Differences between the ST4 and the Monster S4? - Ducati.ms

trader220 · Dec 13th, 2011, 1:40 pm

How technically different are these bikes. More specifically, I can pick up a salvage titled 2002 S4 on the extreme cheap. Should I do it and what things are direct bolt on upgrades, what parts or systems could be a nice upgrade with some fairly easy tweaking?

Airbox? Exhaust?, Fuel Management? Any benefits in stripping those parts? Fork or brake upgrades?

Thanks again, this board has been a great resource.

**Gearbox** · Dec 14th, 2011, 3:08 am

What are you trying to achieve with your project ?

SS904 · Dec 14th, 2011, 7:08 am

The Monster S4 uses a modified ST frame. The differences would be in packaging the electronics and battery to fit under the tank, faring mounts and the sub frame. A lot of parts would be transferable, but not upgrades if you're talking about a standard S4. Brakes and suspension would be the same as the ST4. If you’re talking about an S4r, you'll have better spec parts more like and ST4s, except for the single sided swing arm, which would bolt on to the ST with little trouble.

Exhaust is not interchangeable. Frames are not, as the sub frame is not the same. Wheels (assuming standard S4) would be the same, suspension and brakes, the same. I don’t think the wiring and electronics would be useful beyond a few spare parts (like the ECU, coils, sensors) as everything is different due to the dash and packaging being unlike the ST. In the back of my mind I am thinking the Monster version of the 916 had heads with smaller valves, but I could be thinking about the 2V Monsters compared to the SS bikes. Easy to look up though. All in all you may end up with a lot of spare parts, but no real upgrade parts unless it's an S4r. Might not be worth the garage space. If the bike is too cheap to pass up, maybe strip it for a track day beater.

MarkST · Dec 14th, 2011, 7:17 am

Quote:

Originally Posted by SS904

In the back of my mind I am thinking the Monster version of the 916 had heads with smaller valves, but I could be thinking about the 2V Monsters compared to the SS bikes.

Shallower heads on the exhaust side so it fits into the 851/888 derived Monster/ST frames.
It's an ST4 motor. Exactly the same.

SS904 · Dec 14th, 2011, 7:19 am

I take some of that back! Did a little looking, as it is a slow morning, and from the pictures it looks like the standard S4 comes with the aluminum swing arm, 5 spoke rims, and the same front rotors as the ST4s. Also a few extra carbon goodies like belt covers and rear hugger. Depending on the price, may not be so bad after all for those upgrades. You could always part out the rest and make some money back.

SS904 · Dec 14th, 2011, 7:23 am

Quote:

Originally Posted by MarkST

Shallower heads on the exhaust side so it fits into the 851/888 derived Monster/ST frames.
It's an ST4 motor. Exactly the same.

Yeah, that part I knew. All 4V ST, Monster and 2002 748s have those lower profile heads. I was thinking actual valve diameter was smaller on the M bike. They did that for a while on the 2V monster 900 compared to the 900 SS.

SS904 · Dec 14th, 2011, 7:32 am

Ahhh, found the difference. A trip to Bikerboy.org confirms a difference that I was remembering, but it is not the valve diameter. The Monster has a 40MM exhaust, while the ST has the 45MM headers. So in the quest to use S4 parts on an ST this has no bearing as the exhaust will not fit anyway, but it probably also means different fuel mapping and also the rev limiter is lower on the S4, so the ECU (chip in this case) would not work out.