Winter Layup - 1995 Ducati 900 Supersport

[OddDuck]

Is there a special set of screw drivers or something Ducati mechanics use for carb tuning? Bet they don't remove them in the shop.

Didn't see a set of these in my workshop manual... in the meantime this works:


The smaller screwdriver to the side is the hex driver bit that fits into the air-fuel mix adjustment screw. Doesn't quite reach the pilot jets though.

[OddDuck]

Voltaire, might have something for you... starting.

I'd been on a road trip over the weekend with a mate and had real issues starting from cold, first thing in the morning. It was a little nippy, nothing serious, but I really had to crank the hell out of the bike to persuade it to catch. Lots of cranking the throttle to squirt some petrol to richen it up, lots of backfires in the motel parking lot first thing in the morning, etc etc...

Anyway, I'm at the 60,000 mile service now and as part of that I've changed the plugs, finally.

Guess what, it fired up on the first crank. It caught literally the first time the motor turned over, first revolution, that kind of thing. There were no tricks with cranking the throttle to give it a squirt or two of petrol first.

I'll still have a play with pre-heaters for starting but for now it looks like carbon deposits on the plug insulator are a lot more important than I'd thought. The old plugs are badly blackened but still starting and running. They're not dead but it's now clear that they were walking wounded.

I'd been running 9's, might have been running a grade too cool. Carbon will deposit on the plug insulator at running temperatures below 450 C and needs temperatures between 450-ish to 800 C to burn off again. I've switched to 8's, as NGK recommend, and will have to see what this does to tuning.

I strongly suspect that this changes a lot. I should have been tuning with clean plugs from the word go.

[Voltaire]

My 900 came fitted with a Yoshimura digital readout that gives air temp, air temp off a sensor and voltage...oh and being Japanese a clock.
My 900 will only really 'catch' when the sensor reaches 25+ degrees ( its mounted on the engine somewhere), thats after numerous attempts listening to the life of the sprag clutch diminishing on each press of the starter.
I concluded that the loooooong manifolds need to heat up as the vapour is probably turning back into liquid from condensing on the manifold.

The FCR's might give a bit more ommph and sound nice when you crack them open but I scored a set of rebuilt stock carbs with all the cables and throttle.

Doing the conversion now and the FCR's are in a box to give to the next owner as shelf bling.
I've spent weeks and endless test rides getting my Guzzi lemans 2 running right and am some what over fiddling with carbs.

Conclusion- chokes are useful.

[OddDuck]

I've spent weeks and endless test rides getting my Guzzi lemans 2 running right and am some what over fiddling with carbs.

Yep I hear ya!!

[Voltaire]

Yep I hear ya!!

On the lemans one cylinder was running lean, other rich, both had same jetting and settings.
Once a plug fouled that was it for the plug.
Eventually swapped the carbs over for a test and fault went with carb....one of the Eureka moments.
My mate said stick it on Trade Me but I did not want to see it under optimistic sellers:killingm

To my eye the carbs looked fine, did more research ( trawling internet)
In my Dellorto bits box found some similar sized main jet, emulsion tube,needle and tried this.
Much better, took longer to foul plug on same 30 km run.
Ordered gasket and seal kit, new needles, emulsion tube ( needle jet tube) and idle jet.
Did a 200 km run on Sunday and runs perfectly.
900 is under a blanket waiting for the stock airbox to arrive.

I did change the plugs on the 900ss, I was heading down the route of getting rid of the crap stock ignition and fitting an Ignitech but the rebuilt stock carbs came up on TM at a good price.

[Kickaha]

The current plan is to go shopping for a pair of band-clamp heater elements, designed to fit onto piping, and fit these to the outside of the inlet stub pipes. I have no idea yet if anything's available in 12V / 38 mm. In theory it's got a lot of advantages: I can use the thermal mass of the inlet pipes to store energy, the heater itself can be robust and MIMS (Mineral Insulated, Metal Sheathed), and it's ultimately just a bolt-on modification, not something fabricated. I can also use safeties like bimetallic switches against overheating. Right, further browsing / shopping / building to do.

