1981 SD900 Darmah - Restoration Project

Post pictures of your twin cylinder Bevel Drive Ducati (pre-1985) along with a description here.
pilotg
Diana
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Post by pilotg » Sat Jan 07, 2012 9:15 pm

....the saga continues....

I replaced the buggered sprag, refilled with oil and checked through everything again only to find that the right hand fuel tap was leaking badly.

When I pulled it apart the seal fell apart immediately. I manufactured one from some rubber insertion and fuel tolerant gasket material. All good there.

I refitted the tank and put in some fresh fuel. The carbs were pumped up and then with some trepidation I hit the start button. It took a few minutes but i got it started but the idle was still a tad slow. It stopped and wouldn't start again. The battery seemed to be low on grunt so I stopped for the day and put it on the trickle charge until the next day.

Next morning with a fully charged battery it was still sluggish. In an effort to isolate the problem I removed both plugs and turned it over again. No problems there, it puffed away beautifully, speeding up. Plugs back in and, nothing. It got slower and slower until it stopped and the solenoid just clicks. I dragged out the 1200 jump pack I keep in the 4WD. Even with that hooked into the system it won't turn over so my guess is that the starter motor is sick. That got me thinking...

Perhaps that was part of the problem all along. If the starter was drawing internally most of the power then it would look like the battery was rooted. This in turn would simulate one of the major causes of sprag failure. Am I right?

In the meantime, I know when I'm beat. Whilst there is no Ducati specialist mechanic in my small town there is a new shop where one of the staff rides a modern Duc so it's off to them tomorrow. I've done all I can and now I'd rather spend some cash to have a professional sort out the last niggles and get it running sweet. After that I can tinker.

One day I'll go for a ride, but not this one.

Big sigh.....
1981 SD900 Resto project

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Craig in France
Cagiva Gran Canyon
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Post by Craig in France » Sun Jan 08, 2012 2:46 am

Hi George

1. You don't say what voltage you're getting from the battery. You need at least 12.6 volts after the battery has been left 24 hours after charging. Look on Tinternet but, to give you an idea, here are some values I just found:
12.68v . . . . . . . . . . 100%
12.45v . . . . . . . . . . 75%
12.24v . . . . . . . . . . 50%

2. If you need to buy another battery, get one with the highest Cold Cranking Amps (CCA) rating you can find. The amp/hour rating traditionally used for batteries is largely irrelevant. See Steve's advice on his website. The SVR battery he sells/recommends performs well - I actually use an even bigger one, the SVR 30.

3. As well as a possibly tired starter motor, you should suspect the solenoid. They corrode very badly inside. Not worth trying to repair. They're cheap and widely available as they were used on loads of cars at the time, Landrovers and Minis for example. Here's one on eBay
http://www.ebay.co.uk/itm/LAND-ROVER-SE ... 3a61a294e6

4. Any decent auto electrician will be able to overhaul your starter motor. It's a simple job.

Ciao

Craig

wdietz186
Cagiva Alazzura
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Post by wdietz186 » Sun Jan 08, 2012 5:34 pm

Before you condemn the starter motor have a good look at the cables. if the exposed wire at the terminals is greenish or white you could be dealing with badly corroded cables. The corrosion will creep up under the insulation and cause high resistance and a large voltage drop and all the fresh batteries in the world won't get you started.

pilotg
Diana
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Location: Christchurch, NZ and Brisbane, Australia

Post by pilotg » Thu Jan 12, 2012 1:34 am

Yet another stupid question.....

Ignition timing. Once the pick ups have have been assessed as right resistance and right air gap, what other means have I got to change the timing? I have a degree wheel and a strobe (not used either yet) but I'm not sure what I do if I find that the timing is out. Is it a case of adjusting the air gap? Seems unlikely, but possible. Is there some other adjustable component that I'm not seeing? There is only one possible as far as I can see. Moving the entire pick up plate. I'm not a mechanic or engineer so I'm relying of more experienced/skilled out there to advise.

Status report....

