Your Honda is sick. If it's an indicated 70 mph then it's in reality about 65 or so. A good running 125 will do that. All fuel injected bikes cut the fuel at a certain RPM but the bike should be able to exceed 70 mph in third, wide open

Run some fuel injection cleaner through the bike, like Chevron Techron. Check that the air cleaner is clean. The gas tank may heave a fuel filter that is dirty, restricting fuel flow. Restricted fuel flow acts just like a governor.

Sam

 

I did a Google search. It seems a 750 Shadow does not have a top speed. So much for Google. I should have looked at the horsepower numbers.
45 should get you to 90 and maybe nudging 100 on Saturday night. Windage becomes a huge factor at around 90. If you are light and skinny and tuck in, you will go a bit faster. If you are wide and sitting up, you will go slower. The Shadows do not make a lot of power, but one review I read had it doing the quarter in under 13 seconds, which is reasonable.

Unkle Krusty

 

Hi,

by the way, the bike is located at 8038 masl.

Is this a typo, or do you really live near the peak of Mt. Everest? That would explain the lack of power.

 

I really do wish folks would tell us where they are. And I agree, if he really is 8038 meters above sea level. Well spotted.

Unkle Krusty

 

Honda shadow on the clouds

Hi sirs,

Thank you very much for your support giving me the answers I was looking for. I will check all the things Sam suggested. Sorry for not stating clearly that my Honda is located in a city in SouthAmerica located at 8083 masl...I will ask one more question please, I am planning to install cobra pipes plus a power commander...I guess since the bike is located in a such high altitude, the addition of a high flow air intake (cobra mostly) is a must, am I right?. Thank you for your help again
Regards,

Edward

 

Yes, if you are at such a high altitude, you will need to do everything you can to increase air flow to the engine. Elevation effects engines greatly.

 

Wait, the highest point/peak in South America is 7000 meters in Argentina. The highest city is about 5000 meters in Peru. Your living at 8000+ meters? Anyways your probably still high enough to cause power loss.

 

8038 feet gets him just above the top of most of the mountains in BC, which are around 7500.
Breathing for people is a problem at higher altitudes, and it is the same for engines. It is a problem for the bikes that race up Pikes Peak, and why the electric bike can compete so well. Supercharging, or blowers were the answer for the WW2 fighter planes. Read about the RR Merlin engine.
Fuel injection should adjust somewhat for the height above sea level.
Compression as measured in pounds pressure at the spark plug hole, decreases a few pounds per 1000 feet. You could expect a 16 to 25 pound drop, or more. Less pressure, less power, and slower top speed.

Unkle Krusty

 

Way back in 1970 I bought a new Honda CB-350. That bike would do 70 easily.
There is something wrong with that Shadow.
Oh yeah, 8000 masl? If that is "meters above sea level", you would be dead.
That would be 25000 feet above sea level, like being on top of Mount Everest.

 

So we are talking feet, not meters, right?

 

So far we do not know. Twice the OP has posted masl. I would like a place name. It tends to remove the guess work.

The photo at left was taken at 21 Windermere Crescent, Blockhouse Bay, Auckland NZ, in the early sixties. The frame colour is Tartan Red.
That part of BHB is about 300 feet above sea level. I am at 289 feet above sea level on my Island.

Unkle Krusty

 

Do you get nosebleeds at that high altitude Krusty. I am 39-41' above sea level depending on where I stand in the yard

 

I think the highest I have ever ridden a motorcycle at was last year through Bear Tooth Pass. About 10,500 feet above sea level.

The bike did fine and ran great. (Good stock EFI system)

 

I was just looking up the specs for a V50 Guzzi. While I was at it I looked up a VT750C Shadow Aero. 43hp at 5500. 44 pounds of torque in a bike that weighs 553 pounds and has a shaft drive. 90 tops IMO, down hill with a tail wind. Not surprised the OP is getting 70. At 8068 meters he is between the 11th and 12th highest mountains in the world. I looked that up earlier. But if it is 8068 feet, then I would think he should get maybe 80 to 85.
6000 feet is the highest I have been, and it gets darn chilly up there. I think I will stay in the lower nose bleed section at 289 feet.

Unkle Krusty

 

My Guzzi has 9 more HP, 4 less torque and is 100 pounds lighter. I've had it up to 95MPH passing a truck and I believe the top speed is 105MPHish, so I'm thinking 70MPH seems low, though I'm only at 1,000 feet above sea level.

