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What do you think if i pull the tube out, tape the airbox hole and leave the tube hanging outside for the time being? would that be a huge impact on a fresh air intake? (i wont be riding daily, i would just ride to the mechanic to see if he can do the compression test etc..)
Wouldn't be any impact on fresh air intake - just means that you are expelling crankcase oil mist/vapor to the atmosphere, and depending on where you leave the tube hanging, you might get oil spray on your rear tyre - not good for grip. The crankcase hose to the air box is a pollution device, it has little, if anything, to do with the performance of your bike.

I would suggest attaching a small filter to the end of the hose, (and even replacing it with a longer piece), and moving it somewhere where any oil from the filter wont get near your rear tyre.

Attach something like this:

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That tube is what supplies air to the clean air system so I'd just leave it in. The exhaust gas passing by the other end is what causes a suction. Leaving it out of the air box opens the tiny possibility of sucking in dirt or bugs which could wind up on the exhaust valves.
The oil on the bottom of the airbox could have been caused by an overzealous oiling of the paper air filter, which you're supposed to do.
There should also be a complete and intact foam gasket on the air filter. If it's not there then over time it has been sucked into the cylinders. If their is an incomplete foam gasket then only part of it has been sucked into the engine. Some of it may be lying on the bottom of the filter box.

That frame can be saved. The 7 is worth it. It is one of the most overlooked and underrated bikes of modern times. It's supremely comfortable and quick enough.

When I rebuilt my forks I spent the extra dough to get the Traxxion Dynamics damper rod kit with springs for my weight. The bike actually handles well now, worth every penny to me.
 

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Discussion Starter · #23 ·
That tube is what supplies air to the clean air system so I'd just leave it in. The exhaust gas passing by the other end is what causes a suction. Leaving it out of the air box opens the tiny possibility of sucking in dirt or bugs which could wind up on the exhaust valves.
The oil on the bottom of the airbox could have been caused by an overzealous oiling of the paper air filter, which you're supposed to do.
There should also be a complete and intact foam gasket on the air filter. If it's not there then over time it has been sucked into the cylinders. If their is an incomplete foam gasket then only part of it has been sucked into the engine. Some of it may be lying on the bottom of the filter box.

That frame can be saved. The 7 is worth it. It is one of the most overlooked and underrated bikes of modern times. It's supremely comfortable and quick enough.

When I rebuilt my forks I spent the extra dough to get the Traxxion Dynamics damper rod kit with springs for my weight. The bike actually handles well now, worth every penny to me.
I would leave it in, but my concern is that the inside is a bit oily (engine oil). Also i am concerned of the all grime on the floor of the box - would it be sucked in to the carbs?
 

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I would leave it in, but my concern is that the inside is a bit oily (engine oil). Also i am concerned of the all grime on the floor of the box - would it be sucked in to the carbs?
The grime won't be sucked into the engine because it's outside of the filter. I have yet to open an air box and not see at least a little of oil residue. It's from the crankcase breather. Yours looks like more than usual IMO. So maybe it's from over oiling the filter as well.
There's a catch bottle for the air box down the lower right side of the bike. Did you see if it's full?

Also- Was the foam gasket intact?
 

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Discussion Starter · #25 ·
The grime won't be sucked into the engine because it's outside of the filter. I have yet to open an air box and not see at least a little of oil residue. It's from the crankcase breather. Yours looks like more than usual IMO. So maybe it's from over oiling the filter as well.
There's a catch bottle for the air box down the lower right side of the bike. Did you see if it's full?

Also- Was the foam gasket intact?
Hey man, sorry for a late response. No i haven't checked the catch bottle. I will go to the garage in a few hrs to install carbs. The gasket that connects airbox and airfilter housing is intact and not damaged at all, just oily. I don't think i understand the concept of how the airbox and air filter works man.

To my understanding the box that airfilter is sitting in sucks the air to the airbox and to the carbs. But WHY the oil is collecting in the big airbox where there are open holes to carbs, not outside the airfilter in the smaller box. Well i kinda know why - because the breather is there in that box. Sorry i am just a bit confused on why we need airfilter if the oil is there inside the airbox?

