Author Topic: Help with Plug reads (Read 3070 times)

anotherCB · « **on:** April 05, 2012, 08:58:17 AM »

Ok, this is my first post using Tapatalk, let's see how it goes.....
Can someone interpret these plug readings for me? 1 and 4 seem way too rich, 2 and 3 look almost lean to me. This is after 15 miles of driving with 50% throttle to test the needle settings.
First I thought it's the ignition, since 1 and 4 run on the same coil and 2 and 3 on the other coil, but i checked breaker gap and timing and all looks good
Bike is a K7, running stacks and 4in1, 130 mains, needle two clicks richer. Carbs recently gone through.
Please don't suggest to go back to the airbox, see second phpto why i won't :-)

anotherCB · « **Reply #1 on:** April 05, 2012, 09:14:47 AM »

I guess I put this on the wromng forum, is there a way I can easily move this to the SOHC4 forum?

Duke McDukiedook · « **Reply #2 on:** April 05, 2012, 09:19:17 AM »

Swap the ignition primaries to see if it is the coil to see if the readings follow that train of thought.
When was the last time you cleaned the carburetors and checked float levels?
2 looks more lean compared to 3.

Velocity stacks look cool but are #$%* for street riding, the airbox is the best way to get the best tuning. Stacks are really only good for WOT track riding.

kirkn · « **Reply #3 on:** April 05, 2012, 10:16:49 AM »

So, what's to interpret? Try going leaner on 1 & 4 and richer on 2 & 3 - see what you get.

anotherCB · « **Reply #4 on:** April 05, 2012, 10:24:32 AM »

DukieFrankenkit, last time I cleaned the carbs and checked the float levels was about 3 months ago. Swapping the coils might be something worth trying.

Kirkn, you are suggesting to have the needle settings differently in each carb? First time I hear someone suggesting this but maybe worth trying.

Also thinking about electronic ignition.....

Duanob · « **Reply #5 on:** April 05, 2012, 10:42:07 AM »

I would go with Dukie's advice first. My first thought would be ignition related. It looks like your 2/3 aren't firing off properly. Do you smell any residual gas on them when you pulled them out? Could be something as simple as a bad ground to the coils. Swapping them will give you an anwser one way or the other. When you get all four firing properly then you can do something about the the over-rich running condition of the 1/4 cylinders.

Duke McDukiedook · « **Reply #6 on:** April 05, 2012, 11:18:14 AM »

Oh, if you are running points check the dwell and the surface of the points and possibly swap out the condenser on the 2-3 side for a new one before you do anything else.

dave500 · « **Reply #7 on:** April 05, 2012, 01:37:42 PM »

check the plug caps resistance.

anotherCB · « **Reply #8 on:** April 05, 2012, 01:43:22 PM »

Good suggestions, thanks guys. I will definitely go the ignition route first and check what happens after swapping the parts. I'll keep you updated, might be a few days though until I get to this.

seanbarney41 · « **Reply #9 on:** April 05, 2012, 02:26:07 PM »

just to get you even more confused...1 actually looks pretty good, maybe just a touch rich

kirkn · « **Reply #10 on:** April 05, 2012, 02:35:59 PM »

I thought a plug not firing well would look terrible - black and wet. Those two center plugs look white - like they're running lean. That, to me, rules out all those ignition related things on 2 & 3. I might look at 1 & 4 for ignition problems, except for the fact that the number 1 does indeed look better than number 4, thus ruling out "joint" 1/4 ignition problems (points, condenser, coil). Wire, plug cap - maybe...

