Winter Layup - 1995 Ducati 900 Supersport

[OddDuck]

I called FastBikeGear to check compatibility of the CA Cycleworks coils with the Ignitech CDI's (basically they aren't; they're a good match to the OEM Ducati ignition circuitry but won't work well with the TCIP-4) and ended up having a very informative chat about ignition pickups and testing.

Apparently halving the pickup gap increases the signal by a factor of 4. It is very possible that I'm simply running too wide a gap on the vertical cylinder, given how much of an effect distance has on an inductive pickup. It was also possible that the pickup has had an insulation breakdown to the engine cases and is leaking voltage. Testing one involves draining the oil and opening the engine; testing the other is just raising the tank and getting the multimeter out again.

So tonight I was checking insulation resistances, both cold and after a few minutes idling to get the engine up to temperature. These came in fine, with no continuity measured on any scale, hot or cold. While fussing around, purely by chance, I noticed a strong jet of air coming upwards from the vertical cylinder head. It initially appeared to be coming from around the spark plug. Putting a strip of rag around the base of the spark plug didn't make a difference, then further checking by hand seemed to establish that it's coming from a place close by the rear shock mount, on the left side of the head. I couldn't trace it further. It doesn't seem to be coming from the exhaust flange, and is definitely related to the engine running.

This is worrying. The horizontal head didn't have something similar, when I quickly checked. I'll have to work out a way to trace this air jet's source properly; it also looks like it's a good idea to finally get a compression gauge with an M12 x 1.25 adaptor.

[Rhys]

Crank case breather?

[OddDuck]

Crank case breather?

Yep, almost certainly. Oops. I haven't reconnected it (need fittings to go into the tops of the pods) and the outlet for the little breather tanks under the seat is pointed right at the left side of the vertical cylinder head.

[OddDuck]

I had a few hours clear today so got into the left hand engine cover and re-set gaps on the ignition pickup coils.

The procedure is:

Fairings off
Drain oil into clean pan and set aside for re-use
Clean entire perimeter of alternator cover, especially chain sprocket area (I used kero, a paintbrush and a rag)
Disconnect everything from alternator cover
Remove kickstand bracket and gearshift arm
Undo every 6mm cap screw on cover perimeter (there's one tucked away under the clutch slave)
Using puller tool, take alternator cover off, take care to keep gasket in good shape (this can be re-used)
Connect motor turning tool and remove spark plugs
Get 0.405mm feeler gauge and 10mm spanner, tweak bracket carrying pickup coils to revised position
Explain to freeloading neighbor that rebuilding engines doesn't mean knowing how to connect bluetooth between her phone and her SUV's stereo
Replace cover after wiping gasket surfaces with a clean rag
Reassemble and reconnect everything
Go to turn motor over, realise that oil isn't refilled, fuck fuck fuck that was close, refill oil
OK, try motor now, test pickup coil voltage.

At this point it got a bit Princess Bride, there was some disappointment and I had to get used to it. Coil voltages hadn't increased dramatically, they were still around 0.2 Vac, however the bike was running in a much more stable fashion.

Something that I'd noticed yesterday was that at idle, starting from cold, the bike was only firing on one cylinder. The second would kick in if the revs were increased very slightly. It's odd how an effect like this is only obvious once I was actually listening for it. This was gone, post 4 hour tweak. The bike caught on both cylinders and ran better. The subsequent test ride confirmed this.

Bar tingle is gone. There's still some vibration, I believe it's linked to the inlets running too cold, but it looks like the adjustment worked to sort out the major problem.

That said, it looks like time to replace a few major ignition components. The pickups and CDI's are 22 years old and look every day of it. This adjustment will keep me going for a while, but it'll be best to get ready for replacements soon. Note that in the photos, I've got the feeler gauge transverse (it made a more clear image), but in the actual adjustment the blade was parallel with the flywheel axis.

[OddDuck]

Quite pleased to see the bike make it to this mileage. I know it's nothing compared to what most Japanese sportsbikes can do but I've got to wonder how many of the carbie SS got this far. Just missed out on the 60...

[OddDuck]

South Island trip!

Multiple delays... bad weather, major earthquake, worse weather, and then the third of us couldn't make it. The damn thing was jinxed. Fuck it. Go anyway.

At least, that was the plan. I'd taken the bike out for a proving run the day before sailing and came back with a rear tyre full of Tyreweld (pando?) due to glass... it was repairable but I'd had to run some distance on 20 psi or less and lost most of the rubber, the tyre going from nearly new to just this side of WOF-illegal inside an hour.

It was repairable. A plug would have been $45 or so. I know the sidewalls would have been worked pretty hard, the tyre was going to come back from the trip worn out, why muck around. I've taken a plunge and changed for a Bridgestone T30 touring tyre. A shout out is due to the mechanics at TSS Lower Hutt, who stepped up from a hectic workload and sorted it in time for the ferry - thanks guys!!

