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Is this how your CL175 sounds on the road?

rortiz5

rortiz5

Well-known Member
Joined
Jun 8, 2020
Total Posts
93
Total likes
7
Location
Austin, TX
This is straight up ear porn. The sound of that exhaust is something special. I may be itching to work on my CL175 that’s been held captive in a garage for months now. I have a treasure chest of parts waiting for the first chance I get. Love the acoustics of these exhausts and how this rider seems to always be going for that redline.

 
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IF you re-watch and observe the tach, you'll see that the rider generally has the engine in the "sweet range" (7500 to 9K) when it is producing the sounds you so like......This is typical for the twins which rev happily....Also notice that even when driving more "civilized", the tach rarely is below 6K except during shifts....

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rortiz5 said:
You weren’t kidding!
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I never kid about Honda engines and their enjoyment of high rpm :) it's the truth and I've been fortunate enough to experience it since I was a teenager. The epitome of it IMO was my CBXs with Denco 6 into 6 pipes and the baffles removed. No sweeter sound has been made by an internal combustion engine in my lifetime, only wish I had a recording of it. During my ownership of 2 of them about 10 years apart (early '80s and early '90s), even the second one was well before cell phones were commonplace and the early phones would not have done the sound justice. So, keep the bike properly maintained and when you ride it, let it rip fully and enjoy the wonderful sound of high rpm horsepower production. Most engines Honda made during that era were, based on horsepower per liter, high performance machines with great rideability and low rpm manners when in proper tune.
 
I'm still getting used to the high rev idea on my CM450. I don't go much above 5,500, but I'm making progress.
 
Randall said:
I'm still getting used to the high rev idea on my CM450. I don't go much above 5,500, but I'm making progress.
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Typically, at 5500 RPM you are only using about 50 to 52% of the horsepower your engine's capable of, so essentially, your bike can be twice that powerful........
Please, just to experience it once, briefly run at 8 or 8.5k in fifth gear......(that's closer to peak output)....
It's good to better know/understand the limits of yourself and your machine.....
 
I'll give it a go at 8K in fifth. I would have thought that was a bad thing when I first got this bike earlier in the summer, but I'm learning.

66Sprint, incidentally, my CM450 came to me from the Kazim Shriners in Roanoke with less than 5K on it. Bone stock and shiny as new. Last registered in 1993, and probably the same oil in it from then. Probably the original rear tire, too.
 
Hard to tell if you are joking, but that was 5 months and 2,500 miles ago. I started right off with tires, chain and a couple of quick oil/filter changes. I have done quite a bit since then with the generous support of this forum.
 
Go ahead and spin it up, considering the low miles on the engine and the work you've done redline is fine. It will seem to flatten out after 9K.
This dyno sheet shows where the power is, not quite the same as yours since this is on the modified road bike engine but close enough
Dyno results small.jpeg.jpg
 
You have shown this before, and it is very interesting. Clearly shows HP increases with RPM up to about 9K, is this where redline is?

Couple of questions: Why does torque stay around 20 ft/lbs, when HP increases steadily. Aren't they the same?

And, how is all this measured? From the rear wheel? Shifting thru gears?
 
Randall said:
You have shown this before, and it is very interesting. Clearly shows HP increases with RPM up to about 9K, is this where redline is?

Couple of questions: Why does torque stay around 20 ft/lbs, when HP increases steadily. Aren't they the same?

And, how is all this measured? From the rear wheel? Shifting thru gears?
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Torque and horsepower are different but similar. I'll refer you to this article https://www.caranddriver.com/news/a15347872/horsepower-vs-torque-whats-the-difference/
A flat torque curve is preferential in that the engine maintains the same force to move the bike rather than rising to a peak and then falling off. The latter would mean you need to keep the rpm in the peak range at all times.
The dyno is reading the actual power from the rear wheel, I believe it's done in 4th gear which is the closest one to a 1:1 ratio rather than the lower gears which are under drive or 5th/6th which are overdrive gears.
Depending on year and model Honda marked the redline anywhere from 9,200 to 10,000 on the 450 engines and all the 400's I've seen are marked at 10,000. There's no difference in any of the 450 engines that would reduce the redline so using 10K as a redline is perfectly fine. I have my rev limiter set for 10,500 and have hit it more than a few times.
But as I mentioned the power does start to fall off after @9,000 so I would generally use that as a top rpm shift point for fastest accel.
 
Gadzooks! I spun it up today as suggested. I did some hopping around town, and made an effort to stay in 3rd gear or under. You guys weren't kidding, this 450 roars at 7 -8K, even with my ignition issues. Snappy! I was surprised how much power it had in third gear at 55-60 mph. Going over the bridge to Ft Myers I shifted into 4th at about 60 mph, and it lurched forward. What fun! I can't wait to see how it runs after I get my Ignitech module in this week!
 
Randall said:
Couple of questions: Why does torque stay around 20 ft/lbs, when HP increases steadily. Aren't they the same?
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The best explanation I have heard regarding HP/Torque is that Torque gives you acceleration and HP gives you speed. Alternately it has been said that folks buy HP but drive Torque.

Ergo Torque is what give you the kick in the back when you hit the throttle. Horsepower is what pushes the vehicle down the road at speed. - At least that is how I understand it.
 
Horsepower is simply a representation of the energy (power) required to move a weight, a distance, in a time frame.....
One HP equals the power required to move 550 pounds, one foot, in one second..... (or 55 pounds 10 feet in one second)
Our engines power output is related to engine rev speed, generally rising to a peak, and then tapering off somewhat afterwards....

In our bike's case, Torque is the expression of how that power is applied to initiate forward motion and continue to accelerate......

I can go a bit further into the explanation here, (Thanks Sir Issac Newton) but think it might be better to start another "66Sprint's Classroom" topic about it........
 
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