Topic: What does your tach read at 60mph?

[BobbyR]

When cruising around town I usually choose a gear that will keep the tach at 4K. That is the beginning of the torque/power band for the 750. It allows good throttle response if needed to avoid something and good engine braking for general bike handling.

When getting on a high speed highway, I will usually stay in 3rd to merge into traffic quickly from the on ramp. This could be as high as 70 mph. Once in traffic I just double shift directly into 5th bypassing 4th and move on.

The 750 just loves to run at about 5000 at 70-75 mph and after a brisk ride at those engine speeds for a hour or so you will see how nice it runs afterward.

With frequent oil changes and maintaining your oil levels these motors can rev, they were made to rev. I do not run into the redline regularly, but brief bursts to 7K are not dramtic. 

We have become too accustomed to our cars which can cruise at low RPM s with their electronic 6 speed transmissions.

[MCRider]

I hang out in 5th

I like to keep the motor between 3500 and 5500rpms it seems to be nicer to the motor

If one studies Dyno Charts, you'll see virtually all Jap 4cylinders peak torque occurs at about 5600rpm. There is a reason for this, I have misplaced it. It has to do with engine capacity, piston speeds, Max hp ratios or some such. Nevertheless its true.

So you're range of 3500 to start and shift at the torque peak will be comfortable. Above 5600, torques falls off and horsepower builds. gas mileage falls off, things start to wear faster, gets more exciting, have to pay attention.

Also if you're cruising around town one may want to keep it near 5000 as that's the point from which one can launch evasive maneuvers more powerfully. Sitting near the torque peak.

Unless on highway, I'd cruise a 750 in town in 3rd or 4th wherever that magic 5600 puts me speed wise. Save 5th for the highway.

YMMV

Edit: I see Bobby has posted something similar, so its not just me. 

[BeSeeingYou]

These I-4's are meant to be revved up a wee bit. Heck they would barely stay charged if you guys keep the RPM's that low.

Most of my riding is in town with not too much time on the freeway.  We have lovely lake parkways, other heavily wooded parkways,  and the river road is a nice ride.  Probably spend most of the time at 3000-5000 rpm in 3rd or 4th gear.  Battery charging has not been an issue, have not touched it all summer.  But I will try and be better.   I have to overcome 30 years of riding my XS650 where the idea was to keep the rpm's down to keep my ass from getting numb.

[mlinder]

I hang out in 5th

I like to keep the motor between 3500 and 5500rpms it seems to be nicer to the motor

If one studies Dyno Charts, you'll see virtually all Jap 4cylinders peak torque occurs at about 5600rpm. There is a reason for this, I have misplaced it. It has to do with engine capacity, piston speeds, Max hp ratios or some such. Nevertheless its true.

So you're range of 3500 to start and shift at the torque peak will be comfortable. Above 5600, torques falls off and horsepower builds. gas mileage falls off, things start to wear faster, gets more exciting, have to pay attention.

Also if you're cruising around town one may want to keep it near 5000 as that's the point from which one can launch evasive maneuvers more powerfully. Sitting near the torque peak.

Unless on highway, I'd cruise a 750 in town in 3rd or 4th wherever that magic 5600 puts me speed wise. Save 5th for the highway.

YMMV

Edit: I see Bobby has posted something similar, so its not just me. 

These bikes do love to rev.
One caveat in your statement, though, mcrider. The torque and horsepower curves always cross at 5252 rpm. That's because 'torque' and 'horsepower' are just different ways of expressing the same value.

I've ridden these sohc4's at 7k+ for hours at a time without issue. You aren;t hurting them. You are actually keeping the combustion chamber and plugs adn valves cleaner by getting it all nice and hot for extended periods of time up there.

[MCRider]

I hang out in 5th

I like to keep the motor between 3500 and 5500rpms it seems to be nicer to the motor

If one studies Dyno Charts, you'll see virtually all Jap 4cylinders peak torque occurs at about 5600rpm. There is a reason for this, I have misplaced it. It has to do with engine capacity, piston speeds, Max hp ratios or some such. Nevertheless its true.

So you're range of 3500 to start and shift at the torque peak will be comfortable. Above 5600, torques falls off and horsepower builds. gas mileage falls off, things start to wear faster, gets more exciting, have to pay attention.

Also if you're cruising around town one may want to keep it near 5000 as that's the point from which one can launch evasive maneuvers more powerfully. Sitting near the torque peak.

Unless on highway, I'd cruise a 750 in town in 3rd or 4th wherever that magic 5600 puts me speed wise. Save 5th for the highway.

YMMV

Edit: I see Bobby has posted something similar, so its not just me.  

These bikes do love to rev.
One caveat in your statement, though, mcrider. The torque and horsepower curves always cross at 5252 rpm. That's because 'torque' and 'horsepower' are just different ways of expressing the same value.

I've ridden these sohc4's at 7k+ for hours at a time without issue. You aren;t hurting them. You are actually keeping the combustion chamber and plugs adn valves cleaner by getting it all nice and hot for extended periods of time up there.

