases are the same, and all the non 748/916/996 engine cases are the same - 900, st2, st4 and s4, so you could just use 900, etc cases and fit the 748 bits into them.  the 996, st4s and s4r have wider cylinder stud spacing.  that cures the swingarm issue

the very late 748 motors run the same "testa bassa" heads as the st, s4, and s4r series bikes.  but the pre '02 2v monsters are 888 based anyway, so a normal 4v motor should give the required front wheeel clearance.  altho saying that the triple clamp offset is 5mm less i think.

you'd have to be able to make a new rear suspension rocker linkage i'd think that would work.  all you need to do is plot out the shock, swingarm and pushrod movement for both and it couldn't be too hard to find the link requirements that work.  that way you wouldn't need to modify the rocker mounting in the frame or swingarm, etc.

if you think the hyper is a hoot then you'd want to ride a 748 before you got too far into it.  the extra 350cc make a huge difference, no matter how many valves it has.