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Discussion Starter · #1 ·
Hi everyone!

I have bought a used and neglected ZR7-S a few years back as my first bike. I put some money into fixing it, and I believed my mechanic knew what he was doing at the time. But as time went on, i have noticed a few problems with my bike and started researching etc. Right now i've a brand new Vulcan S as my primary bike, but I still want to bring back to life my old ZR7-S. So i went to my storage, and my bike was runnning like a pile of ... .
Here are the list of problems:
  • The smell coming from exhaust is very strong and bad (smells like a burnt petrol)
  • Once i heat up the engine, revving makes bike to die slowly
  • Also, revving feels like one or two cilinders are not working (here's an example, video NOT MINE: Youtube Link)
  • Engine knocking
  • One spark plug was black, which i cleaned (spark plugs were changed to brand new before this happened)
I know a lot of ppl told me it must be a carb issue and stuff. So i took the carbs and started cleaning them myself. I don't believe my mechanic cleaned the carbs properly to be honest. I will clean every inch of the carbs and put them back to see if my problems went away. Before you ask - yes the manifolds were changed to brand new OEM ones when mechanic did the cleaning.

To add to all this, i am using a stock air box, which i will also clean and try to seal (the airbox smell like petrol and have some sticky resedue on the bottom). I was thinkning of using the carb pods, but since i have a lot of rainy days in my country, i will stick to the airbox.

Also, the video i mentioned, is not mine, but my bike has exactly the same problem as the one in the video! It sounds the same, which i think something's really bad with the engine (Youtube Link).

I hope you guys could help me out here and possibly point to the right direction, so i can join my old bike this season. Thanks!

Here's the picture of the bike which i first fell in love with:
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Discussion Starter · #4 ·
Welcome aboard. 馃嵒
If the bike revs freely above idle I suspect a good and proper carb cleaning will fix it rather than looking at the ignition. The idle circuits are the first to clog.
(BUT, it wouldn't hurt to check both ends of your spark plug wires. Check for corrosion and that they are firmly screwed onto their contacts. I had one wire not even touching the screw inside the boot yet somehow it was still firing though it wouldn't have for long.)

Another thing to check are the valves. Getting out of spec causes starting and running problems.
My money is on the carbs though. It wouldn't be the first time a mechanic didn't do a good enough job.
Thanks man, i will definitely check the carbs. So far i see there are quite a few black pieces inside the carbs, prob rubber pieces from the old manifolds, which makes me believe the mechanic did the bad job indeed. After i clean carbs i am checking spark wires and boots. Ps i bought new spark plugs with new NGK boots and new ignition coils back then and the bike was running very good, it's just now it runs like a garbage... If interested, i will keep updates here, so maybe other ppl will find this useful.
 

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Discussion Starter · #6 · (Edited)
Here's an UPDATE #1

So i was taking apart the carbs and i've noticed a few things i wanna talk about. The obvious one is that my mechanic did a very bad job! I am dissapointed.

The inside of fuel tank looks clean to me, but other stuff around it - terrible! He left an old gasket there (all 4 of them actually), which has cracks and rust around it. It was very hard to remove it, cuz it was glued (factory i think). Here are some pics:
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Bought new gaskets. 4 bolts in total were busted so i have ordered a pack of new 4mm bolts - will replace them all! Also found a fuel filter inside the fuel line where it connects to the carb. Never thought i would find something there.. Its going to the trash bin, cuz i ordered a new fuel line and a bigger (supposedly better) fuel filter, which lets a decent amount of fuel in!
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Next thing was removing carburetors diaphragm. All 4 of them looks healthy, with a tiny bit of rust around it, which can be cleaned, so i wont need to replace em. One thing though, one of the diaphragm housing was completely black.. I wonder what does that mean? Is it bad? (The one circled in red)
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To conclude - i have started the complete washing process.. The jets and other tiny components are in a very healthy state. Cleaned them first anyway. Next update will be probably putting all crap together..

If any of you find something to add, please do, cuz it is my very first time taking apart carbs and cleaning em. I am learning as i go, ofc doing tons of research beforehand.

Thanks 馃
 

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Discussion Starter · #9 ·
The factory doesn't use glue on the bowls. The rubber seals do all the sealing. Judging by your pic, your 'mechanic' didn't have replacement seals so just used some adhesive. I've never seen that type of in-hose fuel filter before - for sure it would be seriously limiting fuel flow.
Yeah i thought the same - it shouldn't be glued.
 

