TOPIC:

Anyone, please feel free to build on my shaky base, and don't hesitate to add anything you think may help to improve my footing. I possess a weak insight for fine-tuning, but will always endeavor to make it better, given a recommendation or two based on knowledge attained through experience. That dyno run was probably the best $50 investment I've made in awhile.

I just want to ride...especially when this bike runs better than I can make it.

That is a good graph, it looks to be running fairly well.
I have done a bunch of runs and this is what I know , the operator plays a big roll and good one is worth his weight in gold!!, the dyno plays a big role from the charts it looked like a dynojet 250i ???

Dynos like to read rich so be careful to not get to lean general street driving is a bit different and being a bit rich isn't a bad thing…but just a bit.
Use the same operator every time you do a run. I watched two different guys dyno my GS back to back with a big difference…. the "kid" who did the first run rolled off the throttle just a bit at the end of the run and then rolled it back on and it messed with the AF reading and the HP reading. WEIRD but true

Way back in 2011 the same guy (Scott) ran a dyno-pull on the bike, when his setup was at a semi-secret location in the Grand Rapids, Mi. area. At the time, he was the only guy around that I knew of with a dyno, and was good at what he did even then with what he now considers outdated technology by today's standards. That run was done before I started changing things on the engine, and I thought it was running better than ever...even back then.

I have a copy of that result, which I may post for reference...mostly stock then.

The charted HP was way-less then than it is now, and it may even have been running rich then too. That was with the old J-head and standard camshafts, typical of the J-engine from 1981-2004 I believe...that's twenty-three years, guy's. It's no wonder ebay is such a great source for parts to keep these bestial-animals alive.

Figured I'd run premium for a change yesterday, but after checking the spark plugs that gas was drained out and put in my truck. For whatever reason, this bike still prefers regular gas. The more expensive fuel stuff just works to make the spark plugs black, and doesn't make the bike run better...but the old truck likes it.

While cleaning the black spark plugs, it occurred to me to check the #3 plug wire with my cheap multi-meter that I finally broke down to purchase a couple years ago.
That #3 cylinder had not fired properly for a long time...it was evident by how that header pipe hadn't blued like the others.
I've been using Accel U-Groove non-resistor spark plugs with NGK resistor caps and copper-core wires, and just now discovered why that #3 spark plug insulator was persistently lighter than the others...

Well, lo and behold that #3 resistor cap was not working properly, if even at all. lol
Now I figure that out , right after the dyno pull...of course... Yep, that's me folks...the one thing that burns well for me is money!!!

Maybe that single deficiency was robbing my engine of power , just when it would have been handy. And oh, it might even have contributed to my poor over-rich condition, since that cylinder wasn't burning the fuel...well.

Please pardon my rant.

It's the little thing's that get over looked.

New wire, comp baffle and 2 sizes smaller mains hopefully will really add up..... that's why I run solid non resistor wires and plugs..... hopefully am getting a little hotter burn from em. Thinking of getting 5 gal of 91 oct pure gas or at least mid grade 89 at BP if I run mine. I most of the time mix 89 and 93 at about a 2 to 1 ratio but have not really been able to tell much of a difference.

KZB2 650 wrote: New wire, comp baffle and 2 sizes smaller mains hopefully will really add up..... that's why I run solid non resistor wires and plugs..... hopefully am getting a little hotter burn from em. Thinking of getting 5 gal of 91 oct pure gas or at least mid grade 89 at BP if I run mine. I most of the time mix 89 and 93 at about a 2 to 1 ratio but have not really been able to tell much of a difference.

The wires are ok since they are wire-strand copper core, but decided to get another set of resistor caps from the UK...nice-new red ones.
That faulty cap may have been causing an issue during the dyno session. Scott said there was something causing electrical interference with the system as he was running it.

May have to take another ride on the dyno. After this simple fix and revised carb jetting, the engine runs incredibly better.

With 127.5 main jets (vs. 132.5), I'm using more throttle rotation range, and the roll-on response is faster-crisper, but yet without pops and spits, even after raising the needle-clips to the third notch. I may go smaller yet with the mains, to see what effect that has, but with dense-warm air ahead it may be good as is. These RS carbs are a trip.

daveo wrote:

SWest wrote: Sounds about right for a shafty.
Steve

Dyno pull printout for review and comment:

I'm a little surprised at, under 56ft lbs of torque.
Is that normal?
And that A/F ratio looks way to rich to me above 5Krpm and will be worse as the weather warms up.

missionkz wrote:

I'm a little surprised at, under 56ft lbs of torque.
Is that normal?
And that A/F ratio looks way to rich to me above 5Krpm and will be worse as the weather warms up.

In a half-arsed feeble attempt to improve it, I've changed main jets from 132.5 to 127.5 and lowered the needles one notch to the 3rd clip-space. Pilot jets are 120, and I switch air jets (between .07 and .08) depending on the air temperature and humidity.
Not sure about my approach, but the engine seems to like it better...

With little other than you guy's advice, I rely on my general ability to figure out how things work...and beyond-obsessive tinkering.
Professional dyno-tuning would certainly make more cents.

Hi Dave
Glad bike is improving
One word on this though
. Changing to many tuning variables at once can make it hard to pinpoint what causes
a good or bad change in performance..
Dave

And it takes time for the engine to "catch up."
Steve

Street Fighter LTD wrote: Hi Dave
Glad bike is improving
One word on this though
. Changing to many tuning variables at once can make it hard to pinpoint what causes
a good or bad change in performance..
Dave

Still experimenting...

Then: 132.5 Main Jets, 120 Pilot Jets, .07 Pilot Air Jets, 4th-Clip on the Needle

Now: 127.5 Main Jets, 120 Pilot Jets, .09 Pilot Air Jets, 3rd-Clip on the Needle

Better...but best
Should I go leaner til it pops...perhaps 117.5 Pilot Jets?