1979 GS 850 Horsepower?

[Sammy_1101]

Hi all,

Got a 1979 GS850 GN with pods and a 4 in to 1 and stubby muffler. Just got it running sweet and it absolutely flys. With 78 horsepower as stock, what sort of power would it have with these mods? Has anyone put theres on dyno with similar mods? And what power increase did you get?

Thanks

 

[sharpy]

so its got claimed 78 HP. with average pipe and pods be like 80 RL HP

 

[Steve]

Yep, advertised stock HP was 78, most likely measured at the crank. Depending on whether the carbs have been jetted and tuned for the pods and pipe, you might have anywhere from 75 to just over 80.

Yeah, you will have what SOUNDS like a lot more power, I'm not sure how much might have been added.

But to answer your question, there are probably not too many here that have actually put their bike on a dyno. Not just 850s, not many of ANY size.

.

 

[sharpy]

well i have and this thing was 105 at the back wheel, and lots of nice brand name parts installed

 

[Nessism]

78 at the crank means about 70 at the rear wheel. If the pipe is a good one and the carbs are tuned well that could add another 5-7% or so but hard to say. You could also wind up losing power.

 

[Steve]

Most of the tuning sites will tell you that a 4-into-1 pipe will give you anywhere from 5-10% increase at peak output, but will also 'give' you a cut almost as large at exactly half that RPM. It's just the nature of the beast, and one of the things that "Tri-Y" headers and "X-pipe" headers are trying to avoid. Not sure just how successful they are.

I did not put a header on my bike for any kind of power increase, I did it for the SOUND. :encouragement:
Unlike others, I don't go for loud. My pipe is actually about as loud as stock, it just has the nice sound of four cylinders breathing through a single pipe. Think of it more like "quality over quantity".

Sharpy, no doubt that you are getting well over 100 at the wheel, but don't confuse Sammy, he is asking about the output on an 850. :-k

.

 

[sharpy]

Sharpy, no doubt that you are getting well over 100 at the wheel, but don't confuse Sammy, he is asking about the output on an 850. :-k

.

Yes i know. but we all know once you start most cant stop. Was just giving a comparison to whats required to get over 100 as thats the 1st target for street tune bikes all cool.

 

[limeex2]

Stock 4V 1100, 30,000 miles, pipe/pods/jet kit, slingshot carbs, retune 107hp/72ft-lb rear wheel. If you don't dyno your bike you will never know what your missing. Heck, on my bone stock Triumph sprint it went from 89 to 96, but more importantly drivability was perfect and mileage went from 36 to 44mpg