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How to let GS to have higher rpm?

  • Thread starter Thread starter Addy Leung
  • Start date Start date
A

Addy Leung

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I did see a lot of different modification for getting more house power by cams, carbs, bigger valves, big bore kit and ignition system.
I have a question to my self how can I make our GS can safely to getting higher rpm as high as the modern bike, let say from our GS red line 9000rpm to the bandit 1200rpm.
Dose anyone hav any suggestion?
What I think is ? a higher rpm bike would have wider power band and we can let our GS have higher top end speed.
 
Addy Leung said:
I have a question to my self how can I make our GS can safely to getting higher rpm as high as the modern bike, let say from our GS red line 9000rpm to the bandit 1200rpm.
Dose anyone hav any suggestion?
What I think is – a higher rpm bike would have wider power band and we can let our GS have higher top end speed.
Click to expand...


Remove the drive chain and hold the throttle wide open? :)
 
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Whilst it is true that a roller bearing crank theoretically doesnt have a rev limit, pistons most certainly do. GS pistons; even aftermarket ones are "old tech" heavy and will not take 12 000 rpm. 10 000 would be an absolute limit IMNSHO.
Dink
 
Hi Dink, Thank you for your valueable information which i never think about and read through before.

Why JE and Weisco do not making some ligther pistons?
what else need to do for 10000 rpm?

I think it may need a varyable igintion timing control such that we can set different ignition timing at differnet rpm range, like the MSD-4.
Do you think so?

Addy
 
Holy throttle crap Batman - 9k puts my old GS1000 well over 200kph - if it goes any faster - I dont wanna be on it 8-[
 
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Yes, me too, I never go faster more than 170 KMH on my GS1100 and actually it can go furrhter and may be 200kmh.
however, I am very interested in getting my GS to be good enough to follow the modern bike on the road, like the R1 it can be very easy over 250kmh.
Although I dare not ride on it with its top speed but I will let someone dare ride on it over 250kmh.
 
The valve train needs to be lightened and made strong (fun material challenge) to run speeds that high. The cam chain needs to be beefed up, the crank balanced, connecting rods designed differently, lighter, strong, etc.

It's just one of those things that modern technology benefits from, whereas our GS and the aftermarket parts aren't there yet.

~Adam
 
It's just not really possible. Our pistons and connecting rods can't take that abuse, and they aren't designed for those RPM's... You'd have to change the compression as well, as to benefit of the beefier lowerer end. And even if you were to get 12k rpms safetly, your HP peak would still be around the factory redline.
 
If ultra-high top speed is your goal then a more modern bike is in order. By the time you get done modifying your engine to achieve those speeds you will have spent the equivalent of a new sportbike (or more) that will still outrun the GS. You simply can't expect machines designed 30+ years ago to do what a modern bike can do.
 
As was stated here, it can be done, but it's gonna' cost ya'. Pistons, rods, valves, springs, valve retainers, etc., etc.

A higher RPM doesn't necessarilly translate into a wider powerband. Typically, it has the opposite effect.

If you want higher speed, make more HP and gear it appropriately.
 
The 1157 bandit is tapped at 10,500 with GSXR cams. No need to go above that with a powerband that hits hard at 6500.

Forked screw adjuster rockers are not going to be up for much more than that anyway. Everything modern runs shim under bucket now for that reason.
 
If you want more rpm's then just upgrade the valve train. Cams that make power higher up in the rpm's, cam timing at 110 or higher, HD springs to prevent valve float and get the crank welded then cross your fingers.

I like to think my GS is like the tires on my SeaDoo trailer, they don't just wear out.... they just explode. That's why I have spare tire's, crank and cases.

I shift between 9.8K and 10.8K all the time. What's funny is the bike will run just as fast shifting at 9K. Remember the faster it turns the faster it wears. I don't mind tearing it apart every year.

What would scare me is diving into a tight corner with those oem wheels. A bandit would be a good choice or the 1K for the show-offs. But the first thing I'd do is put a 14T sprocket up front and see if I can get up to redline in 5 gear faster. Bang the gears and see what happens.

