Winter Layup - 1995 Ducati 900 Supersport

[OddDuck]

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/

Thanks, have heard similar already and had a look, then and now... unfortunately this project is riddled with fiddly problems. Should work, could work, but just doesn't quite work.

The usual handlebar grip heaters are too long. I've only got 50 mm of clear straight pipe to wrap, and the heaters don't cut down.

Also, handlebars usually never get to hot enough to melt velcro... the inlet manifolds, if running at the correct temperature, are right at the limit for most plastics. Nylon, if that's what velcro is made from, is going to struggle. Sooner or later I'm going to ride on a hot enough day that anything marginal will just melt. Unfortunately that rules the Oxford overgrips out, it's a shame because they actually would go straight on.

The other thing is the power needed. I just don't think the grips will do more than help; they won't nail the problem. The manifolds cool down amazingly fast during startup, as judged by touch. When I ran the calculations for the wattage needed to match the heat of vaporisation during startup, what I found was that even at 450 RPM (starting cranking speed), about 40 watts is needed. Throw in cold fuel + cold air + idling at 900 RPM and 80 watts per manifold does start looking reasonable.

I've had another good long look tonight and I reckon I've got a solution to try:

1) combined split heater and finned heatsink, to be machined up out of aluminium bar or plate

2) monitor thermometers to be installed in the instrument cluster so I can see what's happening as I ride

3) blower fans installed in front of the carburettors, in the empty space where the airbox used to be

4) piping between fans and finned heatsink, with ducting around the heatsink

5) automatic control for heaters and fans so I don't have to worry about switching stuff on or off while I ride.

6) possibly ducting between finned heatsink, wrapping around cylinder head, to exhaust header. My preferred solution is still to warm the stubs up off waste engine heat, rather than cool them

I'll be shopping for a few of the things needed and hopefully placing orders soon... thinking and reading only goes so far, sooner or later it's time to muck in and accept that it won't be perfect or even work first time.

[OddDuck]

Well, now... found this:

http://www.shell.com.au/motorists/sh...commercial.pdf

Technical data sheet for 95 Unleaded. There isn't anything about condensation but the boiling points are instructive.

I've also placed the first orders on Amazon and been finding it very useful as a learning tool. There's a lot available these days that I wouldn't have expected... random browsing is opening up a lot of possibilities. I'm not sure I'll actually use this, but it's certainly intriguing:

https://www.amazon.com/gp/product/B0...d=AFHAE9RJVUMB

Digitally settable thermostat. It's not a sophisticated controller, this is simple slam-bang on-off control. It will oscillate around the setpoint when in use, but if the oscillations can be kept within a narrow enough range, it could work. Certainly being able to combine digital temperature readout with control in one unit is very useful.

[pete376403]

I measured the resistance of that cable - 2.2ohms for 3 metres. Any use?

[OddDuck]

I measured the resistance of that cable - 2.2ohms for 3 metres. Any use?

That's perfect, yes please. PM on its way.

[OddDuck]

It occurred to me that before making any changes I'd better be a bit more sure of what was actually happening. I think the problems are down to thermal effects; so far all I've been doing is pulling over, yanking a glove off and dabbing a fingertip to guess at temperatures. It's not really measurement, just informed guesswork. I borrowed a thermal imager, went for a ride, and shot some images.

The first three photos are to show the angles I used and the targets of interest. These are:

1) the vertical cylinder head and its inlet manifold

2) the ignition coils

3) the carburettor bowls

I've gone on for long enough about the inlet manifolds but the other two deserve a bit of an explanation. I'd found out by accident that the ignition coils get surprisingly warm during operation. I already know that there's a knock-on effect to voltage supply to the coils; as they warm up the supply voltage rises to the nominal 12 V, presumably from resistance increase inside the coil itself. It then follows that if the coil gets hot, resistance increases further, this affects current flow to the coil and its ability to store energy for the next spark, and so a hot coil would adversely affect ignition.

The coils are tucked under the fuel tank, pretty much directly over the front of the vertical cylinder head. They're perfectly positioned to get cooked by rising heat, if slipstream isn't present. Maybe this is one reason the bike starts to behave badly in traffic. At least, that had been my thinking. I hadn't measured it yet.

The carburettor bowls had seemed to get cooler, when quickly checked by hand earlier. If they're getting too cold then presumably this would affect fuel vaporisation. I hadn't measured this either.

So, three simple shots to take. Go for ride, pull over, quickly get the imager out of the tank bag and shoot by the side of the road. Simple enough. The first three photos (the normal ones) show the angles I used. The inlet manifold was easy enough, that's just the flank of the bike. The coils required lifting the fuel tank and were imaged from the side and over the windshield, from the front. The carburettor bowls had to be imaged from under the left clip-on, through a lot of clutter.

