Gone to the Dark Side - Ducati 860 GT

[dguzzi]

We'll need you to start another project when this is done. I love watching the progress!

[canuck750]

I farted around with getting the horn to work for a couple days, very frustrating. I had bought a new horn off  Ebay, just like the original... The problem is when I touched an ohm meter across one of the lugs to the body I get continuity so as soon as I mounted the horn  and turned on the ignition it went off. I tested several of the horns on other bikes and same thing. Then I dug into a junk box and found an old similar horn, and this one had no continuity between the wire lugs and the body, works perfect.

The Ducati horn button connects a ground lead completing the circuit. The hot lead is shared with the two brake light switches. Each brake light switch completes a ground when activated by pedal or lever. So the Ducati horn needs to have a ground isolated from the body.

I had no idea there were differences in the horn make-up though they look the same.

I took the stator to a rewind specialist yesterday along with two Moto Morini stators to check out, the Ducati tested fine, but the three wire harness had a broken wire inside it, simple fix making a new three wire lead and soldering it to the stator, no more blown fuses when I hooked it back up.

The good news is all of the electrical is now sorted out.

Opened up the new electronic ignition I got in the mail this week from a dealer in Europe, ... it's for a Ducati 750GT,    I will send it back for an exchange, not a big deal, just a little bit of an inconvenience.

[jas67]

Opened up the new electronic ignition I got in the mail this week from a dealer in Europe, ... it's for a Ducati 750GT,    I will send it back for an exchange, not a big deal, just a little bit of an inconvenience.

Didn't you have a 750GT project waiting in the wings that you might want to keep that for?

[canuck750]

Didn't you have a 750GT project waiting in the wings that you might want to keep that for?

I had a deal to trade my 1978 Moto Morini 500 for a 1973 Ducati 750 GT but I had to get the Morini cylinder liners repalced beore I could complete the trade. Unfortunatley I could not get the cylinders finished before I left for Europe last fall. When I got back in November I finished the Morini ready to make the trade and then the fellow with the Ducati emailed me to say he had sold it on with another Ducati he had to some other fellow. I was very disappointed.  AT least I have a very nice Moto Morini 500 with a great motor. Over Christmas I was talking to a local guy that has a 72 Ducati 750 GT and he let on he has a basket case with a spare motor that he may be wiling to sell. I think I will eventually fond one to rebuild.

[canuck750]

Some final detail jobs today, finished the electrical so I fit the repro fuse box cover, it is a very tight fit!



The original tool tray was all scuffed up, I cleaned it and then hit it with brake cleaner to get it real clean but the cleaner actually melted the plastic surface, I got some clean black rags and sprayed / wiped down the tray until the finish was uniform, looks 'almost' new. The fuse box will only fit one direction and the hole in the tray is to allow the fuse box lid wing nut to clear, trouble is its not in the right place, so I marked the wing nut location and drilled a new hole through the tray. If the fuse box were rotated 180 degrees the wing nut would match the original hole, leads me to believe the fuse box lid I found was not correct for this bike.



Installed the petcocks and the fuel lines, while I was back around the carbs I installed new jets, fuel valve seat and needle and new accelerator jets





Fit a used fuel cap I had, the original one stuck closed when I installed it, had to carefully pry it off



The finishing touch a new Ducati key fob Charlie sent me!



One job left is to fill the front master cylinder reservoir and bleed the brakes, then its just wipe it down and take it to the International Motorcycle Show when it comes to town in a couple weeks.

Its been fun, I will install the Sasche ignition when the correct unit comes in and then it should be road ready for an inspection in the spring.

[Zinfan]

Bravo!  Another fine thread on a fantastic bike rebuild.  Cannot wait for the next project.

[canuck750]

One last tidbit, I finished bleeding the brakes and fitting the last decals on the forks, then lifted the bike up from my shop overhead crane. I rigged up a digital scale to the hoist, the dry weight of the bike, no fuel in the gas tank, no oil in the crankcase but it does have a battery installed.

459.5 pounds

[Lannis]

One last tidbit, I finished bleeding the brakes and fitting the last decals on the forks, then lifted the bike up from my shop overhead crane. I rigged up a digital scale to the hoist, the dry weight of the bike, no fuel in the gas tank, no oil in the crankcase but it does have a battery installed.

459.5 pounds

I wish everyone who talked about the weight of their bike had one of those scale rigs.   It would save a lot of nonsense talk, requoting of urban legends,  and argument!!

Lannis

[canuck750]

I wish everyone who talked about the weight of their bike had one of those scale rigs.   It would save a lot of nonsense talk, requoting of urban legends,  and argument!!

Lannis

Indeed|!

