spark plugs

My XJ 550 seca is running the stock spark plug. I have an aftermarket exhaust on it and it is running rich. Is there a non resistor plug that is hotter and will this help if the bike is running slightly rich? Could the aftermarket exhaust be making the bike run richer? I have been over the carbs and had a local shop clean, put in original jets, and sync them. I am still having black smoke. I checked the valves and re-shimmed them and they are in spec.
A friend told me that he had a bike blowing black smoke and hotter plugs solved it.

 

Are the plugs showing rich? sooty, dark?

Sounds like a compression check is in order, you may have rings that are needing replacement. If it runs smoky all the time, then rings may be bad. If you only get smoky on startup, then valve seals may be bad.

In my understanding, if you were running so rich that you had black smoke coming out, then you'd soot up the plug(s) and probably not be running for long. If it's still running pretty well, then it could be rings.

Again, compression check should help you troubleshoot.

 

If anything the exhaust should lean it out a bit.

Condition of air filter?

How about this thing? http://xjbikes.com/Forums/viewtopic/t=31872.html

Another really good possibility is float levels. The spec in the Mikunis is only +/- one millimeter, and if they're set too high you'll run rich. If the shop missed this then it could be the cause. Wet-verify that they're in spec.

Also, the seals in the ends of the enrichment plungers should be inspected to ensure they're still there and able to do their job.

As above, what do the plugs look like (the standard NGK D8EA?)

 

Thanks, I will check for the pod filter, I didn't know it existed and I will check air filter or maybe even just go ahead and replace it even though it looks pretty clean. The smoke is black, I have not worked on bikes much but with autos if the rings are bad it would show up as white smoke. If filters don't work I guess I will check the compression on the cylinders, however it is all of the cylinders not just one. They are all getting the black sooty spark plugs equally. If these don't work I will check the float levels and the enrichment plungers. I just wanted to avoid taking the carbs off the bike, again.

 

Wait... are you running airbox or pod filters?

 

air box.

 

The pod filter reference came from the link that was on Fitz's comments. It lead to a post about a small air inlet in the air box that has a small filter that they were calling a pod.

 

OK... thanks for the clarification.

Did the shop just bench sync the carbs, or did they sync them to the bike????

 

They told me they sync them on the bike.

 

They may have. I'm still thinking float levels or enrichment plunger seals.

Let's see what those plugs look like...

 

Good call on the color of smoke. I wasn't thinking that hard yet =). One can also tell the difference in the smell, if it's oil / gas / coolant ( cars, LQ bikes ).

Sounds like you're on the right path, good luck.

 

I had time today to check out some of the things that you suggested. When I took the carbs off to check the floats I found out that the guy who had worked on them had put in 115 main jets instead of the 112.5. Could this be the whole reason that the plugs are fouling? I am ordering the correct jet size and I know it has to help.

 

Yeah, that would definitely do it. Trust, but verify when having someone other than yourself work on the bike.

 

Going up 2 sizes on the mains is a "recommended starting point" for a bike equipped with a stock air box and aftermarket, 4-1 pipe.

But it also depends on the pipe. What aftermarket exhaust do you have?

 

I am not sure of the type of muffler but when I get home this evening I will check it and let you all know. Thanks for your help. I feel like it is getting real close. I rode it for a few miles and it runs OK but it is using too much fuel and the plugs are still showing it is running rich. They are all about the same. I will try to take a picture of them next time I take them out and post for you.

 

is it just a non-stock muffler (headers and collector still intact)?

 

The exhaust is a 4 into 1 and the name on the exhaust says Kerker systems.

 

Ahhh. There we go.

Ouch. At least it's a quality part.

Does it still have the baffle in it or is it wide open? (I had one of these...)

 

I know this seems silly, but the way you word it, makes it sound like you had the carbs synced THEN checked and reshimmed the valves....which would throw the carbs out of spec....right?

 

This is also how I understood the story.

 

It sure would. That's why valves come first.

 

Sounds like I need to start over on the carburtors. The bike is running and seems to run well above 3000 rpms. I think that this means it is a problem with the pilot circuit. The carbs are clean. If it is fouling plugs at idle and I have the correct pilot jets in would it make sense that maybe I need to replace the parts of the pilot screws, such as the o-ring, washer, and spring or should I replace the screws also. They look fine but it doesn't seem to make a difference whether they are out 2.5 turns or at 1/2 turn out. What is the order of checking the carburation. Float levels first, set idle, and then sync.

 

If the pilot screws make no difference between 2.5 turns an 1/2 a turn out, then there is more that needs cleaning. Pull the pilot screws, replace the o-rings, and flush out their passages/ensure they are clean.

Float levels need to be precisely wet-set.

Pilots all at 2.5 ~ 3 turns out.

THEN you do your running vac sync.

 

I will need to put together a vacuum set up. What range will the vacuum be in. I have access to some vacuum gauges at work that are in inches of water and I think they are 0 to 30. I can get some other for higher vacuums if needed.

 

Sorry it took so long. Here is a picture of the spark plugs after about 30 miles. These plugs are the D7EA instead of the D8EA as they are suppose to be hotter.