Thoughts on cruising RPMs?

[Andrew Vanis]

Got the 81 750L running well and was wondering today about RPMs at cruise. Seems I can be in 3rd or 5th at 55 no issues either way. What are ya'll thoughts on RPMs while cruising?

[Rob S.]

Cruise in top gear. Downshift for hills or passing.

[Andrew Vanis]

sure, but at what point are the RPMs too low. Yeah, I get when it starts to lug/surge its too low but is there another too low or at least lower than "optimum" what ever optimum means?

[Rob S.]

My guess is that as long as it's not lugging, the lower the revs, the less the wear and the better the gas mileage. I could be off, but not by much.

Of course, every bike, especially those ridden very conservatively, needs to stretch it's legs and get near redline occasionally. Keeps the innards clean.

[Steve]

Most GSes seem to work best between 1/2 and 2/3 of redline.

Your 750 is probably geared so 5000 RPM will get you between 65 and 70 MPH. No problems there.

In a lower-load situation, like in town, lower revs will work, but if you have to quickly apply throttle to avoid a situation, you simply will not have enough response and will have to downshift to get into a power range. The time it takes to downshift a gear or three just might be the same amount of time it would take you to get out of the situation. No need to cruise through town at 6-7000 RPM, but definitely keep it above 2000.

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[rphillips]

Kind'f related, why my 2000 Kawasaki ZRX1100 & my "99" & "05" Suzuki Bandit 1200's still have 5 spd., roughly direct dr. in 5th gear, transmissions, while the old mid "80"'s Suzuki & Kawasaki 550cc & 600cc bikes had 6 spd O/D transmissions. My newer bikes seem to need, & would be happier with a the taller O/D gearing, way better than those old 550 & 600cc bikes, that had absolutely no passing power, without down shifting a time or two. Why on earth do the more powerful 1100 & 1200 cc bikes of today still have the 5 spds., & why did the mfg's, back in the 80"s put the 6 spd. O/D's in the much weaker mid sized bikes, when the larger more powerful bikes were much more capable, & actually needed, in my opinion, a taller gear for cruising at a lower rpm. To me, it still doesn't make sense.

[Burque73]

My owner's manual states to shift at these intervals,

1st 0-12mph
2nd 12-19mph
3rd 19-25mph
4th 25-31mph
5th over 31mph

That seems too low to shift from 4th to 5th, especially merging onto the highway. Cruising at highway speeds, since my speedo is still wonky, I keep it around 5500 to 6k ish in 5th. 6500rpm's is around 80mph and fuel mileage suffers, but the engine doesn't seem to mind staying there.

[850 Combat]

Those are probably break-in numbers.

On my GS1000s and 1100, I like the feel of accellerating from 2000 or 2500 rpm. Some old roller bearing Porsches had early lower end bearing failures which were blamed on lugging. I figure if it pulls hard, its in its power band, and its OK. For cruising, bine tend to get a harmonic drone over 5500 rpm, so I tend to keep them under 75 or so to avoid that.

I don't think you are going to hurt it.

[Steve]

6500rpm's is around 80mph and fuel mileage suffers, ...

Yes, it is, and yes, it does.



.

[Andrew Vanis]

Yes, it is, and yes, it does.



.

Steve, have you reset the tripometer since 14,000 miles?

[Steve]

No, it's still climbing. Maybe not as quickly as I like, but it's not been reset.



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[81gs7501166]

Most jap air cooled inline 4s like 3-4K as a minimum cruise. I feel like even though they will pull lower than that, you might be doing some damage. My sohc cb750 doesn't charge the battery below 3.5K. They are ment to spin, not lug.

[tom203]

I'm lazy and often leave it 5th as I putter thru a 25 mph village zone ...rpms less than 2k and no signs of lugging as I exit. Charging stays above 13 volts even at idle .

[eil]

My rule of thumb when putting around town is that I generally pick the gear by dividing the MPH by 10. So 20-30 in second gear, 30-40 in 3rd, and so on.

Unless accelerating, as you do. And I try to accelerate a lot.