Pictures of my plugs

[SuprSlow50]

Ok, let me start off with my setup...and say that I appreciate any input that you may have.

 

421 Cub, milled and rechambered stock head. Compression was 140/135psi when it was 10-15 degrees F, and with a little oil in the cylinder 159/150psi (It is suppose to have 165 with fresh topend, according to previous owner, but I have no way to verify this).

 

35mm pwks

pilot=48

air screw 2.0 turns out

needle=CEL on 3rd clip

main=165

 

CPI inframe

VF3's

+7 timing

50/50 mix of 93 and VP C-16

Elevation 450-500ft

 

 

Below are some pics of my plugs that have been in there awhile, and the ones I will be using to warm it up tonight before I throw a fresh set of plugs in and make a pass. I just wanted to see if you guys had any input based on these plugs...well, that and I had some free time while a work so I wanted to get this thread posted now instead of later when I will be out on the shee.

 

Note: I did not do a plug chop to check the fuel ring since I will be reusing these plugs to warm up the motor, and I figured it was useless to do a chop on a set of plugs this old. Also, the last time I had these plugs in, the timing mark was very visible and just after the bend in the "L" towards the center electrode, which is just about perfect in my book. I'm not sure why, but I couldn't see the timing mark now.

 

 

 

 

 

 

 

Edited March 16, 2011 by SuprSlow50

[SonOfSand]

They look lean in those pictures, might be different in real life. I like more brown on my plugs, are you a drag racer?

[SuprSlow50]

No, this is my trail/dune bike. I think it might be because of the flash that the last pictures look lean. In person, I would say the first two pics are the most accurate in terms of how they look. I was messing with the camara settings to get the best pics and the last 3-4 pics I took made the plugs look light/lean. Hopefully, it will still be light out when I get home so I can use sunlight to take the pics.

Edited March 16, 2011 by SuprSlow50

[Pasi S.]

I´m not an expert here, but...

 

My friend has a 421 CUB, it has CPI´s (if), 34 PJ´s, VF3´s, +4 timing, K&N´s and coolhead with *** of compression using 105 race gas.

 

He has 45 pilots, D177 needle 3.rd clip, and 162 mains and it was a tad on a rich side. This was at sea level and 12-15*C.

 

So I think that you are close. If that motor was mine I would try a smaller pilots and few size under that 165 and see how it runs, but that´s just me.

 

 

-Pasi S.

[SuprSlow50]

So I just got done warming up the Banshee and swapping out the B9EGV for a fresh set of BR8ES, went around the block and then made a 1-4 pass and shut it down. I dont want to chop the plugs bc with my ear/eye scope I can see down to the base of the porcelain and it has a fairly thick (maybe 2mm?) dark grey fuel ring. The porcelain near the electrode is nearly white on the left cylinder and the right is a slight greyish. I am not sure if I didnt get enough time or heat into the plug yet to get a good reading. Please let me know what you think. Sorry for the lack of pictures, the damn camara battery died right away...

 

 

 

[RedMonKey]

looks lean to me bro..no color just bright white

[SuprSlow50]

Let me know if I am wrong on this...the very base of the porcelain is the fuel ring which would be WOT, and the upper part of the porcelain, near the electrode, would be the pilot/needle circuit, is this correct? I am only use to checking for the fuel ring on nitrous motors in drag cars where you are only WOT. Should I drop the clip one position? Did I give it enough run time to even get color into the plugs?

Edited March 17, 2011 by SuprSlow50

[sleeper06]

A 421 cub on gas with 35s is damn close at 165 mains,48-50 pilot,cel 4th clip.If your plugs are reading diffrent i would look into a possible air leak which is a half hour test if you have the equipment,or ohm out your plug caps for proper resistance.Another thing when tuning carbs is bowl height,its the single most important thing to do to set the stage for proper jetting,35s are 16mm.Also being that far off on compression side to side worries me

[SuprSlow50]

Yea, the compression worried me a little bit too, but no one seemed to say anything about it whenever I mention it. Kevin at HJR said it's time for a new set of pistons and rings. I did a leak down test Sunday and had some good leaks on the UPP intakes, so I put rtv on the gaskets and it held 6psi for 25 minutes without budging. I am going to just chop the threads so you can see the fuel ring. From what I see with my eye/ear scope, it appears to be dark grey and 1.5-2mm or so. I will post up the pics tomorrow after work.

