Higher-flowing filter in stock airbox to help slight richness?

[t3rmin]

Ok I'll just say up front, spare me the "pull off the carbs and fix it right"! ;-) I know what I *should* do -- this is about what I can "get away with". ;-) Humor me, ok? :-D I'm quite capable of pulling the carbs and adjusting the floats, but, having done it several times, I absolutely *LOATHE* getting the carbs back into the airbox boots...

Anyway, I've got a slight low end richness which results in gradual plug fouling. Probably the effects of minor float height mis-adjustment. I was wondering today whether switching to a UNI or K&N filter (I'm running a stock filter now, AFAIK) might be an OK work-around for it. The theory being the slightly higher air flow may lean the mixture out a bit. Word is you can run a K&N or UNI in the stock airbox without rejetting, even though they do flow a bit more. This sounds like it might be just the thing.

So the question is: do the K&N or UNI filters actually flow more? If so, which one is least restrictive? Am I completely off my rocker or might switching air filters actually have a positive affect on slight richness?

 

[nabrams]

When you say "foul the plugs", I assume you mean they eventually get to a point where they won't fire anymore. I'm guessing you wouldn't care too much if the plugs keep on doing the job.
So: If it was just a "slight" richnesss it would not foul your plugs to that degree.
If it's that bad then it's doubtful that you'll get an air filter that will solve the fouling and at the same time not be too free-flowing for all RPM ranges.
Is it all plugs fouling? If it's just some, then it could be electrical (coil, wires, caps - see other posts) or just the carbs for those cylinders.

 

[t3rmin]

Yeah they all foul pretty evenly, but it takes some time. It seems to be mostly low end -- i.e. I've noticed they foul more quickly if the bike has spent a lot of time at idle or low speed running. Eventually it gets to the point where one or more don't fire.

The bike isn't blowing smoke and is running fantastic. Even has good gas mileage. The ignition system is functioning GREAT. New Dyna S., good coils, +12v feed direct from battery to coils via relay, new NGK boots. It'll jump a good hot spark 1/2 inch or more.

I've got stock exhaust and intake and clean-as-a-whistle, freshly-rebuilt carbs with stock jetting.

I do believe it to be a "slight" richness, considering the above, which is why I figure a slight leaning via more airflow might help. The carbon buildup is gradual and the plugs don't look horrible when they come out -- just fouled enough to cause spark trouble. It does not appear to be oil fouling. And according to the best CV carb tuning info I've ever seen:
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html
... it would appear likely the float levels are a little off.

I may or may not try the less-restrictive air filter thing, but it was just a thought I figured I'd throw out there. Can anyone speak to which is less restrictive: the K&N or the UNI? The UNIs are under $10...

 

[tkent02]

Have you tried running it with the airbox lid open ???

Have you tried running it with the airbox lid open ???

Don't know how the airbox is made on your model, most of them you can open the lid and see how it runs with more airflow.

But it sounds like something is amiss inside, if so it would be better to fix it than to do something else wrong to cover for it.

Two wrongs don't make it as right as it should be.

Are the pilot screws and idles mix screws adjusted properly?

Perhaps the choke is not shutting off completely?

Perhaps you have incorrect spark plugs which are a few heat ranges too cold?

Could be something else, these just popped off the top of my head.

 

[t3rmin]

Thanks for your reply.

Don't know how the airbox is made on your model, most of them you can open the lid and see how it runs with more airflow.

Hey that's right. I'll have to ride around without the lid for a while and see how it goes. Good call.

But it sounds like something is amiss inside, if so it would be better to fix it than to do something else wrong to cover for it.

Two wrongs don't make it as right as it should be.

Well if air/fuel ratio ends up closer to the mark such that plugs stop fouling, I'd be happy. Don't really care if technically the floats are a teensy bit off. Theoretically if the airfilter evened out the mixture it could even be making slightly more power...

Are the pilot screws and idles mix screws adjusted properly?

Perhaps the choke is not shutting off completely?

Perhaps you have incorrect spark plugs which are a few heat ranges too cold?

Could be something else, these just popped off the top of my head.

