It is currently Sat Sep 22, 2018 6:49 pm

All times are UTC





Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: New member with 750 sport 1989 from Belgium
PostPosted: Mon Mar 05, 2012 11:51 am 
Offline

Joined: Mon Mar 05, 2012 11:22 am
Posts: 7
Location: Belgium
model: 750 Sport
year: 1989
Hello everybody.
My name is David. I'm 37. I'm from Belgium and I have a 750 sport from 1989.
First, I have to say that my english is a little bit limited but I'll try.
I have Ducatis since 1997. I have always had 2 valve Ducatis. I'm not a mechanic but I try to do the maximum by myself.
Before asking some questions I must say that I found a lot of interesting things in this FORUM which is really what every Ducati passioned must read absolutely. So a thousand Thanks to you all.
Last year, I bought a 750 sport wich is for me a beautiful and particular one in the 2 valve Ducatis.
I also bought a 750 ss from 1994 just for some pieces, like 17 inch... .
Now, I also put 38mm MIKUNIS. Some adaptation with the cables but it work.
Badly, by removing the tank, I broke the electrical connexions of the fuel pump.
Now that I have replaced the connexions, My fuel pump is always working. And when I put the key "ON", it works, it works, .... without stopping. Then I try with the start button and I think the motor has too big fuel and doesn't start. It smells fuel when I do that.
Do you think I can remove the fuel pump and the linkage sinside the tank ? How can I do that ?
Do you think it will be possible to fix it ? Do you think it's an electrical problem ?

Thank you very much


Top
 Profile  
Reply with quote  
 Post subject: Re: New member with 750 sport 1989 from Belgium
PostPosted: Mon Mar 05, 2012 9:31 pm 
Offline
paso grand pooh-bah
User avatar

Joined: Sat Sep 03, 2005 12:00 am
Posts: 1318
Location: SF Bay Area
model: 750 Sport
year: 1990
Welcome to the site.
good to see another Sport in good hands.

The fuel pump will stay on all the time. You need to have a "T" in the fuel line, and run that back up to the tank. In the middle of the bottom of the tank there are two nipples. One is for Venting, the other is Return. You need to attach the line from the "T" to the Return nipple. This will keep your pressure to a manageable level for the carburetors. In normal operation, there will always be fuel being returned to the tank. You can see it flowing back into the tank when you look into the tank through the open filler hole.

You can not remove the pump from a Sport, as the fuel lines in the tank are about half way up in the tank, and you will get only a few gallons of usable range. (you will 'run out of gas' with two gallons still in the tank)

The fuel pump and connection are the same as the SS.

Since you bought the SS for parts, the 17" conversion will be a simple replacement of parts. The back wheel is easy as replacing parts. The front would be best if you swap out the entire front end. (forks, triple clamp, wheel, brakes, bars)

Your English is very good. I'm sure you will have a lot of fun with your bike this coming summer.

Cheers,

_________________
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


Top
 Profile  
Reply with quote  
 Post subject: Re: New member with 750 sport 1989 from Belgium. Fuel pump ?
PostPosted: Thu Mar 08, 2012 7:17 pm 
Offline

Joined: Mon Mar 05, 2012 11:22 am
Posts: 7
Location: Belgium
model: 750 Sport
year: 1989
Dear ducinthebay,

The "T" line you talk about, is it the same as it was with the weber carbs ? I had the return you said in the tank with my WEBER carbs.
First I have to say that when I tried to start the bike for the first time with the mikunis, my lines were full of fuel but they were not plugged on the tank. The motor starts really good until the carbs were empty. Then... you know.
Now I have plugged on all the lines, my motor won't start.
And what I wanted to say with the fuel pump, was in my remember, The fuel pump worked for a few seconds when I put the key "ON". Then it stops. Now the fuel pump doesn't stop after a few seconds. DO you Think it's the reason why the carbs cannot manage the pressure. Do you think one of my new connexions (they are 4 as you know) is maybe broken.

Thanks a lot


Top
 Profile  
Reply with quote  
 Post subject: Re: New member with 750 sport 1989 from Belgium. Fuel pump ?
PostPosted: Fri Mar 09, 2012 4:38 am 
Offline
paso grand pooh-bah
User avatar

Joined: Sat Sep 03, 2005 12:00 am
Posts: 1318
Location: SF Bay Area
model: 750 Sport
year: 1990
davidgoblet wrote:
Dear ducinthebay,

The "T" line you talk about, is it the same as it was with the weber carbs ? I had the return you said in the tank with my WEBER carbs.

Yes, the plumbing schematic should be the same as with the Weber. Hopefully you put in all new fuel lines though.


Quote:
First I have to say that when I tried to start the bike for the first time with the mikunis, my lines were full of fuel but they were not plugged on the tank. The motor starts really good until the carbs were empty. Then... you know.
Now I have plugged on all the lines, my motor won't start.


Sounds like the carbs work, you just have too much pressure at the carburetor and it is flooding the engine, making it hard, or impossible to start.

Quote:
And what I wanted to say with the fuel pump, was in my remember, The fuel pump worked for a few seconds when I put the key "ON". Then it stops. Now the fuel pump doesn't stop after a few seconds. DO you Think it's the reason why the carbs cannot manage the pressure. Do you think one of my new connexions (they are 4 as you know) is maybe broken.


My fuel pump runs all the time. If the key is ON, the pump is ON. The excess fuel just gets returned to the tank. My ST has a similar feature, except that they have a regulator so the pressure stays high in the lines for fuel injection. The Paso and Sport had a very cheap pressure regulator. It was a main jet jammed into the return line. I removed that.
You may hear the pump when you first turn it on because it doesn't have any back pressure, and spins at a high rate. The pump in my Sport you can hear all the time, or at least that's the way mine is. I am running Dellortos, and those don't need much pressure. I don't think the Mikuni's need much pressure either, but I'm only guessing.

What is the fuel line configuration of the SS you have? Same fuel pump.

Cheers,

_________________
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


Top
 Profile  
Reply with quote  
 Post subject: Re: New member with 750 sport 1989 from Belgium
PostPosted: Fri Mar 09, 2012 6:51 pm 
Offline

Joined: Mon Mar 05, 2012 11:22 am
Posts: 7
Location: Belgium
model: 750 Sport
year: 1989
Well,

For the fuel lines, they are the same as my 750 SS.

For the Fuel Pump, it's also visibly exactly the same.

The difference is that I haven't plugged on the plastic pipes which are coming from the mikunis to a plastic box. They are in the number of three and they all come into the same plastic box wich is attached in the left side of the frame. It was like that on the SS.
I don't know if it is necessary to do like that and what is the function of these pipes.
Do you see what it is ?

Thanks a lot


Top
 Profile  
Reply with quote  
 Post subject: Re: New member with 750 sport 1989 from Belgium
PostPosted: Sat Mar 10, 2012 1:09 am 
Offline
paso grand pooh-bah
User avatar

Joined: Sat Sep 03, 2005 12:00 am
Posts: 1318
Location: SF Bay Area
model: 750 Sport
year: 1990
Those are breathers for the carb. They are there for equalization of pressure. I don't know enough to tell you if they are needed, or if just a length of hose is adequate.

Cheers,

_________________
Duc in the Bay
1990 750 Sport x2-Rosso Blanko (900ss copy) & Nuovo Nudo (Scrambler project)
1991 907 -mostly stock
2002 ST4s - Lots of mods.


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC


Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  


cron