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Discussion Starter #1
Years ago I rode a Honda CB350 which produced low to mid-30's HP. Why does a KLR650 with an additional 300 cc's produce about the same HP?
I'm sure this is a stupid question, but it's the only kind I've got.
 

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I'm pretty certain that your CB350 was a twin cylinder, correct?
One would expect a twin to have higher HP and a higher Red-Line, but with less over-all torque and possibly even a spike in both of its HP & Torque curves when plotted on a graph , compared to the 300cc larger single cylinder.

Part of it is the state of tuning for the engines intended purposes. Regardless of single vs twin cylinder design.
 

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Besides an extra cylinder, your CB350 had higher compression, probably larger-area valves (than a KLR650), a camshaft with higher lift/duration/overlap than the KLR's, and . . . quite possibly, a 180-degree crankshaft (insuring a constant air-volume crankcase, not pumping in and out whole displacement with each crankshaft revolution, as does a single-cylinder engine). Add to that, the higher rpm (as pdwestman says). So . . . the CB350 can process more fuel per unit time than a KLR650, cc of displacement to cc of displacement.

Not that a single can't develop horsepower; KTM690 (with only 690 cc displacement) produces nearly 70 maximum horsepower (maybe, measured at the crankshaft, not the rear wheel).
 

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My son's ZX6R produces 123hp from 15 less cc's ....but it peaks at 14,000 rpm. All that to say that the engine's design and design goals play a bigger part than the displacement does.

Sure the KLR isn't a hp leader, but it is torquey, runs on crap fuel and can last forever.

Dave
 

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Since I bought my '08 KLR new it gets parked next to my 1972 Honda CL350 which currently has 6k miles. The engine is essentially identical to the CB350, displacing 325cc.

The Honda is remarkable for a 1968 design but its character is very different from a KLR. The power starts at 4000 RPM and the quoted HP peak is somewhere closer to 9000 RPM. As tough as it was in its day that engine can't touch the durability of the KLR engine. They were prone to cam bearing seizure and by 20,000 miles usually needed a top end refresh.

The KLR is more like a lawn tractor and I mean that in the best way possible. It's torque that gets you where you're going, not horsepower.
 

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Since I bought my '08 KLR new it gets parked next to my 1972 Honda CL350 which currently has 6k miles. The engine is essentially identical to the CB350, displacing 325cc.

The Honda is remarkable for a 1968 design but its character is very different from a KLR. The power starts at 4000 RPM and the quoted HP peak is somewhere closer to 9000 RPM. As tough as it was in its day that engine can't touch the durability of the KLR engine. They were prone to cam bearing seizure and by 20,000 miles usually needed a top end refresh.

The KLR is more like a lawn tractor and I mean that in the best way possible. It's torque that gets you where you're going, not horsepower.
Did the CB / CL 350 engines have an external oil pipe feeding the camshafts? If so, maybe their banjo bolt oil feed holes were too small.

It is still a small miracle to me and others how my 1987 KLR650 cams & transmission managed to survive with the already very small 1st oil feed hole restricted to about 1/2!
 

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Did the CB / CL 350 engines have an external oil pipe feeding the camshafts? If so, maybe their banjo bolt oil feed holes were too small.

It is still a small miracle to me and others how my 1987 KLR650 cams & transmission managed to survive with the already very small 1st oil feed hole restricted to about 1/2!
The CB/CL/SL350 oil passages are all internal. The Achilles heel of the engine is the archaic piston and check ball oil pump which is driven off of the rear of the clutch basket once per revolution. The centrifugal oil filter worked well enough except few owners knew it was there and fewer still bothered cleaning it.

We also have to keep in mind that those old engines came with fat pre-EPA jetting, a luxury the KLR never had in stock form. My KLR gets 53mpg on average. The puny 350 gets only 50.
 

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Discussion Starter #9
At the time I thought I was asking a "simple" question. Further research on torque/HP has given me a headache. Thanks for all of the input...
 

