Author Topic: Yes, I'm re-installing "Tonti's revenge" airbox  (Read 426 times)

Offline brider

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Yes, I'm re-installing "Tonti's revenge" airbox
« on: May 10, 2022, 07:54:42 PM »
I've been running K&N's for a couple of years now, but they're kinda ugly, kinda louder than stock, and I sensed zero performance improvement on my Cal 2 Auto (no surprise there). Since I DIDN'T toss my original airbox when I swapped to K&N's like I swore I would, I'm going to go ahead and re-install it.

So I was elated to find MG Cycle actually stocks the original carb-to-airbox boots, since my originals are as hard as if they were machined from 7050-series bar stock.

And I was AMAZED that they offered a complete stock airbox assembly, and only $60 to boot! Of all things, I would've expected THAT to be unobtainable, or of so low demand that only NOS or used boxes would be available.

The memory of how difficult it was to work with has faded, so I'm going to give it another try. Wish me luck.

'85 Cal II Auto
'86 LM IV (sold)
'71 Ambo project
Wish'd I'd never sold:
'72 Red Eldo
'74 White Eldo LAPD
'77 Convert with DB bags
'06 Gas Gas EC300

Offline Antietam Classic Cycle

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #1 on: May 10, 2022, 08:15:03 PM »
The "Tonti's Revenge" airbox was the earlier one with cylindrical filter. The square filter 'box is easy by comparison.
Charlie

Online bacongrease

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #2 on: May 11, 2022, 07:30:27 AM »
 Some  of Italy's engineers should be adored.


  Many should be castrated.

 :popcorn:
« Last Edit: May 11, 2022, 07:31:26 AM by bacongrease »

Offline dxhall

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #3 on: May 11, 2022, 08:15:30 AM »
My Ď90 LM V had crappy pod filters when I bought it.  It ran pretty well, and the plugs showed a good chocolate-brown color.

The bike came with the stock box.  Since I didnít like the pods, I bought a K&N filter and installed the stock box.  The bike ran like crap and wouldnít pull past 5000 rpm.  I pulled the plugs and they were almost white - showing a mixture that was way too lean. 

The obvious conclusion from this is that the stock box with a K&N filter flowed a LOT more air than the pod filters.

On another note, Iíve found that the best way to install the carb-to-box tubes is to first heat them with the heat gun.
« Last Edit: May 11, 2022, 08:17:06 AM by dxhall »

Wildgoose Chase Moto Guzzi

Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #3 on: May 11, 2022, 08:15:30 AM »

Offline Road Rocket

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #4 on: May 11, 2022, 10:08:52 AM »
Proper jetting on somewhat new plugs will be a dull white on the tip of the insulator. After many miles the exposed porcelain may show a tan or mid brown or grey color...Readingg plugs requies lookinf deep inside, the shell color and ground electrode
 This photo shows plugs from my 79 750 Triumph after about 15 miles of fast riding....The plug shows a slightly rich mixture that is a safety factor on old air cooled stuff

Rough Edge Racing with a new name but still the same pin head

Offline brider

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #5 on: May 11, 2022, 10:45:12 AM »
The "Tonti's Revenge" airbox was the earlier one with cylindrical filter. The square filter 'box is easy by comparison.

I was not aware of this distinction. As I said, the memory has faded so that I don't feel the pain anymore, but I recall thinking that this design couldn't possibly be any more difficult to install/remove.
'85 Cal II Auto
'86 LM IV (sold)
'71 Ambo project
Wish'd I'd never sold:
'72 Red Eldo
'74 White Eldo LAPD
'77 Convert with DB bags
'06 Gas Gas EC300

Offline Antietam Classic Cycle

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #6 on: May 11, 2022, 11:15:59 AM »
I was not aware of this distinction. As I said, the memory has faded so that I don't feel the pain anymore, but I recall thinking that this design couldn't possibly be any more difficult to install/remove.

This is what I was referring to. Notice the many pieces that fit just so, and the rubber plenum that rarely fits well and rots away. Changing the filter is a big job, usually requires the tank off, battery out, both carbs off and then disassembling the thing piece-by-piece. Especially aggravating on a Convert with all of it's extra hoses.





By contrast, the square-fin air box is simple to change the filter on.



Charlie

Offline brider

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #7 on: May 11, 2022, 04:16:19 PM »

By contrast, the square-fin air box is simple to change the filter on.


I don't know if that's just dry humor or if you're being serious, Charlie, but I see that square filter sandwiched between several extremely difficult-to-remove-in-place components, and I recall having to have to remove the tank and carbs, too. And I have the Auto plumbing, too.

Thanks for the diagrams, good reference.
'85 Cal II Auto
'86 LM IV (sold)
'71 Ambo project
Wish'd I'd never sold:
'72 Red Eldo
'74 White Eldo LAPD
'77 Convert with DB bags
'06 Gas Gas EC300

Offline Kiwi_Roy

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #8 on: May 12, 2022, 02:01:46 AM »
When I bought my Convert a friend gave me one of these filters.
Several of you suggested I should question his friendship.
When I finally managed to install it I swore it was there for life LOL
72 Eldorado
17 V7iii Special
76 Convert
Half a V9 Roamer

Moto Guzzi - making electricians out of riders since March 15 1921

Online Scout63

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #9 on: May 12, 2022, 05:55:10 AM »
Iíve gone both ways, and like pods a little better for ease of maintenance.  I do respect the stock cylinder airbox though. It means not having to install a Lemans breather also.
Ben Zehnder - Orleans, MA USA
1971 BMW R75/5
1972 Norton Commando Combat Interstate
1973 SL 125 so very rusty
1973 V7 Sport
1977 BMW R100S
1977 LM1
1978 Ducati 900SS
1978 Yamaha SR500
1979 V1000G5

Offline brider

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Re: Yes, I'm re-installing "Tonti's revenge" airbox
« Reply #10 on: May 16, 2022, 06:31:22 AM »

By contrast, the square-fin air box is simple to change the filter on.





This thread has had enough discussion but I have one more question: On the bottom of item #24 (the airbox aft of the filter element that the 2 carb elbows are attached to), there is what I THINK is a stock water drain port. I say "think" because years ago when I was using it, I plugged it up thinking "Why in the heck is there an open port for the carb boots to suck un-filtered air from right above the gritty trans breather screen?", and whatever method I used to plug it now can't be removed without damaging the box so I can't further examine it.

Has anyone else noticed this funny-place-for-a-drain?

That's all.
'85 Cal II Auto
'86 LM IV (sold)
'71 Ambo project
Wish'd I'd never sold:
'72 Red Eldo
'74 White Eldo LAPD
'77 Convert with DB bags
'06 Gas Gas EC300

 


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