The bike is starting on the first compression stroke and running OK. The starter motor brushes were shot and there were a few shorts in different areas. Little things added up to make a big problem. I'm so close now I can smell the hot brakes and tarmac.

Rgds

George
1981 SD900 Resto project

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BevHevSteve
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Post by BevHevSteve » Thu Jan 12, 2012 6:03 am

Do not touch the pickup locations - either the plate that holds both or the individual pickups. You need a special tool to reset these that hardly anyone actually has (I do though)....
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pilotg
Diana
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Post by pilotg » Thu Jan 12, 2012 11:05 am

Good advice Steve. I do have a pick up setting tool. I checked the settings after i replaced the sprag and found that whilst one was set correctly the other was out by quite a bit. Using the tool I reset it so that they are both the same now. The threads were cleaned thoroughly and then blue loctite was applied.

I'm still not sure what I can do if the timing is out though.

Regards

G
1981 SD900 Resto project

pilotg
Diana
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Post by pilotg » Fri Jan 13, 2012 1:09 am

It's off again.

The starter was rooted. Well, the brushes were. They, and the armature were black. According to the mechanic (I relented and took it into the shop) it looks as though it had been arcing badly.

The carbs have been balanced and set up properly. The slide screw had worn a notch into the bottom of the slide and it kept hanging up. One slide would stay open by 3mm.

Starting really could not be easier. A momentary twist of the throttle, turn the key, light press of the button and away it goes, every, beautiful, magnificently sonorous time. I'm starting to believe the stories I've been told about how Darmahs are supposed to start.

The 32s will have to wait til next year, but that doesn't seem an issue anymore.

We have a big Ducati rally coming up in New Zealand and it's not far from me so I'll be heading there in March.

Thanks again for all your help.
1981 SD900 Resto project

machten
MHR / S2
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Post by machten » Fri Jan 13, 2012 3:18 am

Starting really could not be easier. A momentary twist of the throttle, turn the key, light press of the button and away it goes, every, beautiful, magnificently sonorous time. I'm starting to believe the stories I've been told about how Darmahs are supposed to start.
Well done and congrats on your persistance, pilotq! Sounds like it's time for some ride'n in the land of the long white cloud!!!

Enjoy :-D

Kev

pilotg
Diana
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Location: Christchurch, NZ and Brisbane, Australia

Post by pilotg » Sat Jan 14, 2012 1:23 am

No, thank YOU Kev! You and the other great contributors to this forum make the whole job so much more manageable.

I'll admit to waking up at 2 and 3 am and logging on to see if someone had left a reply to more than one of my questions. Sometimes the problems seemed to be unending.

Realistically, without the internet I could not have done it. Not just the advice but the parts and photos that helped me see how things should look.

I'll have a few weeks enjoying the new toy and then think about summarizing it all as a way of trying to help those that follow.

See you guys on the road!! Finally.... :-D :-D :-D :-D
1981 SD900 Resto project

pilotg
Diana
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Location: Christchurch, NZ and Brisbane, Australia

Re: 1981 SD900 Darmah - Restoration Project

Post by pilotg » Wed Jan 18, 2012 11:01 pm

Update......

I am now road legal. It sailed through without so much as a cough. Why no smilie?

I can't get from second to third gear and even first to second is a struggle. I'm guessing having read a few posts on transmission problems, is that the selector spring is slack. It doesn't sound like a major repair so I'm not so disheartened. I've also read about how precise the screw adjustment has to be. I'm not sure what screw they are talking about. The gear change lever moves freely without being slack, however, no gear is selected. It takes repeated upward clicks to find second. Unlike most Darmahs finding neutral is unpleasantly easy. It's nearly 25 years since I rode a motorcycle so not being able to get above second is probably a lifesaver!