Most specs on-line claim the wet weight of the 860 GT is 504 lbs. The gas tank is 5.2 gallons, I assume they mean imperial gallons ?- 7.2 lbs per imperial gallon that equates to 37 lbs, add in the 5 liters of oil and that combined with the 459.5 dry weight is pretty close to advertised wet weight  On the other hand most specs claim the dry weight of the 860 GT as 408 lbs, but I think they would subtract the battery and the fork oil as well, still no way that would reduce the true 459.5 lbs down to 408 lbs.

My 1978 Moto Morini 500 weighed in at 369.5 lbs, no fuel, no battery but a full crank case of oil, the advertised dry weight in Moto Morini literature is 368 lbs, pretty close to actual!

Over the winter I am going t weigh all of my bikes just to see how accurate the factory specs are.

Now what would be real interesting is to see what real dyno specs are compared to the published factory numbers, I bet the actual is around 15 ~ 20% less than the lofty values the factory claimed.

[geodoc]

750 GT 472.5 with full fuel & oil.





.

[Lannis]

Now what would be real interesting is to see what real dyno specs are compared to the published factory numbers, I bet the actual is around 15 ~ 20% less than the lofty values the factory claimed.

The "real" dyno specs will be from the back wheel.

Some factories either took the dyno values or extrapolated the values from the crankshaft.

I think Kawasaki used to take them from the piston crown .... 

Lannis

[geodoc]

All run off the same dyno:

[Lannis]

All run off the same dyno:

Those are all believable.

UNlike the manufacturers published HP/Torque figures for those bikes!

Lannis

[huub]

nice data , i once had a V7sport dynoed , it just about reached 50 HP,
looks in line with these results.

[s1120]

nice data , i once had a V7sport dynoed , it just about reached 50 HP,
looks in line with these results.

Kinda makes you wonder how now everyone calls bikes with under 95 HP underpowerd. :) 

[Lannis]

Kinda makes you wonder how now everyone calls bikes with under 95 HP underpowerd. :)

Most common disease out there in moto-world.    Someone's saying "Yeah, I put a chip and some slip-ons on it, it's pulling about 160 HP I reckon, but I need about 10-15 more horsepower, yep, that's right, not quite fast enough ...."

when what really is happening is they've got a bike that the factory "tested" at 130 HP, it was actually making 110, and after the owner modified it, it's making about 90 ....

Lannis

[tazio]

I was surprised by the torque figures for the Kawasaki 750 Mach lV compared to the Kaw 903.
My misperceptions about 2 strokes I guess.
Kawasaki sure had some bases covered in this performance area!

[s1120]

Most common disease out there in moto-world.    Someone's saying "Yeah, I put a chip and some slip-ons on it, it's pulling about 160 HP I reckon, but I need about 10-15 more horsepower, yep, that's right, not quite fast enough ...."

when what really is happening is they've got a bike that the factory "tested" at 130 HP, it was actually making 110, and after the owner modified it, it's making about 90 ....

Lannis

LOL!  Yup thats about it. Back in my hot rod days we had a list of HP increases for the guys like that.. "Ohhhhh chrome valve covers!! Thats good for 15 extra HP!!!"     

[keener]

Nice to see these old dyno graphs ....the Z1 seems a bit short as 52 plus ft lbs was the norm at the time, about the same as the 750 cept it started much earlier .roll ons in 5th from 2500rpm were possible with a 903 , the 750 not so much

[Muzz]

WOW Jim, what a difference between the old and the new.

A beautiful piece of work.  I am in awe of how you achieve such beautiful results with often just common sense down to earth methods.

Between you and Chuck, I have learned heaps.  Thanks.

[canuck750]

Thanks Muzz!

I have put the Ducati in the vintage bike show at the International Motorcycle Show as it comes through town this weekend. Coldest week of the year, not fun to move bikes when its been -35C and then add in the windchill, BRRRRRR.





We have been allotted enough floor space to display 22 motorcycles. I organize the little display and our only criteria is hte bike has not been shown at this event in the past 5 years, I am always amazed at what shows up. The beautiful little cycle next to the Ducati is a Jawa - a 1957 'Pionyr' - 50cc two stroke 3 speed.

This green bike is a 1957 DKW RT 250 VS, found on a farm in northern Alberta with original owners and shop manual, the owner was a farmer who had John Deer equipment, the bike was originally black but the farmer had some green paint on hand.... The Auto-Union 4 rings are stamped on many of the bolt heads, it runs like a charm



One of our local CVMG members family were a Honda dealer in 1964, his father owned a farm implement dealership in a small town in Manitoba, one day his dad returned from Winnipeg with a big crate in the back of his one ton pick up - HONDA stamped on the side and inside - 3 Honda Cubs. This bike is one of the original three and still owned by Sam, the original owner, 16 years of age back in 1964.



a rare 1979 Ducati Regolarita - 125cc Two Stroke - 6 speed, found with another one in a shed in southern Alberta, needed a total rebuild, next to it a 1974 KZ400 - found two blocks from the new owners home, sitting in a garage under a cover for over 30 years!



