Compression vs: Leakdown testing results -Want opnions on MY results, please & thanks

[Tim Frank]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

I was curious about this and took a couple of minutes to speak with the Federal mogul tech folks.
They list the correct plug as the "YC".
He would not or could not offer an opinion on what symptoms (if any) would be caused by using the "C".

He did tell me that the plug recommendations actually originate with the spark plug manufacturer. The application design engineers (in this case E'rude) provide the spark plug guys (in this case Champion) with the operating conditions, and whatever other parameters are relevant, and the spark plug guys come back with a recommendation from their existing line-up....or if there is nothing close enough, presumably, a quotation or the custom supply of what they need.

 

[MACH1SCJ]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

omc johnson evinrude #507872 so I think that is factory manual.

I swaped the primary & secondary coil leads & the top cylinder still seems to be weak, Wont stall the motor but the bottom cylinder will stall it. So that should eliminate a spark issue, to include the coil, power pac & charge coil as not being my problem, agreeded?

I have installed the QL78YC champ plugs yesterday. so I think we can eliminate that altho I think I will rotate them on cylinders just to make sure I did not get a bad one.

 

[MACH1SCJ]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

omc johnson evinrude #507872 so I think that is factory manual.

I swaped the primary & secondary coil leads & the top cylinder still seems to be weak, Wont stall the motor but the bottom cylinder will stall it. So that should eliminate a spark issue, to include the coil, power pac & charge coil as not being my problem, agreeded?

IT DAWNED ON ME DRIVING TO WORK THAT THAT ONLY ELIMINATES THE COIL & PLUG WIRES & NOT THE PRIMARY FIRING CONTROL CIRCUIT.

 

[boobie]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

That is correct. You could have pack or other probs.

 

[MACH1SCJ]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

I took it out for a river trial. It started nice & easy as it normally does, it did not stall. It ran great at 2000 rpm & higher, It was rough at lower rpm & felt like it was misfiring below 1000 rpm when in gear with a little smoke.

Looking at the plugs & piston tops, after the run, the top cylinder plug was not as dark & the piston top was cleaner & looked oily... I want to go back to my orignal thought that the rubber foam sound deadner the P.O. added, which rubbed the flywheel & made foam dust, has clogged the idle circuit somewhere. I think I will go through the carb again. At least the top one. Maybe i should try rotating the carbs & see if the weak cylinder follows it?

Few questions,
1) The stater is only for charging the battery, and the charge coil is for the ign circuit?
2) What triggers the pac to fire the coil?
3) Can the trigger or power pac fail only at low rpm?

 

[AlTn]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

1. yes
2.the trigger sensor which is incorporated into the powerpack in the UFI ignition system
3.from readings on the forums, the powerpack can fail in a multitude of ways...the UFI system was utilized for 4 years then discontinued with the ignition system < on the 2 cylinders > reverting to the sensor coil and power coil under the flywheel and the powerpack mounted externally...at marineengine.com it seems your UFI system will be discontinued effective summer of 2012, so at some point in the future, reverting back to the older system will be a must

Have you tried hooking up a timing light to each plugwire and observing the stobe for erratic firings in the lower rpm ranges?

 

[damnskippy]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Could this possibly be a reed valve problem

 

[MACH1SCJ]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

1. yes
2.the trigger sensor which is incorporated into the powerpack in the UFI ignition system
3.from readings on the forums, the powerpack can fail in a multitude of ways...the UFI system was utilized for 4 years then discontinued with the ignition system < on the 2 cylinders > reverting to the sensor coil and power coil under the flywheel and the powerpack mounted externally...at marineengine.com it seems your UFI system will be discontinued effective summer of 2012, so at some point in the future, reverting back to the older system will be a must

Have you tried hooking up a timing light to each plugwire and observing the stobe for erratic firings in the lower rpm ranges?

Oh, thats what that "summer 2012" means I had seen that & wondered.

(go back to my first post bottom paragraph of this thread) I did hook up a timing light & at first I thought I was droping firings, something like 1 firing ever 400 - 800 but my timing light stopped flashing completely at times, but still showed the rpms on it, so now my timing light might be acting up...IDK... I need to get my lab scope out!

Funy thing is it looked like it was the bottom that was dropping firings but that is not the weak cylinder on cylinder drop test.

Could this possibly be a reed valve problem

I had found some carb spitback after I thought I cleaned all the rubber foam from the idle circuit. I cleaned the reeds at that time as they had rubber foam on them as well. The spit back was less but still there to a point. I installed new chris carson marine reeds & there is now virtually no spitback, however the carbs definitely have different sounds. I checked on the new reeds when I had the carbs off again & they looked good.

 

[MACH1SCJ]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Rain coming, so I decieded to pull the boat out, but since I was there I had to get a little fishing in. The engine idled & did not stall nice not having to fight to get it into gear.

I installed a couple of inline spark testers but it was to bright to really tell for sure if ign was dropping.

It was misfiring at idle, 1200 rpms & up felt good.... sounds like a carb idle circuit right? I rechecked w/ inline spark testers last night & spark looked almost perfect. I do not think it is spark at this point.

I rotated the carbs & now both cylinders will stall the engine. Also idle came up 100 or so rpm., however it is still a little rough, rougher then I want. Anyone know why the carbs have different air bleed jets?

 

[MACH1SCJ]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

So rotating the carbs changed the power balance results. so I pulled the carbs apart again, core plugs & all. the only thing I found was a single fiber strand. I think it is carpet fiber, there was some in the fuel filter when I changed it. However it was stuck no where near the idle circuit. I now need to decide where to put each carb.

 

[Tim Frank]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Anyone know why the carbs have different air bleed jets?

Not why, but the upper carb orifice is smaller according to the chart in my manual.....its a #29 and the ID is 0.029"
The lower is a #31 and ID is 0.031" Seems they number them in "10-THOU".
Maybe they got swapped? Other than those orifices, the carbs appear identical. When YOU interchanged them, do you know which went where?

I have had varnish build up in jets like this and had to "ream" them with an exact size drill.
If you can access (or have) a #68 drill bit, that is bang on .031, and you could use the shank to verify the bore is not restricted.
The closest drill for a #29 jet is a #69, but is 0,0002" oversize. Check that one first with a toothpick to see if you can get any "scrapings" off the ID.

 

[MACH1SCJ]

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

Re: Compression vs: Leakdown testing results -Want opnions on MY results, please & th

The 29 was on on top orignally, & 31 on bottom, I didn't change the air bleeds around. Before I swapped them the engine would run on just the lower cylinder & after the swap it would almost run on both cylinders. Seemed to be more even on cylinder power balance.
The lower plug has a larger dark arear on it then the top plug.

The jets were clean, I ran wire through & got no residue/varnish, as I too have seen that on many small engines.

I was wondering if the air box recirculate vent is why the different size jets.

I hope to get them carbs back on soon & try it out again. Maby the carpet fiber I found was sucking up the idle tube. I am also wondering if the idle tube is leaking at the top of the carb bore.

I had orignally ruled out a carb issue because propane enrichment had no positive effect, and a 1/8 turn of the idle mixture needle in either direction had an effect of lowering the idle speed.