They will go fast, most prostock bikes are base off the GS anyways, 1428-1500 cc's 2 valve and 4 valve motors. The only differance is all the goodies inside the case's.
 
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yeah you dont need high rpm to make horsepower and to go fast, shoot... our bike we shift at 10,000 rpms and runs 7.30's @ over 180 all the time, the best has been 7.31@184, next time out should fall in the 20's with ease...richie
 
I think one of the biggest thing is to make sure the bike makes power up that high is a good cam thats degreed around 110/110. The second concern is that you don't float a valve when your spinning it that hard. You protect against that with TI retainer, stainless valves, and some good spring like the ape springs. If you really want to throw some money at it some flatslides, good pipe, and god ignition sure wouldn't hurt.

I think higher than 10,000 is pro-stock stuff. Heck my busa redlines at 10,800. The same place I got the rev limiter on my gs1100 set at.
 
I think the easiest and cheapest solution to more rpm's it to put in a GSX750R motor, my '90 redlined at 12.500, limiter at 13.500. \\:D/
 
robinjo said:
I think the easiest and cheapest solution to more rpm's it to put in a GSX750R motor, my '90 redlined at 12.500, limiter at 13.500. \\:D/
Click to expand...


And that was the re-configured long stroke 750 motor. Big bore muscle bikes don't need to go above 10,500. A mild 1157cc Bandit motor makes over 100bhp at 6500rpm. Not thats grunt.

Rev On, Ed.
1983 GS750ED
2005 GSF1200SZ
1992 900SS
 
Now, I see some key points here would help in getting higher rpm that they are need to have good balance on cranks, make moving parts lighter weight as possible, cams degree to 110/110, stronger valve springs and etc...

What are about the ignition timing? The stock on GS is mechanical advancer and it have 35 degree advance after 3500rpm and then all is same.
Do we need a programmable igintion unit to have more advance ignition timgin at higher rpm, let say after 8000rpm?

dose the modren bike have variable timing igintion control at different rmp?
 
Addy Leung said:
Now, I see some key points here would help in getting higher rpm that they are need to have good balance on cranks, make moving parts lighter weight as possible, cams degree to 110/110, stronger valve springs and etc...

What are about the ignition timing? The stock on GS is mechanical advancer and it have 35 degree advance after 3500rpm and then all is same.
Do we need a programmable igintion unit to have more advance ignition timgin at higher rpm, let say after 8000rpm?

dose the modren bike have variable timing igintion control at different rmp?
Click to expand...
You can always power time an engine. What you do is set your timing at maximum advance (whatever RPM that would be), instead of at idle. This way your advance is correct at the top end. After all, if you are racing, who cares about idle?

This is an old drag racing trick. Of course, to make power all the way through the RPM range of interest you need to have an advance mechanism, either mechanical or electronic.
 
Addy - trying to keep up with other riders is one of the things that causes a lot of deaths on the road - especially when it comes down to contests of top speed. Anybody can twist a throttle - it won't make you a better rider.


Appreciate your bike for what it is.



-Q!
 
Well.. the GS550 didn't buzz it's valves till 12k, and the motor has probally seen 13-14k. That's on a 60,000 mile set of valvesprings. And the motor survived.

There's a lot more to it than just "getting the motor to spin that fast". The bottom end components are pleanty strong. LIke it's been said it's the valvetrain you'd need to worry most about.

You won't see a broader powerband, but you may see more power. You will need new cams, you'll need to port it. You'll need bigger carbs. you'll need to re-enginer an exhaust to work with the higher rpms. You're looking at a massive project. All those things come togother to make a narrower powerband.

However, to address your questions. Those being wanting a wider powerband, higher top speed, and more horsepower? Those are all easily taken care off by changing the gearing of the bike, which will allow a higher theroetical top speed. You can use nitrous, a supercharger, or a turbocharger, to make the horsepower to use the new gearing. Turbochargers, and displacement superchargers all will widen the powerband as well. If you "do it" right. Centrifugal superchargers are a differnent story. As is nitrous.
 
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