And away we went... I'll avoid a hyperdetailed route description. We had a lot of fun, highlights were the Buller Gorge, the run around Lake Brunner, the West Coast run through Punakaiki, the history at the Blackball pub, and the run north from St Arnaud past Tophouse deserves special mention. That Tophouse road (and carrying on through Golden Downs) is just amazing. Maps may show it as gravelled, it's fully sealed now.

The Picton-Blenheim-St Arnaud-Murchison road is now the main route and is chocka with trucks, caravans, campervans, everything really. St Arnaud through to Murchison is almost completely solid yellow lines, both sides of the road - no legal passing except in a couple of spots. There are quite a few roadworks, one of which is dangerous because they haven't bothered cancelling the old road markings. If you get a bit zoned out and follow these without thinking (it's an old one lane bridge, now doubled), the markings feed you onto the wrong side of the road, or into the bridge endposts. I think that one's just a bit south of St Arnaud.
There is quite a bit of recent chip seal laid down, if you see a 50 km/h sign, expect loose gravel on the road from recent patches.

Driver behaviour was pretty good - a lot of courtesy shown, very little or no aggro.

Ferries: Interislander was good, Bluebridge was good too. No problems with either service.

Bike went well, new tyre handles a bit different to the old S21 and took a spot of getting used to, but I think I'm warming to it now. Overall a fantastic trip and I'm really happy we did it.

[SVboy]

Nice! Good to se you get some rewards for your efforts!

[OddDuck]

A while ago I had a spot of spare time, enough to run through some calculations of what's needed for the inlet manifold heaters. There are quite a few constraints:

43 mm inlet manifold diameter
50 mm available straight length
80 watts needed per inlet (more about that later)
12 V supply
Warm-up time of roughly 10 to 20 seconds before trying to start the engine
Heaters will have to run until heat from cylinder head takes over

It turned out that if I lathed up a 55mm OD, 43mm ID tube and ran a drill lengthwise through the perimeter at regular intervals, allowing a 3mm pitch spacing, I'd get roughly 50 passes. Going end-to-end is preferable to spiral wrapping because it allows the heater mount to be split lengthways, which is really the only way it can be fitted anyway. It can then be secured with hose clips or springs.

Skipping over a lot of calculations, it works out that a single row heater would need insulated wire of between 1 to 3 ohms per meter in order to deliver the necessary power. Power drawn from the wiring loom is a consideration, too. 160 watts at 12 volts means drawing 13 amps. I have a spare 12V line off the horn which is switched through the ignition key, but 13A really needs a dedicated relay with its own fuse. I'd like to include some device for reducing power drawn in steps so that warming can be reduced as the engine warms up, before finally being switched off completely.

Anyway... I'd bought a couple of cheap electric blankets off Trademe and spent tonight taking one apart. I think I've learned a hard lesson here about reading things properly: it's not a low-voltage blanket, and the 13 meters of heater wire I've pulled out of it has a resistance of 61 ohms per meter, with both inner and outer conductors twinned up. Won't work. Damn. At this point I think I'll skip doing the rounds of the op shops and just see what I can order via Amazon / Youshop etc... just so long as it's on its way.

[Ocean1]

On the hydro schemes the big cats point blank refused to start most winter mornings.

Until you kicked some diesel soaked rags under the sump and lit 'em.

Only takes about 10min...

[OddDuck]

Some things I'd found out over the last few weeks worth of reading, thinking, playing with ideas, and running calculations. No particular order, although they're numbered.

1) serious amounts of thermal wattage are needed to cope with latent heat of vaporisation at high throttle settings. Obviously cooler inlet air means better volumetric efficiency, but below a certain point fuel will simply drop out of suspension and the engine will be drawing lean air-fuel mixture and liquid fuel. Generally this thermal wattage simply comes from the ambient air and isn't a problem, but it can be an issue in very low ambient temperatures.

2) it's possible to warm inlet air, inlet manifold walls, or carburettor bowls, or all three. All of these have been done before, this isn't new.

3) petrol will start condensing out at surprisingly high temperatures, once fuel-air mix comes in contact with an object. Things really don't have to be that cold for it to happen. I found a paper (OK, from 1921) which listed detailed work carried out on two long-gone blends. Of key interest was the temperature at which condensation fell to zero, it was around 60 to 70 degrees Centigrade. No wonder inlet manifolds are run hot. Obviously 95 octane isn't whatever was available in 1921, but the basic effect won't have changed.

4) petrol boils at surprisingly low temperatures, just a few degrees up from the earliest condensation temperature. This would be why carburettors are always insulated from their engines, I guess... boiling a carb bowl dry would be something of a problem.

5) it's amazing what can be bought for a smartphone these days, you can get thermal cameras from FLIR and borescopes from various companies as well. Both could be very useful tools for garage work.

