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Discussion Starter #1
I'm interested in more compression on my 996 and am deciding between the pistons and shaving the heads 1mm. If I take the heads down what pulleys do I need, some are different sizes and colors, and where can I get off set pulleys.

Comments on HC vs shaving?
 

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You'll need either adjustable pulleys or std ones and offset keys to reset the cam timing if you cut the heads. Plus you might end up cutting the piston valve reliefs deeper. There are loads of piston kits for the 916-998 engines. Keep it simple, I'd say.
 

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Discussion Starter #3 (Edited)
Agreed on simplicity. I didn't think about the cam pulleys. I was thinking idle and tensioner pulleys. But, dialed cams, with higher compression with proper squish would sure be nice. It would give the pep I'm looking for until I move on to another engine.

Can I use the stock belt tensioners?
 

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Nothing will give you that much PEP unless you increase displacement. And I'm not sure that's possible on this engine.
I wonder if you could change compression by installing a thinner gasket and HC pistons instead of shaving. Again only worth it if you could do it yourself because it would be a minimal return in performance. You could install light weight cam pulleys, flywheel, clutch, pistons all in one shot. Then get it all dialed in.
Have you tried changing over your chain to a lighter weight one with a larger sprocket....definitely will perk up acceleration.
 

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Nothing will give you that much PEP unless you increase displacement. And I'm not sure that's possible on this engine.
I wonder if you could change compression by installing a thinner gasket and HC pistons instead of shaving. Again only worth it if you could do it yourself because it would be a minimal return in performance. You could install light weight cam pulleys, flywheel, clutch, pistons all in one shot. Then get it all dialed in.
Have you tried changing over your chain to a lighter weight one with a larger sprocket....definitely will perk up acceleration.
dialing the cams alone makes a huge difference in the performance of these motors. and yes you can increase capacity of them as well. you can bore em out to 100mm. or you can stroke em. i finished a build on one that included a 5.5mm longer stroke with the stoke bore making it a 1079. that motor has scary mid range! pretty fun to ride actually. it hasn't been to the dyno yet so i don't have any numbers to post.
 

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dialing the cams alone makes a huge difference in the performance of these motors. and yes you can increase capacity of them as well. you can bore em out to 100mm. or you can stroke em. i finished a build on one that included a 5.5mm longer stroke with the stoke bore making it a 1079. that motor has scary mid range! pretty fun to ride actually. it hasn't been to the dyno yet so i don't have any numbers to post.
Dont mean to hijack your thread but.................................. I'm after more midrange. Would you please send me a PM describing in detail what you have done? Thank you much, Matt.
 

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Don't remember the specifics now, but I had 1mm skimmed off my 916 heads and swapped the pulleys for larger (+1mm?).

There are 3 (maybe more?) sizes of pulley, denoted by the colour; black, gold & silver, I understand that they are all OEM pulleys from different models; 916, 996, 748 with dropped exhaust cam etc, surely someone on here will know the specifics?

916 uses the black pulleys as stock and I swapped them for the gold (+1mm) which means I can the belt tension without the teeth being too close and didn't need much offset woodruff keys to get the timing.

I had this done in combination with gasflowed heads, cam dialling & squish and got approx 15% power increase...
 

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If you want midrange, ask tomtom at hypertrick. He has loads of experince building and tuning the old 4v with emphasis on midrange.

When i had my SPS he figured HC pistals + a portjob and bigger valves where the best bang for buck mods once Id done camtiming. I already had the sps cams in there.

Stage 1. Stock parts
Camtiming + setting squish+mapping
45mm stock exhaust is ok.

Stage 2. Drop in parts
High compression Pistal pistons. Hotter cams (sps are great steetcams)
50 or 54mm exhaust is enough.
You getting close to a retrofit 999/1098/1198 engine retrofit being more economical in the long run

Stage 3. Full monty
Bigger valves + porting. 57 corse system recommended. Stroke and bore can give almost 1150cc.. But your pushing the envelope. A 1198 engine retrofit gives more power and longevity at this stage.

Building the engine the right way will keep peak power at under 10k rpm.

But as i said.. Tom at hypertrick or Chris at CJS knows alot more then me..
 

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Discussion Starter #9
Based on the age of the engine I'll probably wind up dropping in HC pistons. If I had adjustable pulleys, or offset keys, I would do the squish + cam + map and be done with it.

I want a little more out of the engine until I pick up a 999S or 1098. I have a bit of slop on the clutch shaft and am also thinking I may have some issues with the piston and or rings based on bits out oil in vertical exhaust manifold area. But that may valve seals.

When I remove the top ends and see the condition of the barrels and everything else I will decided what to do, if anything at all, and maybe just put it back together with proper squish.
 

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dialing the cams alone makes a huge difference in the performance of these motors. and yes you can increase capacity of them as well. you can bore em out to 100mm. or you can stroke em. i finished a build on one that included a 5.5mm longer stroke with the stoke bore making it a 1079. that motor has scary mid range! pretty fun to ride actually. it hasn't been to the dyno yet so i don't have any numbers to post.
A dyno graph would be cool., I have a kitted 999 w/ S cams, Pistals which dynoed at 149/86 w/ a slip. Since added a full w/ a remap so I would like to get it dynoed again to see if it picked up any HP....by my seat of pants dyno the full made a marked improvement....but I would hate to abuse it on another dyno run.
I didn't know you could bore and stroke 996 w/o doing alot of modding to the cases. That sounds like a fun motor to have for the street, plus the 996 has a very distinctive exhaust note made better by the bore and stroking I would think....
 

