Confession time: lost an air filter - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 28 (permalink) Old 08-11-2018, 08:44 AM Thread Starter
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Confession time: lost an air filter

OK, you're gonna get a kick out of this story. I don't want to tell it, but I might have really screwed up here. It's yet another story about the impatience of wanting to ride overtaking the knowledge that even the unexpected problems must be met with the right solution.

TL;DR: I crammed an air filter screen into the intake in a ball, and I want to know what the most likely outcome of this was, now that the screen is missing. Oh, the title of this should be "lost an air filter SCREEN", actually. Too late to change it now.

So, as some of you know, I struggled with getting my bike started for a couple of days in a row, and it turned out to be an AGM battery that went bad, after only a month (I got it replaced on warranty). That's a weird enough story, but hold on.

While assuming that it had to be anything else, other than the battery, I did a lot of things. One of those things was a carb backblow. The first step in that procedure sounds like it's saying to remove the air filter cases (ears) if you have them. I finally decided that it must really be about the carb vent tube, which comes out behind the right ear only, so I only removed the right ear.

But there's the rub: I removed the right ear completely. Meaning I took it off the rubber duct. And the rubber duct is a TIGHT fit to get back in, but of course, since it's really flexible, it's not the end of the world, once you know how to do it.

But here's the beginning of my problem: Once when I was taking off that right ear, I thought I needed to remove the bolts that secure the air filter, so I did (that's another reason to read up on these things before, instead of guessing). When I put those bolts back in, I must have done it wrong (too tight into the plastic or whatever), because now those bolts won't come out. And the fact that they won't come out prevents me from being able to remove the air filter from the air filter case.

I am assuming that the only practical way to get the duct back into the air filter case, once the duct is installed in the bike, is to PULL it from the outside, with the air filter removed. Because I certainly have no chance of getting any leverage on that duct, to be able to PUSH it into the back of the case. Heck, there's not even enough space for my hand.

By the way, the ear shave mod is definitely in my near future. Heck, it might even have to be today.

OK, so I put my bike back together after the battery fiasco, and wanted to take it for a test ride and make sure everything seemed fine. But I tried and tried to get those air filter bolts out, to no avail. I tried for a long time. I even considered cutting them off with an angle iron, which of course meant that I would likely damage the case and have to buy a new one, but desperation had sort of set it. I was also concerned that the angle grinder would catch the air filter on fire, or at least melt it. So I didn't consider that for very long.

So I have to be able to ride the bike, right? (first lie) And I'm responsible, right? (second lie, I guess) so I'm not going to run the bike without an air filter. That would be crazy.

So the obvious solution: Wad the foam air filter SCREEN (which can pop right off the bolts) into a ball and cram it into the hole where the duct goes. It will sit there and filter the air (maybe a little too much... one can't be sure). Maybe it will pop out while I'm riding (and heck, maybe it did), which of course negates the whole "won't run without an air filter" thing. Maybe it will get sucked into the intake and go into lord-knows-where (though I think I know -- the carb).

"But it will probably be fine, at least for a short test drive," I told myself.

So, I did take a ride. It wasn't long, but it wasn't just around the block at 20 mph either. I got up to speed and was out for 30 minutes or so. I even forgot that I had this "workaround" in place.

Fast forward to today. I got up early for a nice morning ride. I'm looking around the bike and I see the missing ear. "Oh yeah," I thought. "That."

So I check to make sure the balled-up air filter is still there, and it's GONE.

OK, I'm not a complete idiot (yeah, okay -- that's debatable at the moment). Clearly I'm not going for a ride this morning, and probably not until I get a new air filter screen, and perhaps an entire new air filter case and filter (or just do the ear shave and buy whatever filter I need for that).

But, of course, my situation could be much worse. What is the likelihood that the air filter was EXPELLED from the opening, and just ended up on the street. That's bad, because I ran the bike without anything in there at all, but it was a short time and it's probably not that big a deal.

A more likely scenario is that the screen was sucked INTO the intake (since that's the whole point of the intake), and one of two things happened: First, there's something in there that the screen is just resting against, because it's too big to be sucked in. So it's still doing what I asked of it (even though it was a stupid thing to ask), just in a harder-to-get-to place.

Then there's the scenario that concerns me more, which is that the screen got sucked directly into one of the carbs, at which point I'm not sure what may have happened. But it seems likely that it's just sitting there in the carb, not able to be broken down and "digested," but not able to be removed either. And it's just going to make the performance of that carb worse and could even damage the carb (and may have already).

A less likely scenario is that the air filter has not only disappeared, but it has been fully and completely digested by the bike, and has already left (in some form) via the exhaust pipe. I don't think it's likely, but it is a bad-ass thing to imagine -- that the Beast just chewed right through it without a thought.

I will say this: I took off last night when a light turned green. I wasn't hot dogging it, but I was "being a motorcycle" and getting gone at a decent clip. And as I cranked through the gears, I heard this sound and felt this sensation that I haven't experienced before. It's hard to describe, but if you told me it was the sound and feeling of an air filter screen going being chewed up by a carb and expelled by the exhaust system, I wouldn't say it was inconsistent with that. It was a sound and feeling that concerned me momentarily, but it was over as soon as it started, and everything else about the ride was inconsequential.

I think I know the answer, but I don't like it. You guys can help me confirm it:

I had already assumed I would be taking my carbs apart this weekend, when I couldn't figure out why the bike wouldn't start (before I realized this new AGM battery was failing). Once I replaced the battery, I breathed a sigh of relief that I wouldn't have to get into the carbs.

