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Discussion Starter #1
Hello,
I have an engine GSXR 750 1991 GR7AA-B R716 in Inazuma frame.
I rode the Cafe Racer race in Glemseck 101 this year.
My engine has 112 HP and 74Nm on the rear wheel.
I only have polished combustion chambers in engine, KN filters and adjusted original carburetors.
Do you have any tips on engine modifications ???

Camshafts, carburetors, pistons, exhaust??

Thank you, Radim
 

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Likes to race old junk.
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Welcome to the forum.
Cool bike!


You've asked a fairly vague question...
What are your goals? What's your budget? What do you hope to gain? Do you still want to be able to ride it on the street, with good manners?
Head work, cams, high compression pistons, rods, flat slide carbs, headers...you can quickly spend thousands chasing 20hp.

The cheapest performance option, would be to stuff a Bandit engine in there.

If you do a search, here or Google etc., you would see what is available. It all depends on how much you want to spend, because there really is no limit to what you can do to one of these engines...907 or 955cc kits, turbo, supercharger, nitrous...it's all been done before.
 

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Discussion Starter #4

I have a limit for our race 750 ccm.

I have the original exhaust pipe and I want to replace it, but I don't know what to the inner diameter of the pipes??

I heard it's good to change the cams, but I don't know from what engine and if only exhaust or even intake??

Thank you, Radim
 

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I have a limit for our race 750 ccm.

I have the original exhaust pipe and I want to replace it, but I don't know what to the inner diameter of the pipes??

I heard it's good to change the cams, but I don't know from what engine and if only exhaust or even intake??

Thank you, Radim
Hi Radim.

Nice bike. Please answer Beairsto's questions he is extremely knowledgeable and can help a lot.

"What are your goals? What's your budget? What do you hope to gain? Do you still want to be able to ride it on the street, with good manners? "
 

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Discussion Starter #6
Welcome to the forum.
Cool bike!


You've asked a fairly vague question...
What are your goals? What's your budget? What do you hope to gain? Do you still want to be able to ride it on the street, with good manners?
Head work, cams, high compression pistons, rods, flat slide carbs, headers...you can quickly spend thousands chasing 20hp.

The cheapest performance option, would be to stuff a Bandit engine in there.

If you do a search, here or Google etc., you would see what is available. It all depends on how much you want to spend, because there really is no limit to what you can do to one of these engines...907 or 955cc kits, turbo, supercharger, nitrous...it's all been done before.
Discussion Starter • #4 6 hours ago
Edit

I have a limit for our race 750 ccm.

I have the original exhaust pipe and I want to replace it, but I don't know what to the inner diameter of the pipes??

I heard it's good to change the cams, but I don't know from what engine and if only exhaust or even intake??

Thank you, Radim
 

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Likes to race old junk.
Joined
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1,631 Posts
It looks like you guys are having fun!
I assume this is low budget stuff...traditional grassroots kind of thing...it's cool.
Personally, I would just start with gearing it for the 1/8 mile drag and see how that improves your run.
It's challenging to find performance parts for a 28 year old engine, but they are out there. I suggest that you pay for a membership, so that you can access the Classifieds here.
Maybe someone can jump in with '91 GSXR pipe specs...the system would likely needs to be re-worked to fit your Inazuma chassis.
What are the rules? I think you should spray it...that's cheap performance, as long as you don't get greedy.
Where are you located?

Cheers,
Scott
 

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the event looks like fun. always nice to be around other like minded motorcyclist.

that frame appears to be from a bandit. what is your location?
 

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Discussion Starter #11
the event looks like fun. always nice to be around other like minded motorcyclist.

that frame appears to be from a bandit. what is your location?
Hello,
I'm from Czech Republic :)

This frame and tank is from GSX 750 Inazuma.
 

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Discussion Starter #13
It looks like you guys are having fun!
I assume this is low budget stuff...traditional grassroots kind of thing...it's cool.
Personally, I would just start with gearing it for the 1/8 mile drag and see how that improves your run.
It's challenging to find performance parts for a 28 year old engine, but they are out there. I suggest that you pay for a membership, so that you can access the Classifieds here.
Maybe someone can jump in with '91 GSXR pipe specs...the system would likely needs to be re-worked to fit your Inazuma chassis.
What are the rules? I think you should spray it...that's cheap performance, as long as you don't get greedy.
Where are you located?

