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Hi Guys
Everybody is probably sick of talking about the famous Keihin 41mm flat slide conversion but I never do things without a ton of research and thought and measuring and weighing up options and annoying everyone with question over and over and........
I just had a thought. When doing this conversion it seems you can adapt to your existing air box via some kind of adaptor or you just remove the assembly and run pods.
If anyone has pics of either method could they post em so I/we can all view. I like the idea of changing it up with pods but I also respect the original design philosophy so please post so they can be compared.
 

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I have split single FCR41s on my Monster with individual pod filters (using the above referenced K&N intakes as they protect the air screws and allow easy filter fitment) and these work very well but if I was fitting a racked pair of carbs I would stick with the airbox as, apart from being more practical, I believe it would make more power.

Filters over the intake interfere with the airflow around the open end of the stack, as I found out at the dyno where we got better power at the top end (4hp IIRC?) with no filters fitted but (unlike my old Guzzi) you just can't run open intakes on the Ducati as one is directly in the firing line of the front wheel and the other points upwards.

In fact if I could devise a suitable airbox for the splits I would as I believe it would be an improvement but, unfortunately it's not a very practical option.
 

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I have run both ways and for me it depends on what you are building the bike for. They each have pluses and minuses so it is more a matter of application.

If you are building a custom or shooting for some max power level I think that will lead you to split singles and/or pod filters.

If you are planning on building more of a daily driver then a bank of carbs with a airbox will have benefits.

With a airbox you have the option of running better filtration (paper) or better airflow foam/oiled gauze), With pods I know of no paper filters. With a airbox rain has little to no effect on driveability, I have run pods enough to expect rain to effect driveability . The split singles have idle whips on each carb and if you use them you take the bike out of synchronization a little bit each time, with a bank you have no such trouble and I seldom need to re-sync banks of Keihins.

If you live in a sandy area I would run an airbox with paper filtration if possible because the amount of sand that gets through a foam /gauze filter will show up in your motor. You could use dirtbike filter oil to prevent this but then the jetting will need to be adjusted as the thicker oil restricts air flow making it richer.

A bad filter will cost you Hp, a good filter will not. A good filter is also there to protect the engine so you need to strike a balance between the two. I just had a 853 on the dyno and it had the small snap on filters attached to the bellmouth , I swapped them for another foam airfilter that also went over the bellmouth but had more room. Net gain almost 8% Hp up 7 RWHp. Both could be considered pods as they went over /on the bellmouth and both were foam media. But the mount was different and this is where the problem was. Any filter should be lower Hp than no filter as the filter is restricting air and richening the mixture, unless you are running NO filter then you should always gain some without.

If you are making a custom then the looks do matter and i will admit a set of split singles with pods just look better. I have both my track monster with split singles and pods and my street monster with a bank (of 39's) that is just right for daily street usage .
 

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I’ve not heard anyone else complain of this but fitting the airbox back onto the FCR41’s is a PITA. The carb mouths are slightly oval but the airbox rubbers are round. I just can’t get them to fit on when putting the airbox back on. Instead I have to take the carbs completely off and fit them to the airbox first, then mess about refitting the fuel line etc with hardly any room to reach. Refitting the throttle cables to the carbs is not my favourite job either.

That said, the carbs are awesome. You’ll definitely notice the difference. It transformed my bike. So much more responsive, and smoother (less vibration).
 

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Motor is a fully built 985 so it was decided some extra cooling would be its best interest. I have a couple built 1000ds motors where it was also needed for race use.
 

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I’ve not heard anyone else complain of this but fitting the airbox back onto the FCR41’s is a PITA. The carb mouths are slightly oval but the airbox rubbers are round. I just can’t get them to fit on when putting the airbox back on. Instead I have to take the carbs completely off and fit them to the airbox first, then mess about refitting the fuel line etc with hardly any room to reach. Refitting the throttle cables to the carbs is not my favourite job either.

That said, the carbs are awesome. You’ll definitely notice the difference. It transformed my bike. So much more responsive, and smoother (less vibration).
I take the airbox rubbers out of the airbox, and fit them to the carbs and tighten up the clamps, then fit the carbs, then fit the rubbers back into the airbox. F'n PITA, and usually results in blood loss (the edges of the airbox 'mesh' under the filter are razor sharp in places).
One trick that I use is dishwash liquid (good 'ol Palmolive green - works well as a tyre bead lube too) smeared around the rubbers, then use a combination of flat nose pliers, and a screwdriver to pull the rubbers into place, and get the airbox to fit into the locating/sealing slot of the rubbers.
 