A real nice 1977 Bonneville and behind it a gem of a 1969 BSA Thunderbolt, both nut and bolt restorations

[keener]

Great  to see such interest in the vintage bikes in Edmonton , love that little twinjet ...brings back some great memories

[canuck750]

Great  to see such interest in the vintage bikes in Edmonton , love that little twinjet ...brings back some great memories

We have seven months of winter ..... if you love motorcycles and live up here then restorations and fiddling is one way to keep the passion alive while the roads are covered in ice and snow.

The Twinjet is a 1969 model, all original. Not in the pictures is a 1964 Honda CL78 - a Canadian model 305 Dream, it has 2.2 original miles. It was bought new in Edmonton from Scona Cycle, the owner took it home and promptly dropped it on his first ride. The Dream then stayed in the original owners garage for nearly twenty years. The Dream was then returned to the original dealership where it sat on display until last fall when the dealership was sold and the large collection of mint Honda's went up for sale.

Similar story with this pretty 1971 Yamaha GS7- under 900 original miles, sat in a local motorcycle shop for a very long time until the dealership changed hands and the new owners didn't have any love for old motorcycles. Next to it is a 1966 Suzuki K-15-80 - under 100 original miles, sad story it was bought by a young man who left for Vietnam and did not return, his family kept the bike in their New York state home until it was sold a couple years ago.

[keener]

canuck750......the 300 dream  i had a friend that had a red one new , i remember racing him on my Twin jet and i won in a sprint ...
So many small Japenese bikes i should have kept... 

[nick949]

Beautiful work Jim  . I know a bike that's aching for that treatment.   

Nick

[Canuck750]

Restoring an odd bike is one thing, fettling the faults is an all together different adventure. I 'finished' the rebuild in time for the January 2020 International Motorcycle Show and have spent a lot of the past month sorting out a bunch of small issues with the Ducati in preparation for a mechanical inspection and registration to get it onto the road this spring.

After I fitted a new Sache electronic ignition the big twin fired up after tow kicks and once warmed up and the idle adjusted it ran quite well. Over the next couple days I found several annoying oil leaks from the top end, both heads had slow drips from joint surfaces in the bevel bear cluster housings. The only way to fix the leaks is to drop the motor and tear apart the heads, frustrating. At least the engine drops straight down with only having to remove three long bolts, remove the drive chain, exhaust headers, carbs and the breather hose.



I can say from experience with Moto Guzzi big twins the Guzzi is not know for oil leaks, the Ducati has a lot of joint surfaces to seal

I decided to break down the heads, lean all mating surfaces and add a thin wipe of RVT sealant between the paper gaskets and alloy.



I did manage to get the motor out, the heads re-sealed and all back in the frame in about 6 hours.



Other niggles, the charging system doesn't, Bevel Heaven now sells a universal solid state reg/rec for around $100 and I found a NOS stator / alternator for $240

One of the front calipers is weeping and so on it goes.

This seems to be par for the course in my experience with putting these old lumps back together.

How do others fair with sorting out the little things of fresh restorations ?

[geodoc]

With my 750 GT it took about a year an 1/2 to get it all sorted. The Dyna S failed, the ST2 stator failed, the regulator failed the battery failed, oil leaks mainly from porous castings, front hub had a defugalty that caused brake rotor wobble. So yes, I feel your pain.




.

[Canuck750]

With my 750 GT it took about a year an 1/2 to get it all sorted. The Dyna S failed, the ST2 stator failed, the regulator failed the battery failed, oil leaks mainly from porous castings, front hub had a defugalty that caused brake rotor wobble. So yes, I feel your pain.
.

Thanks George!

It can get discouraging at times but I will get to the end of this one too, I think …...

[Rough Edge racing]

Those dyno tests above are from a comparison road test done by Cycle magazine in 1973. Most of the bikes were tuned by factory mechanics but still  stock. So the bikes sold off the showroom floor may have had less power.

[blu guzz]

Pardon me for coming late to the party, but just looked at those charts.  Total surprise to me.  The oil burner leads the pack, nearly identical power and more torque than the legendary 900.  The Rocket 3 bested the Honda 750, what's up with that.  I was a teen when these bikes ruled and was just as excited as anyone to read the mags about the latest, greatest speed burner.  We all just knew the 750 Kawi was death on two wheels.  I was pulling for the Triumph/BSA (because Triumph was just so cool) to be faster than the Honda and that they would somehow make a comeback in the market. It blows me away that the vaunted Honda 750 barely made 50 HP.