megareg
07-08-2009, 10:31 PM
I posted this in the Katana forum, Crazymofo suggested I post it here as he knows a few that would be interested in it, if anybody wants more info, just email me.
This project has been 2 1/2 years in the making, anyway, what I was planning was to add 1988 GSX-R 750 carburetors, the oval ones, I just did not want to add the pods as it would look like it was a 'highly' modified Kat, I wanted to keep the stock appearance as much as possible, so I had to find a way to adapt the stock plenum and filter to these carbies, and thus also not having the problems when pods are used.
I finally got some reasonable parts for the 36mm jobbies I had bought years ago of E*ay, the slides were shot, emulsifier tubes no good etc. etc. BUT, they were Dynojetted 136!!
To modify the stock plenum, I first cut away the stock velocity stacks and trimmed a bit more to fit the velocity stacks from the 1988 GSX-R 750 carburetors, then I trimmed the outside to fit into the plenum I had trimmed, I then mounted it all and the space that was between the plenum and the stacks ( that were mounted on the carbies) I filled in with some of that quick setting plastic weld stuff, that gave me the distance and alignment that was needed so that I could get the plenum mated to the stacks by a plastic welder, unfortunately, they could not be welded as the materials are different, so Sikaflex was used.
I finally fitted the fuel lines and then started it, after a few minutes it settled to a nice idle of around 1100 rpm, I thought I set everything up before I mounted them, the air screws are set to 2 1/2 turns out and the idle adjustment was a pure fluke, so far so good, the filter box and plenum is from TFB (thanks Mike, the lid is a treat, others my want to do the same after seeing this pic).
The throttle cable is too long and I'll have to shorten it, I'm thinking that maybe a solderless nipple may fit or perhaps I'll silversolder another nipple on it, we'll see....
Here are some pics of the job, it might look a bit messy, but it is a proof of concept.
More pics will follow later.
Overview.
http://i287.photobucket.com/albums/ll132/megareg981/36mm_view.jpg
Inside view of plenum.
http://i287.photobucket.com/albums/ll132/megareg981/36mm_stacks.jpg
Filterbox by TFB.
http://i287.photobucket.com/albums/ll132/megareg981/36mm_filter.jpg
I've been a bit busy the last couple of days, so been a little slow on it, however, I put it all back together and did what I could with the throttle cable, its got a LOT of freeplay but I've got a couple of ideas I want to try first before cutting a perfectly good cable.
Well, I took it for a spin today, only a short one though and I can report that the difference is amazing, the mid range is REALLY strong, it pulls from 1500 hard and gets to 5000 real easy, I did try it to 9000 and it pulled hard and evenly all the way to it (not on a public road of course), there are no flatspots either, it just pulls hard whatever revs you are doing, I think a dyno is in order to check what the output is now.
It is a bit rich (judging from my nose) at idle, I think I will try screwing in the air jet from 2 1/2 turns out to 1 1/2 turns out and see where that goes. (1 1/2 turns no good, ran like crap, back to 2 1/2 now)
One thing that is missing now is that fabulous Kat Krackle on the over-run, might have something to do with being a bit rich too...
(there is a bit of a crackle now, must have had a bit of crap in them for a bit earlier)
I'm leaning towards a "Sleeper" (sleeping?) Kat, or a wolf in sheeps clothing...
Here is a photo of how it looks now, I wonder how many people will think that is how they came originally????
http://i287.photobucket.com/albums/ll132/megareg981/36mm_final_view.jpg
I had a bit of time this morning before I went to work so I decided to try what was going in my head on the "adjustment" of the excess length of the throttle cable, what I was thinking was adjusting the throttle RETURN stop so that it would take up the slack, I did not want to cut a perfectly good cable and also I could just put an original unmodified Katana cable in if ever I had to replace it.
On inspection of the housing, there is a ridge for the throttle RETURN stop, all I did was use some of that 5 minute plastic repair putty stuff and "extend" that ridge, here are the pics, they do not show a great detail, but it should give an idea of what goes on, it works well :) :)
This was the first trial go, the "stop" was not high enough, had to add more....
http://i287.photobucket.com/albums/ll132/megareg981/Throttle_first.jpg
This was as far as I could go with the putty, it was up to the top of the housing, but it is enough :D
http://i287.photobucket.com/albums/ll132/megareg981/throttle_second.jpg
And this is how the adjuster looks now, plenty of room for fine adjustment :D
http://i287.photobucket.com/albums/ll132/megareg981/throttleadjustment.jpg
Cheers and I hope it all goes well with whoever tries to repeat my mods.
