GK73A SP2 - Air Filter Solution (big pic thread)

[400_Rider]

Howdy guys.

It gives me great pleasure to FINALLY announce a solution to aftermarket air filters on the GK73A.

Now, my bike is the SP2 model and I did read that the SP model has different carbs to normal 73A's ? however if you are struggling to get aftermarket airfilters to fit your carbs due to the space between each carb being too close together, THIS ... is the answer you have been waiting for

Firstly my journey to get this far has been a painstaking one and a very expensive one, I have tried running with no airbox on, that didnt work, I spent £60 on ITG sock filters, they didnt work and I ended up cutting them up and they went in the bin.

Finally, after another £60 I got there in the end :D

So how did I do it ?

Well while searching on evilbay for a solution I came across an ad for "WEBER 45 DCOE MAX FLOW LOW PROFILE MESH FILTER PAIR", these were £32.50 for just two !!! so I got to thinking, now I wonder if I can use the existing rubber velocity stacks that are in the original air box and put these over the top, in theory that sounded possible, so I decided to give it a shot and ordered 4 of these !

When they arrived, not only did they slot onto the rubber velocity stacks (thats my phrase for the standard rubber airbox attachments - basically its what they are) but they was also a perfect fit :D

I put one of the mesh filters onto the rubbers and onto the carbs, great, looked wicked.. however... I was left with the same problem, the overhang was just too much for the next filter to fit beside it

I pondered what to do for a full day, then the idea came to me.

What if I was to cut off, with scissors the black rubber round the mesh filters, leaving just the mesh then mould these to the rubber velocity stacks leaving zero hang over - the idea was born and I got the scissors out with great anticipation.

I cut off and removed all the black rubber from the mesh filters, when I had done this the mesh fell apart in 3 layers, top and bottom were the same mesh and the middle layer was a very, very fine mesh.

I then a layer at a time of the mesh over the velocity rubber and used the metal rubber clamps to tighten and mould the mesh to the shape of the rubbers, when I did all 3 they slotted together and I then fitted them over the rubbers and tightened with the clamp.. perfecto maximus :D

All 4 fit perfectly.

I have a stage 3 factory pro jet kit for my bike and it says you must remove the standard air box and use aftermarket filters, only aftermarket filters dont fit my carbs, this.. is the only solution I have heard of for the SP model, and to be honest, I prefer the look of these to any set of K&N's.

Without further ado, please check the pics below, each pic shows something significant, how I trimmed the rubbers, comparison of standard mesh filter to a trimmed one, also how they didnt fit on the bike without modification, and finally all 4 done and on.

Man typing this post feels good, I can put this behind me now and move on to getting the thing running lol.

Enjoy,

Matt :)

[Chalky]

Looks fucking brilliant mate!!

Couple of questions tho :D

the rubber bit (sort of side wall bit) looks like it has been replaced with fabric, is it fabric? If it so, is it a special kind?

are they standard jubliee clips (i think that's what they're called)? and did you get them with the air filter kit?

and I take it, it would work for the GK76A as well? Because I'm told they can't have the individual air filters either.

Sorry about all the questions dude, just very impressed.

Oh yer, do you have a picture of the filters on the bike, side on view?

[400_Rider]

OK time to answer some Q's :D

Right, the fabric your referring to is really just to tidy things up a bit, I used self emalgamating tape or whatever its called as there was some sharp bits of mesh sticking up, so I bent it all round and used the tape to stop me stickin mesen with the fine bits of mesh around the edges, thats all that is, it isnt necessary to do.

The clips are from robinsons foundry and are brand new original ones, I could not find a aftermarket one that size (62mm) but only like 8mm wide band, there not too expensive and they look mint, if you do this though you will need 8 new ones, 1 top and 1 bottom of each stack.

Yep this will work on ANY bike YAYYYYYYYYYYYYYYYYYYY the only additional width is the width of the rubber clips which is like 2mm so yes this will work with any bike out there.

I don't have a side view pic exactly but the pics above show it at most angles, I will take more when the tank is on.

I have only one more mod I am considering to these modified filters .... RAM AIR !

I am just thinking about it at the moment while the bikes in bits, well it won't be a true ram-air as such as there isnt a closed air box, but because there is so much air under the tank now I was thinking of routing a cold air intake from the front of the bike to the filters, but am now thinking because theres SO much air available now and such a gap it might not need a cold air feed anyway and lets face it, all air is cold at 120+mph

[Variablevalves suck]

Looks nice!
Theres a guy sells a ZXR4 forced air box on ebay, you could take a look at the pictures of his for some ideas. :D

[400_Rider]

Cheers Variable I'll check it out :D

[gsxr400 racer]

i ran individual pods on my 73 with no problem and there used to be a article on the old board telling what k&n fit in the stock air box with a small mod...handy though what you did...Im running race carbs (flatslides) with the stock air box and no filter.

[400_Rider]

I just want mine to start now, still havin no joy with it idling it's ok if its at 3,000 try and lower it and it will a bit, take it out for a run and come to a set of lights and it just wants to stall all the time

Also with these filters on, when I try and crank engine, if I give it any throttle even a tiny amount you can hear it getting wayyyy too much air and it like drowning it

Anyway I got some new plugs ere to go in tomorrow, NGK CR9EK, gonna see if that makes a difference wish me luck

[gsxr400 racer]

tell me what the plugs look like but i would bet yo need to raise the needle you got a jet kit in it?

[400_Rider]

I've spent about 700 quid on this bike and it's still not working

Anything that can be replaced has been replaced, new stage 3 carb kit, new emulsion tubes, new idle jets, new plugs (tomorrow although 'old' ones only 3 month old) new barnett clutch, new cables, new filters, new bulbs all round... I don't know what else I can do to make this bike work.

First problem I want to get round is it will not start off the button, when I hit the start button the engine cranks over and theres a burbling in the exhaust like it wants to start, but the bugger just wont fire

I have taken out all the plugs and took a video to show you them all sparking, plug 1 and 2 was both brown and plug 3 and 4 was both jet black.

I am not sure what this means, could it be that the only reason this is not starting is because the idle screws arn't set correctly ? also I have fiddled about with my idle and not sure if twisting it forward or backwards raises the revs, maybe its set too low for it to fire, I am not sure.

Anyway heres what the plugs looked like :





Here is the VIDEO :

http://www.youtube.com/watch?v=ABCgSt5KAf4

Any ideas why its not starting before I take a hammer to it lol.

[gsxr400 racer]

its not starting because the plugs are fouled new plugs will cure this for a minute i would find out why the two are real black common faults for this are going to be weak coil, bad spark plug wires or caps, carbs leaking fuel into cylinder...ie bad orings or a pinched oring (use electrical grease when installing) loose pilot jet...choke plunger on those cylinders sticking or not fully closing...what size main is in it now?