Duanob · « **Reply #11 on:** April 05, 2012, 04:34:09 PM »

Quote from: kirkn on April 05, 2012, 02:35:59 PM

I thought a plug not firing well would look terrible - black and wet. Those two center plugs look white - like they're running lean. That, to me, rules out all those ignition related things on 2 & 3. I might look at 1 & 4 for ignition problems, except for the fact that the number 1 does indeed look better than number 4, thus ruling out "joint" 1/4 ignition problems (points, condenser, coil). Wire, plug cap - maybe...

if they are not firing there is no fire or heat or explosion. Unburned Gasoline by itself would keep them squeaky clean if they were new going in. The two center plugs look hardly used at all. Just my $0.01. If it were my bike that's where I would start.

anotherCB · « **Reply #12 on:** April 05, 2012, 04:40:21 PM »

I am pretty sure they all fire, I checked header tems frequently.

mrrch · « **Reply #13 on:** April 05, 2012, 07:08:03 PM »

Might consider checking the actual fuel levels in the bowls with the clear hose method(may be low in 1 & 4).
I'm running the same v-stacks with my Mac 4-1 with opened up baffles.

grcamna2 · « **Reply #14 on:** April 05, 2012, 08:07:11 PM »

I'm sure you've already done a good carb synch., also..I wonder if you're pants are somehow blocking the intake's on #1 & #4 and sort of choking them ?

anotherCB · « **Reply #15 on:** April 06, 2012, 05:27:24 AM »

Good point on the pants, who knows? I'll put on my speedos and do another lap :-)

kirkn · « **Reply #16 on:** April 06, 2012, 06:18:10 AM »

eww eww ewww....

That's more than I needed to know.

anotherCB · « **Reply #17 on:** April 10, 2012, 07:40:54 AM »

Did anyone have problems accessing the site? The www.sohc4.net didn't work for me for days. Now someone told me to use http://forums.sohc4.net and I finally got back in.

Anyway, here's what I did. I switched the condensers and did another 10 mile lap at about 45 mph (something like 1/4-1/3 throttle I would say). The plugs pretty much look the same as before, allthough 4 looks better now. I don't think switcheing the condensers made a difference.

Without changing anything I road again for about 10 miles, this time at ~75-80 mph. Plugs look much better to me. So I really don't think my problem is in the ignition, what do y'all think?

mrrch · « **Reply #18 on:** April 10, 2012, 11:24:07 AM »

Try running around at a lower speed again and see if #4 soots up again, might need a fuel screw adjustment on #4.

kirkn · « **Reply #19 on:** April 10, 2012, 11:54:45 AM »

Agreed - not ignition.

anotherCB · « **Reply #20 on:** April 10, 2012, 08:18:27 PM »

I just came back from a long ride, doing 60-70 most of the time. Will check plugs tomorrow and post a pic. I think I will focus on the carbs then.
As Mrrch suggested I aiso check the fuel levels again and do another carn sync. I let y'all know how it goes.

grcamna2 · « **Reply #21 on:** April 10, 2012, 09:27:00 PM »

It's a bunch of work trying to get you're bike to run good for the street w/ stacks on the carbs, huh.It'd be good to check the weight of each float and see if any of them had fuel leak into them.Did you try shaking each one to see if they are empty ?

How are you're accelerator pump jets(one in the throat of each carb)pumping ? I'd do a thorough check and overhaul of the entire accelerator pump system also.
That system could be "blobbing" raw gasoline into each carb throat rather than atomizing the fuel into a fine mist to be more cleanly burned w/o fouling out you're cylinders. I believe Velocity stacks are particularly sensitive to that type of thing.

anotherCB · « **Reply #22 on:** April 11, 2012, 06:04:55 AM »

grcamna2, you are right, but that's the fun part, isn't it? :-)

Good point on the float weights, I have never checked those. The accelerator pump I believe works fine, I checked it more than once and it shoots fuel in all carb throats.

I checked plugs this morning and they were still a little too sooty for 1 and 4. It seems that beyond 75 mph or so everything looks good, and at lower speeds (or less throttle) I have the rich conditions on 1 and 4.

Anyway, I will go through the carbs again and do another thorough check. If I don't find anything wrong, has anyone used different settings on each of the carbs, say different idle screw settings or different needle settings from one carb to another?

mrrch · « **Reply #23 on:** April 11, 2012, 06:52:45 AM »

What condition are your slide needles? I had a couple that were corroded and would have been smaller diameter and would affect mixture in theory, so I replaced them.

mrrch · « **Reply #24 on:** April 11, 2012, 06:54:22 AM »

130's may be too rich, I'm running 120's (went down from 125's that I put in during my build)

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Author Topic: Help with Plug reads (Read 3070 times)