 

I routinely went to the end of the Mount Whitney Portal in CA @ 8,360 feet above sea level, on motocross bikes and streetbikes. This paved road ends at the entrance to the Mount Whitney trail that leads to the summit @ 14,505 feet.

I've ridden and driven many times through the Eisenhower tunnel on Interstate 70 in Colorado, @ 11,158 feet.

I've also ridden and driven into Death Valley, CA and visited the lowest point in North America @ 282 feet below sea level.

85 miles separates The lowest land and the highest in CA, and is a great ride, when the weather is nice.

There is a 3% drop in HP for every 1,000 feet above sea level.

Sam

 

motorcyclespecs.co.za has specs on lots of bikes, and or a link to a place that does.
For many they have original test notes.

45 horsepower is about the average of the early Triumphs, BSA and Norton. These are the bikes that the Ton up guys rode. The Cafe racer style, came from these guys, who would meet at the Ace Cafe in London. The Triumph motor was the most hotted up. Many could do the ton, 100 mph, after mods. " Just For Kicks " is a song by Mike Sarne about these guys.
The air is a bit denser in the late evening, and often a bike would run a bit quicker then. Beer also helped. So the answer to a common question " How fast is your bike, or car ? " It does about 95 but will do the Ton on Saturday night.

Fast forward and a 400 twin like my twin OHC Yamaha and the 450 Suzuki were making 45hp. They too could do the ton. But be wary of the claimed numbers. They were done by young skinny guys in leathers, and tucked in. My XS400 does 92 WOT with a senior sitting upright, and a lot of other junk bolted on.

The 500 Guzzi I was reading about claimed 103 with 43 hp. I doubt it. My 68 Dunstall claimed 140 mph with about 55 hp. Not a chance. And so on.
Over the years the top average speed I have witnessed is about 90. What has changed, is now cruisers are doing it, rather than cafe racer types.

Unkle Krusty

 

https://www.google.com/url?sa=t&rct...eroVT750.htm&usg=AFQjCNH2eJNyHbhsQlnpl0NztzEr7i8M-Q&sig2=Uv7jrTQtXCUfdfmmZTl75g


PERFORMANCE
Fuel mileage: 31-34 mpg
Average range: 135 miles
0-60 mph time: 7.24 sec.
60-80 top gear acceleration: 8.48 sec.
Quarter-mile acceleration: 15.49 @ 83.28 mph
Read more at Honda Shadow Aero 750 Motorcycle Test | Motorcycle Cruiser

(1) Torque: 47.2 ft/lbs at 3000 RPM.

(2) Horsepower: 45 HP at 5000 RPM.

Sam:biggrin:

 

HI, I am very sorry for the mistake in the conversion....my city is about 2450 msal = 8038 feet above sea level..I apologize for this mistake

 

HI,

I apologize for this mistake, I meant 8038 feet above sea level...just 2450 masl


very sorry

 

Sirs,

Thank you very much for your answers. I apologize to all of you for the stupid mistake I made in the units, it is 2450 masl or 8038 feet above sea level.
Once again, thank you all
Regards,

Edward

 

No worries Edward. We figured it was feet.
Lots of places out West are that high. Bishop CA comes to mind.

Unkle Krusty

 

Even at 8038 ft, I would think it should do more than 70 MPH. No?

 

I would expect the fuel injection control system to be able to compensate for that much pressure change and keep the bike running well. I am thinking something is wrong with the air intake path. Maybe a partially plugged air cleaner?

 

Hi,

Thank you for your answer. I think I will install cobra pipes plus cobra FI2000R and cobra high flow air intake. All I want is not to be left way behind in the high way when travelling with my friends, so I will like to reach at least 80 mph

 

The FI will likely compensate for the reduced air density up there and the bike will continue to run fairly well, but you will not be making book HP.

 

I would highly, highly recommend finding out what is wrong before you start throwing parts at it.

 

My old 2008 Aero gets 52 mpg and easily does the "ton" (although I don't recommend trying to cruise at that speed as wind tosses the bike around quite a bit above 90).
I have regularly cruised at 80 - 85 mph on my aero have pushed it over a ton a couple of times while passing.
This bike can do 70 at the top end of 4th gear.
These bikes like to revved a bit more than you would expect.
At his altitude a hi-flow air filter is a must.