The first three infrared shots were taken with the ignition switched on but the engine not running, showing the coils warming up under supply voltage. This was over roughly three or four minutes.

[OddDuck]

And now starting... I cranked the motor from cold, got it to the point where it would just maintain idle, and took a few images.



There were more, but this one shows the basic idea: the inlet manifold takes much longer to warm up than the cylinder head. Head temperatures got to 45 C or higher very quickly after the engine caught. Manifold temperature appeared to lag behind for some time.

The manifold is shiny metal, rather than painted or oxidised... that's a problem for a thermal imager, because shiny won't let heat out or heat in. It acts like a mirror instead and reflects the surroundings. The images can't be taken at first glance. There's an oxidised flathead screw covering the vaccum tap, though, and that's a good target (just to the left of the crosshairs in this image). Image colour can be used to assess temperature, you don't have to rely exclusively on the crosshairs reading.

[OddDuck]

Right, five minutes down the road, bike idling roadside.

[OddDuck]

Another ten minutes down the road, rolling at a steady 50 k's the whole way. I took the time to get the seat off and put the tank up, taking two images of the coils. The carburettor body is the near black object, with clutter everywhere.

[OddDuck]

At this point I'll cut the images down to stuff that might be interesting in terms of things like warm tyres, muffler temps etc. I went up a hill, rolled around in suburbia for a while, came back on the motorway, then rolled slow (1st gear, to mimic traffic) home, trying to get the engine to behave badly before putting the tank up again to have a last look at the coils.

Some early conclusions:

1) coil temperature doesn't seem to be affected much by slipstream, it gets to high 30's and seems to stay there. Further checking is needed, though. I haven't tried this during a hot day downtown, when the bike thundering tends to become a real problem, even with the inlet manifold insulators.

2) inlet manifold temperature moves quite a bit, depending on ambient, throttle loading, slipstream etc. The manifolds seem to be running at roughly half the cylinder head temperature, with OEM gaskets and the fibre insulating top hat washers I'd made up.

3) bar tingle definitely comes back below a certain inlet manifold temperature, I think around 65 C, and goes away above about 70 to 75 C.

4) there is a cooling effect on the carburettors from the fuel. So far it only seems to be a few degrees, but I haven't had any chance to go beyond 1/8th throttle for any length of time. I don't know how or if this crosses over to bar tingle or excess noise, though.

5) no matter how quickly I pull over and get the imager out, I'll never get accurate pictures of what's happening while I ride. The manifolds change temperature too quickly, as seen by monitoring for a while after getting off while leaving the engine idling. On-bike logging is needed to get decent data.

It was still a decent start and worth doing again during hotter conditions. Ambient for tonight's run was around 17 to 18 degrees.

[OddDuck]

Finally got around to the 3000 mile valve check / service... post rebuild, clearances should be checked at 1000 miles, then back to the regular 3,000 mile intervals. I wanted to pull every shim and measure length so I'd know what to order, if clearances changed.

This meant finding a way to lock the valve once the opener shim was removed. This has to be done, otherwise there's a chance that the valve will drop into the cylinder. The valve stem seal will probably catch the valve by the collet groove, but if that valve goes in then it's frame off engine and head off cylinder time.

Holding the valve in place against the piston crown is possible, but that gets fiddly... there's only one place in the cam rotation where the top rocker will slide across, allowing access to the shim stack, and that only seems to happen with the piston well down in the cylinder. I'd have to remove the timing belts to do it. Easier to secure the valve.

I tried a twist of wire, with insulation left on for grip, but this didn't work particularly well. Oil-soaked PVC insulation on chromed, polished, oiled valve stem just doesn't grip particularly well, especially since the wire has a habit of opening up again. I also tried a loop-and-choker arrangement of wire and cable tie, but the cable tie didn't slide up the wire properly, cutting into the soft insulation instead. Frustrating.

In the end I just used 3mm wide cable ties directly on the valve stems, between valve guide seal and opening rocker arm fork. This gripped securely. No issues using it - there's enough clearance to push the opening arm down far enough to get collets and shim out - but I had some trouble removing it. I really didn't want to mark the valve stem or cut into the valve guide seal.

In the end using sidecutters straight through the ratchet mechanism of the all-plastic tie, avoiding either side of the loop and never getting the cutter jaws close to the stem or guide seal, worked. The little tongue of plastic that serves as the ratchet ended up popping out, just waiting to jam in somewhere, so that had to be found and removed.

