Gear Ratio Question

[Neveragain55]

Before I start, I promise all of you that I searched the internet and all types of forums for the answer to this question, but all of that research only made my head spin……..

 

The 1989 GSXR1100 bike had a stock tooth set up of 15T (front) 48T (rear)

The motor going into “Project X” is a modified, punched out 89 GSXR1100 Slingshot motor (1186 kit)

The wheels are from a 1995 GSXR750 (17” straight, three spoke wheels)

All of these parts will be stuffed into a modified & braced 1980 GS750 frame with modern, upside down GSXR750 front forks, and a braced JCM rear swingarm.

I’ve been instructed to go with a 14T (front) / 43T (rear) set up if I want more top end (which is what I want) without losing all of the upfront & midrange punch.

Again, the wheels are the stock 17” units, 180 (rear) / 120 (front)

All of the charts I’ve seen online put the 14T / 43T set up at a ratio of 3.07

The stock set up of 15T front / 48T rear gives it a ratio of 3.20

These ratio numbers mean nothing to me and despite all of the videos I've watched and articles I've read, my thick head still doesn't get it.

 

It’s very simple:

Is the 14T / 43T setup the best in terms of getting good top end (over stock) without losing too much of the lower end and midrange punch  

(in other words, is it a good compromise)

 

                                                                                                                      As always, thanks in advance.......

 

 

 

 

Edited February 11, 2021 by Neveragain55

[Gixer1460]

The bigger the number = the lower the overall ratio and lower top speed and slower accelleration (unless you have excessive power!)

The smaller the number = the higher the overall ratio and higher the top speed and faster accelleration.

There is always a compromise between accell. and top speed!

BTW for best / longest chain life the front sprocket should be as big as possible - chains don't like 'tiny' diameter sprockets!

[MeanBean49]

4 hours ago, Neveragain55 said:

Before I start, I promise all of you that I searched the internet and all types of forums for the answer to this question, but all of that research only made my head spin……..

 

The 1989 GSXR1100 bike had a stock tooth set up of 15T (front) 48T (rear)

The motor going into “Project X” is a modified, punched out 89 GSXR1100 Slingshot motor (1186 kit)

The wheels are from a 1995 GSXR750 (17” straight, three spoke wheels)

All of these parts will be stuffed into a modified & braced 1980 GS750 frame with modern, upside down GSXR750 front forks, and a braced JCM rear swingarm.

I’ve been instructed to go with a 14T (front) / 43T (rear) set up if I want more top end (which is what I want) without losing all of the upfront & midrange punch.

Again, the wheels are the stock 17” units, 180 (rear) / 120 (front)

All of the charts I’ve seen online put the 14T / 43T set up at a ratio of 3.07

The stock set up of 15T front / 48T rear gives it a ratio of 3.20

These ratio numbers mean nothing to me and despite all of the videos I've watched and articles I've read, my thick head still doesn't get it.

 

It’s very simple:

Is the 14T / 43T setup the best in terms of getting good top end (over stock) without losing too much of the lower end and midrange punch  

(in other words, is it a good compromise)

 

                                                                                                                      As always, thanks in advance.......

 

 

 

 

Google gearing comander

Put all the details in, and play about with sprocket sizes. Will give you all the info you need 

[dupersunc]

3 hours ago, Gixer1460 said:

The bigger the number = the lower the overall ratio and lower top speed and slower accelleration (unless you have excessive power!)

The smaller the number = the higher the overall ratio and higher the top speed and faster accelleration.

There is always a compromise between accell. and top speed!

BTW for best / longest chain life the front sprocket should be as big as possible - chains don't like 'tiny' diameter sprockets!

Way to confuse the bloke even further. 

Ignore that ^^^^ it's incorrect.

Gear for high top speed= slower acceleration

Gear for Lower top speed= faster acceleration

 

Simply.  Stock Gsxr1100 gearing 15-48  is good for a genuine 160mph, with a tail wind and stock aero, and a very, very  long straight. 

Your proposed gearing is theoretically good for 168mph.  

a Gs750 with a stock Gsxr motor won't pull 168mph.  aero drag will stop you before you run out of revs.

go with stock gearing

 

[bluedog59]

Erm, I think you may have got a little muddled re acceleration.

