HIGH FLOW AIR FILTERS (REDUCED INTAKE WITH CAP AND HOLE INSIDE)

[SATANSAM]

Hi there folks!

Here I am again with my crazy ideas...I'm customizing my 2nd gsx750es. As it came without the air box I'm putting 4 high fow air filters KN style.

I was about to start with all the testing, rejetting, needle hights blablabla BUT I thought "Why don't you put one of these plumming caps inside each filter and make a small hole in each one of them until the bike runs fine?" You know, these PVC plastIc ones that can be modified to the right size. Maybe controlling the right amount of air into the carbs, the nearest to the air floe the airbox gives...If it works it could reduce a lot of time and headaches!

Cheerz&beerz!

 

[denisd]

Let us know how you get on lad! 

[Gixer1460]

Having or not having an airbox has nothing to do with airflow. An airbox will flow as much air as an engine needs right through WOT and with a filter in place! Open carbs will rarely be able to use more air than that. The difference between airboxes and open carbs / individually filtered carbs is the 'quality of air delivered' not the quantity! Air boxes are designed to provide a 'still' air reservoir that the engine draws upon - this air is fairly linear in delivery and accelerates through the venturi drawing the fuel up. Open or individual filters pull chaotic air and so have a lesser effect through the venturi - maybe a reason most will need bigger jets whilst producing little more power when run back to back? This chaotic air really messes with CV function also. The dual carb pod K&N's help the two connected carbs have a 'pot' of air - not as good as an airbox but better than singles! Case in point - GSXR1100 'M' 40mm CV's - difficult to tune for pipes etc. WITH an airbox, virtually impossible without!

And If I understand your intention - why would you want to bypass the filter with unfiltered air? 

Edited February 14, 2022 by Gixer1460
Added wordage

[SATANSAM]

16 minutes ago, Gixer1460 said:

Having or not having an airbox has nothing to do with airflow. An airbox will flow as much air as an engine needs right through WOT and with a filter in place! Open carbs will rarely be able to use more air than that. The difference between airboxes and open carbs / individually filtered carbs is the 'quality of air delivered' not the quantity! Air boxes are designed to provide a 'still' air reservoir that the engine draws upon - this air is fairly linear in delivery and accelerates through the venturi drawing the fuel up. Open or individual filters pull chaotic air and so have a lesser effect through the venturi - maybe a reason most will need bigger jets whilst producing little more power when run back to back? This chaotic air really messes with CV function also. The dual carb pod K&N's help the two connected carbs have a 'pot' of air - not as good as an airbox but better than singles! Case in point - GSXR1100 'M' 40mm CV's - difficult to tune for pipes etc. WITH an airbox, virtually impossible without!

And If I understand your intention - why would you want to bypass the filter with unfiltered air? 

Nice reply thanx Gix,

Well basically I thought it was all a matter of EXCESSIVE AIR FLOW. I've compared riding with and without air box (in a twin bike) and it was in middle to high range when the bike drowned/choked and asked for carb update. My intention was closing the air flow somehow. I'll give it a try anyway, might stabilize a bit. 

My intention is CLOSING the air flow inside each filter, exactly the same in each filter tube. It's a very cheap try anyway as each plumming PVC cap costs round 0.10 quid and is easy to make shape...

[SATANSAM]

1 minute ago, SATANSAM said:

Nice reply thanx Gix,

Well basically I thought it was all a matter of EXCESSIVE AIR FLOW. I've compared riding with and without air box (in a twin bike) and it was in middle to high range when the bike drowned/choked and asked for carb update. My intention was closing the air flow somehow. I'll give it a try anyway, might stabilize a bit. 

My intention is CLOSING the air flow inside each filter, exactly the same in each filter tube. It's a very cheap try anyway as each plumming PVC cap costs round 0.10 quid and is easy to make shape...

HOLE not WHOLE you cnt
OKOK SOrry 

[TonyGee]

A few people have had success with this and back in the 80's I did an experiment with it.  I had a 4 cylinder chop (gsx1100 engine) and the mid range was fecking crap so......   what I did was wrap some tape round the 4 filters about half way and it worked, bike ran sweet as.  their was a guy who did the same thing on his bike on a forum but he did the mod on the inside of the filter so the filter looked normal. now is it restricting the air flow or stabilizing it ???????  don't know, all i know it worked   

[Gixer1460]

Ah ! What happens if you get the holes wrong and suck all the bath plugs into the engine? LOL! Maybe not the daftest idea ever on OSS but possibly close to it 

[Neil-IOM]

HI all,   many years ago, and i mean many my first real project was a gs750 frame with a gs1000 motor, bored to 1100 with some yoshi cams and a set of 28mm slides. I pissed around like an 18 year old does and found a one piece K&N style filter in a breakers yard,  no idea what make it was but it looked pretty cool at the time and i did the obligatory messing with jets etc for weeks  on end with endless plug chops as you do . I finally found the sweet spot by wrapping about a third of the holes up with black electrical tape, test run plug chop, unwrap a bit more, same again and again until i got it spot on. That was the way when you earned a pittance and dyno's hadnt been invented, happy memories, gotta love the eighties home brewed spray job, my first ever, i remember rubbing off the mint red original paintwork off the ET tank cos i wanted it yellow,   .....and 35 years later still havent shaken the suzuki 

[SATANSAM]

16 hours ago, Gixer1460 said:

Ah ! What happens if you get the holes wrong and suck all the bath plugs into the engine? LOL! Maybe not the daftest idea ever on OSS but possibly close to it 

They would never bee sucked into the intake as the caps would be pressed between the manifold and the  inside edge of the filter.

[gsxwill]

Same as others  bit of tape round the filters till they ran OK 

Strangly only had the issue with my gsx models, gs models all ran OK without the tape