Airbox/Injector removal - Wrist Twisters
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post #1 of 25 Old 10-30-2017, 05:54 PM Thread Starter
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Airbox/Injector removal

Hiya,
I have a Cb919 2002 and looking for some advice.
I bought the bike recently and the previous owner had left it standing for almost 8 months. Now the bike runs on the 2 Right cylinders and the left 2 remain cold-lukewarm. I have changed the oil, Spark Plugs with no change in the result.

I have a feeling that the 2 left injectors would have been clogged up, have used injector cleaners with no result. Now i have to go ballistic on it and get the injectors out, but to get to the injectors i gotta remove the freakin Airbox. The problem lies that Honda has put a screw right under the frame which i have somehow managed to remove, the airbox is still not budging. Not sure if i just need to pull it apart harder, just dont want to break anything.

Read forums where people have hinted at taking the engine off the frame as a easier solution. Before i go to that, just wanted to check if anyone else has removed the airbox or injectors without the whole engine coming off?

Cheers

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post #2 of 25 Old 10-30-2017, 06:06 PM
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Did you check the coils first? Make sure they are plugged in and grounded? Swap coils to see if the problem moves?
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post #3 of 25 Old 10-30-2017, 06:40 PM Thread Starter
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Originally Posted by Pvster View Post
Did you check the coils first? Make sure they are plugged in and grounded? Swap coils to see if the problem moves?
Not sure if the coils would be an issue. The right 2 cylinders are running 1 from each coil. So my guess till now was that if the coil was busted, then both sparkies from that specific coil wouldn't work.

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post #4 of 25 Old 10-30-2017, 06:52 PM
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Originally Posted by roger1charles View Post
Not sure if the coils would be an issue. The right 2 cylinders are running 1 from each coil. So my guess till now was that if the coil was busted, then both sparkies from that specific coil wouldn't work.
Not necessarily. Also check the connectors at the coils as well as the plug boots.

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post #5 of 25 Old 10-30-2017, 06:59 PM Thread Starter
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Just remembered that i had checked the sparkies and had installed new ones. Sorry, should have mentioned that before.

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post #6 of 25 Old 10-30-2017, 08:01 PM
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I would also have had a good look over it, while bike could still run, before pulling it apart. Probably to late now.
You can listen for injectors working with a screwdriver held to ear. Those injectors don't often block, were the plugs wet?
But if the bike sat on its stand leaned to the left for a long time it might be worth a look. My bike had sat this way for a long time with no fuel. Condesation and corrosion caused a white jelly to form in the fuel delivery line. The one the injectors are pushed into. Injector 1 had this crud in its inlet basket. Still moving fuel but.
Your airbox/throttle body is removed in one piece. With everything disconnected gently pry boots off cylinder head. Use a pry bar. One boot a bit at a time. Gently work your way across. The whole airbox/throttle body assembly should move back a little and out the left side. Throttle cables are disconnected at handlebar and pulled through still attached to throttle bodies. Have fun.
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post #7 of 25 Old 10-30-2017, 08:57 PM Thread Starter
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Thanks mate, I'll give that a go. Cheers

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post #8 of 25 Old 10-30-2017, 09:02 PM Thread Starter
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Quote:
Originally Posted by Islandboy View Post
I would also have had a good look over it, while bike could still run, before pulling it apart. Probably to late now.
You can listen for injectors working with a screwdriver held to ear. Those injectors don't often block, were the plugs wet?
But if the bike sat on its stand leaned to the left for a long time it might be worth a look. My bike had sat this way for a long time with no fuel. Condesation and corrosion caused a white jelly to form in the fuel delivery line. The one the injectors are pushed into. Injector 1 had this crud in its inlet basket. Still moving fuel but.
Your airbox/throttle body is removed in one piece. With everything disconnected gently pry boots off cylinder head. Use a pry bar. One boot a bit at a time. Gently work your way across. The whole airbox/throttle body assembly should move back a little and out the left side. Throttle cables are disconnected at handlebar and pulled through still attached to throttle bodies. Have fun.
Just one more thing, you mentioned- "Your airbox/throttle body is removed in one piece. With everything disconnected gently pry boots off cylinder head. Use a pry bar. One boot a bit at a time. Gently work your way across. The whole airbox/throttle body assembly should move back a little and out the left side."

Does this mean i didnt really need to get the damn Airbox screws out? i could have just started at the Boots and that was it?

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post #9 of 25 Old 10-30-2017, 09:31 PM
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Yep. You split the airbox on the bench after removing it. Throttle bodies attached. I don't even know how you got to that top screw. There's one more screw. It's buried in the middle of the airbox at the back. Impossible to get at until airbox assembly is on bench. Checkout workshop manual.

