Gone to the Dark Side - Ducati 860 GT

[SmithSwede]

Beautiful bike.  I’ve really enjoyed this thread.   Thanks for all the photos. 

I’m surprised at how heavy this thing is.   But, scales don’t lie. 

[Roy gardner]

Thanks George!

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

You have done a spectacular job of this, dont get disheartened. Most old bike builds take some de-bugging. I'm still making minor changes and additions to my Vincent, but I have over 4000 miles on it.
I have just picked up on this post after several months away. Did your engine recon man put new bronze seats in the heads, or did he fit good quality ferrous seats?

[Canuck750]

You have done a spectacular job of this, dont get disheartened. Most old bike builds take some de-bugging. I'm still making minor changes and additions to my Vincent, but I have over 4000 miles on it.
I have just picked up on this post after several months away. Did your engine recon man put new bronze seats in the heads, or did he fit good quality ferrous seats?

Thanks for this, I am not sure what the new seat material is that the machine shop installed. The shop I have used for many years sent the heads off to another specialty shop they use for the seats, my machinist is a long time flat track and moto cross racer and he told me that installing the seats was beyond his comfort zone. When I picked up the heads he told me he would honor his quoted fee even though there were several hundred dollars more spent, I couldn't accept him eating the fee for what he could not have foreseen but I was impressed that he would even offer to have absorbed the additional cost, some guys are fantastic.

[Roy gardner]

Thanks for this, I am not sure what the new seat material is that the machine shop installed. The shop I have used for many years sent the heads off to another specialty shop they use for the seats, my machinist is a long time flat track and moto cross racer and he told me that installing the seats was beyond his comfort zone. When I picked up the heads he told me he would honor his quoted fee even though there were several hundred dollars more spent, I couldn't accept him eating the fee for what he could not have foreseen but I was impressed that he would even offer to have absorbed the additional cost, some guys are fantastic.

That is unfortunate, they have perpetuated the problem. I asked because I could see in your "before" photos the yellow of the bronze seats. Sadly, the machinist has replaced them with more of the same. Bronze seats are too soft and the valves pound into them, even with spring return Ducatis, desmos are worse. It is a curse in old British bikes too, even Vincents, but most Vincent owners expect to have modern ferrous seats fitted.

It was magnanimous of your machinist to stick to his quote and generous of you make up the difference, well done. 

[Canuck750]

I chased a Brembo caliper weeping this morning, the small O ring that seals the two caliper halves refused to form a seal. I sanded the faces smooth on a flat plate, still leaked. Brand new Brembo O ring and caliper seals, I found a fatter viton O ring and fitted it, problem solved. Then after it was all back together my ham fisted turning of a 1/4" wrench snapped the speed bleeder off, damn! could not get the remnant out as the recessed sprung ball bearing prevented getting any easy out in and a milling bit just spins the hard ball. The speed bleeders have a very thin wall to the body and it takes nothing to snap them. Luckily Charlie send me four left hand calipers to rebuild and I made use of the best one to replace the one I junked.

Two steps forward and one step back.

[Antietam Classic Cycle]

 

[geodoc]

That is unfortunate, they have perpetuated the problem. I asked because I could see in your "before" photos the yellow of the bronze seats. Sadly, the machinist has replaced them with more of the same. Bronze seats are too soft and the valves pound into them, even with spring return Ducatis, desmos are worse. It is a curse in old British bikes too, even Vincents, but most Vincent owners expect to have modern ferrous seats fitted.

It was magnanimous of your machinist to stick to his quote and generous of you make up the difference, well done.

Most likely beryllium - copper seats. When Guy Martin in Montreal did my 750 GT heads that what he used. WAY harder than bronze alloy seats.



http://www.performanceheadengineering.co.uk/services/valve-services/valve-seat-replacement/



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[lucky phil]

Ducati Bevel engines are all ball and roller bearing and the oil pump runs at low pressure.  Only the Mille engine uses plain bearings and runs at high pressure.

True, but big ends only.

Ciao

[huub]

Most likely beryllium - copper seats. When Guy Martin in Montreal did my 750 GT heads that what he used. WAY harder than bronze alloy seats.



http://www.performanceheadengineering.co.uk/services/valve-services/valve-seat-replacement/

berillium bronze isbrilliant stuf for vale seats,
over here (europe) the use of berilium bronze is banned , the dust and fumes it creates when machining it is poisonous (carcinogene)

.

[jbell]

Jim, I didn't see it in any of your pics but there is a "chain guide" you can get to keep the chain from sawing into the crankcase.  It mounts just in front of the centerstand bolt.  Beautiful restoration job...........as always.

