1990 750 Sport Rebuild

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

1990 750 Sport Rebuild

Post by jpitz31 »

Well, here goes. After having ignition problems and the digiplex ignition dropping dead. I switched over to the kokusan ignition system only to have a high speed miss and cutout problem. I spent several months troubling shooting and finally got the engine running fine by switching out to the newer flywheel.

I made the 17" 900ss wheel conversion and now that everything is sorting out. I decided to tear the bike completely down and perform a major clean up and rebuild.

I will try to document my progress as I go through the rebuild.

Here is the first image of the bear engine sitting on the stand.

I am waiting for some engine tools to arrive and have been checking some prices and parts availability from the local Ducati dealer.

Image

Thanks

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
Tamburinifan
paso grand pooh-bah
Posts: 1527
Joined: Thu Jun 21, 2007 12:00 am
model: 907 I.E.
year: 1991
Location: Gothenburg, SWEDEN

Re: 1990 750 Sport Rebuild

Post by Tamburinifan »

Keep on sharing, always interesting! :)
Gert

907 I.E. -91
M900 -97
MTS 1100s -07
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Thanks Gert.

After running around picking up assorted cleaners, solvents, paints and primers. I started in with some cleaning and prepping.

I took apart the instrument cluster and evaluated the condition. The gauge faces were ok, but the paint on the needle indicators were faded. I do not want to crack open the gauges, as they function properly. But are in need of cleaning.

The black paint on the bezel is faded and the gauges are a bit corroded. So I decided to clean up the gauges with a bit of scrub pad and 220 grid sand paper. I will repaint the bezel but have not decided if I want to paint the gauges or polish them.

Also when taking apart the instrument cluster, after almost 20 years there was a broken piece of plastic. I am trying to watch the expenses on this rebuild so buying new parts to replace every thing is out of the question.

I took some abs plastic pipe cement and glued the section of broken instrument cluster back on. The image shows the section glued back in after one coat and sanding and one more coat to fill in some minor holes. When fully cured I will sand, wet sand and use polishing compound to finish the instrument cluster.

Not bad for about $1.50 for a can of abs cement.

Image

Image

Thanks

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Well,

Been out of town all week, Just got back and found that some of the engine tools have arrived.
I purchased all of these from ebay. I still need two more to get the motor apart. Guess I have to bite the bullet and order them from Ducati.

I examined the brake and clutch master cylinders and found that they needed rebuilding.

The good news: I called Steve at Bevel Heaven and he has the 13mm clutch master cylinder rebuild kit in stock.

The bad news: According to Steve, Brembo does not make a rebuild kit for the 16mm front brake master cylinder. I had to purchase a new master cylinder. Not a happy camper.

For those of you who want to rebuild the clutch master cylinder there is a trick to the dis-assembly. The brake master cylinder has a normal snap ring that you can remove with long snap ring pliers.

The clutch master cylinder has a ring but it is not a snap ring. Take a small mallet and a very small round punch and lightly tap one side of the ring. The ring will pivot up and you can grab it and remove it with your fingers.

Here are the pics.

Image

Image
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
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jcslocum
paso grand pooh-bah
Posts: 1714
Joined: Mon Jul 19, 2004 12:00 am
model: 750 Paso
year: 1988
Location: Eastern Shore, MD
Contact:

Re: 1990 750 Sport Rebuild

Post by jcslocum »

Looks like you are having fun and will get to know your Duc very well over the winter months.

How far are you going to dig in with the engine???

Keep the updates and pictures coming!!!

Jon
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Thanks Jon,

Yes, I am doing a no stress build, I plan on having fun with the build and learn as much as I can.
It will depend on how the heads and cylinders look when I examine them. I plan on doing a full dis-assembly, but will see depending on the condition once I open her up.

I also plan on documenting as much as possible so others who want to have a go will have enough information to assist them with the rebuild.

Thanks

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
User avatar
jcslocum
paso grand pooh-bah
Posts: 1714
Joined: Mon Jul 19, 2004 12:00 am
model: 750 Paso
year: 1988
Location: Eastern Shore, MD
Contact:

Re: 1990 750 Sport Rebuild

Post by jcslocum »

Joe,

The bottom end is very stron in these engines. Was there an issue with it before??? Freshening up the top end is good and maybe add some hi-comp pistons along the way. I have been deep inside many times as have other here so you have a great resource here to assist.
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Jon,

Nothing appeared to be wrong with the bottom end. The compression check was 90 psi in each cylinder when I checked.
I am concerned about the valve guides as the spark plugs always appear damp.

Yes, the resources here on the forum are the best.

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Right after New Years I picked up the Powder Coat setup at Harbor Freight Tools when it was on sale.
I found a used oven on craigslist for free. An electrican friend wired in a 220 volt outlet in the garage for me.

There is a powder coat company called Powder by the Pound powderbuythepound.com/ that sells powder and powder coat supplies for a good price.

So I decided to give powder coating a try. I figure with out too much investment I can powder coat everything with the exception of the frame with the oven. If things go well I might even give the frame a try with either heat lamps or build a cheap propane oven.

Here are some images:

The basic Powder coat unit

Image

A few samples of Powder coating.

Image


I have found that I get better results when I heat up the metal to 400 degrees F before I powder coat.

I have also been experimenting with distance of the gun to the material. I have also tried flat black powder coat and then a clear powder coat on top of the flat black. In some of the examples I was getting some orange peel.

When the distance was increased and the metal was powder coated right from the oven the orange peel was less.

I am now going to try a thinner coating of the powder and a slightly lower temperature and bake slightly longer.

I will keep everyone posted:


Thanks

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

I picked up a cheapo media blaster at Harbor Freight Tools and ordered a wheel polishing kit from the Eastwood company.

