Are Side-by-Side Engines more Reliable than V-Twins?

[HYPERR]

Get the Blasphemer Gummi....

Not going after a "Blasphemiser", I just want to hear what he considers to be inherent limitations and why - that's all. Don't make mountains out of molehills, m'kay?

Well the 45 degree angle to start. No question this is an example of function following form. From a function standpoint, it is not the best angle. Far from it. The reason Harley continues to use it is becaus they(and their customers) feel it is the most aesthetically pleasing to the eye.

There are much more.....but I'm sure you know that.

In case you misunderstood me, this isn't a knock on Harley. Harley has the full know how and the technology to make a much more efficient engine if they wanted to. But it wouldn't look, sound, and feel like a Harley.

[Gummiente]

In case you misunderstood me, this isn't a knock on Harley.

I didn't think it was. King Robb, however, seems to be looking to make an issue out of it.

I'm just curious as to what you think the "inherent flaws" are and why. As for the 45 degree angle of the cylinders, it actually has nothing to do with function following form. If you trace the history of motorcycle engines back to the early 1900's, you'll find that narrow angled v-twins were a very popular motor for racing applications because they allowed a small but relatively powerful unit to be installed in a small frame. The drawback to the design is that it requires heavy flywheels to dampen the vibration from unequal firing pulses (modern fixes include the counterbalancer and rubber mount systems), thus restricting the RPM's. But the advantage is that it allows for lots of torque in the low to mid range - which is right where you want it when riding two up on a loaded, heavy motorcycle. It is not, however, the best design for a sport bike... but then we get into the whole apple vs oranges thing.

[king robb]

NAh I was just clowning. Try not to take me too serious...well as long as money and family aren't involved.

I mean really...how seriously can you take "get the Blasphemer"?

[bandit600]

Gummi, what's the recommended idle for Harleys? The reason I ask is because now that my new bike has a temp gauge (it's water cooled) I find myself paying attention to the engine temps when I'm stuck in traffic. I'm always suprised how quickly it climbs to 220F which is when the fan kicks on. Granted I don't have cooling fins on the block but I'm amazed how that little fan seems to keep everything under 225F even on 90F days.

Anyway, the recommended idle on my bike is 1200RPM. I would think the engine would put out less heat if running at a lower idle. From the sound of Harleys idling it "feels" like it's less than 1200RPM and I've never seen any Harleys stuck in traffic with me ever having to pull over due to overheating. Is it less of an issue because of the lower idle + the enormous surface area of the cooling fins?

I think my air / oil cooled bandit cooked itself once in a traffic jam during a 90F summer day but without a temp gauge I don't know how hot it got or if that was the real issue...

[Gummiente]

Gummi, what's the recommended idle for Harleys? The reason I ask is because now that my new bike has a temp gauge (it's water cooled) I find myself paying attention to the engine temps when I'm stuck in traffic.

The idle for most EFI Twin Cam motors is 1100 RPM. Any higher will cause it to overheat faster in stop and go traffic, any lower runs the risk of not maintaining sufficient oil pressure in the same scenario.

Your liquid cooled motor has a definite advantage in traffic jams, although you still need to keep an eye on the temp gauge. Air cooled motors like Harley's require air flowing over them to remove the combustion heat; when the bike is moving it's not a problem, but when idling even the large surface area of the cooling fins can only dissipate so much heat before overheating becomes a concern.

From what I've heard/seen/read about the overheating issue, it was mostly on the '06 and later touring bikes that had the hard lowers installed on the crash bars. Even then, the issue didn't appear until extended idling in 90F+ degree weather. This all came about because of increasingly stricter emissions regs, Harley had to set up the motors to run very lean - and consequently very hot - to pass EPA certification. I know that my '07 ran HOT in downtown traffic, hotter than my '04 FLHT did, so I had a Power Commander chip installed and slapped on a set of under seat heat deflectors. Much better now.

[storysunfolding]

220 is a pretty standard operating temp for best efficiency. Somewhere around there you're thermostat will open up and the liquid cooling can do it's magic. So no worries and go ride.

[bandit600]

Actually I think my thermostat starts allowing coolant to hit the radiator around 195F. 220F is about when it realizes crap not enough airflow over the radiator and kicks the fan on.

Storysunfolding, you have a DL1000 right? When you're cruising on the highway what's the temp your bike settles into? Mine's hovers around 190F +/- 5 degrees and I just changed out the coolant with the pre-mixed honda coolant.

I'm assuming since we have essentially the same engine with maybe some fueling, timing and cam differences yours would be a good comparison...

Thanks for the info Gummi. I made the mistake of trying to drive into Washington DC during Rolling Thunder last year and there were a LOT of Harleys idling in traffic everywhere and they seemed to be doing just fine and that was in the high to mid 80's... I'll never know what happened to my bandit, it was never the same after that day and I ended up just selling it at a discount...

[storysunfolding]

Nope a 650 with race cams and a heavier flywheel than the SV. However, mine just has bars for heat, not degrees.

[Superfly3176]

Reliability wise, they are equal. The big disadvantage of a vtwin is that the rear cylinder does ttend to run hotter due to a lack of airflow, but materials and designs overcome that. The new HD touring bikes have electronics that shut off the rear cylinder at a stop to keep things cooler.

That's not a disadvantage, thats a hand warmer in the winter!

[Lion_Lady]

I was wondering what people's experiences here are with Side-by-Side Engines vs. V-Twins? I've heard Side-by-Side mounted engines and single piston engines tend to be more reliable than V-Twins. Is this true? Are Side-by-Side Engines more Reliable than V-Twins?

You left out the "flat/opposed twins" ie boxer engines: BMW airheads, oilheads, hexheads, and Ural motorcycles.

P