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Installed a new air filter…bike runs like crap now.

6K views 36 replies 18 participants last post by  h13man 
#1 ·
So, I'm sure this is a simple a/f adjustment fix, right?

I installed a new air filter (genuine Honda part purchased at my local dealer) in my '86 VT500 last night.
Got on to ride this morning and the bike hesitated, sputtered and overall ran like garbage on my morning commute.

Tell me this is an easy fix… :wink2:
 
#3 ·
Just checked everything in the bright sunlight. Nothing appears to be awry. Installation is literally a 1 minute job.
I'm just suspect that the old filter was badly clogged and new filter is, well, new and requires a mixture adjust in order to work properly.
Up until last night, the bike had been running great w/ no hesitation at all.
I guess I could put the old filter in when I get home and see what happens...
 
#5 ·
So, any ideas why a brand new OEM air filter change would make a decent running bike run very badly?
 
#6 ·
Happen chance??
But a new air filter shouldn`t cause this problem...
I`d be double checking everything I touched changing it...


EDIT>>
YES, put the old one back in and see though????
 
#7 ·
Anything is possible.. With that said, highly doubt the new filter "caused" this. I would really take a look again, very slowly and methodically check around, It really sounds like something just got knocked loose or simply fell off. Over thinking simply cost money and time, KISS first.


Mark
 
#8 ·
I'll definitely give it another close inspection, but the only thing in the area of the air filter is what looks like a small drain hose that passes by the lower screw.
I did notice that the new filter looks to be oiled…or packed in oil? Is this normal?
Maybe I'll give the dealer a call to see what they think...
 
#9 · (Edited)
Since the Honda filters are paper element, that SHOULD not have been the case! If it was a UNI filter it still should have been dry with you putting a light coat of filter oil on it but packed in oil!? Wow, does anything is possible bites back here!


Mark
 
#12 ·
That's the plan when I get home.
I called the dealer and talked to both the parts guy and the service guy and they're both at a loss…said it should run better, not worse.
Service guy did say that maybe a small piece of dirt got loose and is now stuck in one of the carbs…maybe, maybe not.

So the plan is to limp it home and then swap filters. If it's still bad then something else is going on and I'll try some Seafoam in the fuel.

btw: I checked the carbs and it looks like the a/f screw covers were never drilled out, so they haven't been touched at all.
 
#13 ·
:shock: ...How filthy is the old filter? .. Had it ever been changed? ..If it's completely clogged and some guy had been monkeying with the fuel to compensate, then installing a brand-spanking-new high flow filter will create under-fueling issues..

I assume you have installed something like a K&N filter which can be cleaned and oiled? If you think the filter is saturated with oil, clean it.. lots of YouTube how-to's out there which can walk you through the steps.. Can't imagine that being the issue, But, stranger things have happened..

But! ..If it were me, I would do what Jimbo suggested, replace the old filter - to see if the bike picks back up.. If it does.. then carbs might need adjusting..

If the bike was running fine with a clogged filter before, then it can run Better with a new, clean filter.. Just needs work re-checked to make sure there are no loose seals, or maybe otherwise ??? .. the carbs... ??

When I changed out the filter in my Vic, they advise you stuff a clean rag into the opening to prevent anything falling into your air-intake..

So ...Check for rags too!! ;) .. :mrgreen:
 
#17 · (Edited)
Seems logical that you have the wrong filter, the cover/box isn't seating all the way, or something related. A gasket not seated right ?

Did you possibly add oil to your crank case too when you changed the air filter ? Over filling the oil has been known to pool crankcase oil in the air filter box area via crank case breather tube. (Not sure on your model) Long shot I know, for your whole filter to be oily it would have to be an awful lot of overfill tho.

Filter upside-down ?

Sometimes a part winds up in the wrong box before the consumer buys it. Your dealer can compare them easily enough.
 
#18 ·
Update: I put the old filter back in this morning. The bike rode like a champ w/ no hesitation, no bogging, no nothing but great acceleration.

To answer some questions: the old filter is dirty, but I guess not too horrible because the bike runs fine. The "oil" on the filter is apparently only on the outside of the metal casing that screws to the air box, so there shouldn't be any oil in the filter itself. I don't know about other Shadows, but it's virtually impossible to install the VT500 air filter incorrectly. It literally fits 1 way and 1 way only and it's obvious if it's not properly installed.

Now here's what's interesting: the attached picture is what the new filter looks like. My old filter looks similar, except that it does not have the perforated metal screen around it. It's just the corrugated filter w/o the screen.
Maybe there's an issue w/ that screen being there?

