My Custom GT550 Build: The GTX-R550

[GTX-R550]

So with yours, is the engine set up to be a stressed member with that monocoque frame? Were the GSXR engines stressed members on that bike, or were they mounted with rubber bushings?

No ..i have the sub frame bolted up solid but the engine is still allowed to move . I think the engine would shake you off the bike if it was mounted up solid so we will see what this does to the handling as the GSXR engine was bolted solid to the frame but they also were solid mounted in the frame you are wanting to use .

Hey Dave how badly do you reckon these engines would shake the frame? You might find these interesting http://www.tonyfoale.com/gallery/StrFrame/home.htm" onclick="window.open(this.href);return false;
Quite the builder from back in the day and converted some space frames to stressed member frames. Thanks for the tip on the 89 gsxr being bolted in hard. I figured since it was a space frame it would have had rubber dampers. Makes sense though that it wouldn't be for power efficiency and such.

Do you have any detail pictures I could see of your bike?

[Suzukidave]

[GTX-R550]

Oh man, that is beautiful. I like the cradle, when I was looking for frames there were a lot that were this style, but I lacked the creativity to think of making that sort of cradle for it. THough now that I've come up with my plan it will be similar in execution.

[Suzukidave]

Many may feel bad of me for doing it but i purchased a GT frame without a title from the junk yard and cut the cradle off it , that was the easiest way for me to do it . The engine is about 2" longer than the GSXR 750 engine so i had to tip the GT engine up in the rear just a bit so i could tuck the exhaust pipes in close enough so the front wheel wouldnt rub on full shock . It still only misses by around 1/2" .

[Suzukidave]

[Suzukidave]

I like also that i can remove 3 bolts that secure the subframe to the frame and the entire engine assembly comes out .

[GTX-R550]

Very Cool. I may change directions as I have an untitled junk frame. The frame's certainly restorable, but it needs some love, both shock mounts are broken off, threads need re tapping, needs paint of course, etc. Hmmm.

Good to know about front wheel clearance. I wonder if the later gsxrs have a much smaller steering head angle than the 89, I might have a little less of a problem there. Cool!

[Suzukidave]

I didnt have a stock GT750 setup to measure from so one of the list guys did a quick measurement from the the swingarm pivot to the rear of the front wheel and that let me know quick things were going to be tight . I did a bit of engine placement juggling ( with a empty engine ) to figure out where it had to go to fit in . Side to side it was easy as there is a bit over 1/2" on both sides of the head clearance to the frame . i had to cut away the area around the oil injection pump and the front sprocket cover had to be shaped a bit to miss the GSXR frame .

[GTX-R550]

I didnt have a stock GT750 setup to measure from so one of the list guys did a quick measurement from the the swingarm pivot to the rear of the front wheel and that let me know quick things were going to be tight . I did a bit of engine placement juggling ( with a empty engine ) to figure out where it had to go to fit in . Side to side it was easy as there is a bit over 1/2" on both sides of the head clearance to the frame . i had to cut away the area around the oil injection pump and the front sprocket cover had to be shaped a bit to miss the GSXR frame .

Yeah I'll have to some shaping myself, I do believe. I have an empty engine and cylinders to play with as well. That first GT I bought that was full of water was pretty shot. Might be able to salvage a few internals. The crank can be restore I imagine, but I've been using it to situate things in the frame, too.

So how many miles have you put on your GT build? Have you done any track days with it?

[Cragdog]

Simply awesome Dave, I really dig your bike. That awful mess of electronics in the back would make my head explode! haha

[GTX-R550]

Hey all,

Finally got into the garage again over the weekend. No school, so I'll probably be back at it this evening as well.

So here's what I did. Last week I cut my old title-less GT frame, cleaned some tabs off, etc. Then I spent the week eye balling, comparing, measuring and such.
Then I did a rough chop on the GSX-R frame, still leaving some aluminum to work with. Easy does it, huh?

Let's see.. What else. Currently the biggest factor weighing on my mind is how I'm going to:
A) angle the engine so the head pipes don't interfere with the front wheel.
B) make sure the head clears the frame.
C) Restore the the empty space frame to being a supported, empty space frame.


On Part C-
I've got some plans for how I'll mate the GT parts to the GSX-R frame. Down the line, or sooner, if I can I get ahold of the tools, I would like to make the engine frame out of aluminum and be able to weld that solidly to the GSX-R frame. For now, I'm going to make some mounts with the mills at school, maybe CNC, to mate the two frames together. I'm not entirely happy with the sacrifices in frame strength that this is going to produce, but one piece at a time, the solution will present itself.


Anyway, here're some pics. Be nice, it's still a rough draft! Hahaha


The vision:

[GTX-R550]

P.S.
Oh, and I have a different swing arm on the way. SV swinger wont work due to the fact that the SV has an exhaust heading out between the frame and monoshock, as a result the shock mounts are way off center. I could fabricate shtuffs to make it work, but I honestly have enough stuff to fabricate for this already that I'd rather go as bolt on as possible for the suspension components.

[Cragdog]

Did the heads not fit with your current configuration? Hard to tell, but it looks like the ram-air might fit the upper frame nicely.
Keep up the good work and keep the posts/pictures coming!

[GTX-R550]

Did the heads not fit with your current configuration? Hard to tell, but it looks like the ram-air might fit the upper frame nicely.
Keep up the good work and keep the posts/pictures coming!

I'm not quite sure I follow you. I don't have any cylinders on that engine due to just keeping weight of it down while I'm moving it a lot, angling, position, etc.

As it is now, the head and cylinders hit the original gsx-r frame down tubes, so I'll have to trim them up a bit.

[Suzukidave]

Looking interesting all right .. does it look l;ike the 2 out side exhaust pipes will clear the 2 pieces of front frame ? Do you plan on removeing the stock seat sub frame all together and get the one designed for the tail piece you have ?