Mixture screws are set well; could possibly be leaned out a bit more, but they're already clamped down somewhat to compensate for the floats. ;-) (I know, I know, but I absolutely **HATE** putting those carbs back on! ;-)) Carbs have been vacuum synced also. The bike idles smoothly and all 4 pipes heat up equally.

Choke is definitely moving freely and fully releasing.

Plugs are correct NGK D8EA's, but going up to the next heat range *would* probably keep them from fouling. However, that is one "hack" I'm not sure I'm comfortable with. Before I did that I'd mess with the floats. Evening out the mixture with more airflow is a slightly more sensible workaround, IMHO.

 

[salty_monk]

My bike had NGK 7's in it when I bought it. Maybe he'd had similar problems in the past. It had a carb tune just before I bought it.

I could see they were too hot for it by the plug colour when I pulled them out after aroun 700 miles of use but sounds like it could sort out your problem nicely if you're after an easy "work-a-round"

Dan

 

[Guest]

Try turning your idle mixture screws in a 1/4 turn each and see if that helps. Unless of course you only have them out a 1/4 turn:shock:

 

[nabrams]

Maybe the filter in there now is over-oiled? Is there something else restricting airflow?
My experience has been that until you find the actual problem you don't really end up solving it.
Trying a different filter for a while is definitely a cheap experiment worth trying.

 

[GS850_Coug]

I'm thinking that adjusting airflow using the filter to fix a low-rpm issue will just throw you out of whack at higher rpm. You will then be flowing too much air, causing lean at higher rpms. For me, this would be a must not. High RPms=more heat; lean condition=more heat. Lean+high RPM=too much heat. Bad idea to me.:-s

 

[t3rmin]

Maybe the filter in there now is over-oiled? Is there something else restricting airflow?
My experience has been that until you find the actual problem you don't really end up solving it.
Trying a different filter for a while is definitely a cheap experiment worth trying.

Well I did oil it with regular motor oil, but I sopped it completely dry with a towel. It's not pooling in the bottom or anything -- it's definitely not over-oiled, I made sure of that. Whether 10-40 is more restrictive than real air cleaner oil I'm not sure...

Yeah I figure it's a cheap/easy thing to try.

And I don't really think there's much of a risk of being overly lean and hot and burning it up with just changing the filter in the stock airbox... Slapping on pods maybe, but even then you hear more about crappy running than burnt up motors.

 

[t3rmin]

Try turning your idle mixture screws in a 1/4 turn each and see if that helps. Unless of course you only have them out a 1/4 turn:shock:

Well they've been turned down little by little over time and it has helped lengthen the lifetime of the plugs. I may be able to squeeze them down a bit more while still having a decent idle, but I think I'm approaching the lower limit as it is.

 

[49er]

I'm thinking that adjusting airflow using the filter to fix a low-rpm issue will just throw you out of whack at higher rpm. You will then be flowing too much air, causing lean at higher rpms. For me, this would be a must not. High RPms=more heat; lean condition=more heat. Lean+high RPM=too much heat. Bad idea to me.:-s

I agree with coug. Don't go for a less restrictive filter. Also, you risk burning a hole through your pistons if you go hotter on the plugs to fix the slight fowling of your plugs.
Bite the bullet and pull your carbs again. If the floats are set correctly and you dont have a leak in them, check the condition of your float needles and seats. If all checks out ok, you will need to reduce the size of your pilot jets. You say you've been screwing the mixture screws in further than you should anyway.

 

[rednutt]

been there done that

been there done that

I also had the problems with my plugs fowling up (D8EA) I rang NGK thay suggested I run DPR8EA and I also sent my plugs to NGK to see if its me or if thay realy are braking down.Thay are going to test them for me but thay have had them for 3 months so thay must be bizzy (lol).With the air filter you dont youse engine oil you use filter oil it is a bit thinner than engine oil.What I found is that the bike is not a town cruser it is designed for the highway. So if ya gona ride them around town RIDE IT LIKE YA STOLD IT. The plugs last longer then. I was advised to stop being a girl and to stop nursing it.When at the trafic lights give it a slight rev or 2.I love the sound of a 1100 with a 4-1 plus it dose not let the idle foul the plugs...