I intend to ride the bike down to Powersports East today and let them see the difference between the two filters and see if they have any ideas.

Thanks for ALL of the great responses so far. Being a motorcycle newbie, I'm really learning a lot quickly thanks to the help of the great folks on this forum. :)
 

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#19 · (Edited)
Well, obviously something is different. The screen on the filter is not enough to restrict the air flow. Glad to hear the bike is running well and keep us up on what your dealer has to say. I wonder now if you didn't have a high-flow filter in there and the stock filter is just too restrictive.
 
#20 ·
Bad filter??
HMMM!!!
I had the wrong oil filter in the correct numbered box once...
I check them since that episode...
Might try another replacement filter???
You got the right ones looking at it later today, HOPEFULLY FREE of charge, since the replacement ain`t right>???


Good Luck & let the peanut gallery know your outcome...
Please,
D
 
#21 ·
So, the folks at the dealer said the filter with the screen is the correct one and it supercedes the old filter w/o the screen. It should be a drop-in and go procedure, but for whatever reason the bike now runs lean, so a quick adjust of the a/f mix should correct it.
What I think I'm going to do is go buy some spark plugs, too, and wait for my next sunny day off and do a full tune up, drilling out the adjust screws and everything and see how it runs then.
In the meantime, I think a can of Seafoam is probably not a bad idea for the old girl...
 
#22 ·
Hmmm....these bikes are lean to begin with, but if your AF screws aren't even drilled out, it shouldn't be lean enough to cause this much trouble from a new air filter.

IIRC - there is a gasket at the base of the filter so all of the intake air must flow through the filter. Maybe that wasn't seated?
 
#23 ·
Considering factory A/F setting and you still have stock filter and stock exhaust I would not drill out Pilot screw. I think you may have dislodged some contaminant when you removed old filter and that needs to be cleaned. Try seafoam first and see. Otherwise you may drill out and adjust forever as the contaminant/debris changes.


G.
 
#24 · (Edited)
Not sure if anyone has mentioned this yet or not, but the A/F screws only affect IDLE, and don't do hardly anything for normal operating parameters. Adjusting them will do (next to) NIL for how the bike will drive.


I'd have to agree with everyone else, obviously SOMETHING is wrong, but I doubt it's due to a proper filter change.


I know, it shouldn't need to be said, but did you install the filter the right way? If it's like I believe it is, there's an opening on one side while the other side is solid. If you installed it so that the solid side is against the inlet for the carburetor, I'd be surprised if it would run at all.
(I know, it's a long shot, but I've seen guys struggle with a bike that wouldn't start, only to find out that the kill switch was off. :wink2:


Choke isn't stuck on, is it? Fuel pump? Fuel valve? There's a reason, and I've usually found that if they creep up quickly and unexpectedly after a simple maintenance, they're typically a simple fix, just not simple to locate sometimes. Good luck!
 
#25 · (Edited)
I'm with the above.....don't fix anything that was right before the attempted filter change. I still think the "oily filter" is the suspect, or there is a gasket missing at the base of it, faulty from the factory, something. Running right with the old one is proof enough to me. Not gunk down in it, not rich/lean, not filter in the tank, not plugs, not clamp holding air box on etc..........they all doing their job when the old filter is there right ? Can only be the new filter or how it fits in.

Go online and to the various motorcycle parts guys.......they got pictures usually of the factory type filters , see if they match.

"If it ain't broke, don't fix it." does apply here. Still. Go get one of the origional filters and see how it acts. Chances it will be right as sunshine, save you lots of hassles, and give you good reason to get your money back on the "new and improved" version. I've never had a filter that was blocked or partially, but you never know.

@smilie's theory of high flow filter makes really good good sense at this point too, but if you have compressed air, blow the old one out so you can feel good about it and ride on at least till you find one like it.

And @jwinker 's theory of no gasket in place sounds real too. Very easy for a nice little gasket or ring to go missing out of the box.

One other thing I learned in my 70 years of keeping small motors doing what they are supposed to do : not all dealers and mechanics are built the same. Not all parts come to you right, even if the box says they are. These guys don't know the history of your bike right ? Did any of them ever work consistently on a bike of that year and model ?

Did you show them the new one you have and they match it with another right out of the box ? At this point nothing much else would convince me.
 
#27 ·
On your air filter, install weather stripping in a circular pattern, around the smaller end. There is a trough there that should be filled by a factory gasket that has since been discontinued. I had this exact problem on my bike which is one year older than yours, same engine. It's a $5 fix and I also installed some as a gasket around the inside of where the filter screws on. The bike has never run as good as it does now!
 
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