question on when to shift

[later_aligator]

I have a new-to-me '81 GS450T and I'm also a new rider.

When I up- or down- shift on a manual car, I listen to the engine and it's clear to me when to shift. On the bike, it's not so clear, in part because the previous owner put on rumble pipes that make the engine very loud.

On a car, the ideal engine speed is about 2000 rpms but a friend told me that a bike is more comfortable with it's engine revving at closer to 3000 or 4000 rpms.

So which is right? When should I be shifting? There's no information in my service manual about this, nor did my bike come with an owner's manual.

Thanks in advance.

[Steve]

For leisurely acelleration in town, 3-4,000 will work just fine.

If you are riding in a more ... er ... spirited manner, shift at the redline on the tach.

.

[koolaid_kid]

Small engines want to rev. From suzukicycles.org - "Engine type: Air-cooled 448 cc parallel twin, DOHC, 4 valves. 44 hp/ 9.500 rpm" meaning it reaches peak power at 9500 rpm. I'd try around the 5000 to 6000 rpm range and see what it feels like. Of course, I do prefer the spirited style of riding.
Look at http://www.suzukicycles.org/GS-serie...-S_specs.shtml for a bit of info on your bike.

[DanTheMan]

Also, a good clue as to whether you're up shifting too soon is if the bike feels like it's starting to buck. That will tell you you're lugging the engine down too hard and you need to be in a lower gear.

[doctorgonzo]

Mine is a 1000, but shifting at 4000 is a leisurely cruise around town, merging into traffic on the interstae I regularly shift at 9000. I've never pegged the tach, but I've reved it to 11,000 before.

[tkent02]

Short shifting small engines is not good for them, not efficient. Makes them run hotter, they have less oil flowing, less electricity being made for the charging system. It also seems to be a good idea that you at least know how much power it has. There is probably three times the acceleration at 8,000 as there is at 2,000. Take it up to the red line, feel the power come on. Just make it a days lesson to learn the engine's response, at all it's RPM ranges. After that you will probably have a better idea of when to be shifting. I know you are a beginner so be careful, find a good road without any cars. Go easy at first, it may surprise you what that 450 can do. You need to know what it can do before you get out with traffic. I had a friend with a Yamaha 750 triple when they first came out. He never wound it up, always shifted it early, he had no idea it got stronger with higher RPM. He also had no idea why I would outrun him easily on my GS550, and when we swapped bikes I would outrun him on his. I had to actually make him keep it in second gear and wind it all the way up. After that it was a little harder to outrun him. :-)

[Kerry]

When you're a new rider on a "new" old small-engined bike, it sometimes takes awhile to lose the fear that the thing will fly apart at high revs. It won't

On The Flame! (550), I never shift below 4,000 rpm, even when I am doing the most leisurely around-town cruising. For more spirited riding, 7-8,000 rpm shifts are the norm, with gusts a good deal higher...

The small engines really do like to rev. If you can get into that mindset, riding is a lot more fun and a lot healthier for the bike.

Good luck!

[Redman]

Hello again L A,
(no, I am not stalking you, am just available and interested. Home due to lack of work.)

About "what rpm to shift", or "what rpm to run at", some comments:

- If red line is 9500, then think of this:
4 or 5 thousand is only about 50% of redline.
And 6 or 7 thousand is only about 70% of redline. So engine can do that all you want.

- Like Tom tkent02 has said, More rpms is more torque and even more horsepower and is more available acceleration (acceleration, not just speed, acceleration). Run up the rpms to what ever acceleration you want for the situation. So that's how you decide how high to run up the rpms. Run rpms up to how ever much accleration you want. This is same concept as in shifting a car.

- Think of this: Is about the same question, but thinking of it from an other angle. You can go 40 mph in most every gear, right? And in each gear, going 40mph would be different rpms, right? So the answer to which gear to be in to go 40mph would be which ever gear that gives you the rpm you want for the acceleration you want.
And.... the answer to what rpm to run at is what ever rpm is needed for the acceleration you are going to want.

- How close you let yourself run up rpm to close to redline is just a matter of how close you want to watch it so dont go over redline (and you have lots of other things to watch for than just staring at tach, right?)


- Maximum horsepower is not necessarly right at redline, but is usally somewhere close, maybe 80 or 90%. The rpm redline is more based on the mechanics still working, stuff like the valves following the cams and boring stuff like that, or the mechanics not failing and things not breaking.

- As far as how low to let the rpms get;
There is a few concerns,
One is again how much accelleration is available. If you are trying to accelerate but want to accelerate more than it is, need to downshift to bring up rpms.
Another is too low of rpm (say, 1500) the charging isnt putting out much, so if run there for long time (miles and miles) may not be charging battery.
But the biggest concern is too low of rpm the oil pump isnt putting out enough for the engine to protect itself from putting any load strain on the engine, the oil pressure is what is holding the major metal parts apart form each other so ther is not metal to metal friction. This oil pressure too low condition from too low of rpm for the load is about the same rpm so low that cant accelerate at all and then engine chuggs and bucks and doesnt accelerate . So for both of those concerns, if rpm so low that have hard time accelrating (called "lugging"), need to downshift to get rpms back up. (nice of the engineers to make it that way so lugging is about same as not eneough oil pressure).
These are all the same as driving/shifting a car.
Another concern is that if low rpms (say 2500) that letting off the throttle more doesnt have much effect as far as engine braking (compression braking) to slow you down. You are letting off gas to slow down but it doesnt, so is a problem related to you controlling bike (not a problem with engine). So down shift before you get into that condition.

Hum, this reminds me of when I was teaching my daugher to drive a standard transmission. At one point she was real annoyed and said, "Quit trying to explain everything to me. I am not going to design a new car. I just want to drive this car. Just tell me what to do with these pedals and this lever."

Okay, short answer:
IF you are not trying to accelerate much, then running it up and shfting at 4 or 5 thousand should do you okay. If you are trying to accelerate more then run it up higher like maybe 7 or so.

.

[Turtleface]

When you're a new rider on a "new" old small-engined bike, it sometimes takes awhile to lose the fear that the thing will fly apart at high revs. It won't
Good luck!

THIS! You can even disregard the small-engine part. For the first month of riding my 1100, I thought the top end was always on the brink of disaster. Once I became accustomed to the noise, I started to shift at 5k instead of 3k, for "normal riding". Saw an increase in fuel mileage, which may be more related to increased smoothness on the throttle, and having the engine more wound out makes it easier for me to find the correct engine speed while shifting, resulting in an overall more enjoyable ride. Now, the top end sounds better to me when it's being pushed.