What is missing here?

[JohnieBraaf]

Dear forum members,

I just bought a second hand Ducati M600 from 94, and while cleaning and checking the bike I noticed a hole in the carburetor pipe.
There is a threaded hole in this pipe, with nothing in it. This looks a bit odd to me. Does anybody know what is missing here?

See the picture for a detailed view:


If I look at the carburetor pipe of the other cylinder I notice that from this pipe a hose is going to a vacuum pump like thing located under the right side of the seat.

Until someone can tell me more about this mysterious hole I am afraid to ride the bike and break anything, so don't hesitate to share your thoughts. 

Jan from Belgium 

[Speeddog]

That hole needs to be plugged.

An M5x8 screw will do it.
A washer and a little sealant would be good too.

[JohnieBraaf]

Ok thanks for the quick reply! 

Plugging it won't be a problem, but do you think that the missing bolt could have caused damage?

[oppet]

It will run very lean with plug of. soon as you get it plugged you should notice very different running if not there maybe something gone wrong, like piston or sparkplug

[oppet]

maybe you wont hear it in idle, but it must have popped when you have driven it

edit i mean popping sound

[A.duc.H.duc.]

As previously said, would have leaned the bike out a lot, did it have any running issues before?

If you remove your emissions stuff, you'll actually pull the hose off the other intake tube and plug that too.

Justin

[sur4die]

there should be 2 of those holes on each of your intake runners. 

each intake would have had a emissions nipple on the outward facing holes.  These are the nipples that the ckank case vent would have connected to.  They are also used to attach a manometer when measuring the vacuum to synchronize the carbs.
The vertical intake's inward facing hole feeds the fuel pump while the horizontal intake's inward facing hole should feed the vacuum actuated petcock.

[A.duc.H.duc.]

there should be 2 of those holes on each of your intake runners. 

each intake would have had a emissions nipple on the outward facing holes.  These are the nipples that the ckank case vent would have connected to.  They are also used to attach a manometer when measuring the vacuum to synchronize the carbs.
The vertical intake's inward facing hole feeds the fuel pump while the horizontal intake's inward facing hole should feed the vacuum actuated petcock.

Well that's the full answer.

[sur4die]

 
i've spent entirely too much time futzing with my fuel system
 

[JohnieBraaf]

Very very good, 

So I now know I have to get a new nipple, to be able to sync the carburetors afterwards.

But you are telling me that I can unplug the emission hose connected to the other intake runner:

If you remove your emissions stuff, you'll actually pull the hose off the other intake tube and plug that too.

Does this make the bike run better, or have any other consequences?

[Howie]

There is a possibility the carbs may need to be synched after plugging.

[sur4die]

the whole concept behind the emissions equipment is that you are combusting the non tail pipe "emissions" of the engine.  these emissions are gunky things like "blow by" that exit the engine via the one-way reed valve in the crank case breather.  while this process reduces some of the bike's noxious emissions it basically amounts to piping a unregulated mixture of cruddy oil/fuel into your combustion chamber.

this is why most people remove the canister and hoses and just vent these noxious emissions to the atmosphere through a little cotton/gauze filter (K&N).

check out the ducatisuite write up on the topic
http://www.ducatisuite.com/emissions.html

[Big Troubled Bear]

If I look at the carburetor pipe of the other cylinder I notice that from this pipe a hose is going to a vacuum pump like thing located under the right side of the seat.

Vacuum pump is actually fuel pump