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Who Can Read These; How Do My Spark Plugs Look? Kind Of Weird...


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To me, 1 and 3 are richer (all seem pretty rich, especially on the black side). They all have a strange half brown, half black thing going on. I rotated them in the second picture so the brown is facing up on all plugs.

For reference I have a uni foam filter, TBR slip on, 130# mains all around, 40# pilots all around. Depaired, desnorkeled.

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Well, they all seem really rich. Are you noticing poor performance? Did you up the jet sizes?

If you clean them off and run them again for a 15 minute ride are they dirty again?

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I think the bike runs really well actually, except when it gets hot. It tends to bog down and overheat. my coolant also seems to disappear. I haven't run them after cleaning, I just replaced them. The jet sizes were like that when I got it.

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Seem very rich to me. Seem odd that the black deposts are up on a few theads, were all the plugs a bit loose? Are they the heat range recommended?

The only way to really check how your plugs look and how your carbs are mixing is to take a plug chop at the speed where you normally run, for me somewhere 4000/4500.

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for the disappearing coolant, check your rad cap, it may not be holding pressure

usually an aftermarket slipon and air filter will make a bike run leaner.

more info, are the 130 jets original??

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Guest Recalcitrance

The overheating and the richness may (MAY) not be related.

On the surface, it just looks like you might need a new radiator and/or the plugs may have been loose.

Your engine would run hot if your bike were running lean, but since it seems you have (more than) enough fuel flying through, I think Yoshi is right in saying you may have other issues.

Since your coolant is disappearing but you didn't mention a leak, is it possible that your coolant is leaking into your engine and burning off?

:huh:

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remember that you cannot get much info from just taking your plugs out and having a shufty. You have to install new plugs, rip it all the way through all throttle openings, pull the clutch, kill the motor and coast to a stop in order to actually read plugs. Although you very well may be rich, those plugs could mean anything in relation to the last time they were used.

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Those are reasonably normal it takes a while or a real good run to burn off the richness from starting on the choke circuit they have a slight tan colour which indicates proper burning ratios . new plugs and a plug chop are the only true ways to check mixtures but it must be done without using the choke as that definitely enriches the fuel mixture ,engine at proper tempertaures .

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No leaks. I installed the plugs last time, and made sure they were tightened to manual specs. Please explain this plug chop procedure.

I did think to check the thermostat, all is working and coolant flows I think I may just be low when it overheats (has only done it twice, just coincidentally it was very hot: 100 deg F +)

130# is not stock (according to manual) 128# front 125# rear is stock for my CA bike.

Plugs are recommended CR9EH9 and gapped correctly.

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Please explain this plug chop procedure.

.

"...install new plugs, rip it all the way through all throttle openings, pull the clutch, kill the motor and coast to a stop..."

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remember that you cannot get much info from just taking your plugs out and having a shufty. You have to install new plugs, rip it all the way through all throttle openings, pull the clutch, kill the motor and coast to a stop in order to actually read plugs. Although you very well may be rich, those plugs could mean anything in relation to the last time they were used.

+1, and you need to read the base of the porcelain inside.

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GL429

in order to comply with equality regulations, I dare you to produce a similar comparison chart for the ladies on VFRD...... :goofy:

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. Please explain this plug chop procedure.

On a carbed bike, 90% on the time you are running on the needle, so that is where the plug check should be done. The way I do it on my carbed bikes is get on the highway with a rest area or exit a few miles ahead, run the bike in whatever gear that keeps the throttle about half open, don't move the throttle too much, and when you come to the pull off of your choice, be careful, don't move the throttle, pull in the clutch and hit the kill switch at about the same time. When the engine is stopped that is when the throttle can be closed.

Pull the plugs.

That will show how each carb is running in the rpm range that matters the most.

Doing a plug chop on a gen five is a real PIA, because of the front two plugs, not sure about the eariler gens.

I suppose if you have set up all four carbs very carefully at the same settings, just checking the rear two plugs will give a good indication of whats happening to all four.

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Unleaded fuel does NOT produce the same colouration as leaded fuel, so the charts you see are nowadays generally bogus. So the perfect tan described in visual effects above is NOT correct.

Almost every plug I have pulled from an unleaded clean burning engine is a pale grey to very slightly brown colour. If you are looking for the mid tan colour as used to be the case for a plug chop on a leaded fuel burning engine & find it, you are either very rich or are burning some oil.

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Ok thanks for all the pointers. I just installed new plugs so I will take a plug chop today. The front right requires complete removal of the radiator with my wrenching setup so it may not come out.

Unleaded fuel does NOT produce the same colouration as leaded fuel, so the charts you see are nowadays generally bogus. So the perfect tan described in visual effects above is NOT correct.

Almost every plug I have pulled from an unleaded clean burning engine is a pale grey to very slightly brown colour. If you are looking for the mid tan colour as used to be the case for a plug chop on a leaded fuel burning engine & find it, you are either very rich or are burning some oil.

So are you saying this is incorrect?

Another peculiarity with this bike, the temp gauge sits just in the range right above C 90% of the time. Unless I ride very hard (even my track day it didn't get close to H) or it is very hot outside will it get above that.

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Mohawk is from the UK and they may have different fuel additives ,ours will be a light tan colour even the ethanol stuff will give a slightly lighter colour . I have changed a lot of plugs and their colours are all over the place due to driving styles, fuel delivery and engine state of tune .Good luck !

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" So are you saying this is incorrect? "

Yes from my experience.

"I got all this from a Free hand out I recieved from NGK Spark Plugs back in 1977" So in 1977 that was normal for leaded fuel as noted in the brochure page re lead deposits.

From the pics suplied in that brochure, the leaded "Tan" look is best in pic 14 & I've seen results when we had leaded fuel between 13-16 in good engines.

But since unleaded cam e to be the norm here, most plugs look like 19-21. The fact that most unleaded engines run quite lean for emissions complience is one reason for this & the other is that no lead means a lighter colour on the plug insulator.

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