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Discussion Starter · #1 ·
Hi I am trying to figure out what is wrong with our 98' CBR600 F3 and was wondering if someone could help point us in the right direction....

Ok here we go bare with me I am a female and, dont know to much about them... This bike has set for 3yrs we got it out put New gas in it cleaned the carbs and it does not want to start. If we give it a shot of Carb & Choke cleaner it will start... When ya Rev it up and, then let off it will backfire. Put new plugs in along with the new gas and, still does the same thing... It only has 3,000 miles on it :(

I dont know whats going on and, any help would be wonderful. When he uses the Carb & Choke cleaner and, when it starts if on idle it will sit there and like rev up and down to the point you think its going to shut off.. But, then it will repeat again and again up and way down.. Ok well hope for some answers soon... Thanks in Advance for all your help !!!!!!!!!!
 

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sounds like the carbs still

You said they were cleaned, but if it runs on carb cleaner, then you have splenty of spark, surely there is air around, so fuel is your issue.

The lumpy idle is due to partially clogged lines/jets.

Did you fully disassemble the carbs and spray cleaner into every nook?

Check your fuel lines and fuel filter.
 

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sounds like the carbs still

You said they were cleaned, but if it runs on carb cleaner, then you have splenty of spark, surely there is air around, so fuel is your issue.

The lumpy idle is due to partially clogged lines/jets.

Did you fully disassemble the carbs and spray cleaner into every nook?

Check your fuel lines and fuel filter.
:plus1: also check all vaccume pipes and inlet rubbers, that there are no splits, or that any of the pipes have come off linking the carbs...:thumb:
 

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Discussion Starter · #4 ·
Does all the brass pieces unscrew out of those carbs?? He is tearing it apart as I sit here and type away.. This is only the 3rd time he has done this.. He also was wondering if and which jet has if any may have a screen in it?? I could be wording this all wrong but, hey I'm trying hehe.. Fuel lines and fuel filters are wonderful..No problems there..
 

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blow all the jets through, and make sure the float is working right and the valve opens and closes fully. Take your time and remember to check the filter on the tank valve (if it has one) before you put carbs back on, pour some fuel in clean glass to make sure its all good in there.
 

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Some of the little brass pieces that you are talking about are called jets. You have main and pilot jets. These jets have very tiny holes and can be clogged very easily. All these jets need to be removed and cleaned very well. Becareful when removing them because they can be damaged really easy. Their are also little brass screws called idle mixture screws on the bottom of each carb. The screws require a special D shaped tool to remove or adjust on Honda motorcycles. After all of the jets and idle screws are removed and cleaned then you need to get a couple cans of carb cleaner and spray every passage you can find in each carb until carb cleaner flows through each one perfectly. Carbs have several little passages and all of them have to be clean for the carbs to work. You also need to make sure that the little spring loaded pins in the end of each float needle moves freely or your floats won't work properly.

Also when you took the float bowls off of the carbs after it wouldn't start when you cleaned them the first time was there any fuel in the bowls. Your bike should have a vacuum operated fuel valve on its gas tank. If it is varnished up it could be stuck shut. Or it could have a vacuum leak and need to be replaced. Either of these conditions will not allow enough fuel to get to the carbs. Now what I have just told you is just a quick reference on how to clean carbs. You really need to know what you are doing or have a manual to make sure you get the carbs cleaned right.
 

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Discussion Starter · #10 ·
We have a manual sorry if I (a woman) don't explain things well haha.. He removed everything cleaned with Carb cleaner did remove some dirt out of one of the jets and, was hoping that would fix the issues... But it didn't...

I know he is getting very frustrated with this bike and, hope that some type of information I give him from everyone's advice a light bulb will go on in his head and, the problem will get fixed.

So please keep them coming so I can relay to him when he is out there messing around with it... Oh and to Roland5color to answer your one question yes the float bowls had fuel in them...

Just does not make any sense to me or him ;) Ok keep em coming.. Thanks Again
 

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Where in PA are you? I'm in Philly. The carbs for my 95 F3 are sitting here next to the table. Just finished cleaning them and I'm rewiring the bike atm.

Could be a couple things outside the carbs. Have your boyfriend visually verify the coils are in the right order and the plug cables are going to the correct plugs. If it's not firing in the correct sequence that could cause a lot of the problems. Also something easy to mix up when playing with the plugs (almost guilty except I caught it before firing it up). Could be a leak somewhere as well. Carb boots not fully seated is another easy miss (guilty) after the carbs have been removed.

What's the bike's history? Were you able to start it prior to cleaning the carbs? It's possible there's still some varnish from old gas clogging the carbs. After that it might be time to break out the voltmeter to test the electrical
 

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Discussion Starter · #12 ·
Bike History: bought the bike brand new in 98' don't even have 3000 miles on it. New battery four new plugs if ya give it shot of carb cleaner it idles smooth the number 4 plug keeps filling out. not sure if it is still a jet dirty or if its not getting enough air or gas not sure. it seems to run good from 6grand to 14. has a dead spot off idle til 4grand. occasionally when you rev it up n let off it will backfire. but the number 4carb has a plastic valve on the side with a rubber hose on it not sure but, 1 2 3 are burning good. thanks for the info keep it coming fella's im a learnin' ..
 

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Discussion Starter · #13 ·
The bike charges at 14volts, the fuel pump started out just slowly bumpbumpbump and then all of a sudden it took off n started pulsing alot faster and harder and now its leaking after it started pulsin harder leaking around the crimp. so ordered a new one of those and waiting for it to arrive. burning octane just not sure why number 4 is acting up... do you think just running it would clear it out???
 

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The bike charges at 14volts, the fuel pump started out just slowly bumpbumpbump and then all of a sudden it took off n started pulsing alot faster and harder and now its leaking after it started pulsin harder leaking around the crimp. so ordered a new one of those and waiting for it to arrive. burning octane just not sure why number 4 is acting up... do you think just running it would clear it out???
you can bypass the fuel pump long enough to get it running. when you say burning octane you mean its running on gas?
 

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#4 keeps fouling out so I'd check for spark on it wire. Use one of the good plugs to check. Just put a known good plug in the plug cap, ground it off the frame and see what kind of spark you get. If none or weak, might be something wrong with the wire or coil.

The backfires could be AF but can't really say cause its not running without starter fluid and the airbox is off. Can't really adjust the AF till it starts on its own and has the airbox on.

Fuel pump prolly isn't a concern till the leak is fixed. If there's a leak it's not going to run correctly. MidwesterneRR got the right idea. Bypass and gravity feed till the leak is fixed / get the bike running
 
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