Motor shuts off only while riding. Video shot for clarity. - TwoWheelForum: Motorcycle and Sportbike forums
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post #1 of 22 (permalink) Old 11-13-2007, 02:34 PM Thread Starter
 
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Motor shuts off only while riding. Video shot for clarity.

Alright. I've been working on my CBR600 F3. I have brand new plugs, a fairly clean air filter, and just got the carbs synched up along with the air/fuel mixture adjusted. I also just replaced the Fuel Filter and have new 93octane gas in it.

But if I run down the street and don't stay at 7,000rpms+ the motor dies out. At first I thought it was stuttering but now I'm sure it dies and is coming and going back to life. It only does it while riding.

Now the guy who worked on my bike said it looked like my rubber boots(Think that's what he said) looked pretty dry that are on my Carbs. And he believes it might be sucking in extra air. And I'm thinking that might be it because it only stalls out when running around 30-40mph plus unless I'm hard in the gas and up in the high RPMs. At low speeds it revs just fine and has no problem running. The idle does vary some though.

Here is some video I took. Around 43seconds I put it in either 3rd or 4th while running. It sits at 4k and then when I pull in the clutch the RPMs drop to zero. When I put it back in first it starts up again. But it won't start while cruising and just hitting the ignition.

http://www.youtube.com/watch?v=9MbqhhQdD34

Hope this video helps. And any input would be great.
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post #2 of 22 (permalink) Old 11-13-2007, 04:15 PM
 
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Could it be your kickstand switch or maybe a brake switch freaking out? It might be killing your engine.

I can only believe that some electrical bit would make your engine act that way.

Might also want to check the plug wires are going to the right cylinders.
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post #3 of 22 (permalink) Old 11-13-2007, 05:05 PM
 
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from what it sounds like, you need to take the bike and check everything thouroughly. safety switches, look for cracked rubber in the intake, etc.
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post #4 of 22 (permalink) Old 11-13-2007, 05:19 PM Thread Starter
 
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I showed the video to the guy who last worked on my bike. He told me that the rubber boots that connect the carbs to the intake/head were really dry and he is sure that those are allowing air in. And that the bike sounded like it was running really lean. Which with the bike moving around 40mph or so it's forcing air in much faster than in nuetral. Which is why it runs fine at a stop but won't start back up while moving.

He also said he feels that someone put a jet kit in there. But from what I heard the bike is bone stock. But in the plastic peice that is on top of the carbs that has the large pipes going into the carbs. I see bolts stripped out badly so I think it is possible someone put jets in it but I'm still not sure. It has stock exhaust but then again the guy who owned it may have sold the aftermarket exhaust. There was no aftermarket air filter.

I ordered the rubber boots today. Then he's going to go through the carb when they do come in to make sure it wasn't jetted. Then once that is fixed I think he talked about doing a Leak test to make sure before I spend a ton more money on it that the motor is in good condition.

I'm going to wait a couple weeks before I do anything.
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post #5 of 22 (permalink) Old 11-13-2007, 05:42 PM
 
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pull the plugs out and take some pix of it.
spray some wd40 around the boots and see if sucks it in. it should smoke out the pipe if leaking or it might even seal the leak.
could also be a sticking needle or spring in the carbs.

i would disassemble the carbs and look for tears, re-clean and resync.

-a|ex
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post #6 of 22 (permalink) Old 11-13-2007, 05:54 PM
 
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the intake boots cant hurt especially if they are dry! If they are cracked it could cause some problems. you can check to see if they are cracked by removing the carbs and holding your hand over the hole on each tube then crank the engine over and see if it holds suction to your hand.

Have you replaced the battery or do you know that it is good? I know my GF's shadow had a battery that was crapping out and was causing some strange running issues. Just might be a good idea to check as a new battery is fairly cheap and never hurts to have new.

Also you said he adjusted your air/fuel mixture. How did he do this and not know if you have a jet kit? The only way I know to change mixture is by changing your jets or needle height! if he is talking about adjusting the screws on the bottom of the carbs then that does nothing except adjust your idle fuel mixture.
Here are some links to DynoJet talking about their jet kits installation and stuff im not sure if they are accurate to your model
http://www.dynojet.com/pdf/1189.pdf
http://www.dynojet.com/jetkits/jetkit_info.aspx

either way it is a decent place to start looking for an understanding.
Another good place to look is http://home.factorypro.com/ click on the Product Support button at the top of the page and start looking at that stuff.

Hope this helps a little
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post #7 of 22 (permalink) Old 11-13-2007, 07:54 PM Thread Starter
 
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Quote:
Originally Posted by Joe4g63gsx View Post
the intake boots cant hurt especially if they are dry! If they are cracked it could cause some problems.
He said they were bad enough that he decided to not take off the carbs when he initially lookd at them. Instead he changed the spark plugs and adjusted the screws at the bottom of the carbs.