The smaller number (3.07) will give a higher, theoretical top speed but acceleration will suffer.

The larger number (3.20) will have the opposite effects.

What gearing to run is down to want you want out of your bike/riding.

What type of riding do you spend of your time doing ? Motorways ? Town ? Playing on fast, back lanes ? Are you bothered about MPG ?

The Factories tend to know what they are doing so I would stay off as close to stock overall as you can get and tailor it to suit yourself from there.

[TonyGee]

i think starting somewhere near stock and then experiment with other sprockets, fronts are pretty cheap, its what i do. 

[Neveragain55]

7 hours ago, Gixer1460 said:

BTW for best / longest chain life the front sprocket should be as big as possible - chains don't like 'tiny' diameter sprockets!

I've seen that comment about "chains not liking small sprockets" and have heard guys saying it on YouTube all day today, Jesus you guys really know your stuff.......

[Neveragain55]

4 hours ago, MeanBean49 said:

Google gearing comander

Put all the details in, and play about with sprocket sizes. Will give you all the info you need 

Found that site, put the info in........................confused the hell out of me......

 

I'll go back in tomorrow after a good nights rest, thanks for the reply.

[Neveragain55]

4 hours ago, dupersunc said:

Way to confuse the bloke even further. 

Ignore that ^^^^ it's incorrect.

Gear for high top speed= slower acceleration

Gear for Lower top speed= faster acceleration

 

Simply.  Stock Gsxr1100 gearing 15-48  is good for a genuine 160mph, with a tail wind and stock aero, and a very, very  long straight. 

Your proposed gearing is theoretically good for 168mph.  

a Gs750 with a stock Gsxr motor won't pull 168mph.  aero drag will stop you before you run out of revs.

go with stock gearing

 

I actually thought about that, I thought "does any of this really matter anyway because this bike is going to be un-faired and the drag will probably never allow the bike to reach the speeds a faired bike would reach".

The motor isn't stock though, she's been punched out and she has an 1186 piston kit.

My mechanic say's the engine should be pumping out roughly 170 horses, if not a little more.

We'll dyno her when she's completely assembled, and I'll report back to let you know just how much she's really putting out.

[Neveragain55]

4 hours ago, bluedog59 said:

Erm, I think you may have got a little muddled re acceleration.

The smaller number (3.07) will give a higher, theoretical top speed but acceleration will suffer.

The larger number (3.20) will have the opposite effects.

What gearing to run is down to want you want out of your bike/riding.

What type of riding do you spend of your time doing ? Motorways ? Town ? Playing on fast, back lanes ? Are you bothered about MPG ?

The Factories tend to know what they are doing so I would stay off as close to stock overall as you can get and tailor it to suit yourself from there.

All excellent points....

 

I'm basically a weekend warrior, and my thing is going stupid fast on long straights....

The problem is, I also love jetting past slowpokes and I don't want my midrange punch (that I would need to pass & merger with) to vanish in an attempt to gain more speed on the top end.

After reading all of your replies I'm definitely getting educated, thanks.....

[Neveragain55]

4 hours ago, TonyGee said:

i think starting somewhere near stock and then experiment with other sprockets, fronts are pretty cheap, its what i do. 

Not a bad idea........thanks...

[MeanBean49]

4 hours ago, Neveragain55 said:

I actually thought about that, I thought "does any of this really matter anyway because this bike is going to be un-faired and the drag will probably never allow the bike to reach the speeds a faired bike would reach".

The motor isn't stock though, she's been punched out and she has an 1186 piston kit.

My mechanic say's the engine should be pumping out roughly 170 horses, if not a little more.

We'll dyno her when she's completely assembled, and I'll report back to let you know just how much she's really putting out.

Your mechanic sound extremely optimistic, or talking crank figures.

[Dezza]

Stick with stock GSXR gearing if the chain doesn't foul on anything. The increase in power from the engine mods will be offset by the GS 750 being about as aerodynamic as a VW hippy bus.

[Gixer1460]

7 hours ago, Neveragain55 said:

 

The motor isn't stock though, she's been punched out and she has an 1186 piston kit.