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i agree with you 100% tomtom. while its possible, its not the best solution. when i mentioned it, i was just stating it could be done.

building a high power 996 is a tough one. while its somewhat easy to get more power out of em, you will end up with reliability issues with things like the cases. but building one that makes more power at lower revs is a great compromise.
 

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I've just started rebuilding my old 996SPS after it has sat in boxes since 2003 .... just after the front rod let go after too many race km's. Nuf said !!
It's my last bike left and it'll be a road and occasional track unit.

So with regards to this thread ie getting more out of a 996, I'm doing the following using parts I've got left from the good old days ie ....pre recession when I actually had an income and spent too much building and racing blinged out 996's.

- Flow heads and fit some 31/37 valves.
- HC FBF pistons (not the best but what I have)
- Lightened and knifed crank
- Some lightweight corse engine pullies/cogs left over and a lightweight flywheel
- adjustable cam wheels
- setting squish and timing (essential).
- 50mm Arrow exhaust
- bigger airbox and cf underseat engine breather (not essential)
- Bore the throttles to 54mm .. maybe
- improve suspension (revalve and respring the Showa forks) and service the Ohlins shock
- improve brakes with radial master and oem 4 pad brembo calipers (have these)

I realise that by having the parts on my shelves it's not comparable to the thread here but imo and experience ..... head work, sps cams, timing, lightweight flywheel, light wheels and improved brakes and suspension .... these are the best bang for $ upgrades.
Forget the rest.
 

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Discussion Starter #14
DO NOT bore the 996!
Its to lame to take it. its really maxxed at 98mm.
Pushing the 98mm bore seems fine but at boring to 100 it flips out, dont do that, its too fragile head to cylinder.
While the thread has derailed from its original purpose, and I am glad it has, boring out to 100mm was something I was thinking. Seeing how the subject has been brought up I shall ask:

"If I sleeve the cylinder out to a 100mm bore will that go better then bore + plating?"

My guess is that a sleeve would offer the much needed stability and reliability. Please to share your thoughts as I can have this done for free and am very tempted.
 

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While the thread has derailed from its original purpose, and I am glad it has, boring out to 100mm was something I was thinking. Seeing how the subject has been brought up I shall ask:

"If I sleeve the cylinder out to a 100mm bore will that go better then bore + plating?"

My guess is that a sleeve would offer the much needed stability and reliability. Please to share your thoughts as I can have this done for free and am very tempted.
You can get many many miles of smiles out of a 100mm bore on the 996. When the fiber head gaskets didn't last, BCM replaced them with muli layerd gaskets from Cometic. I never had a head gasket issue after that. The engine cases lasted for 40K miles or so with the 100mm bore installed. I think they gave up around 65K total engine miles. Not BMW reliabilty but pretty good for a ducati. But this was with street riding and an occasional trackday. I have been very happy with this mod. I went with this option over SPS cams to get more power throughout the rev range, instead of just mid to top.
 

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Discussion Starter #16 (Edited)
You can get many many miles of smiles out of a 100mm bore on the 996. When the fiber head gaskets didn't last, BCM replaced them with muli layerd gaskets from Cometic. I never had a head gasket issue after that. The engine cases lasted for 40K miles or so with the 100mm bore installed. I think they gave up around 65K total engine miles. Not BMW reliabilty but pretty good for a ducati. But this was with street riding and an occasional trackday. I have been very happy with this mod. I went with this option over SPS cams to get more power throughout the rev range, instead of just mid to top.
Cometic is the route I would go. When you did the 100mm change did you sleeve or bore with plating? And, did you give the head a 100mm chamber or leave it at 98mm?

And lastly, does the 999 piston, not the 999R, have a 20mm wrist pin?
 

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Cometic is the route I would go. When you did the 100mm change did you sleeve or bore with plating? And, did you give the head a 100mm chamber or leave it at 98mm?

And lastly, does the 999 piston, not the 999R, have a 20mm wrist pin?
Millennium did the boring and plating. They also repaired the bore that was damaged when the cases let go.

The heads were left stock. I finally got around to timing the cams last winter and the midrange really picked up after that.

My engine didn't use 999 pistons, but high compression pistals. I'm not sure if the 999 piston wrist pin height would work with stock rods.
 

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I'm interested in more compression on my 996 and am deciding between the pistons and shaving the heads 1mm. If I take the heads down what pulleys do I need, some are different sizes and colors, and where can I get off set pulleys.

Comments on HC vs shaving?
Not 100% sure about the colors. Only 99%. The gold color pullies from S4/ST4/ST4S and later 748 (lower echaust cam) have bigger diameter then the black ones from the superbike. I installed black ones (smaller diameter) on my stroked 984 S4 to be able to install the belts as I had to shim the cyliner base 2mm to compensate for the longer storke and the different pistonsI used. I also used gold (black original) ones on my old 851 to be able to get high tension enough.

Jocke.......
 

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And lastly, does the 999 piston, not the 999R, have a 20mm wrist pin?
yes it has a 20mm pin. the compression height is too far off and the piston would be sticking out of the cylinder unless you used multiple base gaskets or had custom ones made.
 

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Lots of cool stuff here....changing from one colored pulley to another would affect performance how? I assume that each color code represents a diff. diameter. Is this just a cheaper way of getting more performance out of existing cams?
 
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