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Discussion Starter · #1 ·
Please Help!!
I have a 1994 CBR600f2 that will not start, things I have tried:

Replaced Stator
Replaced Plugs
Replaced Coild
Replaced Rectifier
Replaced Battery

All I can get it to do is crank crank and more crank then let go of start and BOOM backfier with 1 foot flame. After I replaced plugs it started just fine I let it rund for 15 minutes turned it off and it hasn't started again since. BTW it wasnt running before the plugs either. It was layed down also few week prior at about 5mph by my buddy so there is some scraped on stator cover. What should I do?
 

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check for spark, and make certain you have the spark plugs connected to the right coil.

if you have spark, and you have things hooked up right. it isn't an electrical problem.

i suggest you check your air filter, and clean your carbs.
 

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Discussion Starter · #3 ·
Replay

There was no spark when we changed the plugs it seems like a sensor or something, could the ignition pick up sensor cause this?


check for spark, and make certain you have the spark plugs connected to the right coil.

if you have spark, and you have things hooked up right. it isn't an electrical problem.

i suggest you check your air filter, and clean your carbs.
 

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it is a trouble shooting guide. it points to lots of things that could be the problem.
 

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the joke is in your hand
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inspect any wires that could have been damaged in the crash.

crashes can damage things and it doesn't look like it did. for instance, my buddy's R6 had a cut wire for the kickstand inside the rubber jacket. the rubber jacket had no marks on it at all.
 

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second chimp in space
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So it ran after the crash when you changed the plugs? You're not very clear about the timeline here. When's the last time it last ran properly, and what happened since then? In storage? Did you buy it like this?

The plugs are getting fouled. Maybe the mixture is too rich. Maybe the fuel is old.
My first attempt would be to change the plugs again, then let it run for as long as possible. Go ride it so as to get fuel going through all parts of carbs.

It does the backfire because the sparks aren't firing when you crank, but when you let go of the button the engine is still turning but the starter isn't drawing current. So the plugs get all the current, and there's enough to light up the mixture that's been loaded into the exhaust. I've had this happen to bikes before and all they needed is a plug change. Then you have to fix whatever's fouling the plugs, but that might just mean running the bike.
 

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Discussion Starter · #9 ·
Bike was running fine but would die at stop once in while. was told stator tested bad so replaced it...same effect. then wouldnt start at all unluess full throttle on choke and die when let go. then no start at all. tested plug wire...no spark but replaced plugs with iridium plugs fired up immediately let run about 15 minutes turned off and hasnt run since. i have replaced coils, rectifier, battery and cdi
 

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sounds like there might be more than just electrical issues going on. get your battery fully charged, then re-check if you have spark or not. if you do not have spark trouble shoot that first, get spark going.

If you do have spark then look at your air filter, should it be replaced?

once that is done move on to the fuel system. how long has the gas sat in the bike now? has it gone bad.
have you run ethanol gas threw the bike?

any way inspect you intake boots to see if they are leaking, and clean your carbs.
 

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Sounds like fuel delivery to me.

The F2 uses a vacuum petcock, so when functioning correctly it will only flow gas when the carbs produce a vacuum condition to open the petcock's diaphragm. There are two hoses that come out of the petcock. A larger hose (about a 1/2 inch diameter fuel line I think) that flows gas to the carbs, and a smaller hose (about 1/8 inch diameter) that runs from the petcock to the left most carb, on the same side as and nearish to the stator.

If the bike was laid down on the stator side/left side, it is possible this vacuum line was knocked loose or damaged. Or it could have been disconnected accidentally while pulling the bodywork to repair the stator. Pull the bodywork and inspect that line. If it's come off the carb or damaged, there's a good chance that's your problem.
 

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second chimp in space
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Again, you haven't said if the crash has anything to do with this or not.

Now what you're saying sounds like it's been getting worse and worse over time. So which is it? Crash or slow decline?

wouldnt start at all unluess full throttle on choke and die when let go.
Check the valve clearances. I've had a bike do this because the valve clearances were too tight and the valves weren't closing all the way.


BTW, stator/RR might have been bad, but that's the charging system. The bike should be able to run for hours on the battery alone.
If the petcock is not letting any gas through then you won't be able to charge up the exhaust with fuel. Each carb has a drain plug on the bottom. Open one and see if there's any fuel in it.
It's acting as if it's rich. So it might be rich (unlikely unless someone did so on purpose), the spark is weak (which you say it is, but then new plugs fixed this?), or the valves are off.
 

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You may have two problems actually.

First problem, if it was stalling out at idle before the crash, and wouldn't fire without being at full throttle,that sounds like one of two things. Either 1. the carbs are gummed up, particularly the idle circuit, or 2. there's a cut or hole in a vacuum line (not the same one as i listed in the earlier post, but other vacuum lines to the carbs). If it'd been sitting all winter, I'd bet it's #1, and can probably be resolved by running SeaFoam through it once it is running.

The second problem is what I listed earlier with the vacuum line to the petcock preventing any fuel from flowing to the carbs, and that's why it won't start now.

So first check to make sure the vacuum for the petcock is working and fuel is getting to the carbs. Then, once it is running, try putting SeaFoam through it with the next tank of gas to clean out the carbs and jets. I've heard (and tried) riding between 45 - 60 MPH, getting the revs up over 7000rpm and then quickly letting off the gas and coasting down to 40 over and over again is a good way to do this. Helps to run the SeaFoam through the jets and the vacuum created when suddenly cutting the throttle helps to pull any gunk through.
 
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