What about wrap on handlebar heater elements, probably not quite big enough in diameter though http://www.aerostich.com/aerostich-warm-wrap-grips.html

How hot do they need to get and how quickly?

[Grumph]

The electrical contractor I once worked for had on the shelf Element Tapes. Came in various lengths and widths, looked like a woven cotton tape with a metallic thread through it. Two wires coming out one end. I asked about it and was told it was for DC applications.
I never had a use for it, so it stayed on the shelf...Business has changed hands but it's probably still in stock.

[OddDuck]

What about wrap on handlebar heater elements, probably not quite big enough in diameter though http://www.aerostich.com/aerostich-warm-wrap-grips.html

How hot do they need to get and how quickly?

Thanks for that. Interesting that there are under-grip heaters available - I'd never heard of them before but it makes sense that they're out there.

I had another look at the inlet stubs the other night and the straight length available for wrapping a heater is very short - only around 45 - 50 mm. The pipes themselves are 150mm-ish but a lot of that gets taken up with the rubber boot/insulator/seal for the carburettor, the flange, the vacuum gauge fitting and the curved neck.

So far the winners are the stick-on silicone heaters from RS, mostly because they'll go straight on. They're cheap enough - $40 each - and it's a spot of work cutting some stainless shim for backing plates, but that's all that's needed to fit them.

As to how hot they'll need to get... it's a bit of try and see for this. I honestly won't know until I give it a shot. 5 watts isn't much but if the stubs are warmed up before I turn the motor over, I can store the 5 W being pumped in and raise the temperature to whatever is needed.

[OddDuck]

The electrical contractor I once worked for had on the shelf Element Tapes. Came in various lengths and widths, looked like a woven cotton tape with a metallic thread through it. Two wires coming out one end. I asked about it and was told it was for DC applications.
I never had a use for it, so it stayed on the shelf...Business has changed hands but it's probably still in stock.

I had a quick look last night and there's quite a bit available. Most of it's mains powered, for underfloor heating or similar, but there are some DC versions around. The stuff I was seeing is called Trace Heating Cable, RS have a lot, there a lot of insulation / heating companies with it, and Omega Engineering in the US have a lot of it too.

The trouble is fit. As I'd replied to Kickaha above, the area available for fitting a heater is restricted (unless I machine up a collar or something) and it really limits what can be placed. There's also heat, vibration, petrol resistance... whatever is built will have to be clamped and secured very carefully against vibration because otherwise the heater elements will either snap or will chew their way out of the insulation.

[Voltaire]

The electrical contractor I once worked for had on the shelf Element Tapes. Came in various lengths and widths, looked like a woven cotton tape with a metallic thread through it. Two wires coming out one end. I asked about it and was told it was for DC applications.
I never had a use for it, so it stayed on the shelf...Business has changed hands but it's probably still in stock.

Its called Trace Heating, when I worked in the UK it was wrapped around pipes to stop them freezing.

Air cooled VW's had an exhaust heated inlet manifold to assist cold running.

I think the Ducati inlet manifold to the front cylinder is just too long for cold starting with carbs without chokes.

[OddDuck]

Heaters on order, in the meantime I finally got onto an issue that's been waiting for a while.

The rear brake caliper is positioned vertically above the axle. This means that the brake pads are hanging from their retaining pin - their weight isn't carried by the caliper in any other way. Vibration plus abrasive brake dust means that they've been cutting grooves into the retaining pin, also the pin itself has been cutting its way downward in the caliper body, ovalling the pin's hole.

I got the verniers onto various components. There's a pair of half millimeter cuts in the retaining pin, a matching half mill in each pad's tongue, and nearly a mill in the caliper body itself.

This means that the pads are slowly but steadily working their way downwards. Fresh area on the brake disc is being brought into play, it isn't the same thickness as earlier metal, and now the pads are only engaging on their edges. The brakes themselves have become spongy due to spring / flex in the pads, as the gap in the middle is taken up. This would all settle down if I used the rear brake a bit more of course.

I'm not wild about replacing an otherwise perfectly good caliper because of one ovalled pair of holes. What to do...

First: stop the pin flapping around loose in the caliper body. Second: take up the vertical slack between pads and pin. It'd be nice to include something with some shock absorbing qualities in this modification, if possible.

