GS 1000 engine in GSXR 1100 first gen frame?

[John Kat]

I ordered the top frame beam extensions today.
They will cost me more than the frame itself...
In the meantime, I decided to extend the top frame beams along a straight line as it will not only look better but it will also give a little more headroom for the cylinder head.
Contrary to what I mentionned earlier, by extending the top rails, the rake angle will decrease slightly which is also a good thing.
Last but not least, it should now be much easier to fit the GSXR 1100 OEM air filter, well know to be a nightmare to work with!
The resistance to traction specification for the aluminum I'm using is 280N/mm2.
As the cross section at the weakest point is roughly 500 mm2, it should resist to traction of 140 KN or 14 tons.
Seems OK to me?
It's not the strongest available but it is suitable for welding.

 

[Pedda]

Hey John,

just found this project thread. Do you still need that lower crank case? Bad conscience here... :uncomfortableness:

 

[John Kat]

Hey John,

just found this project thread. Do you still need that lower crank case? Bad conscience here... :uncomfortableness:

Hi Pedda,
Don't worry, I know it's a pain to ship large parcels through the post.
I'm currently working another alternative here in France so let's wait to see if it works out?
As you have swapped engines back and forth, do you know if the GSX cases fit with no modification in a GS 1000.
I'll check with my Katana but would appreciate your input.

 

[Pedda]

Don't have any GS experience, only GSX. But as far as I'm aware the cases are pretty much the same. Should be good enough for mock-up purposes...

 

[John Kat]

I got the upper frame rail extensions back for the machinist and luckily I got the two frame halves united again.
Next will come the bottom frame rail extensions but that's easy in comparaison.
I'm not too keen to get that done until I get a hold on a bottom engine case...
Here's the result so far:

 

[John Kat]

A final test to see if everything fits before making the lower rail extensions.
There could be an issue with non-CV carbs but the engine will most probably sit a little lower in the frame.

 

[JTGS850GL]

How long is it going to be for you to get a lower case for that engine????

 

[John Kat]

How long is it going to be for you to get a lower case for that engine????

Too long to my liking but I found one today here in France.
In the meantime, I've devised a jig to ensure the frame is straight when it gets welded.
Still have to have it built however...

 

[ozman]

looking good there john

are you going to cut and lenghten the downtubes to get the bottom tubes to line up ?
with cutting top rails and moving forward you are also moving up seems if you are lining up the tubes correctly you would need to do 4 cuts not 2

 

[John Kat]

looking good there john

are you going to cut and lenghten the downtubes to get the bottom tubes to line up ?
with cutting top rails and moving forward you are also moving up seems if you are lining up the tubes correctly you would need to do 4 cuts not 2

You are right, except that I will connect the downtubes through a small Z to avoid two further cuts.
In practice, it should be almost unoticeable.
In fact adding two more cuts would introduce further issues as the sloping portion of the downtubes is not parallel...
Here I've used the Keep It Simple adage to his fullest.

 

[ozman]

sounds like you have a plan, keep posting progress

 

[Carter Turk]

I thought I heard it's not possible to join un matched case halfs, as they are line bored for the crank and transmission shafts.

 

[John Kat]

I thought I heard it's not possible to join un matched case halfs, as they are line bored for the crank and transmission shafts.

Quite right but I'm only using them as a jig to finalyse the fitting in the frame.
I want to get the bike complete before transplanting the engine from my GS 1000 XP.

 

[Carter Turk]

Got it! Enjoying the build thread and all the hurdles.

 

[John Kat]

I got the frame reunited today as I got the bottom rails extensions back from the machinist.
As you can see there is a little step in these to cater for the lowering of the front end.
Good news for the bike's geometry.
By the end of the week I should get some GS 1000 engine cases I bought from Germany.
Another good news is that upper case engine mounts will most probably be reusable.
That much less to machine!

 

[John Kat]

The engine case finally got to me and in no time flat I had them positionned in the frame.
There is no big surprise except that there is still some work to do...
In fact the bottom rear of the engine case is just a little too wide to fit between the frame mounting brackets.
It must be a question of 1 or 2 mm each side that can be filed away.
As you will see in the pictures the engine is "attached" through the OEM front right upper mount.
Lenght wise it's almost bang on and within the latitude of my top frame extensions.

 

[John Kat]

It can be done
Not only can it be done but it can de done (almost) economically.
Of course it's not for the faint of heart as you have to cut a GSXR 1100 G/H chassis into two...
It's definitely a racing type bike as the fitting is very tight.
For instance the motor has to be assembled before going into the chassis.
Now I need to hire Valentino to test it out.
Next step is to design the gussets to hold the engine in place.
I will start with the top rear and the bottom front first as they will help align the engine in the frame.
Here's what it looks like so far:

 

[John Kat]

I've ordered the brackets to support the engine in the frame but I won't get them until mid april...
In the meantime, I checked that the GS 1000 OEM air box ( at least the front one) will easily fit in the frame AFTER installing the carbs.
Very good news indeed when using CV carbs.
In fact, I also checked to see if the VM carbs would fit and the answer is NO as they hit the top frame rails.
So CV carbs it will be!
I'm still devising a frame alignment set-up fixture but if anyone had a good idea, I would be interested.
So far, I'm contemplating using a laser beam that would be attached to the middle of the swingarm pivot and aimed towards the front of the bike.
At first I would lift the beam to strike the middle of the bottom triple tree and then lower it to illuminate the front wheel axle.
If it strikes it in the middle both times, the frame is straight!

 

[tatu]

Is there any way you can reduce the curve in the bottom rails to put straight joiners in rather than the Z piece?
Will the frame be welded and fixed or will it be dismantalable to unbolt the two halves, or a mix like one side fixed and the other removable to make the engine in and outable?

 

[John Kat]

Is there any way you can reduce the curve in the bottom rails to put straight joiners in rather than the Z piece?
Will the frame be welded and fixed or will it be dismantalable to unbolt the two halves, or a mix like one side fixed and the other removable to make the engine in and outable?

Hi Chris,
It would be difficult to "straighten" the downtubes in order to align the bottom rails in my opinion.
All tubes will be welded to get maximum rigidity.
Suzuki took care of introducing the engine in the frame of the OEM GSXR chassis as the bottom right rail is bolted in place.
I will keep this feature on my frame.