Maybe if you have a patience to explain me, or point me to some articles or vids, i would greatly appreciate! Just don't want my carbs to suck in the oil resedue from the bottom of the big airbox.
 

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Discussion Starter · #26 ·
I think i kind of got the idea - the tube that goes from inside of an airbox (previous page pic circled red with number 1) it sucks air from the airbox same as carbs, am i right?
 

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First, there are two gaskets at the air box. One is a rubber o-ring that should be fine. Just clean it and re-use.
Then there is a foam gasket that is glued to the filter itself. When they get old and dry the foam breaks apart then either drifts down into the bottom of the air box or gets sucked into the engine. Or a little of both.

As for the crankcase breather, it is there to suck the oil fumes and byproducts of the combustion process that slips by the rings. You can't leave that caustic vapor in the crankcase or you will get oil sludge everywhere in the engine and acids eating away at metal parts. (All cars and trucks have them as well.)
And the stuff is nasty. If you've ever took a whiff and breathed in that vapor while cranking over the engine you'll swear you burned the hair in your nose and just took ten years off your life. It is bad. You won't do it again.
In fact you can tell the condition of your rings while cranking the engine with the spark plugs in but no wires hooked up. If you're getting a lot of pumping out that hose, that means compression is getting by your rings excessively, meaning your rings are worn.

If you look in at your engine from the left side of your bike you'll see a little fat hose that comes out of a round cover then immediately turns in to the bottom of the air box. That is where the engine sucks in the crankcase vapor then burns it in the cylinders sending it via the exhaust pipe into the atmosphere to destroy the ozone layer and end life on earth.
You'll also see a small rubber hose next to it which is the hose to the catch bottle. I suspect yours is full and needs emptying.

Just clean out the airbox and make sure the drains are clear. If your filter is old, get a new one and make sure the spongy foam gasket is in good shape.
The main air gets into your airbox through that wide flat snorkel. It too has a foam silencer that should be removed because that foam disintegrates too.
 

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I think i kind of got the idea - the tube that goes from inside of an airbox (previous page pic circled red with number 1) it sucks air from the airbox same as carbs, am i right?
Make sure you read my post #27.

But that 3/4 inch hose you pointed out in the air box is to add oxygen to the exhaust system to help combust any unburned mixture before it leaves the muffler.
As the exhaust gas is drawn out of the exhaust system, by the Venturi effect, it draws fresh air from the airbox which washes over the exhaust valves and the hot gases ignite any unburned fuel mixture. It is the burbling sound you hear on deceleration.
 

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Discussion Starter · #29 ·
Make sure you read my post #27.

But that 3/4 inch hose you pointed out in the air box is to add oxygen to the exhaust system to help combust any unburned mixture before it leaves the muffler.
As the exhaust gas is drawn out of the exhaust system, by the Venturi effect, it draws fresh air from the airbox which washes over the exhaust valves and the hot gases ignite any unburned fuel mixture. It is the burbling sound you hear on deceleration.
First, there are two gaskets at the air box. One is a rubber o-ring that should be fine. Just clean it and re-use.
Then there is a foam gasket that is glued to the filter itself. When they get old and dry the foam breaks apart then either drifts down into the bottom of the air box or gets sucked into the engine. Or a little of both.

As for the crankcase breather, it is there to suck the oil fumes and byproducts of the combustion process that slips by the rings. You can't leave that caustic vapor in the crankcase or you will get oil sludge everywhere in the engine and acids eating away at metal parts. (All cars and trucks have them as well.)
And the stuff is nasty. If you've ever took a whiff and breathed in that vapor while cranking over the engine you'll swear you burned the hair in your nose and just took ten years off your life. It is bad. You won't do it again.
In fact you can tell the condition of your rings while cranking the engine with the spark plugs in but no wires hooked up. If you're getting a lot of pumping out that hose, that means compression is getting by your rings excessively, meaning your rings are worn.

