Author Topic: Spark plug reading (Read 1704 times)

AlekStooge · « **on:** July 03, 2020, 07:59:43 AM »

Hi, inexperienced with spark plug readings here. Could someone give me their opinion on if this is carbon or oil fouled? Engine was rebuilt. I have been looking at several different charts and plug comparisons. Plugs look and feel more sooty than wet when wiping them.

Here is some of the work I've had done and carb setup on a 1978 CB 550k PD46C carbs

JMR head work
Stage 2 port
126-00 megacycle
1mm OS intakes
Serdi
Hard welded rockers
Slotted cam sprocket
59mm pistons

Carbs (elevation 759ft MSL)
4 into 1
Individual air filters (Generic, couldn't find K&N)
108 main Keihin
45 pilot Keihin, I thought I had 42s, I'll get back to that.
12.5mm floats
Needle clip in the middle

Couple more things before I show you the plugs.... I pulled off the carbs and valve cover. I was certain it was oil but then I took a look at my jetting and saw the 45 pilot. I was away from the bike for about a year, I forgot. When I would kick the bike I would get hissing sometimes, hinting it is a valve leak. Probably due to me learning how to degree a cam and damaged one in the process. The bikes idel is stable at times and goes up at others.

Here are the plugs. 1-4, bike was upright when ran.

Here they are again, don't remember the order.

I didn't do a leak down because I don't own compression guages. Before I dig further into it start buying new gaskets due to teardown, I want to get some of your opinions?

If you're here just tell me the stock airbox works the best. You're right. If you don't have anything constructive to contribute to the given situation, respectfully go ahead and save it because that ship has sailed and I don't regret it.

Thank you for reading the whole thing.

Alan F. · « **Reply #1 on:** July 03, 2020, 08:42:45 AM »

I'm also not an expert but I support your cause.
They are all nicely balanced though so loud cheers for your success there.
My first question, is the condition of these plugs from normal riding or is this a 'plug chop' with fresh plugs accelerating to redline then pulling in the clutch and killing the engine and coasting to a stop to pull plugs for analysis?

What are your air screw positions?

Perhaps lower the needles one position?

Jerry Rxman Griffin aka MuthaF'er · « **Reply #2 on:** July 03, 2020, 11:16:12 AM »

Looks consistent across all 4. Fully charged battery? Charging system tests done? Road or garage test? What RPM range at load when doing the plug chop? Did you "rebuild" the carbs and if so what brand kits?

AlekStooge · « **Reply #3 on:** July 03, 2020, 11:26:30 AM »

Ok, I want to get a compression tester NAPA auto parts made by Lisle with 10-18 mm fittings for about $100 or the Motion Pro equivalent?

All the testing was garage at idle or 1/4 open. Spark plugs are the same very easy to clean off between start ups.

Battery is 12.6. Charging system is not in service at this time. Phase wires from stator need a connector.

As for carbs they were cleaned several times, not fully rebuilt. New floats, jets, needle gasket... from 4into1 I think that is it. I haven't done anything to the air screws ever.

Alan F. · « **Reply #4 on:** July 03, 2020, 11:58:27 AM »

So still within the RPM range where air screws affect idle.

I'd verify their position (turns out from gently seated) and list it here for reference.
Have you visually verified float height with clear tube after changing floats?

Jerry Rxman Griffin aka MuthaF'er · « **Reply #5 on:** July 03, 2020, 12:40:39 PM »

Do a load test on your battery after you fully charge it. I go to Advance Auto for that. Do not rely on a voltage test.

Considering the consistent colors I would not spend $$ on a compression tester now unless you just want to add one to your tool kit.

Did you properly set the carb float heights? Considering you didn't touch the air screws the floats may be too high?

Play with the air screws on the carbs. See where they are now. Turn them in and count the turns. Do not force them onto the seats. Lightly touching only. Then maybe start at 1 turn out. Go each direction at 1/4 turn each and see how it reacts. If the air screws were replaced were they identical?

AlekStooge · « **Reply #6 on:** July 03, 2020, 06:38:39 PM »

To be honest never adjusted air screws. Will tinker with it. Oh yeah forgot about clear tube method.

Floats are set at stock. That was 12.5 or 14.5 I don't recall will check again.

I went to my friends house to borrow a valve compressor and torque wrench, my tools are 5 hours away. I ordered a Motion Pro compression guage the auto parts store one was crap. I bumped into him again at the hardware store and he invited me back. He restored his R68 and was firing it up today. I stuck around. I decided to take a break. I couldn't sleep last night. Hijacking my own thread here it is. Gotta have fun while doing this.