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Hi Guys
Everybody is probably sick of talking about the famous Keihin 41mm flat slide conversion but I never do things without a ton of research and thought and measuring and weighing up options and annoying everyone with question over and over and........
I just had a thought. When doing this conversion it seems you can adapt to your existing air box via some kind of adaptor or you just remove the assembly and run pods.
If anyone has pics of either method could they post em so I/we can all view. I like the idea of changing it up with pods but I also respect the original design philosophy so please post so they can be compared.
I kept my airbox, including modifying the oil breather line so it would fit back into the airbox (usually abandoned with the FCR upgrade). I'm running a K&N filter, with the stock airbox lid, but with the restrictor 'trumpets' removed.

Watch this video to see what it sounds like. https://www.ducati.ms/forums/17-chit-chat/717883-my-first-youtube.html#post6940121

Best with a big screen, and a subwoofer. ;)
 
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When I did my FCR installation, I kept the airbox without the air snorkels and use a K&N filter. Personally, unless a specific look is required, I think having the airbox is a plus. I know one gets a few extra HP at high RPM with pod filters, but removing the airbox also has a bunch of compromises.

The left side of the airbox near the battery needs to be cut to make room for the throttle cable routing, but the kit provides a template to show where the cuts need to be made or you can find it on-line. Fitting the rubber boots is a real pain. I mounted the carbs to the engine intakes and fit the boots on the airbox. Then I pressed the airbox with boots onto the top of the carbs and tightened the clamps. Like Steve, I cut my hands up fitting the boots to the airbox until I was smart enough to put on a pair of mechanic's gloves. If I had thought of using dish soap it would have made fitting the boots to the airbox much easier.
 

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When I actually worked on Ducatis, I found for problem FCR-airbox fitments, I could pull the snorkels out and attach them to the carbs first and then use a dull screwdriver to seat the snorkels into the airbox. :)
 

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The airbox will give better results, the pods will be much easier to work with . FourRings setup is probably the best you can do in the space allowed. As has been stated , the farther the filter is from the carb, the better. The bigger the interior volume of the filter, the better. The bigger the area of filtration, the better. K&N makes some dual inlet pods for automotive use , Weber carbs and such. If it will fit the space, and a suitable carb to filter boot can be found, the increased area would be a good thing.
 

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Like Steve, I cut my hands up fitting the boots to the airbox until I was smart enough to put on a pair of mechanic's gloves. If I had thought of using dish soap it would have made fitting the boots to the airbox much easier.
:grin2: Hahaha! I don’t think an FCR upgrade is properly complete unless you have drawn blood fitting them!
 
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Similar to what some others have said. I have 41's with an open top air box and drop in K&N filter. It works (and sounds) great but it does make getting at the carbs a chore. For that and aesthetic reasons I really wanted to go to pods but after a fair amount of research the consensus was that using the air box yielded slightly better performance more often than not.
 

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Similar to what some others have said. I have 41's with an open top air box and drop in K&N filter. It works (and sounds) great but it does make getting at the carbs a chore. For that and aesthetic reasons I really wanted to go to pods but after a fair amount of research the consensus was that using the air box yielded slightly better performance more often than not.
FWIW, I dyno'd my FCR 41s with an open airbox and with pods. There was no significant difference. Personally, I think most of what is written is hypothetical rather than practical. If we were discussing motors that put out twice the power of our SS 900s perhaps this would be more relevant.
 

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Ever time I have to screw around with the air box to make a minor adjustment I think about going with pods. Whether there is a real world difference or not, they are definitely less of a pia.
 

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Until you ride with the pods in the rain I would agree with you. I much prefer customers bikes with pods from a working on the bike perspective. And wait until you sync the FCR's with a airbox, that might push you over the edge to switch to pods. But then I ride my bike with pods and ride my bike with an airbox. From a driveability standpoint I will take the airbox as I do ride in all weather and though pods are not the end of the world I prefer an airbox. One mans opinion.

I do think it would be best if everyone had both.
 
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