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post #10 of 25 Old 02-11-2018, 03:12 PM Thread Starter
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Quote:
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Yep. You split the airbox on the bench after removing it. Throttle bodies attached. I don't even know how you got to that top screw. There's one more screw. It's buried in the middle of the airbox at the back. Impossible to get at until airbox assembly is on bench. Checkout workshop manual.
Thanks mate! Following your advice was able to get the throttle body and airbox out. If not for you i'd be still trying to find a way in- the wrong way.


Cleaned the injectors, tested them, put the whole thing back together, still the bloody issue remains. The left 2 cylinders are luke warm. Now I've only tested this on running idle. dont know if some magic would happen if i took it for a regular spin and the left 2 cylinders would suddenly come back to life.

Thinking of taking it to an mechanic and tell him that all the hard work is done, and if he has any clues (electrical maybe??)

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post #11 of 25 Old 02-11-2018, 03:46 PM
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Are the plugs wet from the cylinders that are not firing?
Is the problem still there if you give it some throttle? There is a starter valve system within the throttle bodies that provides fuel to the cylinders at idle, zero throttle input. Some could be blocked.
Fuel pressure regulator fail can cause fueling issues.
Are those cylinders that are cold getting spark?

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post #12 of 25 Old 02-11-2018, 03:51 PM
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Can a Fuel Pressure Regulator fail the other way?

In other words, can a FPR not send fuel when needed?

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post #13 of 25 Old 02-11-2018, 04:00 PM
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Not sure. Just thought it's a cheap easy replacement and it would at least eliminate it. Thay are known to fail but in the way you describe by putting excess fuel into cylinders 2 and 3, I think. Whichever it works off.

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post #14 of 25 Old 02-11-2018, 04:08 PM Thread Starter
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Quote:
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Are the plugs wet from the cylinders that are not firing?
Is the problem still there if you give it some throttle? There is a starter valve system within the throttle bodies that provides fuel to the cylinders at idle, zero throttle input. Some could be blocked.
Fuel pressure regulator fail can cause fueling issues.
Are those cylinders that are cold getting spark?
The plugs were dry, I have a similar feeling that it could be the FPR or the starter valve. the plugs are getting good sparks.

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post #15 of 25 Old 02-11-2018, 04:12 PM
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What if you give it some throttle? With a screw driver held up to injector and ear is injector working while bike is running?

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post #16 of 25 Old 02-11-2018, 04:26 PM Thread Starter
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Quote:
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What if you give it some throttle? With a screw driver held up to injector and ear is injector working while bike is running?
Before i went through the whole"remove airbox, throttle body and injectors", i did check the injectors by using a stethescope. but i'll give it another try. If the injectors are working then i guess we'll be left with just the FPR or the starter valve as the only options?

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post #17 of 25 Old 02-11-2018, 04:43 PM
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Did you check to see that the fuel rail wasn't blocked halfway. Mine was heavily corroded with a white powder/jelly on the inside almost blocking it. You could undo the fuel line bango and see if a long cable tie makes it all the way.

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post #18 of 25 Old 02-11-2018, 06:26 PM Thread Starter
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Quote:
Originally Posted by Islandboy View Post
Did you check to see that the fuel rail wasn't blocked halfway. Mine was heavily corroded with a white powder/jelly on the inside almost blocking it. You could undo the fuel line bango and see if a long cable tie makes it all the way.
Yeah, when i was cleaning the injectors, i also sprayed carb cleaners into the fuel rail. But i didnt look into it(i should have). Will undo the fuel line and check that as well.

Thanks for the continued advice bro

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post #19 of 25 Old 02-14-2018, 07:22 PM Thread Starter
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Update:after everything done. the bike was running like normal.....except the left 2 cylinders were still not going. Dropped it to the machanic, a day later the mechanic tells me its all going.

I ask what was up with it: The sparkies were going to the wrong cylinders. I had accidently swapped #3 and 4....

Fuck my life

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post #20 of 25 Old 02-14-2018, 11:33 PM
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Thanks for the follow up. Nothing serious at least. I wonder why the plugs were dry?

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post #21 of 25 Old 03-05-2018, 02:51 PM
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Garage
@Islandboy any updates on that new snorkel that you were working on ?

