Pod filters and GSX750ES, slides not moving?

[Motovalet]

I’m trying to get my 750ES to run with either K&N pod filters or Ram Air sock filters on OE inlet rubbers. I know using the airbox is the “correct “ way but that’s not an option as I don’t have it and can’t find one for sale. Carbs currently have correct jet kit fitted, looks like a Dynojet or similar? Bike will start, idle nicely and rev up fine in the garage. Once out on the road, it’ll struggle to go faster than 40MPH and runs like a pig, it definitely feels like the slides aren’t lifting enough. Is there any way of getting these carbs to work without an airbox? I note the slides move a lot stiffer compared to later carbs off of oil boilers, BST36’s etc. these all have flat slides and a softer spring, is this the issue, are the springs too stiff? Conversely my Blandit engined Kawasaki runs absolutely fine with jetted BST36’s and Ram Air filters so I know it can sometimes work! All input appreciated!

[gsxwill]

Had same issue with gs 1000 with pod filters, mine was to much direct air flow through the pods, used plastic cone inside each pod to cover 3 fifths of surface area on 1 and 4 little less on 2 and 3!! 

Took a little bit of trial and error, but ran great for 3 years after that!! 

But the great thing about this forum is there will be countless other ways people have achieved the same result, just got to find the one that works for you 

[wraith]

Sounds like the carbs need a good looking at, have you taken the filters off and start/rev the bike to see it the slides are moving?

You may have some bad slide diaphragm/s

[Rampe]

Revving at stand still doesn't mean much, since then the engine needs only food (air&fuel mix) for running itself. On the road the load grows exponentially with speed due to drag/air resistance, but even at walk speed there is the weight of the bike and rider + all the moving components friction added to load = engine hungers for way more food. So first I would check if the slides are worn out and jiggle loose and/or have some wear notches, which could cause them to tackle when the air flow grows and pushes them towards engine. Second - are you sure that the jetting is correct, since it sounds like you haven't ran at dyno? Third, check the pressure hoses, I understood that they're CV carbs. 

 

[cnap504]

Carbs clean?  All jets and fuel passages, are the floats set and working correctly.  And are the carbs getting a steady adequate supply of fuel?

[bitzz]

Have you seen this bike run with these carbs?

[Suzukian]

These bikes need a ventuuri tube with the pod mounted on the end so the the vacuum inside the tube can lower enough (Bernoulli principle) to create the vacuum to raise the slides.  There's a company that makes a tube inside a tube that allows for this.  You do not get more power from pods unless you have done engine work, such as cams, pistons.  The Pods just make the bike lose it's mid range and more peaky.  It changes the power band but adds nothing.  The inferior (and it doesn't matter what pods you use) particulate filtering causing the rings to wear prematurely.  Unless you have new cams, and a free flowing exhaust, even then, the stock filter would be better for the life of the engines, and you could tune it easier to get the results you wanted from your modifications.  On a stock a, a waste of time, and shorter engine life.  You also loose that lovely mid-range power these bikes have. I've seen this done a few times, and it's always been a disappointment.