91 FZR 600 Muffled Sound/Loss of Power

[AeroGunz762]

Just bought a 91 FZR 600, my second FZR (other was a 94) and my first bike after not having one for the last 4 years. Been searching the forums here and other places and I can't seem to find much info on this.
*Note: I'm not a total noob to bike mechanics but I am by no means an experienced mechanic.

Bike seemed to be running fine for the last week or so since I bought it. Nice acceleration, good sound, etc. No issues whatsoever that I could tell. Went to start her up yesterday morning and the battery was noticeably drained, she tried to turn a couple of times, didn't start, and then I just got clicks. Pulled out the battery and hooked it up to my DuraBoost 750 I got from Cycle Gear. Now, this was my fault as I didn't let the battery charge all the way. Let it go for about 2 hours, unclipped it, and she started right up. Drove around a little bit, no issues. About an hour later, left to meet my g/f at the dog park and the bike showd some signs of drainage but started up. Got almost there, stopped at a stoplight, I noticed when revved the throttle hard, it wanted to die on me. If I rev'd real easy it would rev up but if I hit it hard, it would rev down and almost die. Pulled into a parking lot, played with it a few times like this and it eventually died. Wouldn't start, just clicks. Got her home, noticed this time that battery levels were low. Got some distilled water, topped it off, and this time let it charge overnight. (While it was charging, I tore down a few other areas of the bike, which I think is the cause of this problem, which I'll get to in the next paragraph.) This morning I had the green light on the charger, she started up like a beaut and has been running all day except now, I have a different issue. The engine/exhaust (not sure which, maybe both) seems to be somewhat muffled compared to how it should sound. Also, I have a noticeable loss of power. The bike runs, and it will still get up and go, but it's less powerful and there's a kind of muffled sound to it. I kept revving the engine, listening, thinking it was just me but now I'm sure. It sounds different. A muffled, almost deeper sound. I think I also hear or feel more vibation/rattling but that might not be the case.

So, last night, since I had the battery out charging, and I had done some research about the FZR's voltage regulator issues, thinking this might be my problem, I decided to tear down the rear panel and check out the VR just for a quick visual inspection and to get an idea of what I'd be doing if I decide to or end up needing to upgrade to the R6 VR. I took off the VR, looked at it, observed the wiring pattern etc, and re-installed it. After I did that, I decided to tear a couple of other areas of the bike down just for familiarization and some preventative maintenance checks. This is where I think I caused something to go wrong. I removed the tank cover, and removed the intake(?) cap piece that covers the air filter. I pulled out the air filter and noticed it was pretty nasty and is going to need to be replaced. I put it back in, and screwed the piece back in that covers the air filter and compartment. After riding today and noticing the muffled sound and loss of power problems, I immediately assumed I must've caused a problem somewhere in this compartment, or in the air filter itself. It just seems to make sense with the loss of power, muffled sound. Like maybe air is escaping or seeping out or being prevented somehow from getting to the engine.

Just 20 minutes ago whein I took the tank cover off and pulled out the air filter, I noticed a few things. One, the rubber gasket that sits inside that cover/intake piece you remove to access the air filter - wasn't fully seated. 1/3 of the gasket was hanging out of the groove it should've been in. I'm not sure if I put it in like that last night or it came out just as I took it off just now. I'm assuming I most likely put it in like that last night not noticing. If that gasket wasn't seated, could that have caused air to escape and cause the issues I'm having now? I forgot to get a picture of the gasket out of position and I already put it back in and now I can't seem to get it out to get a picture to show you what I'm talking about.

Now, normally I would just put it back in with that gasket fully seated and start the bike and see if that fixes the problem, right? However, after I fixed the gasket, I noticed that parts of the air filter were just covered in what looked like a dirt/sand mixture (I live in Florida). I'll post pics below. I got out some Simple Green and began cleaning. It was really sticky and hard to get off. Thus, I started thinking it wasn't dirt/sand, but the remnants of an old foam cushion/gasket or something. And now I took it all off. Which brings me to my next question. What was that? I'm afraid to put it back in and start the bike now for fear that that was a necessary, albeit filthy, filter gasket of sorts. I might have to wait until tomorrow or maybe longer to get an air filter ordered if the cycle shop doesn't have them in stock. (Auto parts store can order them but that takes a day or two.)

Then again, maybe that gasket had nothing to do with the problem. Could it have something to do with the battery situation? Maybe the VR is bad and now causing electronic issues with the way the bike sounds and runs? I'm at a loss. That's really all I did last night though. Pulled out the VR and mount, put it back in. Fully charged the battery. Pulled out the air filter, put it back in (possibly leaving 1/3 of that gasket not seated).

Here's a pic of the air filter/cabin cover. You can see the gasket is in that rim where it's supposed to be. About 1/3 of it was hanging out when I just pulled it off.



Here's the inside of the cabin with some remnants of the foam gasket stuck to it.




Here are some pics of the air filter with that gunk/foam crap on it before I cleaned it all off.


