Author Topic: Tonti's Revenge airbox drain?  (Read 413 times)

Offline brider

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • Posts: 1384
Tonti's Revenge airbox drain?
« on: March 29, 2023, 02:08:34 PM »
Now that MGC has the carb boots back in stock, I'm about to re-install my stock airbox on my Cal 2. There is a "port" on the bottom face of the box about 1/2" dia on the CARB-SIDE of the filter; now what the heck would that be for? I had it taped off when I previously used the box to prevent un-filtered air being sucked in, but it bothers me now that it's even there and I can't imagine what its purpose is. The "port" is actually a stub-tube sticking out that has a bulb-ed edge, as if a hose should be clamped to it.

It looks like it ALMOST lines up with the tranny breather screen on the topside of the tranny in that area, and if it was to be used as a PCV device, I could buy that. But it doesn't quite line up.

I'm going to install the box with this port blocked off again, but it just bugs me.
'85 Cal II Auto
'71 Ambo project
'02 GasGas EC300
'07 Norge
Wish'd I'd never sold:
'72 Red Eldo
'74 White Eldo LAPD
'77 Convert with DB bags
'06 Gas Gas EC300
'86 LM IV

Offline guzzisteve

  • Gaggle Hero
  • *****
  • *
  • Posts: 11423
  • "Just Ride It"
Re: Tonti's Revenge airbox drain?
« Reply #1 on: March 29, 2023, 02:54:06 PM »
A rubber boot goes on there and is connected to the frame breather system with a hose. Leave it taped off.
There is a pic of it in the Cal II workshop supplement.
« Last Edit: March 29, 2023, 02:55:59 PM by guzzisteve »
"Pray through Carlo & your bike shall be healed"
Location: Planet Earth

Offline Antietam Classic Cycle

  • Gaggle Hero
  • *****
  • *
  • Posts: 14141
  • Happily stuck in the past.
    • Antietam Classic Cycle
  • Location: Rohrersville, Maryland
Re: Tonti's Revenge airbox drain?
« Reply #2 on: March 29, 2023, 03:47:20 PM »
#33 in this illustration. The 14 end goes to the small fitting up behind the steering head tube, the 35 end goes down towards the ground.







Charlie

Offline nc43bsa

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • *
  • Posts: 1353
  • Location: Mooresville NC
Re: Tonti's Revenge airbox drain?
« Reply #3 on: March 30, 2023, 12:32:05 AM »
It looks similar to the arrangement on my MilleGT, which goes to the valve cover vents.
1990 MilleGT

Wildguzzi.com

Re: Tonti's Revenge airbox drain?
« Reply #3 on: March 30, 2023, 12:32:05 AM »

Offline Antietam Classic Cycle

  • Gaggle Hero
  • *****
  • *
  • Posts: 14141
  • Happily stuck in the past.
    • Antietam Classic Cycle
  • Location: Rohrersville, Maryland
Re: Tonti's Revenge airbox drain?
« Reply #4 on: March 30, 2023, 08:37:57 AM »
It looks similar to the arrangement on my MilleGT, which goes to the valve cover vents.

Cylinder head vent hoses go back to the frame cross-member under the rear of the tank. The valve covers themselves have no vent - it's in the head.
Charlie

Offline brider

  • Gaggle Hero
  • *****
  • *
  • *
  • *
  • Posts: 1384
Re: Tonti's Revenge airbox drain?
« Reply #5 on: March 30, 2023, 12:25:23 PM »
#33 in this illustration. The 14 end goes to the small fitting up behind the steering head tube, the 35 end goes down towards the ground.









Thanks, Charlie, I knew there was a diagram somewhere.

Given those (2) destinations (steering head/overboard), I still am baffled by it's function. If the port was ducted to the valve covers I could understand, but it's in a negative-pressure region and that line going overboard is going to suck grit IN, won't it?

I'll just keep it capped off.
'85 Cal II Auto
'71 Ambo project
'02 GasGas EC300
'07 Norge
Wish'd I'd never sold:
'72 Red Eldo
'74 White Eldo LAPD
'77 Convert with DB bags
'06 Gas Gas EC300
'86 LM IV

 

20 Ounce Stainless Steel Double Insulated Tumbler
Buy a quality tumbler and support the forum at the same time!
Better than a YETI! BPA and Lead free.
Advertise Here