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Discussion Starter · #10 ·
There is a tiny fuel filter in the line, before the T connecting to all carbs......that is factory, in addition to the ones on top of petcock inside the tank.

The black below the diaphragm is hard to explain. It may have been flooded at some point. That chamber is supposed to only be exposed to air from the air box.........also the enrichening plunger opens this chamber to the cylinder intake, to supply air (from air box) producing fast idle.......which mixes with the enrichening fuel from the starter jet circuit. But all this should be sucked by the engine vacuum and no fuel should go in there at all.


....can you clean the black????
Yes you can. I cleaned it. I sprayed carb cleaner and wiped it off easily. Actually my 2nd chamber was lightly coated with that black resedue. I know that the owner before me didnt care about the bike at all, so maybe he flooded the engine.. anyways, i am happy that i took it apart and cleaning myself haha.
 

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Discussion Starter · #11 · (Edited)
The factory doesn't use glue on the bowls. The rubber seals do all the sealing. Judging by your pic, your 'mechanic' didn't have replacement seals so just used some adhesive. I've never seen that type of in-hose fuel filter before - for sure it would be seriously limiting fuel flow.
Thinking about it now - if "mechanic" was glueing it back, he couldve removed the rust, but he didnt bothered. I remember i left my bike for a week at his bike shop and the very last day he called me in the morning saying i can collect the bike at the end of the day, and later he sent me vids and pics with my carbs open. I thought that he was literally waiting the whole week just to fix my bike a few hrs before i came collect it. So it would make sense that he left all the crap around the carbs.. I was new to bikes and didnt had a clue. Never going back to him!
 

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Discussion Starter · #12 ·
There is a tiny fuel filter in the line, before the T connecting to all carbs......that is factory, in addition to the ones on top of petcock inside the tank.

The black below the diaphragm is hard to explain. It may have been flooded at some point. That chamber is supposed to only be exposed to air from the air box.........also the enrichening plunger opens this chamber to the cylinder intake, to supply air (from air box) producing fast idle.......which mixes with the enrichening fuel from the starter jet circuit. But all this should be sucked by the engine vacuum and no fuel should go in there at all.


....can you clean the black????
When you mentioned about the flooding, i remembered one odd thing. Every time i ride in the rain, if feels like only one cylinder is working - loss off power, insane and loud backfires and i can't literally ride a bike - it stalls. I think i will get one of those K&N filters and take the airbox out to see if there are any cracks or something that the water can come in. Maybe this could be a problem why the chamber is black?
 

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Discussion Starter · #13 · (Edited)
UPDATE #2

So this update is very short. Basically cleaned everything as much as i could without taking apart all the parts (splitting carbs). The insides are all clean. Every opening and every tiny hole was cleaned properly! Also, all the hard dirt and rust that was building up inside - scraped and cleaned as much as possible. The diaphragm chamber was cleaned as well as diaphragms. It looks good to me. Here are some pics:
Wood Dead bolt Gas Hardwood Font
Automotive lighting Motorcycle Fuel tank Motor vehicle Vehicle
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Motor vehicle Engineering Automotive design Machine Auto part
Motor vehicle Gas Auto part Machine Metal
Hand Finger Nickel Household hardware Font


I know, outside of the carbs should be degreased and cleaned, but i don't have time for this at the moment. For now i need to get this bike working and bring to one mechanic some ppl recommended to ask him to run a check to see if it's worth rebuilding the bike. Specially the engine etc. (the engine has 68k miles on the clock).

So that's it for now, waiting new gaskets, bolts, fuel lines and a fuel filter, so i can close all the caps and get it installed back to my bike. Also, in the mean time i will be checking the airbox and installing an aftermarket K&N filter.
 

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Discussion Starter · #15 ·
I rebuild my carbs in one of those large rectangular foil pans that you buy at a dollar store. It's great for keeping parts from rolling off into oblivion. Plus you can scrunch up the sides of the foil pan to support the carbs.
Don't forget those tiny o-rings on the pilot screws. Easy to overlook.
Looking good. It's satisfying cleaning the carbs to get your engine running right.
Yeah u right, next time i will buy a pan or a tray, now i had to improvise lol. Yes i took out the o rings. They were in a very good shape so i kept them.
 