 

Now assuming the main jet is close based on the plug chop, how do you determine that the pilot is correct? Does anyone do a part throttle plug chop, or just seat of the pants from there?

 

And when you said the most important thing is setting "bowl height" I am assuming you meant float height since you said 16mm, is that correct??

[WINDYCITYJOHN400]

Yea, the compression worried me a little bit too, but no one seemed to say anything about it whenever I mention it. Kevin at HJR said it's time for a new set of pistons and rings. I did a leak down test Sunday and had some good leaks on the UPP intakes, so I put rtv on the gaskets and it held 6psi for 25 minutes without budging. I am going to just chop the threads so you can see the fuel ring. From what I see with my eye/ear scope, it appears to be dark grey and 1.5-2mm or so. I will post up the pics tomorrow after work.

 

Now assuming the main jet is close based on the plug chop, how do you determine that the pilot is correct? Does anyone do a part throttle plug chop, or just seat of the pants from there?

 

And when you said the most important thing is setting "bowl height" I am assuming you meant float height since you said 16mm, is that correct??

 

You look lean. If you call Jay and get on the dyno, we'll get those carbs dialed in perfect before it burns up.

Otherwise, you might be doing a top end alot sooner than you figured.

You running it "as is" with the gas carbs for the Badlands trip? I think it will be fine for that ride. But if you come to the dunes, you'll want it fresh.

[Snopczynski]

You can't jet by plug color if you run race gas. The toluene in the gas will not cause an accurate reading. You have to go by feel. Go rich until it slows down, and lean it out till it speeds back up.

[crazycanuck]

I have a 421 with 175/175 psi, .044 squish,+7 timing, 39 pwks on C-12 and i find it very hard to go off my plugs. sometimes they look green and yellowish. I did exactly what snoop said and went up with jets until it felt like it fell off. Then went back down til it felt good . My plugs still seem rich but it still pulls forever on top.

 

I dont do any serious racing so i dont need to get greedy yet.

Edited March 17, 2011 by crazycanuck

[Snopczynski]

50/50 mix of 93 and VP C-16

He said this in the first post, did I miss somewhere in the later post where he said he had switched it over to straight pump gas? C16 is 117 octane leaded fuel.

[SuprSlow50]

Snop...I am curious how you cannot read leaded fuel. In doing my plug chop search on BHQ, I read a lot of posts where you say it "washes down the plug" or "The toluene in the gas will not cause an accurate reading." I am confused on this because of my background in drag racing, when tuning a nitrous motor on C16, you still do a plug chop to check the fuel ring. I have been doing this for years (drag racing, not 2-strokes) and I only run straight c-16, the fuel ring at the base of the porcelain will usually be a grey bc of the fuel (i think) but the thickness and darkness would tell you right away if it was lean or rich. Can I not use that fuel ring as a guide in a 2-stroke? Just trying to learn as much as possible.

 

Also, since the right cylinder has a little less compression, I noticed that plug also has a little more color. Can I put a larger main in the left cylinder so that they are running the same. Again, the reason I ask is because normally we would adjust fuel, nitrous, and/or timing per cylinder so that all plugs would look the same. And so we wouldn't burn the motor down because of the leanest cylinder. Or would it be better to run bigger jets in both cylinders?

[Snopczynski]

Snop...I am curious how you cannot read leaded fuel. In doing my plug chop search on BHQ, I read a lot of posts where you say it "washes down the plug" or "The toluene in the gas will not cause an accurate reading." I am confused on this because of my background in drag racing, when tuning a nitrous motor on C16, you still do a plug chop to check the fuel ring. I have been doing this for years (drag racing, not 2-strokes) and I only run straight c-16, the fuel ring at the base of the porcelain will usually be a grey bc of the fuel (i think) but the thickness and darkness would tell you right away if it was lean or rich. Can I not use that fuel ring as a guide in a 2-stroke? Just trying to learn as much as possible.

 

Also, since the right cylinder has a little less compression, I noticed that plug also has a little more color. Can I put a larger main in the left cylinder so that they are running the same. Again, the reason I ask is because normally we would adjust fuel, nitrous, and/or timing per cylinder so that all plugs would look the same. And so we wouldn't burn the motor down because of the leanest cylinder. Or would it be better to run bigger jets in both cylinders?

The toluene is what washes the plug down and makes it so you can't read it. I have no clue why the 4 strokes are different, probably has something to do with the oil being in the gas on a 2 stroke.