Configuration 4

I had an idée that more cc should be nice. 955 sounds like  racing so and that is cool so I started to look for a 955 kit (96mm bore). I found out that most 955 conversions available will need to bore the crank case from 100mm to 102mm to get the bigger cylinders on. Some people have tried to bore the standard 94mm with 100mm outer diameter to 96mm. This normally ends up in tears as the cylinder walls are getting to thin and will crack.

The only kit that I know off that does not need the case to be bored is Fox performance 955 kit. The reason for this is that Ben Fox takes the standard a cylinder and bore them to 100mm (I think) and installs steel sleeves with an inner diameter of 96mm. Clever. I was thinking for a long time to do this but in the end I did not as I sort of think that steel sleeves are old technology. Ducati stopped using steel sleeves in 1983 and since then they are only using aluminium with nicasil coating. A nicasil cylinder lasts forever and steel does not so I like the idée of nicasil. After some time I found some nice used cylinders at Ebay and a bit later some nice 955 pistons. The cylinders just needed an Eddy Currant crack inspection and a slight honing to be as new (almost).

96mm bore makes 955 with a standard crank shaft

A twin needs two of the.

Ferracci pistons made by Wiseco

Same piston from the bottom

Then I was reading at Doug Lofgren page about a 984 he built. That sounded like the bike for me. It is simple to make one.  It is actually very simple. Just take a 900ss crank shaft with 68mm stroke and install it in your 955 and you got 984cc. It is just a few things to remember. Shim the cylinders up 1mm to compensate for the longer stroke and adjust the cam timing as it will change. As most ducati parts are interchangeable between the different models you can just select what you want from the shelf and install it. After some search I found a nice 68mm stroke (900ss) crankshaft. 68mm crank takes a 916 to 944 and increases the compression a bit. As I wanted 984 I needed to use the 955 kit too

Standard 66mm stroke 916 / S4 crank in bottom and 900ss 68mm stroke crank on top. Looks the same from here but it will give me 30cc more

I contacted Doug to discuss my project and thought it was a nice idee but he told me one thing that made me re think my project. He Said  the following."Just 984 will not make you happy." If you want to gain some power you will needed bigger valves and different ports. He suggested to send the heads to Guy Martin at MBP in Canada but I was thinking that it has to be possible to get this work done in Europe. I started to look around and asking some people about porting. It looks like most people thing it is to much work to take the standard 916 heads with 33/29mm valves up to 37/31mm. Almost everyone does 35/30mm. I am sure that 35/30 is alright but I think that if you do something you better do it properly. As no one managed to convince me to not go big I still wanted 37/31mm and the more I was looking around the more every one was pointing me in the same direction. Every one was pointing east. To Canada, to Quebec, to Pointe Claire and to the same Guy Martin as Doug suggested. I called Guy and I found him to be a very nice person. Very friendly, very funny and with a huge knowledge when it comes to make Ducatis go faster and be more reliable. Some of you might know his Testa Rosso heads that makes 102hp from a 2 valve Ducati. Some might know him from his Bevel Ducatis. I decided that Guy was the man for the job and sended him the heads. Later he actually also ended up taking care of my MHR crank shaft and heads.

I finally decided that the 984 had to wait to next winter and she will stay 916 this year. That makes it more fun as I can see how much the heads will give. On top of that I need something to do next winter so the 984 is on hold. Another reason is that I have not decided what conrods I am going to have when she will grow to the 984.

As I had a week of from work and was waiting for my cylinder heads I thought that it could be a good Idée to remove the engine from the frame and split it. I wanted to replace the gearbox from the close ration normally installed in S4 to a standard gearbox. I also wanted to check the crank shaft preload and just generally make sure that all is okay. The crank shaft pre load is a thing that it looks like Ducati does not know how to adjust. It is funny because they tell you in the manual what it should be but they do not set it properly them self. Finally I wanted to take a look at the conrod bigend bearings as I had a feeling that they felt a bit loose. I started to remove the side covers to get access to the “hard to remove” things from the engine when it was still in the frame. It is a bit easier to be more brutal and apply more force on things like clutch basket and flywheel when the engine is still in the frame as I don’t have an engine stand and the engine will just floating around at the bench

Look. All this screws are just waiting to be removed

I did not have the proper tool to hold the fly wheel but this works too. Not according to the manual but what can you do

Later I made a tool to hold the fly wheel. A bit but good to have for assembling the engine

Cover with waterpump and alternator removed

Clutch cover removed

Primary drive  with clutch removed

Oil pump removed

Another picture of the holding tool

Back

Next page

Back to S4 Mainpage