Cheers,
Scott

Hello,
I'm from Czech Republic :) From Pilsen.

You think, spray it with N2O?? :)

When I give N20, must I replace to some engine parts?? pistons, rods? I have original engine :-/

I heard, that it is possible to take the exhaust cam from another suzuki, but I don't know if GSXR 1100 or bandit 1200 ??? :)

I can make the exhaust manifolds myself, but I don't know the ideal inner diameter.

My idea is:

- give an adjustable unit (ignition timing, shift indicator, engine settings)

- set the engine to 110 octane gasoline

- make the exhaust pipe

- maybe replace the exhaust cam and timing the engine

- maybe mikuni rs38 flat slides 🤷‍♂️


Thank you, Radim
 

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Switching to a high octane fuel will really only be beneficial if you increase the compression and/or the advance. advance alone isn't going to do much. If you want more power (while staying in the same bore and stroke) the big things to change are; increase compression, increase flow, and increase advance. The options you stated seem like reasonable upgrades without spending a ton. If you are committing to high octane fuel you can measure your compression ratio, and potentially deck the head to increase compression which is relatively cheap. You can get a custom cam for your application, and port the head in addition to new carbs and a exhaust. If you want to get crazier it gets expensive real quick.

Lightweight forged wheels will increase acceleration
a longer swingarm will let you launch harder

Probably the easiest way to get a faster bike is to go practice launching. I know a guy that has a mildly modified kz750 that will beat most liter bikes on the 1/8th mile because of his setup but its mostly that his reaction time and launching ability is amazing.
 

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Discussion Starter #19
It looks like you guys are having fun!
I assume this is low budget stuff...traditional grassroots kind of thing...it's cool.
Personally, I would just start with gearing it for the 1/8 mile drag and see how that improves your run.
It's challenging to find performance parts for a 28 year old engine, but they are out there. I suggest that you pay for a membership, so that you can access the Classifieds here.
Maybe someone can jump in with '91 GSXR pipe specs...the system would likely needs to be re-worked to fit your Inazuma chassis.
What are the rules? I think you should spray it...that's cheap performance, as long as you don't get greedy.
Where are you located?

Cheers,
Scott
569143


what you think of Vance Hines Propipe ??? :)

hou think, spray it with N2O?? :)

When I give N20, must I replace to some engine parts?? pistons, rods? I have original engine :-/

I heard, that it is possible to take the exhaust cam from another suzuki, but I don't know if GSXR 1100 or bandit 1200 ??? :)

I can make the exhaust manifolds myself, but I don't know the ideal inner diameter.

My idea is:

- give an adjustable unit (ignition timing, shift indicator, engine settings)

- set the engine to 110 octane gasoline

- make the exhaust pipe

- maybe replace the exhaust cam and timing the engine

- maybe mikuni rs38 flat slides 🤷‍♂️


Thank you, Radim
 

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Likes to race old junk.
Joined
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1,631 Posts
The Vance & Hines drag pipe will only benefit a proper big bore, high compression race engine. They are relatively cheap and eBay is flooded with them. Other than making noise, you won't really gain anything with your street bike, you'll have big dips in the power curve.

Nitrous is cheap hp...the problem is, it's easy to get greedy...if a little is this good, people then get burned when they decide that just a little more is better...like most addictions.
As long as you can supply the extra fuel, and can change you're timing...it's pretty safe.
Research it. You can get away with a small shot, using stock internals.

As stated above, 110 fuel won't actually help you unless it's really needed to resist detonation, because you have significantly raised the compression etc.
So no real gain, other than draining your wallet, and race gas smells good.

These engines benefit from port work....carbs, exhausts, cams etc aren't going to contribute much, until you address that.

Check with Kent Cams in the UK.

And again...there's little point in throwing more power at any bike, if you haven't mastered what you already have!
 
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