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My poor CB350. The rear fender was half-cracked through, the frame was cracked in at least three spots, and the pipes were Rockies (with the inserts held in place with split rings) because I had beaten the originals to death. It was ridden off-road a fair bit because back then there were 'motorcycles' which were largely divided between 'street legal' and 'dirt' bikes. The CL kinda sorta bridged the gap, but if you didn't have one you didn't stop just because the pavement ended. Not if there were fish to catch.

What killed it, though, was the cams.

 
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Discussion Starter #12
Wow Tom, major CB350 nastalgia for me. Not sure if I even have a picture but it would look much like yours.
I remember taking mine off-road in the desert east of San Diego. Worked great except in deep sand - the pipes caused too much drag and the tires were useless. Even so it worked (kinda, sorta, maybe). A CL350 would've helped....
The CB350 got me through the oil embargo too, when gas hit 50 or 75 cents a gallon (up from 25 cents).
 

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When the CB died I replaced it with a CL175. When I got in trouble with it I could just stand up and let it go. Got good mileage, though. I rode that for a while and then got a CX500 Deluxe with color-matched Windjammer and Samsonite bags.

The Windjammer had an AM/FM/cassette deck in it. Disco fever, man, disco fever.

@DPelletier's CM looks to be about the same vintage as the CX was.

My first motorcycle was an AMF Sportster. 'AMF' stood for "Awwww, Mother****er! more shit fell off!"
 

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You were tall enough to make that bike look 'small', Tom.

My Junior High basketball coach who is about 7'2" used to ride a CB450 in his High School / College years! :)
 

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The amazing thing was that we used to ride things like that all over the place for hundreds of miles a day with jeans, a levi jacket, 3/4 helmet, work gloves, cowboy boots and we never got sore butts, never got hot or cold, never got tired. We'd stick a hot dog behind the cylinder and have it for lunch. We'd drink from a stream and never got sick.

What the hell happened to us?
 

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Discussion Starter #16
TIME! Hey Tom - a question for you since you had essentially the same 350 as I did many years ago. My bike didn't come with an owners manual and google was just a number in those days.
I too lived in SoCal at the time so it rarely got cold. I've been trying to figure if it's my "sometimers ailment" or what. I know where the choke is located but I don't recall having to use the choke to start the engine on my CB350. The electric starter never worked but neither do I remember it being difficult to start. Give me the bad news; have I completely lost my mind or did I keep it so impeccably tuned that it didn't matter? Neither will surprise me.
 

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I lived mostly in San Luis Obispo at the time and remember needing to use the choke.
 

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TIME! Hey Tom - a question for you since you had essentially the same 350 as I did many years ago. My bike didn't come with an owners manual and google was just a number in those days.
I too lived in SoCal at the time so it rarely got cold. I've been trying to figure if it's my "sometimers ailment" or what. I know where the choke is located but I don't recall having to use the choke to start the engine on my CB350. The electric starter never worked but neither do I remember it being difficult to start. Give me the bad news; have I completely lost my mind or did I keep it so impeccably tuned that it didn't matter? Neither will surprise me.
If the float bowl fuel LEVEL were on the high side and the carbs were prone to dribble on the ground when parked with the kickstand on the 'wrong side' of a slope, it would not surprize me for it to start in that climate with 'No Choke'.

A high fuel level can be quicker to react to throttle position changes. But one may need to ensure that the fuel valve turns OFF (or is manually turned off) when parked.
 

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The amazing thing was that we used to ride things like that all over the place for hundreds of miles a day with jeans, a levi jacket, 3/4 helmet, work gloves, cowboy boots and we never got sore butts, never got hot or cold, never got tired. We'd stick a hot dog behind the cylinder and have it for lunch. We'd drink from a stream and never got sick.
Even . . . drink from muddy hoof prints or tire ruts!

:)
 
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