More annoyingly, when I set off today the bike fired up easily. 400 metres down the road the bike started to cough and run on one cylinder. Then it stopped. After repeated attempts to get it going again I gave up. I waited 5 minutes then tried again. Away again. Another 100 metres, stop. Same again. No power. I'm guessing fuel starvation. Incidentally, I should report that within two minutes of the first konk out a local bikie showed up on foot to offer assistance. After I set off again he sauntered back to his home. When I stopped the second time, less than 5 minutes later, another bikie parked up next to me in his pick up truck. Not only did he offer me the use of his shed and tools to sort the problem, he went back to his house, fetched a ramp and tie downs and proceeded to transport me and the bike back to my house. I didn't know either men before hand. Top chaps :-)

I drained the fuel and have to report that the right hand pet cock was very slow. Both filters looked OK. The temporary seal I installed last week had started to break up so that's the first repair. After that I'll try fresh fuel. If that doesn't work I'll pull the carbs apart and give them a clean out.

My previous experince has been with Jap four cylinder machines. This feels so different. With no recent experience I feel very very exposed on the road and quite out of my comfort zone. When the bike is running well though, the torque is amazing.

Any advice welcome.

G
1981 SD900 Resto project

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Steve Foster
Parallel Twin
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Re: 1981 SD900 Darmah - Restoration Project

Post by Steve Foster » Thu Jan 26, 2012 2:33 am

G,
400 metres down the road the bike started to cough and run on one cylinder. Then it stopped. After repeated attempts to get it going again I gave up. I waited 5 minutes then tried again. Away again. Another 100 metres, stop. Same again. No power. I'm guessing fuel starvation.
I had a similar experience - bike would run fine for a few hundred metres ... then cough and falter. Attempts to start - futile. Sit on side of road for 5 minutes, then it starts and repeats the whole cycle. I eventually found that one of the circular gauze filters where the fuel line meets the carb was blocked with very fine grit. So the bike would run on what was in the float bowl then stop. After five minutes enough fuel would seep through the clogged filter to fill the float bowl again so it would start ...

Cheers
Steve
1974 Ducati 750 GT

pilotg
Diana
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Re: 1981 SD900 Darmah - Restoration Project

Post by pilotg » Fri Feb 24, 2012 12:14 am

New fuel taps arrived today. Fitted. No leaks, great.

Now it won't start again.... I checked the fuel progression to the carbs. No worries there. It's firing on the rear cylinder but not on the front.

I pulled the plug. It was wet and oily. I cleaned it and checked the gap. All good at 0.6mm. I tried holding te plug against the engine whilst turning over. The rear cylinder is so keen it was trying to run on the one pot! Crucially though, no spark from the front plug. I checked the plug/cap connection. Possibly a problem. Retried the spark, great. Refitted the plg and hit the button. Fired and ran straight away, but, now the starter won't disengage. Another go and there's no spark again. So, here's the questions:

Why won't the starter disengage? I'm thinking sticky sprag, which means pulling that lot out again. (i've got to go in there to replace the gear selector spring anyway, so no big deal) But why is it sticking?

Is it possible the coil is on it's way out? How can I isolate the problem part quickly? The problems seem never ending. As soon as I get one fixed another three appear!

Still have the belief that it will come good!!

Regards George
1981 SD900 Resto project

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jaffa
Mariana
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Re: 1981 SD900 Darmah - Restoration Project

Post by jaffa » Sat Feb 25, 2012 8:14 pm

How sure are you that the starter button isnt sticking in?
Jaffa
Volvo Aware Motorcyclist

'78 Darmah
'92 907ie
'82 900 MHR

pilotg
Diana
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Re: 1981 SD900 Darmah - Restoration Project

Post by pilotg » Sun Feb 26, 2012 12:59 am

Definitely not the starter button, but a good suggestion nonetheless. I know this because I've now had it apart and my worst fears have been confirmed.

I know I'm going to get some serious flak over this but the sprag has gone for the third time in less than 12 months. Before the abuse starts rolling in I'll list what I know to be true:

The previous owner sent me the receipts for the last 20 years. In 2010 the sprag, and pick up wiring was replaced by a mechanic. No details as to why.

