888 Base Runs, Mufflers, Airbox Lids and Comparisons

Another one of my bikes, it came along really, really cheap and I just couldn’t help myself. I have a problem with that kind of thing. I was hoping the guy wouldn’t take my unreasonably low offer, but he did. It is actually a French delivered bike that came out here from England, and has changed hands twice now in Australia without ever being registered. The importing owner did the compliance though, so it is all legal. The idea was to just give it a quick clean up, but nothing I do is ever that simple.

It needed lots of mechanical work – chain, sprockets, fork seals, shock rebuild, big service, tyres, base gasket, etc. All the stuff I expect to see in a 30,000 km old 888 that hasn’t been seen as much maintenance as maybe it should. I guess I was keen to see how it compared to the 851, particularly given the fact that the 888 has the 1mm bigger valves. My ST4 exhaust mod had got me confident of getting some real hp out of this bike, and I ended up buying a very cheap ST4 Ducati Performance full system to use. Listed in the catalogue as 45/52mm, it is more like 50/45, with very large headers and the normal DP old style mufflers. It’s not a Termi system, but one of the old Gia-Co-Moto ones. I had to get it modified to suit, but I got that done at the same time as the ST4 system for the 851 (just modified to fit nicely). Anyway, I needed some pipes for this 888, as it had std mufflers and I figured this was as good as any. My ability for self-justification is now fairly highly tuned to my wants.

Actually, this 888 was pretty much all std. This meant I had a totally "factory" base to start from, which is something I like, but don’t often get in a project bike. The 851 was (almost) std, apart from having no airbox lid. Something that was far too much effort to find for a dyno test. Given I had dyno runs for the 851 with std 888 mufflers (and no airbox lid), it was going to give me some good insights into how they varied. Although the Carbon Termis I had used on the 851 have since been sold on, so I stole some Staintune slip ons in stainless from a s/h bike on the showroom floor.

The first set of dyno runs came after all the above mentioned work and big service, with cleaned injectors, new belts, etc, but unchecked cam timing. I just wanted to see what it was like. I knew this would give an "off" result, but didn’t mind. Below are the results. All std is green. Std mufflers with open airbox is blue. Staintune slip-ons with std airbox lid is purple, Staintune slip-ons and open airbox is red. All these runs use a FIM "Megazone" chip. This means the chip has std fuel and ignition maps, but is able to be modified using the ‘zone’ method just like the usual Ultimap chips Duane sells. The Megazone chips are quite a bit cheaper than the Ultimap ones, for the simple reason that they have std maps. For this project, given I was unsure of where I was going to end up, this was as good a chip as any to use. So, I just ran the bike in each configuration, adding or subtracting fuel from the whole map to see what it wanted. All except the "std muffler, open airbox lid" combo made max power with 5% more fuel. The "best fuel" runs are those shown. The first graph is power, the second torque.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Dynograph courtesy of DYNOBIKE (03) 9553 0018

As you can see, similar to the results from any of the reports that deal with this type of airbox design – 851, 888, SS, Monster, ST – getting rid of the airbox lid really brings things to life. Although, more fuel is generally required. To get these best power curves with the open airbox lid, I added 5.4% with the Staintune slip-ons, although the std mufflers where happy with the std fuel mapping. So, given I add another 5% over max power fuel on the dyno for road use, if you were running a std chip with some slip on mufflers and an open airbox, the fueling would be around 10% down on what I would run it at for WOT. Quite a bit, really.

The next graphs are a comparison with the 851, then 851, ST4 and S4 Monster. These were something I was looking forward to seeing. The extra 37cc from 851 to 888 (due to the bore increase from 92mm to 94mm) and 1mm larger valves combine to give more torque (due to capacity) and more power (due to both, but mainly valve size). The curve drops away after 9,000 RPM just like the 851, which I had expected to see given my results with the ST4 headers and the S4 info I’ve turned up. Simply due to the 40mm header diameter running out of flow as far as I can tell. More on that in a later report. The bottom end of the 888 seems a bit low, but it is running ‘as delivered’ cam timing. Which were quite a bit out – see the cam dialing report for the specifics. The 851 is running cam timing set to ‘std’ specs.