Thin-walled heatshrink onto the pin, and running a drill through the ovalled caliper holes to round them again, got the pin located with a light sliding fit. A drilled-out piece of stainless steel tubing then fitted over the pin and held the pads, after their tongues were filed out very slightly. Having a drill set stepped in 0.1mm increments was very helpful for this, I also needed something to chamfer the tube inner edges post drilling so that it didn't carve the heatshrink up when fitting.

There is a catch - the pads have to sit cleanly against the inner walls of the caliper when braking, as designed. They can't load up the retaining pin via their tongues, otherwise the pin will bend. There has to be fore-and-aft movement possible between the pin (or its cover tube) and the pad tongues. I'll have to check this properly in the morning, but it's not a big deal to pull the pad stack out from the caliper and file a bit more if needed.

This is only an issue on high-mileage bikes. I'm nearly at 60,000 miles and it's only really started becoming a problem in the last few months. It's also only a problem on the older bikes. I think that Ducati have revised the design: the newer retaining pins feature spring collars, so they're located in their calipers without being able to bounce around in the holes. The pads will still notch the pins, but it's not a big deal to replace these when needed.

[OddDuck]

I ordered the stick-on 5W heaters from RS and tried fitting them.

Fitting wasn't a problem. Opposite the vacuum test screw, there's a cast-in boss (purpose unknown), this had to be filed off before the 50 x 100 heater would fit properly. I did a lot of smoothing of the surface with wet'n'dry as well.

Testing (on the bench) was illuminating... unfortunately not in a good way. 5W really isn't much power. It took about ten minutes for a fairly paltry temperature rise. I didn't take photos of measuring this (I managed to borrow a thermal imager) but it was around 8 C increase.

There's no way that +8 C in ten minutes, on the bench, in still air, is enough for the job. However it did give me a baseline for what's needed, that being roughly 80 watts per inlet.

I also had a good scout around for heating elements and found out something that might be very useful to someone out there: multi-stranded flexible nichrome wire, insulated in fibreglass, is made and sold - just not around here. Omega Engineering (Australia) have some, but it's the devil to search for it since they don't give it an intuitive name. I'll have to keep looking and post again later. Heater tape / cord is available but it's just too fragile to survive long in this application.

There is an alternative: type K thermocouple extension wire. Radiospares sell this. Type K is a pair of wires, one made of alumel, one made of chromel. The alumel is magnetic, low resistance, and not useful as a heater element. The chromel is approximately 90% Ni, 10% Cr, and has roughly half the resistance of Nichrome V (the 80-20 Ni-Cr alloy commonly used as a heating element). It's flexible and insulated to handle the temperature (if fibreglass insulated). I'd prefer the nichrome flex cable (looking for this stuff is driving me mad, I know I saw it earlier), but the type K could be done if necessary.

[pete376403]

Flexible heating wire - I stripped some out of an old safasleep low voltage electric blanket years ago to make a heated vest. You might find one of those blankets at an opshop.
From your description the wire you are after is very similar to what I used.

Edit. I only used half of a single blankets worth of wire for the vest. I did make a a second one but never completed it. The stitching could be unpicked easy enough if you want the wire. There would be about 2 -3 meters in total.

[OddDuck]

The bike's been running with a nasty tingle coming through the footpegs and the bars, something that gets quite nasty to ride with after a while.

My first thought was that I'd overcooled the inlet stub pipes, particularly since there was unequal insulation on these (slightly thicker washers on the horizontal, it was late, I was tired, we've all been there). Cue a few weeks worth of playing with the insulation on these, with the issue appearing to get better again with each change and then coming back worse than before.

First I tried equalising the paper washers, then taking the paper washers down to 0.5 mm thickness each (worked at first), then fabricating metal top hat washers and changing out the fibre and resin insulator washers in order to run the pipes warmer (also worked at first). I found out a few things while making changes.

1) the resin and fibre insulating washers creep quite a bit under pressure and heat. Given another year or two of service, they'd have failed to clamp properly any more. They were also tight on the M8 cylinder head studs and had to be drilled out again in order to slide on and off properly.