My mechanic say's the engine should be pumping out roughly 170 horses, if not a little more.

Possibly optimistic! I had a 1186 kit, 12.5:1 CR, DJ36 cv's and a V&H 4-2-1 Supersport system, made 144 RWHP on 3 different dynos and fitted in a Z1000J, no fairing and flat bars and ran to about 155 mph (about as fast as I could hang on!) That used 15 / 45 gearing FYI.

[Neveragain55]

2 hours ago, Dezza said:

Stick with stock GSXR gearing if the chain doesn't foul on anything. The increase in power from the engine mods will be offset by the GS 750 being about as aerodynamic as a VW hippy bus.

True.......but she'll be the prettiest girl at Woodstock......

[Neveragain55]

2 hours ago, Gixer1460 said:

Possibly optimistic! I had a 1186 kit, 12.5:1 CR, DJ36 cv's and a V&H 4-2-1 Supersport system, made 144 RWHP on 3 different dynos and fitted in a Z1000J, no fairing and flat bars and ran to about 155 mph (about as fast as I could hang on!) That used 15 / 45 gearing FYI.

Understood, for whatever its worth this guy has been building race bikes (specifically big bore Suzuki race bikes) for about 30 years, and raced professionally all over the US. He took many trophy's home and still to this day has pro's calling him up asking for pointers & tips.

Click on the link and search for Lewis Jolly:

https://www.theautochannel.com/news/date/19980711/news014450.html

There were some other mods he did to the engine other than just the kit , and I'm not engine-tech savy enough to know exactly what he did, but every time we talk about the bike he keeps telling me to be prepared for something a hell of a lot more than what I think. (whatever that means)

I promise to post the dyno numbers once she's done which will hopefully be later on this year towards the end of the summer. 

Thanks for all the advice on the sprockets.....

 

Edited February 12, 2021 by Neveragain55

[MeanBean49]

2 hours ago, Neveragain55 said:

Understood, for whatever its worth this guy has been building race bikes (specifically big bore Suzuki race bikes) for about 30 years, and raced professionally all over the US. He took many trophy's home and still to this day has pro's calling him up asking for pointers & tips.

Click on the link and search for Lewis Jolly:

https://www.theautochannel.com/news/date/19980711/news014450.html

There were some other mods he did to the engine other than just the kit , and I'm not engine-tech savy enough to know exactly what he did, but every time we talk about the bike he keeps telling me to be prepared for something a hell of a lot more than what I think. (whatever that means)

I promise to post the dyno numbers once she's done which will hopefully be later on this year towards the end of the summer. 

Thanks for all the advice on the sprockets.....

 

That explains it, they are Merican horses, always seem to need 20/30 more of them than in the UK for the same spec of motor.

[dupersunc]

7 hours ago, Neveragain55 said:

Understood, for whatever its worth this guy has been building race bikes (specifically big bore Suzuki race bikes) for about 30 years, and raced professionally all over the US. He took many trophy's home and still to this day has pro's calling him up asking for pointers & tips.

Click on the link and search for Lewis Jolly:

https://www.theautochannel.com/news/date/19980711/news014450.html

There were some other mods he did to the engine other than just the kit , and I'm not engine-tech savy enough to know exactly what he did, but every time we talk about the bike he keeps telling me to be prepared for something a hell of a lot more than what I think. (whatever that means)

I promise to post the dyno numbers once she's done which will hopefully be later on this year towards the end of the summer. 

Thanks for all the advice on the sprockets.....

 

Does he know anything about gearing?

[Neveragain55]

4 hours ago, dupersunc said:

Does he know anything about gearing?

Absolutely, and point well taken, and yes......he's the same cat that advised the 14T / 43T split from the stock 15T / 48T if I'm looking for more top end.

He actually got those numbers from a gear ratio chart in his office, but he did explain to me how I would loose some torque on the bottom end by going with those sprockets, and possibly through the midrange. 

We've got quite a ways to go before we get to the part where new sprockets need to be purchased so I figure I'd pick the brains of guys that modify these things constantly for a second, third, fourth, fifth opinion......

I'm a big believer in gathering many opinions on subjects before I pull the trigger.

