GS 1000 engine in GSXR 1100 first gen frame?

[John Kat]

A small but important step forward as I got the rear lower engine mounting tabs drilled.
I must have pulled the engine in and out at least ten times to get it right...
Next step will be to get the real engine in.
From there on, it will be more a question of money than anything else.
Note how close I got the rear of the engine to the swingarm.

[Fjbj40]

Looking REAL good! Awaiting the next progress report! You are doing a great job.

[postman_pat]

I also measured the weight of the frame alone: 17 kg.
Could anyone give me the weight of a bare GS 1000 frame?

I've measured a bare GS1000ST frame as 18.26kg.

A Cycle World test from the GS1000 launch quotes a frame weight of 38.3lbs (17.4kg), but remember, they have different gravity over in Japan!

Don't get too hung up about the frame weight - the GSX-R frame is much stiffer, and the real transformation will be in the wheels and other unsprung mass components.

[John Kat]

I've measured a bare GS1000ST frame as 18.26kg.

A Cycle World test from the GS1000 launch quotes a frame weight of 38.3lbs (17.4kg), but remember, they have different gravity over in Japan!

Don't get too hung up about the frame weight - the GSX-R frame is much stiffer, and the real transformation will be in the wheels and other unsprung mass components.

I was expecting a minimal weight saving.
In fact when I cut the frame into two I discovered that the weight was really concentrated around the swingarm area.
The current hypersport bikes have the swingarm attached directly to rear of the engine cases to decrease the weight much further.
When I started the project I considered using the GSXR 750 frame as a basis as it looks much more like the one used on the XR 41 but it looked so weak that I decided against it...
Apparently the XR 41 racers complained about the frame that would geat weak after a few races.
Thanks for the feedback on the GS 1000 frame weight.

[John Kat]

It was a great day yesterday when I slipped my 1085 engine in my modified GSXR 1100 frame
It was so tight that my helpers thought it wouldn't go in...
Today, I tightened all the bolts and hooked up my standard V&H exhaust on the bike.
A small issue appeared as the internal exhaust bolts of cylinders 1 and 4 can't go in as they interfere with the frame downtubes...
I'll have to try with a nut on a threaded shaft.
Mounting the exhaust showed also a minute interference at the silencer level: maybe one or two millimeters.
It's a racing bike let's not forget!
Last but not least, I managed to get the engine so low in the frame that it should be possible to mount some RS type carbs and not only the CV carbs.
Here are some pictures:

[posplayr]

You recall the GSXR head bolt spacing is narrower than the GS. Not a problem putting GSXR on GS , but the other way around, this is one of the issues.

The other thing to consider might be spigots. The bolt will be very close to the head and the spring retainers will save those threads. Also the spigots push the whole pipe a bit further forward and can add just the needed header clearance. On my ED, I still had clearance for between f fender and exhaust but it is close.
I found some V&H spigots on eBay (a few years back now) and had them machined to reduce the standoff. Here is a picture using hex head stainless bolts into teh head.

spigots.jpg

[John Kat]

You recall the GSXR head bolt spacing is narrower than the GS. Not a problem putting GSXR on GS , but the other way around, this is one of the issues.

The other thing to consider might be spigots. The bolt will be very close to the head and the spring retainers will save those threads. Also the spigots push the whole pipe a bit further forward and can add just the needed header clearance. On my ED, I still had clearance for between f fender and exhaust but it is close.
I found some V&H spigots on eBay (a few years back now) and had them machined to reduce the standoff. Here is a picture using hex head stainless bolts into teh head.

[ATTACH=CONFIG]41109[/ATTACH]

I've never seen a header with spigots but I believe I understand how it works with a small piece of tubing bolted to the cylinder head and the exhaust pipe that slides inside this piece of tube, both maintained together with a spring.
Would be nice but surely not easy to find?
I will try to wiggle the engine left and right to get the bolts in and then secure the engine in the frame.
Not the best engineering practice but I'm sure one can find worse in production cars...

[posplayr]

I've never seen a header with spigots but I believe I understand how it works with a small piece of tubing bolted to the cylinder head and the exhaust pipe that slides inside this piece of tube, both maintained together with a spring.
Would be nice but surely not easy to find?
I will try to wiggle the engine left and right to get the bolts in and then secure the engine in the frame.
Not the best engineering practice but I'm sure one can find worse in production cars...

For track racing that V&H megaphone is probably not the best for cornering clearance. Generally the pipes that come straight down the middle are better and so pulling the pipe is not an occasional affair especially for racing. You say you are going to studs, that will take a load off of the poor threads in the head at least. Still a pita to pull the exhaust.

As I recall the MotoWorks SS pipe has spigots and would be something fitting to your build instead of the megaphone.

Like this:

http://www.ebay.com/itm/GS1000-STAINLESS-ALLOY-EXHAUST-4-1-GS-SOHC-RACE-GS1000S-RACER-WES-COOLEY-GSX-/111709239961?hash=item1a0263ba99

motowerksSpigot.jpg

[dorkburger]

So cool to watch this come together.

[John Kat]

So cool to watch this come together.

Thanks, encouragements are always welcome specially when the outcome is not garanteed...
I believe Napoléon once said to one of his generals: " You must be smart and brave to have reached this rank but are you lucky?"
In all projects one needs a bit of luck as it's almost impossible to foresee all issues.
Here I was lucky as a stud can go into the cylinder head to fix the difficult to reach exhaust bolt issue.
Even better the spacing was exactly the same on the other side.
The engine is definitely well centered in the frame

[John Kat]

I did a quick check this morning about the clearance between the front wheel and the exhaust pipes.
At 60 mm downstroke the tire reaches the plane of the exhaut down tubes.
Going in a straight line the wheel can move further upwards as the tire will move between the exhaust pipes.
There are two solutions: eitheir move to another exhaust pipe or use a 17" wheel.
I haven't decided yet.


Here's a picture with a 18" 3 spoke wheel I might use.

[tatu]

I didn't see that coming, it does look close, what does the original bike have? Dropping an inch in wheel size will still only give a half inch more clearance and that will soon go with a front mudguard and fork flex, spigots with springs would allow you to shorten the pipe at the port.
Its all looking good.

[kingofvenus]

Looks like a custom set of tripple trees just may be in your future?

[posplayr]

Looks like a custom set of tripple trees just may be in your future?

Can't tell really but looks like the triple has zero offset?
i have the 88 1100 forks and wheels and while mine is close not that close. I see one other major difference.

GSXR_side.jpg

[JTGS850GL]

Looks like the engine placement in the frame was a little too forward. Probably also contributing to the close tolerance for the exhaust bolts as well. Amazing what another 1/2" rear offset would have done. I don't think a pipes change will be very easy without a custom header. That initial bend is going to be significantly sharper. Not sure what that would do to exhaust flow. A 17" wheel may buy you some more space but it's still going to be close. More offset on the triple trees will help, but how will that effect handling?

It's been an interesting build and have loved following it. It's a unique experiment and I'm sure things will work out. Sure would hate to think of a hard braking situation leading into a turn with the wheel lodged between the inside pipes.