I've heard and read much about dyno testing on this forum and actually saw the machine on a tour at a local HD stealer. I've sensed that my '05 EGC does not have as much horsepower it once had. Before I drop the $90-$100 for the test, just exactly what will a dyno test tell me?

 

hp / torque / hp curve / torque curve

 

It'll measure torque, that's the pulling power from just over idle to 4000 rpm or so to keep you accelerating, ( or passing a car without a downshift.)

And horsepower, the measurement of output in the upper ranges of rpm to redline.

As a Touring bike, torque is the target for me. ( I haven't been in the horsepower range in months, but I can pass without a downshift thanks to the cams I chose to give me the power where I need it.)

Pretty close to stock you could expect 65 HP and 75 ft./lbs. of torque on your model I would guess.

 

tj316 summed it up. You get a sheet with the hp and torque over the entire rpm range all graphed out. It usually has the peak hp and torque all spelled out for you. Often you will also see the configuration of the bike listed out i.e. 96ci, SE exhaust, 304 cam, SE intake, etc., but not all list out all that stuff. Some just have the hp tq curve graph.

 

It will also tell you the Air Fuel Ratio (AFR), but you need to keep in mind that is only for one cylinder at wide open throttle (WOT).

Without having a reference point for your bike, having a dyno pull done is not going to tell you a whole lot outside of what HP / TQ the bike is making at that time.

I think you would be better off doing some investigation into the overall health of your motor before you spend the cash to put it on a dyno.

Zach

 

If you are concerned about the condition of your engine do a compression test and during your next oil change collect sample for analysis. Compression tester $30-40 and will last you forever, use it as many times as you want.
Oil analysis $10-15.

 

Yup, I agree.

The average dyno gives you torque and hp +- 20% or so. They arent very accurate and unless you have tested the bike before and the bike is exactly the same (ie same tyres, same tyre wear) then the result will change. (Unless its an eddy current dyno).

If you have concerns about the health of the motor a compression test is the best place to start. The sort of wear that costs HP is easily detectable by this cheap, accurate and repeatable test. Other things to test would be injectors for even spray and have a look at the plugs, they will give you insight into the tune of the motor.

Save your $$$ and dont dyno IMHO.

 

Do your home work on the technician performing your dyno too. There's a lot of people out there who really shouldn't be doing them.

Docs Performance Tuning in Florida has a great reputation.

 

Lot of good inupt so far. Another vote for needing an existing baseline to make a comparison to validate the power loss. Don't know if you have done any mods that effect performance. Check all the mechanical stuff and scheduled maintenance first, if all is good, then look at the tune. The AFR reading you get from a dyno will be the most usefull initially, to tell if you need fuel adjustment. The TQ and HP readings are used to quantify the output, map the curves, and to tweak the AFR a little across the curves to smooth them out.