AlekStooge · « **Reply #7 on:** July 07, 2020, 09:02:33 AM »

My compression guage is coming in tomorrow, excited. I been reading threads and the engine FAQ here. Things discussed were hose length adding to volume and quality of guages. The actual numbers aren't as important as within 10% consistency between cylinders.

I was wondering if the location of the schrader valve affects accuracy. Bikemaster has it at the plug end and the Motion Pro has it at the guage. I also am starting to like the Bikemaster one, more adapters for different engines. Just want people's. 02. Thanks

Also ordering more jets soon.

seanbarney41 · « **Reply #8 on:** July 07, 2020, 03:10:44 PM »

best compression gauge ever is your big fat thumb...leakdown tester will give you actual useful information about your engine

AlekStooge · « **Reply #9 on:** July 07, 2020, 03:51:53 PM »

Yeah, I still don't own a air compressor. I heard the thumb trick is moot, since even 40 psi will pop your thumb.

Anyways I got my guage today. Could I do the test without my valve cover on?

AlekStooge · « **Reply #10 on:** July 07, 2020, 05:57:06 PM »

Ok I rubber banded the rockers and put the valve cover back on, didn't set valve lash and put the breather on. No carbs. This is really sweating, about 20-25 kicks per cyclinder till I could get it as high as it will go.

1-195 psi
2-194 psi
3-196 psi
4-195 psi

I guess this means the plugs were not oil huh? I hope isn't so much oil in there that it seals the rings. Wiseco 59mm 10:1 cr, Imput?

seanbarney41 · « **Reply #11 on:** July 07, 2020, 06:27:25 PM »

Well, see? You now know you have good news. You just don't know what exactly that news is.

AlekStooge · « **Reply #12 on:** July 07, 2020, 06:41:51 PM »

Quote from: seanbarney41 on July 07, 2020, 06:27:25 PM

Well, see? You now know you have good news. You just don't know what exactly that news is.

Is it good news? If I don't know what the news is?
I have a feeling you're saying buy an air compressor and a regulator.

seanbarney41 · « **Reply #13 on:** July 07, 2020, 06:51:38 PM »

I know of no way to get 195psi from a 550 other than a perfect seal. I think your plugs were black from carburetion, not oil

AlekStooge · « **Reply #14 on:** July 07, 2020, 07:07:21 PM »

Quote from: seanbarney41 on July 07, 2020, 06:51:38 PM

I know of no way to get 195psi from a 550 other than a perfect seal. I think your plugs were black from carburetion, not oil

Oh ok thank god! Thank you Sean for the clarification too. When you said "You just don't know what exactly that news is." I thought you meant I know nothing from my compression test due to oil sealing up. All it is experience isn't it? Thanks again!

seanbarney41 · « **Reply #15 on:** July 07, 2020, 08:10:56 PM »

If you think about it...kicker ain't movin' much oil around in these...so every stroke would scrape oil off the cylinder walls and move excess out the exhaust. If oil in the chamber was a problem you would not see the compression climb and then level out.

AlekStooge · « **Reply #16 on:** July 07, 2020, 09:05:17 PM »

Cool

I could also check if there is oil on the pistons at TDC after kicking it a bunch of times and sticking a screwdriver with a shop towel over it. I think if these was any type of detremental leak I would get a decent amount of oil on the shop towel... I think.

Gonna order some Keihin jets I'm thinking 42 and 45 pilots and I'll get some more mains 110s and 102s. I have 105s and 108s. Does Keihin make emulision tubes? I have a rebuild set but I think those are Keyster.

AlekStooge · « **Reply #17 on:** July 08, 2020, 01:27:16 AM »

Since it appears I'm burning rich, perhaps I should save my money and not get 45 pilots and 110 mains. Those alone add up to about $70. Or should I just get them and not think about it later.

See setup in first post.

AlekStooge · « **Reply #18 on:** July 08, 2020, 03:36:38 PM »

I got another Motion Pro guage today huh? My Bikemaster hasn't come in yet.

http://forums.sohc4.net/index.php/topic,183454.0.html

I ordered everything mentioned above. Mains 100-110, except 105s and 108s because I have those. 42 and 45 pilots. Jet holder. I read on the forum that generic needle valves are problematic so I emailed Jetrus if I can add them on. I wasn't able to find genuine emulsion tubes but I have a complete rebuild kit from 4into1 so maybe I'll dig into that.

News:

Author Topic: Spark plug reading (Read 1704 times)