Help me build my 996SPS engine.

So after a cam belt jumped some teeth and the valves hit the piston it is time to start the rebuild and I am looking for ideas.

A quick bit of back ground info for those who don't know. I am new to road racing having started this year. I'm 51 and this is my first Duc after an almost 30 year break from road bikes. I'm racing at a club level and about 10 seconds off the track lap record. Plenty of guys behind me but more in front. I have been winning my class though.:biggrin: At the moment the bike is way faster than me but hopefully I am catching up. So I don't really need more power yet but I would like a strong, reliable engine. That being said, if I can make more power without too much expense or reducing the reliability I would consider it.

The bike, 'Sophia' is a 2000 996SPS and I have had the suspension resprung and valved by my local suspension expert. I have a set of carbon BST's to fit once my new ISR Full Floating Discs arrive. There is a Power Commander III fitted and will be mapped after the build. The rear drive is 520 15/41 with TSS quick change sproket carrier and there is a STM slipper. Other than that and a few bits of carbon she is standard.

The following items were found to be damaged or in need of repair. All the valves in the front head, guides appear ok. Front cylinder U/S. Couple of rockers flaking. Cam belt pulleys worn. Front piston slightly battered where it was hit by the exhaust valves. Some tiny chipping of the gear box dogs. But most concerning, one of the big end bearings has been turning in it's bush and both the bushes have been turning in the casings. Pic attached.

I am going to do the following.
1. Replace all bearings and seals throughout the motor.
2. Replace the front cylinder with a second hand one that is 0.5 mm shorter but I believe that can be sorted with base gaskets. :think:
3. Replace all the valves in the front head with second hand ones.
4. Replace any suspect rockers.
5. Fit adjustable cam pulleys or offset keys.
6. Blue print and balance the motor.

What my mechanic Mile is suggesting,
1. Instead of replacing the rings only replace the pistons, rings, gudgeon and bearings with high compression ones. If we only replace the rings then skim the head to get more compression. I think he said 0.3 mm.
2. A lightened flywheel.
3. Replace the main bearings and bushes in the hope that the new ones won't turn or
4. Have the cases bored and new oversize bushes made and fitted.

I am quite concerned about the main bearing bushes turning and don't see how just putting in new ones will guarantee a cure. Mile tells me of a story where he had the cases bored and they then broke the crank and ended up throwing the motor away. Couldn't we pin the bushes so that they can't turn? By pin I mean drill a hole parrallel with the crank into the joint between the bush and the casing so that the bush has half the hole and the casing the other half, then put a tolerance fit pin into that hole. No way it can turn then. Does anyone have any ideas on this? Or should I find new cases?

So there we have it, what do you guys think? Any suggestions or ideas on what I plan to do or what I should do?

Bront

 

Thanks guys.

Bit of good news today. The engineer suggests we Locktite the bushes in and put 2 small pins in each as well. That makes more sense to me than what Ducati have done. How they expect a bush to stay put when they pump a lubricant at high pressure around it escapes me.

I don't want to make this motor too much more powerful as I think that will seriously effect it's life. I want this thing to last as well. What do you think?

 

Thanks for all the great ideas guys.

Ok, I think this is the deal. I don't want to reduce the life of this motor, I actually want to increase it, so big bore kits, high comp pistons and the like are out. I'm afraid I don't have heaps of money for all that as well.

So the plan at the moment is;
1. Balance crank etc.
2. Skim the heads and set squish.
3. Lap all the valves and set the clearances.
4. Change the starter gearing if I can find a set of 999 gears for the right price.
5. Adjustable cam pulleys or offset woodruff keys.
6. Replace all bearings and seals.
7. Possibly replace the gear shift drum with 848 or >'08 1098 one.
8. New rings.
9. Replace damaged cylinder with second hand one.
10. Locktite the main bearing bushes and pin them.
11. Custom map the PCIII.

Think that is about it. I'm still open to suggestions though and ideas on what to set the cams at with this set up?

Yeah Cranker, all those toys would be nice but I find this beast way faster than me already. It is a great bike to ride fast, shit to go slow on. I know it isn't the RIGHT bike to be racing these days but it is just so much fun. And which bike do people stop to look at in the pits? Well it aint the BMW's or the rice rockets! I'm racing in what we call the Clubman class at our local Cape Town circuit, Killarney. Not the best bike track but the only one we have here. At the moment my times would let me race class C but I'm happy in Clubmans for the moment but if I go any quicker I will break out into class B and I don't want to do that just yet. Still trying to learn how to overtake, turn and stop

Anyway for me it is all about having a place to ride my bike as fast as I can without getting locked up or killed. :frown:

Now if I have missed something that you think is essential or just a good idea, then please chip in.

Bront

 

Nice numbers Duc

 

On another forum where I asked the same questions one of the guys is suggesting that pinning the main bearing bushes could lead to cracking of the cases. Does anyone here have any experience with doing this, be it good or bad?

Thanks

Bront

 

The main bearings are roller bearings that are pressed into a bush which is pressed into the cases. By pinning I mean drill a hole parallel with the crank so that half the hole is in the bush and the other half in the case and then insert small round pin. Hope this makes sense.