 

[Road_Clam]

Ok I'll just say up front, spare me the "pull off the carbs and fix it right"! ;-) I know what I *should* do -- this is about what I can "get away with". ;-) Humor me, ok? :-D I'm quite capable of pulling the carbs and adjusting the floats, but, having done it several times, I absolutely *LOATHE* getting the carbs back into the airbox boots...

Anyway, I've got a slight low end richness which results in gradual plug fouling. Probably the effects of minor float height mis-adjustment. I was wondering today whether switching to a UNI or K&N filter (I'm running a stock filter now, AFAIK) might be an OK work-around for it. The theory being the slightly higher air flow may lean the mixture out a bit. Word is you can run a K&N or UNI in the stock airbox without rejetting, even though they do flow a bit more. This sounds like it might be just the thing.

So the question is: do the K&N or UNI filters actually flow more? If so, which one is least restrictive? Am I completely off my rocker or might switching air filters actually have a positive affect on slight richness?

Is your bike bone stock? If so, there should be no reason to be fouling plugs unless you have an issue. Adding a "hi-flow" type filter is simply band-aiding the real problem, and really won't lean out the engine if you have a stock exhaust. How many miles are on this engine? Are you sure your fuel fouling, and not oil fouling? Need more details.

 

[t3rmin]

Is your bike bone stock? If so, there should be no reason to be fouling plugs unless you have an issue. Adding a "hi-flow" type filter is simply band-aiding the real problem, and really won't lean out the engine if you have a stock exhaust. How many miles are on this engine? Are you sure your fuel fouling, and not oil fouling? Need more details.

Yes, it is a bandaid. I think it's obvious my floats set a bit rich. The idea is I want to try to get away with something here! ;-) I've got 22k miles and it is bone stock. Does not appear to be oil fouling.

 

[tconroy]

Well I did oil it with regular motor oil, but I sopped it completely dry with a towel. It's not pooling in the bottom or anything -- it's definitely not over-oiled, I made sure of that. Whether 10-40 is more restrictive than real air cleaner oil I'm not sure...

Yeah I figure it's a cheap/easy thing to try.

And I don't really think there's much of a risk of being overly lean and hot and burning it up with just changing the filter in the stock airbox... Slapping on pods maybe, but even then you hear more about crappy running than burnt up motors.

I can answer that one,i just went through this on my bike.Clean your filter and use the foam air filter oil from Bel-ray.It made my bike run totally different.More air and more power and idles better.I was using regular 10w40 in mine until it started pooling up on the filter and making a mess in the airbox itself.real air filter oil is thinner and catches more dirt.Try that first before anything else.These bikes are very picky when it come to fuel and air ratio mix.Also might want to recheck your float height to make sure they were measured right.Did you measure with or without the gasket?That makes a big difference.

 

[JMHJ]

My experience has been that until you find the actual problem you don't really end up solving it.

An excellent observation. You could apply that to just about anything.

 

[tconroy]

An excellent observation. You could apply that to just about anything.

the problem is not the air filter.The problem is something else that needs to be found and fixed first.The plugs will tell the story.

 

[KEITH KRAUSE]

Compensation jetting never works, just creates different problems.
Your mixture screw adjustments prove a problem exists. I'd never oil a gauze type filter with motor oil.
I know you don't want to touch the carbs. Have you at least proven the electrical system is operating correctly? Timing spot on at both idle and full advance? Coils show correct resistance? Solid/clean connections throughout? Correct gap at the plugs?

 

[t3rmin]

Compensation jetting never works, just creates different problems.
Your mixture screw adjustments prove a problem exists. I'd never oil a gauze type filter with motor oil.

Yep. As I said, I've been sure all along that the floats are a little off. ;-)

I know you don't want to touch the carbs. Have you at least proven the electrical system is operating correctly? Timing spot on at both idle and full advance? Coils show correct resistance? Solid/clean connections throughout? Correct gap at the plugs?

Electrical is great. Fat spark and spot-on timing and advance. Entire ignition has been re-done this year and is working perfectly.


Sheesh -- I should know better than to propose any kind of a "workaround" on this forum! Everybody's very "by the book", but that's OK. ;-)