My son wanted to get involved in the rebuild process so I enlisted his help.

This week-end was spent doing some of the very dirty work of media blasting various parts in preparation for powder coating and painting as well as buffing and polishing some of the aluminum parts.

This part of the rebuild is not the most fun and quite a bit dirty.

I had my son do a lot of the media blasting and I spent most of the time buffing and polishing the aluminum parts.

Neither job is fun and at the end of the week-end I had to sweep out the entire garage of blast media and buffer dust.

In the polishing operation I started out with a 3M green wheel and some spiral sanding cartridges. In the case of the swing arm I used an orbital disk sander with some 80 grit sand paper.

After roughing in the parts with the green wheel I started in with the 80 grit and 220 grit buffing compound.

It is time very time consuming. First you have to dress the buffing wheel and let the compound try for 10 minutes. Then you can start buffing. Then you have to start all over again. I tried to stagger the green wheel and buffing wheel operations so I could keep working without having to wait around.

The worst part is getting into the very small parts of the rear sets and foot pegs. I tried felt polishing bobs but they leave grooves in the metal. The sewn buffing wheels work the best.

This job is really a pain in the behind.

I am hoping we can wrap this up and move on to the powder coating and painting by next week-end. Maybe not though.

Here are some recent pictures.

First one is my son media blasting. I have to give him credit he kept the compressor going most of the week-end and at the end of each day was covered from head to toe with aluminum oxide dust.

Image

The next image is of some brackets that have been media blasted and buffed with 220 grit compound in preparation for powder coating:

Image

The next image is of some of the aluminum parts that have been green wheeled, 80 grit buffed and 220 grit buffed.

Image

Thanks

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
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Mustang505
Posts: 134
Joined: Wed Jan 28, 2009 9:27 pm
model: 750 Sport
year: 1988
Location: Auckland, New Zealand

Re: 1990 750 Sport Rebuild

Post by Mustang505 »

Hi Joe
Funny how we are doing very similar stuff!!! Except I do not have your determination to do it all yourself. I have polished all the small stuff (experienced all the same issues as you) but took the larger parts to a aluminum polishers in town here - wheels, cam belt covers, engine side covers etc. Also had painted parts powder coated by a powder coat firm including the frame and fork bottoms.
Currently redoing all the electrics and will probably rewire most of it. I'll post some pics soon.
Cheers Clive.
Cheers
Clive
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Can't wait to see the pictures Clive, Let me know what your solution is to replacing the electrical connectors. I have started to look at the wire harness and will more than likely redo mine as well.

On a side note, I have to come to your fair city sometime, I want to see the Britten, I have read John Britten by Tim Hanna, Just loved the book.

Cheers

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Well, It rained most of the week-end, so any chance of powder coating and painting parts went out the window.

I am waiting for some small 1" buffing wheels to come in the post so I could not do much buffing. I spent the first part of the week-end washing, cleaning and buffing some smaller parts.

My son and I have been discussing the merits of doing some soda blasting on some of the parts. We made a trip to Harbor Freight tools, and looked at the soda blaster gear. But we did not want to dump $100.00 on a soda blaster and buy 50 lbs of baking soda if it did not do what we wanted to do. So we took the cheap R & D approach.

They had an air blaster kit, used for glass etching and small parts blasting. It had a small nozzle which we need for soda blasting. We then went to the local Costco (large quantity food store) and picked up 13 lbs of baking soda for around $5.00.

I decided that since it was raining I would strip the brake calipers down clean then up, polish up the bolts and possibly media blast them for powder coating.

The more I worked on the calipers the more I did not want to media blast them and powder coat them, but they had dirt embedded in the powder coat finish and some one had painted the Brembo logo red and it just looked crappy.

We did some testing with out make shift soda blaster and found out some really cool things. The soda blaster would remove paint without messing with the smoothness of the finish but would not remove powder coat. The soda blaster works great on removing carbon from pistons.

So we decided to give the soda blasting a try on the brake calipers.

Here are some pictures of our findings:

Here is yours truly doing some soda blasting:

Image

Another shot of the back side of a caliper.

Image

We found that the soda works great at cleaning up powder coated parts.

Here is a shot of a dirty caliper as I first started blasting:

Image

Here is a shot of the caliper as I progressed, Notice that the soda blasting removed the cruddy red paint and cleaned up the gold powder coat.

Image

Here is a shot of the finished calipers before I put them back together:

Image

Here is a final shot of the calipers put back together, calipers washed and polished bolts:

Image

Next week if it does not rain we will hopefully do some painting and powder coating.

Thanks

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
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paso750
paso grand pooh-bah
Posts: 5558
Joined: Sun Jul 18, 2004 12:00 am
model: 750 Paso
year: 1987
Location: southern Germany

Re: 1990 750 Sport Rebuild

Post by paso750 »

Joe, if those bolts you polished are steel it won`t take much time before they start to rust. I made that experience with some frame bolts. Better have them zinc coated unless they are stainless steel.
User avatar
jpitz31
Posts: 84
Joined: Fri Aug 15, 2008 4:10 pm
model: 750 Sport
year: 1990
Location: Escondido, CA
Contact:

Re: 1990 750 Sport Rebuild

Post by jpitz31 »

Thanks paso750, When I was polishing them they appears to be of some alloy. If they start to rust I will just replace them with stainless.

Cheers

Joe
1990 Ducati 750 Sport (mine)
2007 Piaggio BV 500 (mine - daily driver)
2008 Piaggio MP3 500 (wife's)

My Ducati Blog site
http://projectducati.blogspot.com/

Stupidity is not a crime, your are free to go ;-)
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