FZRSupport: the FZROnline Archive

Hello, about a week ago I bought a 1994 fzr600. It ran fine when I bought it, but a few days ago I accidentally ran it out of gas. Ever since then, it won't idle but will start and run if I hold the throttle. So I figured I had a pilot jet clogged and was attempting to get to the carbs when I run into this in the airbox:

A piece of cardboard, covering up this cut out hole:

So the air filter is sitting like this down in the airbox:


-So at this point i'm very confused as to why this is there?

Also the guy I bought it from said he "put a $500 exhaust on", but from what it looks like I think he might have just gutted the stock one. Can anyone confirm if this is a stock pipe?



Any help is greatly appreciated

The cardboard would be covering the hole to stop excess air getting in and leaning out your mixture too much.

The pipe isn't stock, looking at the stamping makes me think its a yoshi pipe

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One of the PO's/engineer in-training hacked the air box thinking they could improve air flow. Realizing the error of their ways they placed the cardboard in the air box to attempt to fix the botched hack job. My advise find a good used stock air box and place the one that you have on the curb for your next refuse day. IMO you are asking for internal engine damage without a properly sealed airbox.

Be advised that when you fit a properly functioning airbox to your motor without any other changes, you may encounter some performance issues. Especially if you have a full aftermarket exhaust. From your photo I would say you have an aftermarket can, maybe a Yoshi. If its just the can and you fit a new to you air box and the jetting hasn't been mesed with you might be good to go. But seeing how someone was trying to enhance performance previously they might of tried their hand and carb jetting. The only way to know this is to have a look see at the jets, needle and needle position. But first I would find a new air box and see how see runs. If everyting is good, you are golden. If not you have some things to look into.

That's a pretty cool Mod! -Maybe he wanted to get to the throttle cables without removing the airbox... :/

Anway, i agree you shouldn't leave it that way. Get another airbox, or find a way to RTV/JBWeld/ or seal a real cap over that hole...

i also agree your Pilot Jets are probably clogged up... Do you have an inline fuel filter?

That's definitely a Yoshimura can.

that's hands down the best laugh I've had today and I concur with everyone else, it appears to be a botched attempt to increase air flow and that is not a stock can.

I was fearing that it was a botched aim at improving performance..guess I'll be ordering another airbox. Also the guy said that it was jetted larger than stock, but didn't specify how much. The general consensus is that It's a yoshi pipe, should I keep it or just go back to stock exhaust with stock jetting?

-also I'm not sure if it has a fuel filter or not yet, but if it doesn't that will definitely be another thing on my list to buy.

Thanks to everyone for the replies.

I run a D&D pipe without touching the carbs and a difference is noticeable to me (use to have stock), even if the jetting isn't changed it's still a lighter pipe than stock.

Follow the fuel line coming from your petcock and you'll find the fuel filter inline if there is one. It's an easy change

Throw up a pic of your header then we can tell you if you should look at jetting more, or give you other input. If you have a full aftermarket exhaust system you will have to jet to that system. Normally if you only have an aftermarket, can stock jetting will be fine. I ran a Micron can only with stock jetting without issues but I acknowledge each can is slightly different but the general consencious is stock jetting is fine.

Here's a few pictures of the header, can get better ones if needed:





edit- photobucket is down so I tried using imgur, will try reposting tomorrow with photobucket

Looks like a stock header. If the carbs have stock jetting you should be pretty close to good to go when you replace the airbox.

mhall41 wrote:The general consensus is that It's a yoshi pipe, should I keep it or just go back to stock exhaust with stock jetting?

Indeed, seeing as the cap says "Yoshimura" right on it...

By the way, I think the piece of cardboard might have been there to seat the filter properly, as well. My K&N needs a foam ring to make a good seal, for instance - you might want to check that it doesn't rattle or move noticeably without the cardboard.

...And seeing as the hole is in the "dirty" air path, I don't really see a huge need to replace the whole airbox, honestly (unless you can get one for $5 or so). Be cheap and just patch it up to the best of your ability...

if you have a in line filter it is prolly in the same place my 95 fzr 600 is in. pull your right side plastic and look under the black fuel tank. it should be right around where the fuel pump is. mine was a white cylinder shapped filter. i woudl go ahead and replace it just to be sure that it is good. that is one of the first things i did when i got mine. i replaced it with a fuel filter for one for a honda boat motor. outbords normally have a higher micron filtering (cleaner fuel on the outlet side) i have had mine on for about 7,000 miles now and havent had a problem with it. the fuel lines are the same size it was just a matter of getting it to fit in there with out jumpping around when i went down the road but there is plenty of room under the tank.

cntryboy85 wrote:if you have a in line filter it is prolly in the same place my 95 fzr 600 is in. pull your right side plastic and look under the black fuel tank. it should be right around where the fuel pump is. mine was a white cylinder shapped filter. i woudl go ahead and replace it just to be sure that it is good. that is one of the first things i did when i got mine. i replaced it with a fuel filter for one for a honda boat motor. outbords normally have a higher micron filtering (cleaner fuel on the outlet side) i have had mine on for about 7,000 miles now and havent had a problem with it. the fuel lines are the same size it was just a matter of getting it to fit in there with out jumpping around when i went down the road but there is plenty of room under the tank.

That's a really good idea on the filter, I'm going to take my filter in and see if I can get one to match up

Also a small update on this, when I had all the plastics and air box/ fuel tank off I discovered that the frame was slightly bent...definitely a day ruiner. So I called the guy I bought it off of and of course he didn't know of it and wasn't willing to refund my money so i found a titled frame on Craigslist and swapped everything over. I have put about 300 miles on the bike without any problems, and the botched airbox. but I just received the replacement airbox in the mail today so hopefully it goes on well as I have had horrible luck with this bike so far (I still love it though).

That sucks but good job on keeping it going, doesn't sound like you're too much into the bike and really they are a lot of fun for the cost.