2) it's possible to make metal top hat washers which insulate nearly as well as the fibre ones do. The trick here is to make them badly; have tapered faces, use supporting washers on the aluminium flange, that kind of thing. Poor contact between multiple layers of metal actually works pretty well as insulation.

3) M8 top hat washers can be hacked up at home without a lathe. M6 flange nuts have a 10mm hex which provides a reference surface. Bench vise, file around the perimeter to take 10mm hex down to 10mm round, a series of drills through the thread at the center and voila, ghetto components good to go.

4) the inlet pipes have quite a temperature gradient across them when running - the fuel and air mixing does suck a lot of heat in - and there definitely seems to be an optimum point of operation. Too hot and the engine's psycho loud, too cool and there's nasty combustion with rough running and loss of power. The trick is getting the right amount of heat conducted in from the engine, and that takes some trial and error. It certainly wasn't right as stock, except for running around at half throttle or more.

5) there can be quite a difference in thermal conduction between different grades / thicknesses of paper washer, particularly if they get soaked through by petrol... or not. OEM lets a lot of heat through, it appears now that this was deliberate. My aftermarket gasket paper is a much more effective insulator, but now I've run into problems with the pipes running too cold.

6) running temperature of the inlet pipes also depends on throttle position, since more fuel & air means more cooling. There's no passive solution here, if thermal conduction from the engine is right for around town, it'll be too cold for highways. If there's enough for highways, there's too much heat for town and the bike's going to get loud in traffic. This is a right pain, no wonder people go to split singles and short inlets, it's the only way to duck this particular issue short of active temperature control on the inlets.

And after all this, it's still running with a nasty vibe... I did some reading and carburettor misadjustment (or even dirt) had caught a lot of people out. Fine, it'll be into the carbies yet again. As a precaution, I pulled the spark plugs out first as a basic check of what's going on.

Horizontal cylinder: super clean, no fouling or overheating, about as close to perfect as I'd ever seen. Vertical cylinder: fouled to the point where the multimeter could measure a resistance across the plug nose, meaning it's rooted. This happened in under 500 miles, the plug was brand new just a couple of weeks ago. Maybe the carbs are delivering different mixtures, but it's doubtful that they're this different.

Further reading pointed out that a fouled plug can be the result of a weak spark. The bike's been fouling plugs on the vertical cylinder ever since I'd bought it. That's before carburettor replacement, before tuning, it's just always been like this. Right... Before going with my gut and laying down cash for new CDI's, I got the multimeter out and checked voltages with the bike on a stand and running. Maybe it wasn't the CDI's. Maybe it was the wiring. Or something.

The pickup coil resistances tested OK for ohms with the bike static (as per workshop manual), but testing while running indicated significant differences in voltages supplied to the CDI's. The horizontal is delivering between 0.8 to 1.2 Vac, the vertical just 0.2 to 0.4. It's possible that this is due to bad gapping, but I double-checked this when reassembling the engine and was happy that I'd got it right.

This seems pretty clear cut, but I went through the rest of the accessible bits of the ignition anyway. Initially the positive voltage sides of things were all running at 9V or so, which seemed to indicate a problem with the feed from battery through main relay, kill switch, and wiring harness. After a few minutes messing around and the bike running, this voltage increased to 11 V, and the coils were warm.

To my mind, this last may also be a factor present in cold starting. It's not just that the engine is cold. It's that the coils are cold too, and presumably are snorting current down to the point where supply voltage is sagging. This wouldn't help sparking, which of course is what's needed when cold starting.

Anyway... looks like it's prudent to replace the pickup coils. It would've been more prudent to do that on the engine rebuild, but hey, spilt milk and all. I'll just be grateful if this finally sorts the issue out.

[OddDuck]

Flexible heating wire - I stripped some out of an old safasleep low voltage electric blanket years ago to make a heated vest. You might find one of those blankets at an opshop.
From your description the wire you are after is very similar to what I used.

Edit. I only used half of a single blankets worth of wire for the vest. I did make a a second one but never completed it. The stitching could be unpicked easy enough if you want the wire. There would be about 2 -3 meters in total.

This is gold. Thanks mate - will do.