Disposable foam earplugs were used to prevent collets / bits of cable tie falling down the oil drain ports into the engine. One note about these, there is just one on the horizontal head, but there are two - one each side - on the vertical head. It pays to get both valve covers off and plug both holes before starting work.

I'd seen a kit from the USA for this kind of work which featured rubber-jawed locking pliers. There are also specialist tools around for holding down the opening arm and locking it down. Initially I'd thought these were pricey luxuries; after the ordeal that was yesterday's effort of pushing with an oil-soaked screwdriver while trying to refit collets, I'm beginnning to see the point of having these. It got awkward. I was down by the front wheel and also working under the tank, access was poor.

I need quite a few shims anyway - there's been some movement, and one valve has moved 0.004" on both opener and closer - so it's shopping time. The MBP valve collets are holding up well but there's a little bit of settling in wear or deformation showing.

[Ocean1]

May not work, there, if you can't live with the piston at bdc, but several time's where the alternative is removing the head I've simply fed compressed air into the cylinder via a modified plug.

It's not mechanically 100% secure, but the valve gets maybe 100kg closing force. On a conventional setup it's enough to pop collets out with a hammer and socket. On a conventional setup you also need a spring compressor that clamps under a rocker shaft or head stud nut.

[OddDuck]

May not work, there, if you can't live with the piston at bdc, but several time's where the alternative is removing the head I've simply fed compressed air into the cylinder via a modified plug.

It's not mechanically 100% secure, but the valve gets maybe 100kg closing force. On a conventional setup it's enough to pop collets out with a hammer and socket. On a conventional setup you also need a spring compressor that clamps under a rocker shaft or head stud nut.

I thought the experienced hands would have a trick or two... yep that'd work brilliantly. I'd have to (finally) get an air compressor and source the adaptor but there'd be no farting around with bits and bobs inside the rockerbox. I'd have to remove the relevant timing belt though, the pressure would drive the piston to BDC and there might be issues with rockers and camshafts.

One of the joys of the desmo system is that there aren't valve springs, very low levels of mechanical force are needed to strip the top end of the valve gear. There's a closing spring for the closing arm but that's all, a half-decent lever is all that's needed to work that.

[Voltaire]

Spent a few hours on Saturday putting the rebuilt stock carbs back on only to find when I went to start it up fuel pissed out the carb...
Took it all apart again an found the float on one carb sticking open due to crap in inlet.
Cleaned it all and put it back together, set the carbs at 1.5 turns out and started it up....ran like shit, flames spitting out of both ends.urry

Gave up and had a selection of craft beers and a curry. Was at the point of taking it to someone else.

The air/battery box is such a PITA to fit I left it off and you can run the engine with the electrics just sat in the space for test purposes.
The spitting was caused by lean idle, google agreed that 3.5 was the correct setting, which it turned out was correct as started up and ran with no choke from cold.
I was a bit surprised by that. Carbs have had a Dyna summit rebuild kit fitted.

Encouraged by this changed the oil, fitted new plugs and cleaned engine.
Did a final assembly and took it for a 35KM spin out to the Airport and back.

Starts easily, idles at a 1000 RPM, pulls cleanly up to the 7500 I tested up the Hillsborough incline section of motorway, will run to below 3000 without the usual Ducati juddering.
Cut out twice after the deceleration but that may be fine tuning as its got Termis on it.

Conclusion: Kehin Flatslides on a road bike are a nice bit of bling but , the increase in power if in fact there is any ( can' say I noticed a lack of it) is not worth the grief of having an engine that is hard to start.

I did notice that the engine was running hotter than I would expect but thats a job for another day, Ducati 900SL can now be easily started and taken for a ride
Mines got a Yoshimura volt meter/cloc/Temp guage, I'll see where the sensor is as it was reading 61 degrees when I got home.

[pete376403]

Supercheap have a range of compressors that would be suitable. Nothing fancy but they do the job. $125 and they have a good range of accessories. No sparkplug adapters though.

[OddDuck]

Voltaire - good to hear, but... sorry I'm going to be a fussy bastard here...

Check your plugs, I suspect that it'll run super rich once warmed up if it's starting without choke. Surprising amounts of heat coming off the engine is something I've been through already and it was associated with running over-rich.

Airbox and filter medium (or lack thereof) will affect starting and idle quite markedly, if you got it tuned for starting with these removed then it's going to be a bit different with them fitted. At least the pilot fuel jet screw is accessible easily, it shouldn't be hard to tweak it again if necessary.

If the plugs are fine then ignore the above, just ride the thing.