No problem, I knew it was 5000+ but I couldn't remember exactly, thanks for the correction. As many here have posted that slightly plus 5000 range is the sweet spot.

I think those who lug the engine riding below 3500 are missing the experience.

[Industrial Cafe]

MCRider-
all the speed limits in my town are 45-65, (55 just about everywhere) which is why I'm in 5th@60 most of the time.
 
You're right, and I pretty much follow that general rule of thumb that you're talkin' about

[MCRider]

I read posts all the time where people say they things like "I hit 80 in third gear"

I was wondering where people shift when they are cruising. I usually keep my tach at around 3,000 rpms. When I'm doing 60 (or 70, according to my spedometer) my rpms are around 6,000. Seems like if I went 80 in third, my engine would explode.

What are your thoughts?
SNIP

Back to your original question, I don't know on a 550. This may help http://www.catherineandken.co.uk/sti/tyres.html

You'll have to look up your ratios in a manual. My Clymer had them for the CB750. remember the speedo error is likely 10% at mid speed.

There are many speed calculators on line, google "top speed calculator" you may find one more friendly.

If you've got a buddy with a GPS you can find the real question which is your speedo error. At indicated 60 you're likely going 54.  Or one of those speed traps that tells you how fast you're going.

[mlinder]

Approximate speeds at RPM for 550's:

[MCRider]

Approximate speeds at RPM for 550's:

Nice chart! Got one for a CB750 with 17/48 gearing?

Also,comments on clutch slippage? I've heard it can be as high as 5% near top end.

[mlinder]

Approximate speeds at RPM for 550's:

Nice chart! Got one for a CB750 with 17/48 gearing?

Also,comments on clutch slippage? I've heard it can be as high as 5% near top end.

This is close:

[IAmCitizenMe]

The 750 just loves to run at about 5000 at 70-75 mph and after a brisk ride at those engine speeds for a hour or so you will see how nice it runs afterward.

I love how clean and smooth my bike feels after a stretch on the highway. Feels like a brand new machine.

I think those who lug the engine riding below 3500 are missing the experience.

After I started reading your responses, I started hanging out in the 5K zone and what a difference! Much sweeter, indeed.



My clutch slips when my engine is cold. When it heats up, she runs like a dream. I think it has something to do with my friction plates, though.

[MCRider]

SNIP

My clutch slips when my engine is cold. When it heats up, she runs like a dream. I think it has something to do with my friction plates, though.

Unfortunately, they don't fix themselves.   
 It will get worse over time.  Don't miss an oil change, you'll be getting flakes of clutch in it.

[IAmCitizenMe]

Unfortunately, they don't fix themselves.   
It will get worse over time.  Don't miss an oil change, you'll be getting flakes of clutch in it.

Oh I know. I change my oil like it's a drug addiction. I'm getting to a first-name-basis with the folks at Auto Zone.

[MCRider]

Unfortunately, they don't fix themselves.   
It will get worse over time.  Don't miss an oil change, you'll be getting flakes of clutch in it.

Oh I know. I change my oil like it's a drug addiction. I'm getting to a first-name-basis with the folks at Auto Zone.

What oil do you use? .....













JUST KIDDING!   

[CBdave76]

Mine reads 3200 at 60 mph.  I changed the stock 48T rear sprocket to a 38T.  Bike is a CB750A (Automatic). Tach was an installed aftermarket.

[IAmCitizenMe]

hahaha. You're too funny. I just realized, however, that I never answered your question from the last thread. haha.
So I'll break the rules and answer it here.
I USED some oil my dad had in the garage. Naive as I was, I put it in my engine. Then when everyone on here looked at me like this  I put some castrol 4-stroke motorcycle oil in.

But I digress.

I just ordered some JT Sprox and a Diamond chain. New clutch kit after that. But even with the $h!tty chain and sprox and the slipping clutch, I'm still getting good speed/rpm from my baby. These bikes are so resilient. After a nuclear holocaust all that will be left will be cockroaches and Hondas.

[Industrial Cafe]

Mine reads 3200 at 60 mph.  I changed the stock 48T rear sprocket to a 38T.  Bike is a CB750A (Automatic). Tach was an installed aftermarket.

Good Lord! I bet that's a bear off the line!

[CBdave76]

Mine reads 3200 at 60 mph.  I changed the stock 48T rear sprocket to a 38T.  Bike is a CB750A (Automatic). Tach was an installed aftermarket.

Good Lord! I bet that's a bear off the line!

Bear! No, more like slooow motion.

[Industrial Cafe]

mine is like a monkey off the line. not amazingly fast but it's having fun doing it.

[IAmCitizenMe]

Mine kinda lurches a little bit when taking off in first gear. I don´t know why that is. But it´s got a little zip to it.

[Industrial Cafe]

lurches?

[IAmCitizenMe]

I knew someone was going to say something about that hahaha.