If you look in at your engine from the left side of your bike you'll see a little fat hose that comes out of a round cover then immediately turns in to the bottom of the air box. That is where the engine sucks in the crankcase vapor then burns it in the cylinders sending it via the exhaust pipe into the atmosphere to destroy the ozone layer and end life on earth.
You'll also see a small rubber hose next to it which is the hose to the catch bottle. I suspect yours is full and needs emptying.

Just clean out the airbox and make sure the drains are clear. If your filter is old, get a new one and make sure the spongy foam gasket is in good shape.
The main air gets into your airbox through that wide flat snorkel. It too has a foam silencer that should be removed because that foam disintegrates too.
Man, thank you for all of this! I really appreciate writing it in whole detail! This is very useful!
I have removed the disintegrated foam from snorkel. Also cleaned oil from both boxes, installed a new K&N filter (yes i oiled it :giggle: ). Gonna give more details in the next update.
 

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Discussion Starter · #30 ·
UPDATE #4

For this update unfortunatelly don't have any pics, because my phone died while i was riding to my garage. Anyways, i have installed back the carbs to the bike. Installed a new fuel hose, but because i didnt have much time, i will be installing fuel filter later this week. Cleaned both airboxes, drained the catch bottle, installed a new K&N air filter. Started the bike and for the first time in like ages, i finally can smell normal gas smell rather than burned fuel smell coming from exhaust pipes. I am happy with the result! Ofc it's not over, i will come back to my garage to finish connecting throttle cables on my handlebar (phone died couldn't check how the damn cables should go) and installing a fuel filter. That is all for the update! Big thanks to Zed7 and Ozninjaguy for helping me and giving tons of very useful information!!! I will comeback with the video and pics on my next update 🤞
 
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1. As long as that hose is inside the airbox and making a tight seal you're fine. It's part of the EGR/PAIR valve system that takes air from the valve cover to be reburned. It's fine.
3. that's a similar vent hose from the transmission, again it's fine.
Just to the right of 3 there's a tiny drain opening. It has some foam in it and looks like the plastic slat in the photo runs into it. It should attach to a hose that runs to a tiny catch bottle located behind the right footpeg cover. The bottle has a tiny drain plug in the bottom for when it get's filled. It's almost impossible to see unless you know where to look for it.

Neither 1 or 3 are the outside open vent lines. There are 4 of those and they attach one to each carb and one up under the other one goes up under the fuel tank. (The other open hose from the fuel tank is the water drain / overflow drain for the filler cap.)

Oil is not uncommon in the airbox, especially if the gearbox was overfilled. You are in fact supposed to oil the OEM filter. That's also why there is a catch bottle.

As for putting in a K&N filter, there are instructions on modifying the airbox for them. I think it involves drilling extra holes. I'm not convinced this is needed, nor will it help your issues.

As per Hugo's comments the tiny fuel filter in the T fitting is stock and as log as clean won't cause any issues. It's there to prevent a blocked carb jet.

The majority of carb issues involve 1. dirty carbs and clogged jets 2. air leak or 3. incorrect adjustment of pilot air jets. It's also important to know you can't really get the bike to run properly with the airbox open and the filter out. You need some of that back pressure to help draw the fuel up from the carb bowls.

Here's a thread showing some info I posted about carbs. Also shows the air needles.
 
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Appreciate this thread. I haven't had my 03 7-s running for a while due to a move and personal illness. Getting ready to start the process of getting it running again. Hoping the carbs are working well since the last time it was running. I"ve kept gas out of the system so hoping not to have to pull the carbs and clean them out. First I need a new battery
 

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Appreciate this thread. I haven't had my 03 7-s running for a while due to a move and personal illness. Getting ready to start the process of getting it running again. Hoping the carbs are working well since the last time it was running. I"ve kept gas out of the system so hoping not to have to pull the carbs and clean them out. First I need a new battery
If the tank and carbs were dry you might be lucky. You can also flush the system from the beginning by doing the following:

