I was verysurprised this weekend to find that one of the local dealers in Atlanta will do a very simple dyno run, with A/F ratios for $50... Its not a tune, but it could give you, or the guy working on it, a clue what and where to adjust.. Just a thought... Mine is running very well, but I'm thinking of having it done simply for my final fine tuning and just knowledge of what the bike is capable of.. Of course, if I let them wrench on it, the price will go up significantly from there.. May not be an option or your best bet, just thought I'd throw it out there that there may be other options in your area....


With that said, I'd follow the other recommendation to take it back to your old timer... He had it right at one time and made the changes that changed that.. He knows your bike and will require the least "learning curve"..

 

I am not worthy...but you don't need a dyno, you need an air/fuel ratio check....if the magic 13:1 ratio is there and its running like crap then its something else wrong and either the dyno won't fix it or it will destroy itself during the run.

At the risk of being a smug ******....these are cruisers, if you tune the *** outta them and then thrash the snot out of them...they gonna die..."offerings to the God of speed" as Burt Monroe used to say.

Having said that...when you say it runs bad....what are the symptoms?

 

To the original question 'is a dyno worth it? IMHO yes. However as Spanners so shrewdly points out, make sure that any problems are sorted out first. On the other hand a decent tuning shop will do that before putting an unfamiliar bike on the dyno, as I know from firsthand experience. A dyno offers the opportunity to have an optimum tune and in the case of my ole lady and her S&S 107" that is priceless!

 

Dyno tuning vs. traditional tuning is like comparing Perrier water to tap water...just a fancy way of charging more for little benefit. Like others indicate, unless racing the bike and want/need 100% to give leg-up on competition, not necessary. Need to figure out why your ride's not @ optimum and get it corrected. Could you possibly have broken something while you/buddy were messing w/tune?

 

Worth the dyno time just for diagnostic information.

Is it running rich or lean? (And where? Cruise or WOT)
Accelerator pump dumping too much fuel or not enough?

If fueling is good, then you can concentrate on the ignition. Will save you time and money.

A good dyno operator will not run a bad running bike and will not continue a run if things look bad.

Even if a diagnostic dyno session does not pin point the exact problem, you will at least know what not to try to fix.

 

I'm going to vote for the carb still being the issue. I know from experience that sometimes if a carb is off it will both cough through the carb and backfire out of the exhaust. From what I have seen if there's backfiring through the exhaust it's rich. And, it's just hard to know till everything is warmed up. But, in the cases that have affected me there were times when I really wanted to say that it was the ignition when logic said it was the carb, it was always the carb. You did say that the advance had been massaged. It might be a good idea to put that back to something less aggressive and start from there. These kinds of grimlins can be a pain to root out. I had a buddy that had a similar issue. He assumed that it was everything but what it turned out to be..dirt in the jet.

 

Bought my bike used and it wasn't running right. Was WELL worth the $400 I spent to have it dyno tuned. Runs fantastic now.

 

Apparently your bike needed tuning, but honestly, unless you are squeezing out the last smidge of power, a dyno is not necessary. With an otherwise sound motor, an experienced wrench should be able to get it close enough for street use without much effort.

This stuff isn't rocket surgery. I was tuning air-cooled VWs in the late 70's and we never had a dyno. By "tuning" I mean setting the timing and setting/adjusting the carb. There's nothing else to it.

Dynos are very nice when you are doing things like experimenting with different, valves, heads, cam profiles, stuff like that. And on an computer motor where you can dial in all sorts of different ignition and FI parameters, dynos are a great help.

But for a mud-hut simple, carbureted Evo motor with a standard ignition system, any wrench who tells you you need to buy dyno time so he can tune it either doesn't know what he is doing or is milking you.

 

Omaha, things have changed a lot since the 70s old chap! I've owned Harleys all that time and have watched developments along the way. While your comments may be OK for a near bog standard Evo and an owner who doesn't want much of it, a lot has happened in the bike world, why even to the benefit of our Evos. There is great scope to improve performance of our older bikes, using modern technology and modern tuning parts and expertise, including a dyno. It's a personal choice and, having buried my head in the same sand, I now see the light! A dyno is a great tool. Backyard tuning has had it's day IMHO, along with the exposed roller chain......

 

Ask the guy that did the last tweeks to revert those back. Myself I like to change only one thing at a time in tuning. Swap main jet go test. Swap intermediate go test. Swap ign curve go test.