[LesP]

I'm not totally sure but the rubbing block was not added until the shock absorber length increase around 1979/1980 but one could be fitted.
#
Its only a couple of M6 threaded holes in the lower frame plate to add one.

[geodoc]

I'm not totally sure but the rubbing block was not added until the shock absorber length increase around 1979/1980 but one could be fitted.
#
Its only a couple of M6 threaded holes in the lower frame plate to add one.

Here's the one on my 750 GT w/ 12" shocks. You can just see the Delrin collar I made for the swingarm so it wouldn't get gouged from the chain too.





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[lucky phil]

I chased a Brembo caliper weeping this morning, the small O ring that seals the two caliper halves refused to form a seal. I sanded the faces smooth on a flat plate, still leaked. Brand new Brembo O ring and caliper seals, I found a fatter viton O ring and fitted it, problem solved. Then after it was all back together my ham fisted turning of a 1/4" wrench snapped the speed bleeder off, damn! could not get the remnant out as the recessed sprung ball bearing prevented getting any easy out in and a milling bit just spins the hard ball. The speed bleeders have a very thin wall to the body and it takes nothing to snap them. Luckily Charlie send me four left hand calipers to rebuild and I made use of the best one to replace the one I junked.

Two steps forward and one step back.

Viton seals aren't recommended for brake fluid. EPDM (Ethylene Propylene) is though.

https://www.efunda.com/designstandards/oring/oring_chemical.cfm?SM=none&SC=Brake%20Fluid#mat

https://www.marcorubber.com/o-ring-material-quick-reference.htm

Ciao

[Canuck750]

Jim, I didn't see it in any of your pics but there is a "chain guide" you can get to keep the chain from sawing into the crankcase.  It mounts just in front of the centerstand bolt.  Beautiful restoration job...........as always.

I got one of those 'case saver' Delrin rub blocks from Bevel Heaven, need to install it.

[jas67]

I got one of those 'case saver' Delrin rub blocks from Bevel Heaven, need to install it.

That case saver thing something my 750GT needs?

[Canuck750]

That case saver thing something my 750GT needs?

Check the Bevel Heaven web site, he recommends them for all bevels. My 860 engine case does show some sign of chain contact, not terrible but it did get munched on.

https://store.bevelheaven.com/Chain-Guard-Case-Saver-etc/

[geodoc]

Check the Bevel Heaven web site, he recommends them for all bevels. My 860 engine case does show some sign of chain contact, not terrible but it did get munched on.

https://store.bevelheaven.com/Chain-Guard-Case-Saver-etc/

I got mine here along with instrument housing, indicator lights and various other bits:

https://tinyurl.com/ycoe7cp2




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[Roy gardner]

Beryllium Bronze! Astounding. I guess it could be adequate for the job, we generally regard Aluminium Bronze as the hard wearing bronze, but Beryllium may do the job. As Huub said, there are over exaggerated health issues around the machining of Be Bronze. American aircraft manufacturers  were still using when I was in the industry and we werent allowed to machine it without dressing up in Ebola suits and using vacuum cleaners at the tool tips to catch the swarf. Good luck, I dont expect the engine will do a huge number of miles in reality, it's not like you are going to ride it to the bottom of Chile or anywhere, are you?

[Shineyhead]

Hi Jim,
I recently acquired a 1975 Ducati 860 GT that I'm in the beginnings of restoring. Mine started life the same color as yours and I am planning to return it to the stock color.  I am loving reading the thread about your project and your finished product is awesome!

Do you still have your Duc?  I am wondering if you would be willing to share some particulars of your process when I have any questions - every time one question is resolved, another pops up?

Sincerely,
Mark

[Canuck750]

Hi Jim,
I recently acquired a 1975 Ducati 860 GT that I'm in the beginnings of restoring. Mine started life the same color as yours and I am planning to return it to the stock color.  I am loving reading the thread about your project and your finished product is awesome!

Do you still have your Duc?  I am wondering if you would be willing to share some particulars of your process when I have any questions - every time one question is resolved, another pops up?

Sincerely,
Mark

Yep still have the 860, it’s a very nice bike to ride. One of the few ‘affordable’ bevel drive L twins, non desmo heads , first gen are kick start only, sorted a few more things over the past couple years. If replacing the Dellorto carbs stick with the stock 32’s, the 36’s Bevel sheaves sells are set up for a Guzzi twin and are over fueled. Wolfgang Haerter at Columbia Car and Cycle stocks the 32’s or he can properly set up the 36’s as he did for me. The Sasche ignition is well worth the cost.

Feel free to ask questions.

Thanks

Jim