This project has been 2 1/2 years in the making, anyway, what I was planning was to add 1988 GSX-R 750 carburetors, the oval ones, I just did not want to add the pods as it would look like it was a 'highly' modified Kat, I wanted to keep the stock appearance as much as possible, so I had to find a way to adapt the stock plenum and filter to these carbies, and thus also not having the problems when pods are used.
I finally got some reasonable parts for the 36mm jobbies I had bought years ago of E*ay, the slides were shot, emulsifier tubes no good etc. etc. BUT, they were Dynojetted 136!!
To modify the stock plenum, I first cut away the stock velocity stacks and trimmed a bit more to fit the velocity stacks from the 1988 GSX-R 750 carburetors, then I trimmed the outside to fit into the plenum I had trimmed, I then mounted it all and the space that was between the plenum and the stacks ( that were mounted on the carbies) I filled in with some of that quick setting plastic weld stuff, that gave me the distance and alignment that was needed so that I could get the plenum mated to the stacks by a plastic welder, unfortunately, they could not be welded as the materials are different, so Sikaflex was used.
I finally fitted the fuel lines and then started it, after a few minutes it settled to a nice idle of around 1100 rpm, I thought I set everything up before I mounted them, the air screws are set to 2 1/2 turns out and the idle adjustment was a pure fluke, so far so good, the filter box and plenum is from TFB (thanks Mike, the lid is a treat, others my want to do the same after seeing this pic).
The throttle cable is too long and I'll have to shorten it, I'm thinking that maybe a solderless nipple may fit or perhaps I'll silversolder another nipple on it, we'll see....
Here are some pics of the job, it might look a bit messy, but it is a proof of concept.
More pics will follow later.
Overview.
http://i287.photobucket.com/albums/ll132/megareg981/36mm_view.jpg
Inside view of plenum.
http://i287.photobucket.com/albums/ll132/megareg981/36mm_stacks.jpg
Filterbox by TFB.
http://i287.photobucket.com/albums/ll132/megareg981/36mm_filter.jpg
I've been a bit busy the last couple of days, so been a little slow on it, however, I put it all back together and did what I could with the throttle cable, its got a LOT of freeplay but I've got a couple of ideas I want to try first before cutting a perfectly good cable.
Well, I took it for a spin today, only a short one though and I can report that the difference is amazing, the mid range is REALLY strong, it pulls from 1500 hard and gets to 5000 real easy, I did try it to 9000 and it pulled hard and evenly all the way to it (not on a public road of course), there are no flatspots either, it just pulls hard whatever revs you are doing, I think a dyno is in order to check what the output is now.
It is a bit rich (judging from my nose) at idle, I think I will try screwing in the air jet from 2 1/2 turns out to 1 1/2 turns out and see where that goes. (1 1/2 turns no good, ran like crap, back to 2 1/2 now)
One thing that is missing now is that fabulous Kat Krackle on the over-run, might have something to do with being a bit rich too...
(there is a bit of a crackle now, must have had a bit of crap in them for a bit earlier)
I'm leaning towards a "Sleeper" (sleeping?) Kat, or a wolf in sheeps clothing...
Here is a photo of how it looks now, I wonder how many people will think that is how they came originally????
http://i287.photobucket.com/albums/ll132/megareg981/36mm_final_view.jpg
I had a bit of time this morning before I went to work so I decided to try what was going in my head on the "adjustment" of the excess length of the throttle cable, what I was thinking was adjusting the throttle RETURN stop so that it would take up the slack, I did not want to cut a perfectly good cable and also I could just put an original unmodified Katana cable in if ever I had to replace it.
On inspection of the housing, there is a ridge for the throttle RETURN stop, all I did was use some of that 5 minute plastic repair putty stuff and "extend" that ridge, here are the pics, they do not show a great detail, but it should give an idea of what goes on, it works well :) :)
This was the first trial go, the "stop" was not high enough, had to add more....
http://i287.photobucket.com/albums/ll132/megareg981/Throttle_first.jpg
This was as far as I could go with the putty, it was up to the top of the housing, but it is enough :D
http://i287.photobucket.com/albums/ll132/megareg981/throttle_second.jpg
And this is how the adjuster looks now, plenty of room for fine adjustment :D
http://i287.photobucket.com/albums/ll132/megareg981/throttleadjustment.jpg
Cheers and I hope it all goes well with whoever tries to repeat my mods.