Most efficient RPM - Stromtrooper Forum : Suzuki V-Strom Motorcycle Forums
DL1000A - 2014-2016 DL1000A - 2014-2016 (L4-L6)

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post #1 of 7 Old 05-19-2017, 01:03 AM Thread Starter
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Most efficient RPM

So, here's my rather rambling question:

I did the front sprocket change, going down a tooth, which was a good decision based on the type of riding I do. However, I have some thoughts, and would enjoy hearing others thoughts.

First, I was a bit surprised by how much it increased RPM at any given road speed. I had read it would be an increase of 300 RPM, but seems more to me. But I don't take a very scientific approach to these things. Anyway, it seems like I'm spending more time running my motor around 4500 RPM. Before, I would run it closer to 4000, even less, and rarely got above 5000 before shifting. Now I'm regularly hitting 6000 before shifting. It certainly feels more sporty! And max HP is around 8k, is it not?

Now, I believe this motor makes peak torque at about 4500 RPM, so it would be good for the engine, and maximize "efficiency", to run it at that speed, no? Also, I've always believed a rule of thumb that one should keep the engine somewhere around the middle of the rev range for cruising, which for this engine just happens to be around 4500 RPM. So, all in all, it would seem to me that 4500 RPM would be the optimal engine speed, and that by changing my sprocket, in addition to better rideability for my conditions, I've also done my engine a favour by now keeping it in the optimal RPM range most of the time, whereas before, I was running it a bit below optimum. Does that make any sense??

I look forward to those brighter than I offering some analysis.

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post #2 of 7 Old 05-19-2017, 03:05 AM
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What is "optimum"?

There's at least three different "optimums" that you can define. Max HP, Max torque and lowest fuel consumption.

All this can be derived from the performance tables. But as far as lowest fuel consumption is concerned, this is generally achieved in the highest gear (lowest RPM) you can reach without the engine stumbling. The reason is that higher RPMs also lead to higher losses due to oil/water pumping, friction and such.

On my DL1000, when cruising I tend to shift up to the highest gear possible given my speed, using a minimum RPM of about 2500. If I need to accelerate, I just drop a gear or two for greater HP and torque. Cruising at 4500 sounds terribly wasteful to me.
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post #3 of 7 Old 05-19-2017, 06:29 AM
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Max torque is at 4,000 RPM on a stock DL1000A.

I find the stock gearing perfect for my needs, however I was interested in changing the countershaft sprocket to a 16T for better performance and I wondered what the effect would be on fuel consumption.

As an experiment, with the stock gearing I road a 36 km (22.4 mile) quiet section of freeway at 115 kph (71 mph) on the speedo, twice back to back.
The first time was in 6th gear (4,000rpm) and the second time was in 5th gear (4,400rpm). At this speed in 5th gear the engine revs less than 100 rpm faster than it would in 6th with a 16T sprocket.
The fuel consumption for the 6th gear run was at 23.8 kpl (56 US mpg)
Using 5th gear the consumption was 21.1 kpl (49.8 US mpg), so approx 12% more. That's enough for me not to change to a 16T.
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previously DL650K6
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post #4 of 7 Old 05-19-2017, 09:28 AM
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Cruising just below 4k RPM's will give you the best gas mileage, consumption goes up quickly beyond that. The 16T gives you better acceleration and works good in the dirt, but is not ideal for long highway riding except at slower speeds which may not be safe.
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post #5 of 7 Old 05-19-2017, 10:31 AM
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Quote:
Originally Posted by Bugzy View Post
Cruising just below 4k RPM's will give you the best gas mileage, consumption goes up quickly beyond that. The 16T gives you better acceleration and works good in the dirt, but is not ideal for long highway riding except at slower speeds which may not be safe.
You mean a 14T.....16T would suck in the dirt.

I have been running a 14T for about 14-15K now. It's great off road, sporty up to 70ish & after that it gets a bit buzzy and does not seem to have any more snap left on those hard passes up to 85+.

The Gearing Commander Website(awesome) shows 371 more RPM @ 70mph using the 14T over the stock 15T:
Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator

@ 70 I'm running 5561rpm, so I'm close to getting out of the torque range.

Blues, also with a 14T on, your speedo will be almost 9mph off @ 70(showing 61 on speedo), so make sure you use a gps or a phone app to verify your true speed.

'15 DL650XT
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Last edited by Motor7; 05-19-2017 at 10:38 AM.
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post #6 of 7 Old 05-19-2017, 11:35 AM
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Watch what forum we're in. A 16T front is smaller than the stock 1000's 17T and larger than the 650's stock 15T front. Methinks we've started to mix models here.
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post #7 of 7 Old 05-19-2017, 11:39 AM
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^ ahh yes, good point!

'15 DL650XT
"You do your own thing in your own time"
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