Any ideas?? Is it safe for me to start the bike after having cleaned all of that foam off of the filter? Or should I just get an air filter before trying to start it up again? I was just about to do an oil change, spark plug change, and coolant flush, since it probably hasn't had one in a while. I realize that perhaps multiple things could be causing this problem but it seems odd that right after I messed with the filter is when the bike started behaving differently.

Any help or ideas would be much appreciated. Thanks!

[kilika2]

I can't believe I read the whole thing. Jk. A couple of things. First, I would replace the vr on it anyway anything before 1995 I would. I had almost the exact same thing you are talking about. I had a significant loss of power and the exhaust wasn't as loud. I will bet my bottom dollar you have a cylinder not firing. If you don't have access to an infrared thermometer an easy way to tell is start the bike up and let it get to temp... Then take a spray bottle with water and squirt each exhaust about two inches below the block. I bet you will find that one with let the water sit longer. It will probably be around 100 degrees instead of 4-500. There are multiple things that could cause this. However I'm betting that a clean and sync of the carbs will help out. However check all your plugs to see if they are fouled (replace anyway because who knows when it was last done) and that all your plug wires are connected. As for the crap in the air box. I would just clean it all really thoroughly and go from there. You can run it with out a filter to check the stuff I said and to check the vr via thwarting flow chart, but you run the risk that something can get lodged in your carbs. Which is possible that that is what happened before too. Causing your current situation.

Chris.

[kilika2]

Here is a link for trouble shooting the vr. In the wiki is a link for carb sync and clean.
http://fzronline.com/wiki/doku.php?id=v ... flow_chart
Chris.

[AeroGunz762]

My first novel! LOL. Thanks for that info, makes sense. I realized after reading your post that when I messed around with the air filter, there's a good chance a lot of that grimy, deteriorated foam gasket gunk could have dislodged and spread all over the place making its way down into the carbs. I'm gonna try that spray bottle trick and since I was already planning on changing plugs, I'm gonna go ahead and do that. Seems likely that, like you said, carbs are gonna need to be cleaned. Thanks for the help!

[AeroGunz762]

Ok, so didn't get a chance to start working until earlier tonight. I just finished changing plugs. Feels better, definitely more power, still kinda sounds muffled. One of my plugs had some corrosion on it. I'm gonna do a quick oil change and coolant flush and I picked up a motor treatment (CRC) for bikes that supposed to be a carb cleaner. You can put it in with the fuel, oil, or directly to the combustion chamber. I also think I might have engine ping. I normally ride with a helmet but since working on my bike I've been riding around the neighborhood each time I do some work without one. I don't know what ping is, but this sounds like something that would be called ping. It's a high-pitched, rapidly repeating sound. Almost sounds digital it's so high and fast. Probably like 10-20 times per second I hear it. It's not super noticeable but I hear it faintly. It almost sounds like high pitched fast beeping. I was going to put that motor treatment (supposed to help with ping, clean carbon deposits, etc) in with my fuel and put some in the crankcase when I change the oil here shortly. Anyways, the plug changed helped out I can feel it. I think my third cylinder (last plug I changed) wasn't firing. That's the one that had corrosion. And now despite still sounding muffled, when I pulled back on the throttle, there was no hesitation. It got right up and went with full power which felt pretty good. Oh, I also have a K&N air filter coming which should be here in the next few days. Alright well I'm gonna get back to working...

[AeroGunz762]

Oh yeah, forgot to mention, I'm a little sketchy with tearing down the carbs myself. It's the synching I'm worried about. There's a mobile bike mechanic (reputable) in my area that told me they'll come out and do it for $240. I'm probably gonna go with that since I have the cash, and I want to know that it's been done right.

[kilika2]

I'm not going to tell you what to do but I wouldn't pay for the carb sync and cleaning. That's 240 dollars you can use for something else. I didn't look up the directions in the wiki, to post On here, but I know they are thourough. I was worried about it the first time. I read through the directions 100 times or so. I took about four hours to do it all because I was worried about messing something up. I can do it in less than 2 now. The materials to do it yourself cost less than 20 bucks too. Plus you will learn more about your bike. I'm confident you can do it since you have changed the plugs and oil on your bike. Thats about as tough as the carbs. Just more parts and smaller as well. If you want someone to do it that's cool. I saw where you have some other issues going on as well and sometimes a little piece of mind goes a long way.

To sum it up though I bet you could do it on your own. And you would learn a lot about carbs. I know I did.

(haha this is my 1000th post.)
Chris.

[AeroGunz762]

I might give it a try. I honestly do hate paying people for stuff I can do on my own. As a weapons repairer, I know I can usually follow a manual and figure stuff out as long as I have instructions. I guess it couldn't hurt, if I f*k it up, I can always go ahead and pay that $240 I was gonna pay anyways to fix my mistakes I'll prob give it a go...

[Ronfaren]

Did you ever find the solution to this issue ? It sounds very simular to my bike.

Thanks