Honestly after reading all of the replies, and thinking logically about how fast this bike will go, how I ride, where I ride, and what she'll be able to do "real-world" once she's finished, I'm starting to think that maybe Deeza is right......................just leave the stock gearing alone.

Naked bikes naturally "feel" like they're going much faster than they really are due to the fact that they're un-faired, and putting this monster of a motor in a truly Old-School frame is going to be mind blowing enough as it is.

Still not sure........but thanks for the reply.

 

 

 

Edited February 13, 2021 by Neveragain55

[Neveragain55]

10 hours ago, MeanBean49 said:

That explains it, they are Merican horses, always seem to need 20/30 more of them than in the UK for the same spec of motor.

Max horse power from a 1989 GSXR1100 was 143hp @ 9500 rpm (US spec)

Max horsepower from a 1988 GSXR1100 was 125hp @ 9500 rpm (UK spec)

 

Just found this tonight.......never realized, it sucks on a million levels, and it's incredibly unfair.

 

On the other hand, Suzuki, in their infinite wisdom decided "not" to sell this bike here in the states:

 

Our loss, so I'd say..........we loose.

 

 

Edited February 13, 2021 by Neveragain55

[MeanBean49]

5 hours ago, Neveragain55 said:

Max horse power from a 1989 GSXR1100 was 143hp @ 9500 rpm (US spec)

Max horsepower from a 1988 GSXR1100 was 125hp @ 9500 rpm (UK spec)

 

Just found this tonight.......never realized, it sucks on a million levels, and it's incredibly unfair.

 

On the other hand, Suzuki, in their infinite wisdom decided "not" to sell this bike here in the states:

 

Our loss, so I'd say..........we loose.

 

 

Dont believe everything google tells you.

The power figures quoted back in those days were wildly optimistic at best. 

Everywhere got the same spec engine and if anything the US were lower powered sometimes because of extra emissions stuff.

My point was whenever you look at Dyno figures they generally seem to give higher readings for the same spec of bike in the US for sone reason, possibly using different correction factors or crank figures.

Its not like theres some hidden magic tuning secrets the UK doesnt know about. Not that it matters, its just a number on a bit of paper

[Dezza]

1988= slabby (J); 1989= slingshot (K). Slingshot has an updated larger capacity engine and a completely different chassis that added mucho kg and by comparison handles like a supermarket shopping trolley on rollerskates. A GSX1400 is not OSS.

[Neveragain55]

8 hours ago, MeanBean49 said:

Dont believe everything google tells you.

The power figures quoted back in those days were wildly optimistic at best. 

Everywhere got the same spec engine and if anything the US were lower powered sometimes because of extra emissions stuff.

My point was whenever you look at Dyno figures they generally seem to give higher readings for the same spec of bike in the US for sone reason, possibly using different correction factors or crank figures.

Its not like theres some hidden magic tuning secrets the UK doesnt know about. Not that it matters, its just a number on a bit of paper

 

Understood......

Honestly it did seem odd to me when I saw those figures last night on various sites.

Splitting hairs with horsepower number isn't my bag though.

Going from a 750cc motor up to damn near 1200cc's is more than enough for me, regardless of the horse power output.

I will post the ultimate numbers whenever she gets done along with a full write up within a build thread.

Thanks again for the replies....

 

 

[Neveragain55]

6 hours ago, Dezza said:

1988= slabby (J); 1989= slingshot (K). Slingshot has an updated larger capacity engine and a completely different chassis that added mucho kg and by comparison handles like a supermarket shopping trolley on rollerskates. A GSX1400 is not OSS.

She may not be Old School but she "looks" the part, and she's awfully pretty. (in my opinion)

I actually started out wanting to get a Kawasaki ZRX1200R, but when I compared the specs (and looks) of that bike compared to the GSX1400, I thought, I'll just stick with Suzuki. (brand loyalty)

Then I found out that they're not sold here, and that's when I got the idea to just build a beast.

I came across Spikes thread in here purely by chance where he built this:

 

 

And I decided I had to have something similar (if not exactly) like this.

 

 

[clivegto]

I am going to use 14/43 on one of my bikes with a big bore kit. According to gear commander with my set up speed will be 141mph at 8500 revs, so I recon top speed will be about 146mph.