I blew the first sprag due to a stuffed battery and possibly a bad starter motor. My ignorance of the dangers was a major factor.

The bike was then rewired, re plugged and a new battery fitted. The pick up setting was set correctly with the pick up tool.

Second sprag blew because the electrician wired the coils back to front and I was a meathead.

I then sent the bike to a mechanic and he cleaned and set up the carbs correctly, balanced and tuned them. He then replaced the brushes and the earth wiring to the starter motor. At this stage the bike would fire and run sweetly from the first compression stroke.

Then came the fuel and gear selection issues.

I can say with all honesty that I took on board the advice given re starting. This was the sequence that has led to the third sprag failure:

cough,BLAT...cough,BLAT...cough,BLAT...BANG!!!

Check the fuel progression. OK

cough,BLAT...cough,BLAT...BANG!!!

Check the plug, clean, adjust the gap, check again, OK, replace.

cough,BLAT...BLAT,BLAT...run with starter not disengaging, stop.

Thinking.......

Next day.

Swap plugs front to rear...

BLAT,cough...BLAT, cough.... A HA!!!!

Change bad plug.

BLAT,BLAT...BLAT,BLAT...run great. Stop.

CLUNK.................. mmmmmm?

Took sprag out. It fell to bits in my hand. Both the spring and the cage are distorted.

Now, I know you guys are the experts. What has me wondering is why the bike had be garaged for ten years? Maybe it was blowing sprags before. Why would the previous owner (who owned it for a total of twenty years) have had the sprag changed unless it was faulty?
So, whilst many of you report that you've owned bevels for 30 years and never had a sprag fail, you haven't owned mine. It's so frustrating when I know I'm so close, and did seem to have a fully functioning bike. Then it just stopped working again.

One person has suggested that I change the timing to 5 degrees rather than the 6 degrees. I'm very loath to do this at this stage as I think the chance of screwing it up are too great. Could the coils be on their way out and is it worth replacing them with dyna coils? If so, will the dynas fit onto the exiting OEM brackets?

My plan is now to fit a sprag upgrade kit and go from there. I'm attending the NZDOC rally in Hanmer Springs at the end of March and really want to have the bike ready. As usual, any advice very welcome.

Regards

George
1981 SD900 Resto project

rwhc80
750 GT
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Re: 1981 SD900 Darmah - Restoration Project

Post by rwhc80 » Sun Feb 26, 2012 5:47 pm

Struth George,

You've had enough bad luck to sink a battleship !
I may cop some flak here, but I pass this on as I have experienced a similar issue with my Darmah !
Like you, I originally had starter problems, and battery problems which no doubt contributed to my original Sprag lunching itself. I was very lucky that it simply displayed a symptom of the starter spinning and not turning the flywheel. I first tried a suggestion of a BL Mini auto trans sprag that had to have the outer ring turned down a little. ( A waste of time ! ) I then bought the same SKF sprag that you fitted the second time around. Guess what, within a 1000 kms that sprag had also lunched itself, and was sticking on even when the bike had started. ( Nasty Sound ! ) I had also done many things to improve starting,IE : new earth straps, rebuilt starter, new battery, pickups rewired, carbs tuned, even had an auto elec fit a bypass solanoid to the bike. ( maybe the wrong wording ) but it basically bypasses all the old switch gear connections and sends the current direct to the starter. I have now replaced the sprag again, with the same SKF unit. The bike turns over and starts with the force of the shuttle launch and I am hopeful the Sprag will hold together a little longer this time.

Having said that, I am a little suspect of the SKF sprag that I, and you have used. I don't know what they were intended for, but I suspect Ducati bevel starters was not the original purpose. Please note, I may be wrong with this, and I hope I am for both our sakes.

Re the coils, the OEM brackets won't fit, but Steve has some replacements that will allow you to fit them. If you get a set of Dyna's, make sure they are the black ones not the green ones.
Good luck, you'll get there eventually, and be rewarded with a great bike.
Cheers
Rick
I have desmo disease, I just hope they never find a cure !!!

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