The first curve is power, 851 with std 888 mufflers and open airbox in green. 851 with Termis, open airbox and Ultimap chip in blue. 888 std with open airbox and ‘zoned’ Megazone chip in purple, 888 with Staintune slip-ons, open airbox and ‘zoned’ Megazone chip in red. I didn’t have a std airbox lid for the 851 back then, so that’s why all curves are for open airbox. The 888 mufflers don’t give a dip around 6,000 RPM that the std 851/900SS mufflers give. Both the 851 curves are a bit patchy – usual RPM pick-up deal.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Next are std ‘as delivered’ power and torque runs (except 851, which has an open airbox lid and ‘on spec’ cam timing) for ST4 in red, S4 in green, 888 in blue and 851 in purple. As you can see, the ST4 has the best top end – expected from the bigger exhaust, while the S4 has the best midrange – expected from the shorter duration inlet cams. I would also assume the std mufflers fitted to the ST4 and S4 work a bit better than the older 888 mufflers and far better then the std 851 mufflers. The 4th peak in the ST4 torque curve – at 9,000RPM – is what makes that high RPM power, and is what I talk about as being the benefit of the 45mm exhaust. Whether or not it is power that most people would use on the road is another matter, but this is a dyno based tuning experiment, so finding more power, be it bottom, mid or top end, and the reasons why is what it’s all about. The 1mm bigger valves of the 888 certainly allow its torque curve to hold a little longer (compared to the 851) before falling away at pretty much the same angle as the 851. Both the 888 and S4 have a plateau in the torque curve from the common 7,200 RPM peak of all three 40mm exhausted bikes (S4, 888, 851) until 8,500 RPM or so, but they certainly do not have the final power producing peak at 9,000 RPM the ST4 has.

Dynograph courtesy of DYNOBIKE (03) 9553 0018

Dynograph courtesy of DYNOBIKE (03) 9553 0018

These graphs show what I was really interested in – how much difference the bigger valves make. Quite a bit it seems. Given the 748 heads I have use the same valves sizes as the 888, and have smaller chambers that will increase the comp, the 851 will definitely be getting them when I can get around to it. Should see a 100hp 851 easily with the ST4 headers fitted.

As for the rest of the bike, it runs 15/40 gearing (1 bigger than std at the back due to the fact that I had a new one already), Hyperpro springs front and rear with a revalved shock and some Pirelli Dragon Evo tyres. The minor suspension mods make is a very nice thing to ride on any road surface pretty much, and the Dragons I like as much as any of the other tyres ( Pilot Sport, Z3) that I have ridden fast on. The older Dragon I had on the back of my KR1S didn’t work so well until it was hot (which took quite a while), but the 888 has quite a bit more weight and torque than the mighty KR did, so has no problems at all getting the tyre warm. I did spend a day on a demo 996 with Dragon Evo Corsa tyres some time ago, and they were very special indeed, but the std compound will do my 888 just fine.

I also had a bit of a problem with this bike that was starting to worry me. It was a very tardy starter. To the point where you couldn’t crank it with the fast idle on. It would start up after a few turns just fine with the throttle shut, but wouldn’t even indulge the thought of cranking with it open. I knew the battery I had fitted was ok – it certainly spun the 600M like a top – so I wasn’t sure. After I had done the cam dialing, it would crank with the throttle shut, but not fire. Let it sit for a few minutes go back and away it went. Which was not good, especially as I want to sell it soon. I had checked all the lead ends where they bolted to the battery, solenoid and starter motor – all clean – and the starter brushes, which looked fine.

Then I tried a new battery about to go into another bike, just for a test. It cranked just fine, fast idle on or off. So I was began doubting my battery. However, I also checked the voltage at each point along the starter current path, and the earth circuit back. It seemed that every lead – battery to solenoid, solenoid to starter, earth return to battery – was consuming at least 250 mV each when the engine was cranking. Even though the resistance without load on each lead segment was zero. Given the battery is a bit old, this appeared to be breaking the camel’s back, so to speak.

So, I then tried soldering the connectors to the wire core of the leads. All the std connectors are just crimped, and I figured maybe time had taken its toll. The most important step was getting lots of flux down into the crimp to clean all the corrosion and crap out – this in itself may have made a difference. I only had time to do the battery positive to solenoid and earth to battery negative first up, but after this (and with the same battery charged for a couple of hours) it fired straight up with the fast idle on. Thinking it may have been just the battery charging, I let it sit overnight. Same thing next morning. At this point I began wondering if it was just screwing with me, but day after day it enthusiastically burst into life on the first crank, even with the fast idle on. I did do the rest of the connectors with the solder, but this didn’t seem to make any more difference. So, problem fixed. Just a simple thing, but one that had me thinking the worst, particularly for resale.

[Top Of Page]

Home | Blog | Facebook | Service Enquiry | Products | Reports | The Dyno | Disclaimer | Contact Us