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Discussion Starter · #17 ·
Years ago I saved some pans left over from a party so I had them on hand or I may not have thought of it. Now I use them for everything with small parts, especially springs.
My pilot screw o rings were in good shape as well so I reused them (and also mainly because I forgot to order them when I ordered the other gaskets and float bowl o rings, which were probably able to be re-used).
At the same time I adjusted my valves, which were way out of spec, and that helped most with easy start up and running.
It would be a good time to replace the small o ring in your vacuum petcock.
Nice one. Yeah i will change fuel petcock o rings when i will be cleaning the fuel tank.
 

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Discussion Starter · #18 ·
UPDATE #3

On this update i want to share some stuff i found taking apart the air filter housing. First of all, when i took out the airfilter housing i noticed the oil on the bottom of the airbox, i don't think it should look like that at all! Also, the rust.. That got me thinking is it worth restoring this bike (my plan was to make a scrambler / cafe racer)?
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Also i have checked the inside of the airbox. It looks very bad.. The problems:
  1. The hose that is supposedly to be the air intake, it drips with oil. I think it's supposed to do that because it connected to the engine top. One thing though is it supposed to be this short? Also, it looks like it was cut. This brings me to the next point.
  2. The roof of the airbox looks like the oil was literally spraying all over the box. Wouldn't that short hose blow some oil into the carbs?
  3. The last one i know why the bottom is oily, cuz it collects the oil to the collector, but the question would be - should i attach a short tube to at least block the oil spray to the carbs?
And here's a pic with the numbers to my questions:
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Discussion Starter · #20 ·
There should be no oil spray to the carbs as the crankcase vent tubes to the airbox are, or should be, on the outside of the airfilter, so that any oil spray/mist is caught by the air filter. Judging by the appearance of the bike, I'm guessing that the oil build up is a result of many years of neglect. Also, if there is excessive oil from the crankcase, then you might want to do a compression test as worn rings increase crankcase pressure causing more oil mist/vapour to be expelled.

Finally, the surface rust on the frame seems to be no biggie, but maybe you should strip the bike and get the frame sand/bead blasted and repainted. It really depends on what you want to do with the bike. If you want to make a cafe racer, then I would do that - if you just want a bush basher, I wouldn't bother.

In the meantime, you can just hit the rust with some rust converter to prevent further corrosion.
Ah man, this is very useful!!! Thanks for an advise! Yes the bike was neglected by the previous owner.. He was riding with the broken front fork seals and rear shock absorber. Heck, even left there for a half a year literally on the sun wind and rain! 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..)
 

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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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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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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 馃
 
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Discussion Starter · #41 ·
UPDATE #5

Hey guys, it's been a while.. So i finally got a chance to come back to my garage. I have tried installing the fuel filter and it just doesnt fit lol 馃槄 so I ended up using the factory filter which goes inside.
Anyways, i started the bike it was running for a while.. But once i tried again it was not starting anymore. I could hear it is kinda making explosions but nothing happens. I took out the plugs and they were covered with fuel. I think i f..d up and probably there's fuel in my engine.. Anyways, my goal was to make it running so i could ride to mechanic and see if he could diagnose what's wrong with the engine, but I will ask him to come with a trailer to collect it..

That's that. If anyone could suggest how to clean the fuel of engine without opening it, i would greatly appreciate 馃ゲ
 

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Discussion Starter · #45 ·
Guys, thank you so much for these tips!!! I appreciate your help! And specially with the fuel filter haha. I will add the filter later on, but now i already find a very good mechanic who is willing to take a look at the bike and do a check up to see if the bike is worth putting money into. If i get a greenlight from him, i will ask him to rebuild the engine (if needed) and then i will start the electrical stuff.

Anyway, i will keep you guys updated for the further progress.
 

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Discussion Starter · #47 ·
You don't need to rebuild the engine because of gas in the oil if it was not ridden under extreme conditions for a long time. It is more common than you think.
How many miles on your 7?
I will rebuild the engine if needed. I need an expert to take a look. The bike has 68k miles. I am 3rd owner, looks like other owners never took a good care of the bike. I am very angry and sad.
 
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