Problem with carbon fouling on my spark plugs

[jtascone]

Hello all. I have an 08 Nomad 1600. Bike has 23,000 miles on it. Mods completed are V&H Dual baggers and Kuryakyn Pro Hypercharger, all epa plumbing removed and coasters installed, Dobeck TFI installed, and I installed NGK DPR7eix-9 Iridiums. After a year of fine tuning the Dobeck to get the best mix of smooth idle/acceleration and minimal pinging, I now have my final settings of 2:45, 5, 1 and 9 on the TFI. I can get a little higher and smoother idle at about 2:30, but it pings pretty bad on acceleration under load in 4th and 5th gears. I can get zero pinging at 3 on the TFI, but mileage drops considerably and idle is not nearly as smooth. My problem is, I installed the Iridiums 7000 miles ago, and upon checking them today, there is quite a bit of carbon fouling on them. I'm guessing because I'm actually running at a richer setting than I should to keep the pinging down. Do I have any other options? Should I try a hotter plug? If so, which one? Should I just forget Iridiums and run the stock DP6ea-9 as it's a bit hotter? Should I drop the Dobeck back down to 2:30 to lean it out a little and live with the pinging? Or should I be happy knowing it's running well and just accept the fact that plugs are going to have to be replaced often? Any and all suggestions would be greatly appreciated.

[ldhthept]

Can’t the plugs just be cleaned and not replaced?

[jtascone]

Yes I cleaned them as best I could. But I was told that the tips on Iridiums are very easy to damage. What can I clean the electrode with to keep from damaging it? And if the plugs are carbon fouled, what can I expect to be happening to my cylinder walls, rings, etc.?

[BrokeAss]

Are you using Premium fuel as required?

[MAS Tequila]

If you don't ping with regular fuel, you don't want hi test.

The higher octane rating cools the fuel charge to keep it from detonating early, pinging.

If you run a higher octane than you need, you WILL get carbon buildup due to the fuel not burning completely.

Just wait until you pull the heads someday.

[jtascone]

Thanks for the info! I will definitely try some lower octane to see if that helps. I normally run either 93 octane or 90 non-ethanol. I'll try some 87 or 89.

[jtascone]

So I swapped out the plugs for brand new ones. Took the bike on a nice long ride and then re-tuned my pot 1 on the TFI following instructions exactly. Achieved the highest rpm at about 2:50. That's actually a little RICHER than where it was. Zero pinging now even with 87 octane. My only worry now is that the plugs will actually carbon up even faster at the richer setting on the TFI. I also did an oil change, and there definitely is a slight gas smell to the oil that I drained out. Hoping there isn't a bigger problem around the corner here.

[jtascone]

As I said, I put brand new plugs in her this morning and a fresh oil change. Old plugs are carbon fouled and oil definitely smells like gas/oil mix. I swear I could start my chainsaw with it ��. But the bike literally runs PERFECTLY. I took her on an 89 mile ride today in 93 degree heat. Mixed ride of hills, back roads, highway and city. She performed flawlessly. No pinging, zero misses/hesitation of any kind, zero pop on decel, absolutely perfect. Filled up when I left and filled up when I got back. 89.1 miles took 2.222 gallons so I'm getting just over 40mpg. Don't know how signs can show the bike running rich with that kind of mpg. That's actually better than most list on here. I guess I will just stop worrying and ride it. If anyone has any ideas as to why the oil smells so badly of gas yet everything seems to be running flawlessly, please let me know. Thanks again

[BrokeAss]

With a Gadget intake, Dobeck tuner, and Cobra PowerPro exhaust my 1600 MeanStreak absolutely required premium. Book calls for 91 octane minimum stock. I'd sometimes rotate filling with 93 and 89 in the hopes to make a 91 average mix in the tank, but when it's hot like today it was premium only. Never fouled a plug in 31000 miles of ownership.

[andyvh1959]

If you are getting 40mpg that is pretty good. I bought my 2003 Classic with 26000 miles on it and it has a Power Commander, V&H Bigshots and Baron intake, and all the smog stuff is gone since I 1st got it. Plugs look good, no pinging, but I am lucky to get near 40mpg. Check/confirm the crankcase venting on your bike. If the crankcase is not fully venting (and these big twins pump a LOT of air into the crankcase) it usually means oil mist from the crankcase gets into the combustion chamber. So the sheen or dull aspect of the fouled plugs also matters. Oil fouling plugs are usually shiny black. Gas fouling plugs are usually dull black. Good info here on hotter/cooler plugs:

https://www.ngk.com/what-is-a-spark-...20tip%20hotter.

Gas smell in the crankcase oil is not normal unless the same oil has been run in the engine for 10,000+ miles. If you have some one do a LEAK DOWN test on your bike it may indicate if a bigger issue is the cause. A leak down test can prove out the rings, cylinder walls conditions better than a compression test. For instance, a leak down test may show good results with the piston on the compression stroke at top dead center, but then show excessive blowby at mid-stroke on the power stroke. That may indicate a scratched/scored cylinder wall, or rings near their service limit. Also a leak down test can prove if either or both cylinders are the source of the issue.

It may give you bad news, but it will give you specific results if other engine work is required, or not required. That in itself can direct your actions to run the bike as is, repair the bike, or perhaps time to replace the bike.

[jtascone]

That is great info! I'll call my indy today and see if he can perform a leak down test on my bike. Bad news or good, at least I'll know! Thanks!

[andyvh1959]

Good luck and let us know the results. Not all mechanics have a leak down tester. But in my opinion a decent professional mechanic should have one. I not a trained mechanic, just a home wrench that learned a lot over the decades. I made a leak down tester for myself and it has helped diagnose engine issues a couple of times.

Now, your bike with only 23,000 miles on it should not show any abnormal leak down results. These Vulcan engines are known to go easily 100,000 miles without issues a leak down test would justify to prove or disprove. But considering any work on the 1600 engine practically requires pulling the engine from the frame, a leak down test may clarify that internal engine work is needed. Some say do a compression test, but that only says the engine is or is not making good compression. It really can't pinpoint why compression is low. A leak down test can indicate what characteristic of the engine, intake valves, exhaust valves, rings, valve guides, scored cylinders may be the cause of the issue.

[jtascone]

Ok, so I took a long 200 mile ride today in temps close to 100 degrees. Upon returning home, I decided to take a quick peek at one plug from the rear cylinder and one plug from the front cylinder. Front cylinder plug is as perfect as can be. Rear one has black sooty carbon buildup as expected. I also noticed at idle, that the exhaust pipe coming from the front cylinder smells just like it should, while the pipe from the rear cylinder has a strong fuel smell to it. So, only the rear cylinder is running rich. What would/could cause this? And would it help to run hotter plugs in the rear cylinder? I am running DPR7EIX-9 Iridiums. What would be the next hottest plug? Thanks

[jtascone]

By the way, I have an appointment for a leak down test. Couldn't even get in til the end of August.

[andyvh1959]

A hotter plug, by definition retains more heat in the plug tip and transfers less heat to the head of the cylinder. So it may help some to clean the plug tip, if it doesn't create other issues in the combustion chamber. You can try one heat range hotter but make sure to also listen for pinging/misfires as the fresh air/fuel mix gets in the combustion chamber. A hotter plug may retain enough heat in the tip to cause pre-ignition of the air/fuel mix.

https://ngksparkplugs.com/en/resourc...event%20occurs.