However, given that I did this stupid thing, if there's a decent chance that it got sucked in somewhere it's not supposed to be, and that it's still there, then I need to inspect until I find it. Starting with the big plastic air intake (which I understand may require removing the engine?), and if I don't find it there, then pulling the carbs and taking them apart to look for the screen, assess damage, or both.

Or maybe I'm overreacting, and the screen was OBVIOUSLY expelled out during the ride at some point, or it was OBVIOUSLY sucked in and consumed readily by The Beast, and I'll never see or hear from it again.

In any case, riding the bike right now sounds like a bad idea, because I don't know where that screen is (and that screen isn't, by itself, adequate filtration anyway).

I hope you will take into consideration my honesty as you consider what chastisement I deserve. I throw myself upon the mercy of the forum, and hereby nominate myself for the Hall of Shame, in the Impatience category.

Last edited by readparse; 08-11-2018 at 08:45 AM. Reason: Added TL;DR
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post #2 of 28 (permalink) Old 08-11-2018, 09:05 AM
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But here's the beginning of my problem: Once when I was taking off that right ear, I thought I needed to remove the bolts that secure the air filter, so I did (that's another reason to read up on these things before, instead of guessing). When I put those bolts back in, I must have done it wrong (too tight into the plastic or whatever), because now those bolts won't come out. And the fact that they won't come out prevents me from being able to remove the air filter from the air filter case.

.
Over Tightening the air filter bolts isn't uncommon. What ends up happening is that the nut that's inside the plastic post starts turning inside because it's over tightened. This happened on one of my project bikes and I was able to get in behind the opening and put a vice grip on the inside of the filter box to hold that nut and get the bolts out. You can see what I mean on this pic. Click here

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post #3 of 28 (permalink) Old 08-11-2018, 10:08 AM
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I'd say the 'screen' probably just fell out. It's not a straight shot through the carb. First obstruction is the slide and needle, second is the butterfly. So if it's not hung up in the first 2-3" of the carb throat (should be able to touch it), it most likely fell out.

If caught under the slide, and around the needle, the engine would probably start flooding out on that cylinder due to air restriction and the slide being propped up.

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post #4 of 28 (permalink) Old 08-13-2018, 01:59 AM Thread Starter
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Over Tightening the air filter bolts isn't uncommon. What ends up happening is that the nut that's inside the plastic post starts turning inside because it's over tightened. This happened on one of my project bikes and I was able to get in behind the opening and put a vice grip on the inside of the filter box to hold that nut and get the bolts out.
Good advice. Thanks. I just gave it a shot, and I wasn't able to make any progress. I assume your vice grip was applying pressure to the outside of the top of the post, which is where that nut is. It can't make direct contact, with the nut, right?

I wasn't using vice grips, but I did use my go-to wrench. I didn't get the grip on the nut that I need, but I also wasn't completely sure that I was doing it right. I have to vice grips around here somewhere. I'll see if I can find them.
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post #5 of 28 (permalink) Old 08-13-2018, 11:37 AM
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Sounds like a perfect excuse to do a full earshsve.

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post #6 of 28 (permalink) Old 08-13-2018, 12:37 PM
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You can use a green scrubbing pad with a little oil on it over the intake for a filter and it would be fine until you get something better. Unless you are groven down dirt roads or in the rain you would be fine.

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post #7 of 28 (permalink) Old 08-14-2018, 01:49 AM Thread Starter
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You can use a green scrubbing pad with a little oil on it over the intake for a filter and it would be fine until you get something better. Unless you are groven down dirt roads or in the rain you would be fine.
Thanks for that. I was hoping somebody might say something like "don't worry too much about the air filter, if you're just piddling around town for an hour." I want to get this fixed soon, but I'm not riding the bike AT ALL for now, because the last thing I want is to screw up my engine and have you guys say, "What? You ran without one of your air filters? You idiot!"

Don't get me wrong. I'm sure there's somebody who would say that exact thing
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post #8 of 28 (permalink) Old 08-14-2018, 01:50 AM Thread Starter
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Sounds like a perfect excuse to do a full earshsve.
Yeah, I thought so too. Then I saw how much work is involved. I'm feeling a little lazy for that at the moment. In a perfect world, I'll buy the stuff I need for the ear shave in advance, and then have the stuff waiting for the perfect rainy weekend when I have nothing else to do.
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post #9 of 28 (permalink) Old 08-14-2018, 11:52 AM
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Yeah, I thought so too. Then I saw how much work is involved. I'm feeling a little lazy for that at the moment. In a perfect world, I'll buy the stuff I need for the ear shave in advance, and then have the stuff waiting for the perfect rainy weekend when I have nothing else to do.
Earshave was the first thing I did. Just buy some K&N filters, a crankcase filter, and some new jets. Fiddling with the carbs isn't hard (getting them back on is). Carbs willing, you can knock this out in an hour or so
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post #10 of 28 (permalink) Old 08-14-2018, 05:18 PM
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You might not even need new jets. Seriously it's an easy job. The only hard part is if you want to remove the center airbox under the tank in one piece. Most folks just cut it out.
The great thing about doing an earshave it makes removing the carbs A LOT easier than it was before. (Still not the most fun job on this bike)

Am guessing someone has the part numbers for the pod filters that fit along with a link ???

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