Lidless Airbox - Posts from Roger are Welcome :)

[thedeatons]

Hey folks... Just hoping you guys could clue me in on a lidless airbox rumor I read on a few threads. It seems Roger Ditchfield has successfully experimented with this setup, of cutting the airbox lid, and only leaving the outer ring intact to secure the air filter.

My bike has the following mods:

2001 Red Superhawk - Black Erion Cans - Hawk Carb Setup (48 pilots/2 .020" shims under rear needle, 1 .020" shim under front needle/HRC style front slide) - Stock Air Filter - CBR600RR Stick Coils - 6lb 6-3/4oz Flywheel (R.D. Spec) - Red Line Racing Synthetic Oil - Extended Vacuum lines for Under Seat Carb Sync - PAIR Removal - Goodridge Braided Steel Lines - Rear brake reservoir delete (Tygon 2375 tubing) - 900RR Swingarm brace - 900RR Rear wheel - Black powdercoated subframe & swingarm


Can you guys (especially Roger) tell me if my bike would benefit from this practically free "lidless airbox" mod? (Basically I would buy a used lid, cut it up, shape it, finish it properly, then bolt it on, and rejet accordingly...)

If it is beneficial, perhaps you guys could tell me the appropriate starting point for new jets to compliment the "lidless" setup.


Any help is greatly appreciated.


*By the way, the bike is not ridden in dusty conditions, in the rain, or on the sand dunes, so I'm not concerned about excess dirt or water.


Thanks!
James

[gl_s_r]

As far as I am aware the lid less air box is only appropriate to engines that have had work done to them such as stage 1 tuning.

There have been many posts about trying to get it to run and a lot of comments about it being a pain in the elbow to fuel correctly on a standard engine.

There are still a lot of people chasing air box mods if you search for them and you can see from those where the status of the lid less box ended up and the routes they are going now.

[thedeatons]

Define Stage 1... Some people think that means a jet kit, and a slip-on.... In fact there are so many "entry-level" mods that I don't know what Stage 1 means anymore...

I can't seem to find Roger's email address... Feel free to PM me

James

[gl_s_r]

Seems we answered together there lloydie, kind of figured he rightfully wouldn't put the total answer up as it is his business and income he'd be giving away.

Roger@revolutionuk.co.uk if I remember correctly.

Full stage 1 is a lot more than what you have described.

[ging500]

But still a nice way to spend £3000+

Or sell your storm and buy an sp!!

[leevtr]

But still a nice way to spend £3000+

Or sell your storm and buy an sp!!

Where's the fun in that ?

Depends on how much money you can afford to lose. £3000 on a storm is pretty much a write off, but sp's are holding their money.

[gl_s_r]

I think we all know you don't do all the work and spend that money and expect a return on the investment... as lloydie said it has to be for fun.

[mik_str]

well said, wrenching on the old girl is as much as riding her......

[Virt]

Only if you know how otherwise it's just scary

Sent from my GT-I9505 using Tapatalk

[Virt]

Because I'm obviously using all the storms' power and riding on its limits already

even if I had the money I couldn't justify it

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[VTRDark]

A lidless airbox is going to be a tuning nightmare, a lot of trial and error. It could be a fun learning curve if your prepared for pulling the carbs on and off and making lots of changes plus dyno time.

The airbox is there not only to help protect from the outside elements ie dirt and grime, but to create a pressure differential. Atmospheric pressure enters the float bowl putting pressure on the fuel forcing it through the jets and into the air stream coming in from the airbox. Maybe a fuel pump would help here For this to work the pressure in the carbs needs to be lower than atmospheric . The lower pressure is created by the vacuum inside of the airbox which gives a constant fuel delivery through various conditions like temperature and altitude. Without the pressure differential it's going to be hard getting the jetting dialled in for all conditions.

Then there's air velocity, the speed it enters the carb. The higher the velocity in the carb the lower the pressure. Do you see a pastern here....higher velocity = speed = more throttle (fuel) = lower pressure. When you open the throttle with no airbox/lid you will get less velocity as the air is not passing through a smaller area. Think how a Venturi works, the air speeds up as it passes through the smaller (narrower area). Same principle when it comes to porting. Larger is not always better! So by removing the airbox or lid you will get loads more air but no air velocity. Velocity is needed to atomise the fuel! I would have thought some kind of ramair would help here which obviously works better at higher speeds where more fuel is required.

With the Mori race bikes (Roger) took a different approach which in effect still has a complete airbox including lid. The base of the fuel tank becomes the airbox lid...well, lid shaped to the base of fuel tank.





I admire Mik and others for what they are doing and you never know something may be discovered that has not been discovered before. It's trial and error and can be fun experimenting I also think HRC needles will possibly help along with blocking the main air jet as in the Mori's with ramair.

If your the type of guy that likes to tinker and experiment and have the time to play, then I say go for it. Now is a good time to do it while there are a few others with airbox experiments going on at the moment. It's always good to bounce off other peoples ideas, discoveries and add some of your own. It helps everyone!

I'm not saying it can't be done, but as I said earlier it's going to be a tuning nightmare!!

(:-})

[thedeatons]

Hey... can you guys chat in another post? I was hoping to keep my topic specific to the title, so it can be useful later on.

No offense, but can a moderator clean this up please?


Thanks!
James

[lloydie]

Hey... can you guys chat in another post? I was hoping to keep my topic specific to the title, so it can be useful later on.

No offense, but can a moderator clean this up please?


Thanks!
James

Good luck

[Roger Ditchfield]

Hi James
This is my second attempt answer your specific question but I must have got something wrong when I tried to post it the first time!
The "Lidless" airbox mod is only used in conjunction with Stage1 camshafts in Ported & Gasflowed heads. It also requires a K&N filter (best type for this mod) and a "free flowing" (no baffles and therefore not street legal)Aftermarket Slip-on or full exhaust. Despite several Internet posts to the contrary it is possible to jet the carbs appropriately but this information is not in the "Public Domain". If anyone can remind me how to send an attachment to this site I will post some relevant Dyno charts of a Stage1 bike with this mod otherwise if you wish to contact me on roger@revolutionuk.co.uk I will attach them to my reply. Hope this helps in your quest for information.
Regards
Roger

[edds11]

'airpressure' within the airbox getting into the float bowl has nothing to do with 'pushing' fuel up to the jets..... air velocity going through the Carb body and over the jets sucks the fuel out, this is 'the Venturi effect'. And it is for this reason only that velocity is so important, the higher the velocity the greater the atomisation of the fuel into the airstream, the greater the atomisation the more volatile the mixture is, the bigger and quicker the bang is, it is these last two reasons tuning is what it is.
And hello everyone