Seca 750 HP

I just watched a 750 dyno at 62 hp. From the results around tonight the general consensus was that the numbers were a bit low.

Temp 20c
Bike maintance unknown, looked to be a stock pipe.

Just an FYI. The F4s all dyno'ed between 85 and 101 hp... again I'd more suspect those to be more like 90-105 real world hp (all with aftermarket pipes... my D&D, another D&D and a hindle)

 

Good to know, thanks Woot. Now we woon't be totaly guessing at the HP number.

 

There's the rear wheel hp and cranshaft hp yamahooza probably quotes crankshaft horsepower? a guess...

 

I'm not sure about it either - mine read lower than I expected... but then again mine didn't include the ram air effect of the airbox and I think was running pretty rich at wider throttle robbing a few ponies.

Who knows what state of tune? It ran fairly cleanly... but was stock as far as I could tell.

 

LoL yea man... this things are not powerhouses by anymeans... In fact 60 is a pretty good average number saying the compression ration on these things is very low....

 

The factory always rates horsepower at the crankshaft, not the wheel. So you have parasitic drivetrain loss, and shaft drives have more loss at the wheels than a chain drive model because of the extra rotating mass. Still though, it does seem a bit low. The widely accepted figure for loss through the drivetrain is about 10-15%, so if 86 is the factory rated crankshaft HP, then you would expect RWHP to be 73-77. But you've got all kinds of factors working against you with a 20+ year old bike. Carbs could have been off, compression might be down slightly, valves might not be adjusted perfectly, camshaft timing might have been off (due to loose chain).

85-101 sounds about right for an F4. Sounds like you had a fun day!

 

Here are the cbr's plots... I did them in excel after the fact.

without counting in ram... but I do see a few flat spots in the torque curve. hrm.

peak calculated tork of 38.
peak measured hp 85.2

 

One note about my 3rd gear top speed... with the sprocket change my speeds are reduced by about 14% - stock I should get to 160 something in 3rd gear.

 

Nice flat torque curve for a 600cc bike!! Never really done much studying of motorcycle dyno charts, so I don't know how it compares to others, just thought it was worth mentioning. Maybe that's why people love their CBR 600's so much!! :lol: 8)