GS 1000 engine in GSXR 1100 first gen frame?

[John Kat]

Which triple clamp are you using? I just measured a 91 GSXR 750 triple and the offset is about 1.45". From my ground clearance spreadsheet it appears as if the offset of the 1st Gen 750's is more than the 1st Gen 1100. I have never bothered to back into what the USD triple offset is for the 1100, but 1st gen the 750 has 5mm more offset. That would improve your clearance to the exhaust but perhaps compromise handling a bit.

I see here you measured the GSXR Gen 2 1100 offset at 34mm. My measurement on the 91 GSXR 750 USD fork is 1.45"=38.1mm. 4mm ;Is that enough?
750 forks are 41mm.

http://www.thegsresources.com/_forum...13#post1841713

Going with the GSXR 750 91 would definitely help but I would have to buy the complete fork and the USD design goes against the vintage look...
In fact the original 1st gen fork like you have has most probably also more offset as it was designed to take the 18" wheel.
I will measure the one I have to determine if it's worthwhile.
The good news is that more offset at the triples decreases the trail making the bike more agile.
The bad news is that the 1st gen fork has no cartridge...

[posplayr]

Agreed, the preferred solution is to keep an 18" wheel which is a must to qualify for vintage racing here in France ( allthough I have no intention of racing the bike).
The quick solution is to go to a 17" wheel that I might do in the short term if I don't find a GSXR exhaust.
As for moving the engine backwards, there is no way.
Throughout my design I decided to keep the packaging as compact as possible as if it had come out of the factory using CAD/CAM software.
Extending the wheelbase requires more lean angle to negotiate turns and makes the bike less nimble as far as I know.

Which triple clamp are you using? I just measured a 91 GSXR 750 triple and the offset is about 1.45". From my ground clearance spreadsheet it appears as if the offset of the 1st Gen 750's is more than the 1st Gen 1100. I have never bothered to back into what the USD triple offset is for the 1100, but 1st gen the 750 has 5mm more offset. That would improve your clearance to the exhaust but perhaps compromise handling a bit.

I see here you measured the GSXR Gen 2 1100 offset at 34mm. My measurement on the 91 GSXR 750 USD fork is 1.45"=38.1mm. 4mm ;Is that enough?
750 forks are 41mm.

http://www.thegsresources.com/_forum/showthread.php?206668-A-modern-fork-upgrade-for-17-18-and-19-quot-wheels&p=1841713#post1841713

[John Kat]

You can solve a header clearance issue by changing out the wheels, but that seems a bit contrary to the whole "vintage racer" theme.

Are you sure you can't move the motor back a bit in the frame? It is squeezing the front.

Agreed, the preferred solution is to keep an 18" wheel which is a must to qualify for vintage racing here in France ( allthough I have no intention of racing the bike).
The quick solution is to go to a 17" wheel that I might do in the short term if I don't find a GSXR exhaust.
As for moving the engine backwards, there is no way.
Throughout my design I decided to keep the packaging as compact as possible as if it had come out of the factory using CAD/CAM software.
Extending the wheelbase requires more lean angle to negociate turns and makes the bike less nimble as far as I know.

[posplayr]

The 1st gen GSXR exhausts have apparently the same spacing as the GS so it's worth a try.
Cobra manufactures an GSXR exhaust for this model in stainless steel: http://www.cobra-exhaust.com/Speed-P...0-1100-85-88_1
I believe Delkevic's model for the GS 1000 is also in stainless steel?
It would be ideal as modifications could be done if necessary?
The 17" wheels have an outside radius of 308 mm compared to 331 mm for an 18" wheel.
These 2 cm ( almost an inch) would buy a lot of travel.

At one point I had both my GS and a 1st Gen GSXR 1100 and at least 3 GSXR 1st gen exhausts and two 2nd gen exhausts and I did test trials of all of them. They all fit to some extent or another on the motors. It is clearances that vary. If you ever hope to put a belly fairing on, it will need to be a GSXR header.

You can solve a header clearance issue by changing out the wheels, but that seems a bit contrary to the whole "vintage racer" theme.

Are you sure you can't move the motor back a bit in the frame? It is squeezing the front.

[John Kat]

The 1st gen GSXR exhausts have apparently the same spacing as the GS so it's worth a try.
Cobra manufactures an GSXR exhaust for this model in stainless steel: http://www.cobra-exhaust.com/Speed-P...0-1100-85-88_1
I believe Delkevic's model for the GS 1000 is also in stainless steel?
It would be ideal as modifications could be done if necessary?
The 17" wheels have an outside radius of 308 mm compared to 331 mm for an 18" wheel.
These 2 cm ( almost an inch) would buy a lot of travel.

[tatu]

I think some of the gixxer guys have gotten the titanium pipes to work but the welding requires special skills. I was referring to 86-88 GSXR 1100 (1st gen) and 89-92 (second gen) pipes. IIRC it was 92 was still 2nd gen ?

Ah, ok I was just looking at the shape.

[posplayr]

I think these might be the pipes,

http://www.ebay.co.uk/itm/07-08-GSXR-1000-Exhaust-Pipe-Headers-/271912923831?hash=item3f4f45f2b7

They are certainly different to the GS1000 headers.

I think some of the gixxer guys have gotten the titanium pipes to work but the welding requires special skills. I was referring to 86-88 GSXR 1100 (1st gen) and 89-92 (second gen) pipes. IIRC it was 92 was still 2nd gen ?

[tatu]

I think these might be the pipes,

http://www.ebay.co.uk/itm/07-08-GSXR-1000-Exhaust-Pipe-Headers-/271912923831?hash=item3f4f45f2b7

They are certainly different to the GS1000 headers.

[posplayr]

Those pipes do seem to pull down much quicker.

I had the last 1st Gen GSXR Hindel sold in N. America that I sold last year(mounted but never fired up). Extremely light thin wall stainless and sticks very well up to that frame as it has to to fit under the fairing. Point is that John is probably going to have to get a GSXR exhaust to make this work unless he wants to go for more of a chopper style .

[JTGS850GL]

[ATTACH=CONFIG]41154[/ATTACH]

Here is an 86 GSXR 1100 with USD forks and 17" wheels. I forget what exhaust it is but it is made for the 1100 (stainless 4:1). See how much clearance there is; right tight.

Just about any 1st Gen GSXR 1100 is a very good fit on a GS. The second generation GSXR 1100 pipes (as mine are) generally hang too low.

Those pipes do seem to pull down much quicker.

[posplayr]

Slabbie_forks.jpg

Here is an 86 GSXR 1100 with USD forks and 17" wheels. I forget what exhaust it is but it is made for the 1100 (stainless 4:1). See how much clearance there is; right tight.

Just about any 1st Gen GSXR 1100 is a very good fit on a GS. The second generation GSXR 1100 pipes (as mine are) generally hang too low.

[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.

[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

[kingofvenus]

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

[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.