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post #22 of 25 Old 04-20-2019, 07:25 PM
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Hello all. Like Roger, I also have a 2002 919. Like Roger, I also have two cylinders not firing. I've had it since 2010, it's always ran fine, until recently. I had to replace the battery a few weeks ago, so I put a good Yuasa AGM battery on it. I fully charged and tested it before I installed it. It started great, although I didn't ride it much. Then I decided to siphon the tank and put fresh fuel in, as I do from time to time with both bikes (the other is an '86 Yamaha Radian). I generally use ethanol free 86 octane. Before I filled the empty tank, I put about 40 ml (about an ounce and a half) of Sta-Bil 360 in the tank. I then filled the tank and started the bike. For a few seconds, it ran fine, as it always does, then it began to run like crap. After messing with it a while, I could tell it was not firing on 2 and 3. I couldn't believe that the fuel swap could have actually caused the problem, so I swapped that coil, and had the same problem. Then my starter started locking up. ?? I figured I'd have to pull the injectors and look at them, but never have messed with a throttle body or injectors on a motorcycle. It looks even more challenging than pulling the carbs on the Yamaha. Anyway... while working on it today, I pulled the cover off the airbox, and discovered the airbox was FULL of fuel. It's as if a carburetor float was stuck with the petcock left on "prime", and fuel was dumped into the airbox. My heart sank. I pulled the saturated filter out, got the fuel out of the airbox, and dried it all out. Then I turned the key to watch what would happen when the fuel pump came on. Sure enough, I heard fuel squirt, then saw fuel come out of the cylinder 2 hole in the airbox and start to run down the inside of the airbox. I'm guessing maybe the Sta-bil caused two of the injectors to stick open. I'm not sure what else could be causing that problem. I don't know if they can be saved, or if they will need to be replaced. In any case, that's the spot I'm in. And, yes, I checked the oil level, and yes, it is over-filled and probably has fuel in the crankcase. I'm guessing the reason the starter was locking up is because the motor was hydro-locking, or whatever you call it. Anyone have any ideas? Could my fuel swap and Sta-bil have caused two injectors to stick open? Any other reason fuel would be squirting into the airbox? Thanks in advance for any ideas. And Roger - I'm glad your bike's going again, and it wasn't a big issue.

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post #23 of 25 Old 04-20-2019, 09:47 PM
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Sounds like your fuel pressure regulator has failed. When the FPR fails it will often dump fuel into cylinders 2 and 3 via two little vacuum ports at the throttle bodies.
Replacing the FPR will fix the issue. No need to remove airbox/throttle body etc.

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post #24 of 25 Old 04-21-2019, 11:05 AM
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That's why I posted a message to this group. I figured some people here would have some ideas and helpful information. Thank you! I had no idea what that thing was. I figured it was a secondary fuel filter. I pulled that thing off, and sucked on the vacuum end of the thing. If my concept of what it does is correct, I should not have been able to suck anything through it, but I was. It sucked air straight through the hole that mates with the fuel rail. To me, that means the vacuum line would suck fuel straight from the fuel rail, instead of just working the diaphragm. Also, fuel pressure in the fuel rail would probably push straight through the diaphragm into the vacuum line. I ordered a new regulator, and should be able pop it on by Friday and see what happens. In the meantime, I'll do an oil and filter change, since I'm sure the crankcase is full of fuel. (I drained and removed the tank this morning, since the airbox was once again filled with fuel.) Thank you for taking the time to post. If this fixes the problem, you will have saved me a considerable amount of time, frustration, and money. I'll post the result hopefully by next weekend.

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post #25 of 25 Old 04-25-2019, 05:06 PM
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That was it. Got a new FPR today. Sucked on the vacuum end, and... nothing. That's how it should be. Put it on.. got the tank back on... turned the key on while I watched inside the airbox... no fuel leaking. Put a new oil filter on, refilled the crankcase with fresh oil... pulled the plugs, disconnected the coils, turned the key on, hit the starter button, blew the gasoline out of the cylinders (yeah, fuel gushed out of 2 and 3- ergo the hydro-lock)... put it all back together, and it seems alright. Started up and ran on all four cylinders. I may change the oil and filter again after running it a bit, just to make sure all the crap is cleaned out of there. Thank you for your advice. It saved me a lot of extra time, frustration, and money. All good. I will also mention the fuel pump now makes an even tone / sound when priming / pressurizing the fuel rail before starting the bike. Like someone else said, on another thread (it wasn't Zed... Zed's dead), theirs made a constant sound, then changed pitch at the end of the prime cycle. Theirs, however, made a tone, then increased in pitch at the end. Mine was the opposite. Mine made an even tone, then decreased, or lowered in pitch toward the end. Idk. Whatever. It works. Thank you!
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