Topic: DYNORUN result: bike still runs crap

[ieism]

Just came back from the dynorun, there's definately a problem somewhere.....
He adjusted the idle A/F ratio, that is really easy if you can measure exhaust gasses. The numbers were good enough.
Then did a couple of runs.

I only brought a printout from the first run.



The bike is way lean on 105 mains. He tried adjusting it by plugging the hole that connects to the emulsifier tube temporarely. Normally that should richen things up about the same as a 20 nr. mainjet. But it didn't really. I did improve the torque at low RPM a lot.
In the printout the torque is about 16 at 50 km/h. It was about twice that on the second run with the airhole temporarely plugged
No matter what he tried, we couldn"t get rid of the lean running at high rpm though.

There was no point in revving it to redline, as it was getting dangerously lean. Idle to about 1/4 trottle was pretty good though.

So I now suspect the electronic ignition is not working properly somehow. If we advanced or retarded the ignitionplate, nothing would change on the dyno, so that's strange...

The bike also uses a lot of oil, so maybe valveseals are not good either (I didn't install the valves myself) Compression is rather good for such a high milage old bike.

It was really fun though. You lean a lot about your bike if you have a good dyno operator. The way these guys analyse a problem is really fun to watch.

[bwaller]

So ieism, this is a stock bore 550 with some porting work, pods and different exhaust?

Nice bike by the way.

[ieism]

Thanks.
The bike is a 550K '77
Yes, it's stock bore.
K/N filters
4-2 pipes
Ported head
42 slowjets
105 mains
Needle clip 3rd from top
Floatheight 12 mm
Electronic ignition
Iridium plugs, stock warmth and gap

[j-conn]

very interesting... keep us posted.

[crazypj]

105 main seems pretty small to me, particularly when stock is 98~100.
Personally I think you should start with a 110~115 main,
stock 38 pilot
 air screw 2 turns out
 float level 23mm (+1mm from stock)
 needle DROPPED 1 clip position (2nd from top) as I've always found removing stock airbox richens mid range when main jet is correct size
 If you had a big bore kit I would say go to 112~117.5 main jet, even a 122.5 if you have a race exhaust, its totally dependent on length and restriction in system (longer and/or more restrictive  pipes/silencers need smaller jets)
 PJ

[ieism]

Your number seem to make sense, but not for my bike...
I have a '77 K, they have different carbsetup.
Stock is:
90 mains
42 slow
Clip 2nd from top
12.5 mm floatlevel.

[j-conn]

wow 12.5 vs 23mm for float level is quite a difference!

[ieism]

They are different set up from the factory. And the floats are a different shape too.

I'm just thinking out loud here;
Can an incorrect alignment of the cam cause these symptoms? I'm pretty sure I did it as in the manuals, but it's easy to get it one sprocket tooth too far...I assume rotating the pointsplate would not compensate for a cam that is slightly off, that's why I was in doubt..

Has anyone ever gotten the cam one tooth too far, how would the bike run if that was the case?

[Sporkfly]

I think if the cam was out a tooth you'd definitely be able to tell by listening to it run. It would also vibrate excessively I imagine. So I'd say it's unlikely?

[crazypj]

 Didn't know it was a K.
They run very, very lean when stock, pods are going to make it much worse.
 I didn't see air/fuel ratio on print out, is it there or just a bad scan? ( it should have been done as you probably told dyno operator you were looking for F/A ratios for carb set up. Its not a big deal o insert probe
 I would still go up to 110main, drop needle and raise float level 1mm
Cam timing wont make it vibrate unless valves are hitting pistons?
 It may make it hard to start and/or lose power but you would see corresponding change in low rpm torque
 Carb synch will make it vibrate if its far enough out, otherwise it just makes clutch rattle
PJ

[ieism]

Ok that's a relief. The engine starts really easy (first kick), and makes no strange noises aside from the camchain a little noisy. But it sound pretty much like my other 550 mechanically.

He did do air/fuel runs. One through the gears rolling the trottle, and one 5th gear to full trottle. He did 6 runs in total.

But it was so obviously lean and wrong that I didn't take the prints. The one I did take (the one posted here) was so lean it's off the chart.

[Tim2005]

But it was so obviously lean and wrong that I didn't take the prints. The one I did take (the one posted here) was so lean it's off the chart.

So the AFR at all revs is above 20:1? I'm a little surprised it even runs like that. As ever, start by sorting out the main jet size then sort the needle and pilot after. To get to the ideal 13:1-ish you are going to need about 50% more fuel; it should be possible to approximately calculate the jet size based on cross-sectional area- I think it comes out to around 130. You're absolutely certain that you have the right carbs /fuel level setting?

[ieism]

I think this was the full trottle run.

Anyway, it was clearly visible on the screen while he was doing the run.

The bar went from blue (too rich) at 1/8 trottle to green, and then very fast to yellow/red and at about 7000 rpm it would get so lean that it would do damage.

The dynoman was pretty sure it wasn't just the jetting, and advised me to replace the ignition before even doing another run.

[crazypj]

You need to pull the generator cover and fit a degree wheel to crank then check timing marks on ATD.
I always check TDC marks and cam timing as well
 I forgot to mention, I limited the full advance on my 550 and set it to 36deg full advance with a Piranha electronic ignition (forget what the static timing was, 5 deg or so BTDC) Wore rings out every 8,500~10,000 miles but that was due to the 13,500rpm redline
I've only had one 550K (and several F1/F2's)
PJ

[TwoTired]

I just gotta say, I admire your approach to your bike modifications, Ieism.
I mean, so many people would just make the mods and run it.  While, you are actually checking the results of the mod towards making the entire system work right.
Kudos.
Best wishes toward the outcome!
Cheers,

P.S. I knew those PD carbs were well tuned to the stock exhaust and inlet restrictions.  But, I've never seen documented evidence how much impact changing those devices actually made, before.  Pretty interesting...