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Discussion Starter #21
Call it a tractor. Say it.

Hint: it pulls with a more or less linear torque curve.

"tractor" say it.

Rob, there is a line for me. Maybe a 1098 engine, but not the 1198.
 

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All the ingredients are there with the combo I suggested, short stroke and big valves. I haven’t been able to get much air over 11k with these heads. I’ve got the 999 heads to make flow to 12k but they run out very fast after 11k as well but don’t drop as fast as the 10/1198. RPM in these heads I don’t know about but I wouldn’t give the cases much time. If they could breath well up to 13k or even 12k without dying I’d estimate between (don’t laugh) 140 to 150 high rpm horsepower. By the way I have all the ingredients for the above combination but other projects get in the way, like my rat CX500 cafe racer.😃
 

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Discussion Starter #24
I'll take that nice fact, Belter. I've not looked into those bikes. But it is the old desmos for me for now or XX9.

I may go with the short stroke but don't have nice cams, just A1s.
 

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i'd say the base 749 has a rather linear toque curve and as such, feels rather boring too. i really don't think you're going to get far with bore and stroke variations when what you're really after is an increasing torque curve. you either need some heads that work very well to make some top end power or old school cams that kill the bottom end.

i'm all for pissing away time and money on bikes, but i think this'll be a dead end.
 

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i'd say the base 749 has a rather linear toque curve and as such, feels rather boring too. i really don't think you're going to get far with bore and stroke variations when what you're really after is an increasing torque curve. you either need some heads that work very well to make some top end power or old school cams that kill the bottom end.

i'm all for pissing away time and money on bikes, but i think this'll be a dead end.
I would agree Brad but I don’t think Johnathan is that worried about that this may be a dead end. Hell, I collected all my parts over the years to do just this. I look at it as a fun learning exercises. We have to spend our money on something so why not on something we enjoy.
I say go for it Namor and enjoy the experience 🤠
 

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i've got a 94.5 x 68 954 here.

i just think all this bore and stroke stuff is not what people make it out to be. there's other components in the feel, not them.

i'd be more than happy for him to prove it one way or the other.
 

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i've got a 94.5 x 68 954 here.

i just think all this bore and stroke stuff is not what people make it out to be. there's other components in the feel, not them.

i'd be more than happy for him to prove it one way or the other.
It possibly isn’t Brad and I do agree as I’ve stated that there possibly won’t be any benefits BUT, the fun is in trying. And you shouldn’t try to dampen our enthusiasm. Remember you were a hot rodder your self.
 

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I'll take that nice fact, Belter. I've not looked into those bikes. But it is the old desmos for me for now or XX9.

I may go with the short stroke but don't have nice cams, just A1s.
I love the superquadro engines, but the 899 and 959 and maybe the 1199 were a little lacking to me in standard form. They all felt very '848' ish in a flat mid range but great top end power. I think my favorite to this point has been the 1098. Great mid range power and fun top end power to boot.

Luckily the class I race the 998 in prevents me from pursuing that swap...finally a way to save some cash.
 

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I haven't been around for a while, but the beginning of this thread is about the cylinder height and/or shimming the cylinders. What bout the belts? Maybe I'm missing something?
In the 'good old days' Ferracci offered 1 mm thicker base spacers for 984 kits.(900SS crank, 968 vs 64mm, 888 bore, 94mm) I can't remember where that extra mm was accounted for, but that 1 extra mm made the front cylinder belt tight (some had belt breakage) How are you going to accommodate shortening the cylinders?
My solution was to have Carillo make rods of the appropriate length difference and leave the cylinders alone. Just add or subtract 1/2 the stroke difference.
And, the Carillos were a only few grams heavier than the Ti rods which are difficult-to-impossible to re-use. That's why Ferracci used to sell you a new set for $3000.
If you're using 999 heads, the S4RS cams are the same as the 999S and those are pretty good for performance.
The problem with going with a shorter stroke, is that it is hard to get compression when you do that, or, rather, you loose compression ratio with the same piston crown.
I built a 900S engine with an 888 crank. Bruce had a set of 12:1 pistons for a 900SS (stock bore) and that gave me a reasonable CR with the shorter stroke. I'm sure he was glad to get rid of them and I was glad to have them. You get torque from compression as well as displacement.
 

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Discussion Starter #33
"How are you going to accommodate shortening the cylinders?"
First post, point #3. Over sized pulleys. I'll keep the belt covers off if necessary.

I am sticking with the 996, so no XX9 parts.

Thanks for the input. For now it's a whole lot easier to increase the stroke. Ultimately, the point of the 999S crank is to use the lighter crank and rods since I've not experiences them in the older bikes. Per original post, take logic out of it what i am may do.

But, I have a line on some Carillo rods, and may just take buy those and then lighten and my 996 or pickup the 1100 crank and lighten it (if that crank will work).
 

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i did a 955 once that i think actually came with 926 pistons and i had to space those cylinders up, but not enough to cause belt issues that i recall. i think i was actually relieved the heads didn't need to come down and cause too loose issues. adding an extra 0.6mm base to a 996 to allow for the 900 crank is also fine ime.

be interested to see how far the piston comes out the bottom of the cylinder with the 71.5 crank and any of the rods. i think that'd be the main issue. 1198 rods are 1.25mm shorter?
 

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Discussion Starter #35
I am willing to try the 71.5mm crank on the 996. I will search the forum and see if I can find the post, but I recall that a while back a forum number made it work on a 999S. He said the issue was the rod bolts made contact with the timing shaft, so he has the timing shafted turned done 1mm or so so that the bolts cleared the shaft.
 

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Discussion Starter #36
Found it. User is duc you:
 
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