motorcycle cc question

[jsoceanlord]

I've got a 1979 Suzuki GS1000 GT (L).

It seems to me a 500 cc bike would be better on gas mileage, etc. What's the advantage of all that extra power ? does it help on long trips ? with two people ? going up hills ? It seems like I just use a fraction of the available power on a regular basis. thanks

 

[avbug]

You're correct that for a given rpm, a bigger engine displacement uses more fuel. However, a smaller engine needs to work harder (turn faster, in most cases) to accomplish the same thing a bigger engine must accomplish.

A 500 will get you by, but a bigger bike is better for road trips. In my opinion, if you're going very far, a 750 ought to be about the minimum. Above 1,000 cc is better.

 

[DC9stick]

I've had a Honda 400 for several years it's great for around town but will beat you to death above about 50. I bought a Kawasaki Vulcan 800 V-twin cruiser about three years ago, It's great solo and cruises the highway OK but just doesen't have the comfort zone when riding two up. I just bought a Yamaha Venture (1300) in Dec. and with the weather and work schedule have only been able to ride a couple of times but it's the cats meow when it comes to cruising two up, It doesen't seem to know the other person is onboard. It is also well faired and is comfortable to ride on a little bit cooler days. It's a case of how much horsepower it takes to move a certain mass, A 100 hp engine using 50 HP will burn the same amount of fuel as a 50 HP engine using 50 HP. The 100HP engine will run smoother and last longer.

 

[DoinTime]

In general a smaller displacement bike will have greater fuel economy and lower maintenance costs (due to their more simplistic components). For the vast majority of peoples needs even the smallest of street bikes engines give adequate performance but the penalty is limited top end performance (the illegal side of the performance envelope), poorer ride quality, and less loading flexibility.

Bigger, more powerful motorbikes have the same appeal to people as bigger more powerful automobiles. If you have the extra cash to shell out a more powerful bike will probably be more pleasurable to ride. Nothing puts a bigger smile on my face than riding a wheelie through 120 mph. Try doing that on your 500cc ride!!!

 

[Flyin Tony]

The good old GSXR

This is a little off the post. My dad just built a sandrail with a GSXR 1300 Hybusta ( think thats how its spelled ). The thing is so fast. pushes 180-200 hp. But the chain keeps bustin, water pump, and a bunch of other stuff gets wiped out. Think god for EBAY.

 

[A Squared]

A 100 hp engine using 50 HP will burn the same amount of fuel as a 50 HP engine using 50 HP.

This is not true. There's a variety of reasons but here's 2;

Brake Specific Fuel Consumption is, in part, a function of compression ratio. The more you squeeze, the more efficient the engine (to a point). A larger engine operating with a partially closed throttle will be running at a lower effective compression ratio and will be less efficient.

Internal Friction. As much as 10% of a reciprocating engine's power may be lost due to friction. Obviously, a larger engine will have more internal friction than a smaller one with fewer/smaller cylinders. In round numbers, a 100 hp engine might have to generate 60 hp internally to have 50 hp available at the shaft, while as 50 hp engine might only have to develop 55 internally to have 50 hp optput.

 

[RJPilott]

I get 35-45 mpg on my Harley with stock CV carb and mod pipes. Its 1450cc. I expect to get a little better mpg when i switch to a Mikuni 42mm carb and cleaner. I never really thought about power reduction when riding two up or hills etc. Never noticed a difference i guess, But then again, i dont have a Yamaha or Kawasaki

 

[FN FAL]

If you're going to drive a liter bike, you are going to have to expect liter bike gas milage.

I drive an '81 1100 CC Honda CBX 6 cylinder, 6 carburator, 24 valve, dual overhead cam motorcycle for fun, not gas economy. I don't get much more than 120 miles on a tank before I have to switch the valve to get to the reserve fuel. I think that's about 5 gallons, if that helps out. I had no problems keeping up with a modified GSX 1100 off the line with my stock bike.

 

[avbug]

1982 Yamaha XJ750.

I like rice.

 

[FN FAL]

I bet your 750 is fast...is that a 2, 3, or 4 cylinder engine?