6) using electric heat is pretty much the only way to warm up the inlet manifolds (and possibly the carburettor bowls) before attempting an engine start; power demands are far too high to keep doing this for long once running.

7) some carburettors will stumble on acceleration due to fuel condensing out and creating a temporary lean condition. This isn't to do with fuel being squirted directly onto manifold walls, it's something to do with changes in air pressure inside the manifold and therefore a change in the fuel-air mix dew point. Inlet manifolds - or their hotspots - have to be hot enough and have enough thermal mass to cope with transients because of this.

8) heating needed to the inlet manifolds is almost certainly not proportional to throttle setting. There'll be effects with fluid boundary layers and so on; there'll be a relationship between the two but it won't be linear.

9) using cylinder head heat (through bulk conduction) or exhaust header heat (through ducted air) is the tried and proven way of providing the thermal energy needed to deal with the heat of vaporisation issue. At the same time, it's got to be controlled somehow.

This last point is where the headaches begin...

Low ambient temperature: more heat.
High throttle setting: more heat.
Cold fuel, as encountered first thing on a winter morning: more heat.
And vice versa, of course, the heat requirement is anything but steady.

I want those manifolds to run at a fixed temperature, effectively, with enough thermal mass to cope with transient loads. That isn't too hard. I could just do what Ducati did in the first place and run the inlets so that they're stinking hot no matter what happens, but that means a return to ear-splitting noise in 50 zones or downtown, and I'm not keen on that idea.

So, some options:

1) controlled thermal conduction from the cylinder heads.
2) drawing air around the exhaust headers and blowing it onto the inlet manifolds, controlled via proportional diverter flaps or speed-controlled fans.
3) inserting a line from and to the oil cooler and using engine oil to pre-heat the inlet manifolds, control via thermostat.
4) high thermal conduction off the cylinder heads - enough for sustained half throttle operation or so - and variable speed fan cooling of the inlet manifolds if they get too hot.

4 is about the only option that I can see being practical enough to work. I'd go to aluminium top hat washers to increase thermal conduction, and then it's just a fan blowing onto a heatsink clamped around the inlet manifold, the heatsink possibly with the cold-starting heater built into it.

I'll have to work out a cheap and reliable means of control, possibly bimetallic switches and in-line resistors rather than something complex. The fans are available, the heatsink and whatever ducting was needed would have to be made, but it's within reach for a home machinist.

[OddDuck]

On the hydro schemes the big cats point blank refused to start most winter mornings.

Until you kicked some diesel soaked rags under the sump and lit 'em.

Only takes about 10min...

Now there's a picture for starting a motorbike on a cold morning in suburbia!!

[pete376403]

A while ago I had a spot of spare time, enough to run through some calculations of what's needed for the inlet manifold heaters.
Anyway... I'd bought a couple of cheap electric blankets off Trademe and spent tonight taking one apart. I think I've learned a hard lesson here about reading things properly: it's not a low-voltage blanket, and the 13 meters of heater wire I've pulled out of it has a resistance of 61 ohms per meter, with both inner and outer conductors twinned up. Won't work. Damn. At this point I think I'll skip doing the rounds of the op shops and just see what I can order via Amazon / Youshop etc... just so long as it's on its way.

The devil is in the details...
If you want I can give you some of the LOW voltage single core wire. I have two 3 metre lengths plus what I used to make up one of the heated vests (about 5 metres maybe. I'll check the resistance tomorrow -good meter is at work.

[AllanB]

Inlet heaters.

Here's a couple of options to consider. They may be able to be modified to suit. For the price the first ones would be worth playing with just to see if it helps the issue.



http://www.ebay.com/itm/HOT-Universa...-/141677815322


http://www.webbikeworld.com/r3/heated-motorcycle-grips/

[Voltaire]

Inlet heaters.

Here's a couple of options to consider. They may be able to be modified to suit. For the price the first ones would be worth playing with just to see if it helps the issue.



http://www.ebay.com/itm/HOT-Universa...-/141677815322


http://www.webbikeworld.com/r3/heated-motorcycle-grips/

We used to call it " Heat Trace Cable" when I worked in the UK on hot water boiler systems.

http://www.ebay.com/itm/Minco-12V-Se...C0yElKHvPPPGYQ

I've given up on the non choke FCR's on my 900SL and refitting a set of stockers when I get an airbox....have had to put up with riding a Guzzi Lemans 2 and Vespa PX 200 over summer

[OddDuck]

We used to call it " Heat Trace Cable" when I worked in the UK on hot water boiler systems.

http://www.ebay.com/itm/Minco-12V-Se...C0yElKHvPPPGYQ

I've given up on the non choke FCR's on my 900SL and refitting a set of stockers when I get an airbox....have had to put up with riding a Guzzi Lemans 2 and Vespa PX 200 over summer

Might be able to help you there, I have my old airbox sitting under the house... the lid's been opened up and some of the side reinforcing has been trimmed, but otherwise it's still good. PM me if you want it.