Put an aluminum pan under the carbs to catch any fuel. A disposable cake pan works great as you can bend it to fit.
Open the drains and catch anything that happens to come out.
Leave the bowl drains open.
Pour a bit of fresh fuel into the tank.
Move the petcock to PRIme and let the fuel go thru the hose and into the carbs, and then out into the pan.
The goal here is to flush anything in the bowl or hose into the container. The inline T filter at the carbs, combined with the strainer in the tank should catch any big stuff. You just want to flush out any stuff in the bowls that hopefully didn't/won't get caught in the carb emulsion holes / jets.
After you're happy, turn the petcock back to ON or REServe to stop the fuel, carefully remove the fuel filled pan and tighten the bowl drains.
Check for leaks, dispose properly of old fuel.

Obviously open fuel is very flammable so take all due cares and cautions. I'm sure you know the drill though. :)
 

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The carbs were almost dry, nothing to speak of came out of them. I removed the tank and emptied the little fuel that was still in there. Inspected for rust deposits etc. all was clean. After installing a new battery, New rubber tips on the carb balance/sync ports and some fresh gas she fired up on first crank after I let the carbs fill up on prime. I wanted to see it it would run before I took the carbs off etc. She smoked a little until she warmed up. Went for a short ride and all seems well. I won't be doing much more until I get the brakes back in shape. The rear rotor and pads are in pretty bad shape and the front could use some pads. My bike only has 20K miles on it. I had the valves checked at around 15K and they still had some margin. Started the second day with no more smoke and running well. This bike was a commuter for some time and got a lot of use a few years ago for short trips around town. Hoping to do some riding this summer.
 

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Agree I am adding it to the todo list. I am just happy it runs so well after sitting for three years.
I bought my zr7S a year and a half ago as a winter project. I always liked them. It was in good shape by eye with 19,000 miles. It had been treated well except for the fact that I believe it never had any regular maintenance including never having the valves adjusted. It's hard to believe but when I pulled the cam cover there were no witness marks anywhere. No evidence that a wrench or socket ever touched those bolts. No gasket sealer blobs. Nothing.
All the exhaust valves were way out of spec or too tight to get my thinnest feeler gauge under.
All the intake valves were out of spec. I adjusted them all to the loose end of the spec.

I wound up rebuilding the carbs, new carb holders, rebuilt the brakes, new tires, rebuilt and modified the forks. You name it. It now starts, idles and runs as new. Love it. It's not fair to say it's my favorite bike but last summer my other bikes gathered a lot of dust. It's such a nice mellow bike, I can't wait to get back on it.
 

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I had the cam covers off at 15K and I was near the tight end of the spec on a couple of valves so I know I'm due. Worst part of it was cleaning all of the old gasket off before I put it all back together with a new gasket. I moved from the ATL area to a more rural small town in upstate SC two years ago. I will either find someone who can do the work in my area or will need to find a good source for shims. My first project is to get the brakes back in decent shape so I can ride it some and see if there is anything else that it needs before digging in. Of course I need to do an oil change, chain clean/lube, grease fittings etc... Nice to be at a place where I can think about doing some riding again. I've had the bike since it had 3K miles on it. It was my commuter bike for some time before I stopped riding in 2016 for personal illness. I have developed a really bad knee over the past couple of years so I may be selling it and going to something that let's me be an a more open riding position for my knee. I have to get out and ride to see how it all goes and see how the knee feels.
 

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Turbofish.. Outside of an adv bike or a cruiser, I can't think of a bike with more room than the zr7S. It's pretty roomy. (My inseam is 33 inches).
I had a 650 Versys that was maybe roomier and I once rode my friend's 2002 Yamaha FZ1 which also had a lot of leg room.
Ok, so I just named two bikes with more legroom so that negates my first statement.
Here's one more, my old Kawi KZ1000P police bike. My brother has it now because of his bad knees which he can ride comfortably because of the floor boards. He can't ride my ZRX1200 or my z900 because of the foot peg location but he did find my zr7S comfortable (for a short ride).
 
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