Quote:
Originally Posted by Joe4g63gsx View Post
Have you replaced the battery or do you know that it is good?
Battery seems to be good but could probably be changed.

Quote:
Originally Posted by Joe4g63gsx View Post
if he is talking about adjusting the screws on the bottom of the carbs then that does nothing except adjust your idle fuel mixture.
I believe that's what he did. I probably misheard him.

Quote:
Originally Posted by Backmarker
pull the plugs out and take some pix of it.
spray some wd40 around the boots and see if sucks it in. it should smoke out the pipe if leaking or it might even seal the leak.
could also be a sticking needle or spring in the carbs.
I heard someone say to spray carb cleaner on the boots. If they are leaking the RPMS should pick up. I'm thinking of trying that but I decided to order the boots anyways.

The Spark Plugs are brand new too.

I think tommorow I'll take the carbs off and go through them. The bike also sat pretty much disassembled in a Garage for about 6months.

I was thinking of putting "Seafoam" in there. I heard some good stuff about it.

Appreciate the help guys. If you have any other ideas let me know.
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post #8 of 22 (permalink) Old 11-13-2007, 08:18 PM
 
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Originally Posted by Atlantasmittie84 View Post
The Spark Plugs are brand new too.
.
that's the reason to pull them. new plugs will show how the carbs are working. they should all look the same, if one looks different (discoloration), then you found the faulty carb/cylinder.

-a|ex
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post #9 of 22 (permalink) Old 11-13-2007, 09:08 PM
 
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Quote:
Originally Posted by Atlantasmittie84 View Post
He said they were bad enough that he decided to not take off the carbs when he initially lookd at them. Instead he changed the spark plugs and adjusted the screws at the bottom of the carbs.
that says it all. replace the intake boots. will fix your problem.
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post #10 of 22 (permalink) Old 11-14-2007, 08:53 AM
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Sounds like these boys are steering you towards a intake leak. Do what BM said... with the motor running spray (I prefer cause it makes less mess) brake clean on those intake rubbers. If the idle of the motor picks up... they are leaking and will cause problems. If not..report back and we'll look else where.

Could be something like your coils.




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post #11 of 22 (permalink) Old 11-15-2007, 01:53 PM
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yea it sounds like it is sucking to much air in the tubes that is y it stays running at hi rpms more gas to help adjust for the extra air
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post #12 of 22 (permalink) Old 11-15-2007, 02:31 PM
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Quote:
Originally Posted by Gas Man View Post
Sounds like these boys are steering you towards a intake leak. Do what BM said... with the motor running spray (I prefer cause it makes less mess) brake clean on those intake rubbers. If the idle of the motor picks up... they are leaking and will cause problems. If not..report back and we'll look else where.

Could be something like your coils.
that is what it sounds like to me and brake clean works wonders finding stuff like that too
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post #13 of 22 (permalink) Old 11-17-2007, 02:45 PM
 
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One other oft-overlooked issue is the gas cap breather...this little booger can drive you nuts; I once had a bike t would idle and run at low speed all day long, but as soon as I got to cruising RPM, would stumble and quit...a partially-blocker breather in the gas cap wouldn't allow enough air in the tank to displaced the used gas, causing a partial vacuum in the tank, ergo shutting off the fuel supply and not allowing restarts until the bike had coasted for 10-15 seconds or so....it drove me nuts...

Carefully, try riding the bike with a partial tank of fuel so you don't end up with a wet lap, and ride around with the fuel cap unlatched...if it stops doing the quitiing thing you've found part of your problem.

Always check the cheap/easy chit first....
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post #14 of 22 (permalink) Old 11-17-2007, 10:18 PM
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Yes, what OTB is talking about is vapor lock. But most of the time the bike will just die... but its worth checking out.




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post #15 of 22 (permalink) Old 11-23-2007, 01:18 AM Thread Starter
 
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Houston. I think I found my problem.

I got the carbs off today and even though the boots felt fairly stiff and hard. They didn't appear to be cracked. But taking off the plastic airbox and looking at my exploded diagram of the carbs I noticed the O-rings missing. That has got to be my problem. Here are some pictures...


And nothing below the box...

And I couldn't find anything that looked like number 42...


I feel that has to be it.
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post #16 of 22 (permalink) Old 11-23-2007, 02:28 AM
 
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that will generally do it. report back with your findings.
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post #17 of 22 (permalink) Old 11-23-2007, 04:58 AM
 
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i've actually had this problem myself and all it was, was dirty ass carbs. before you go spending money on mechanics and whatnot, my $.02, pull your tank, drain all the gas, find and air compressor if you don't already have one, and blow it out. then pull your carbs, drain the bowls and blow them too, with a healthy dose of carb cleaner along the lines. you have to remember that carbs for bikes are extremely sensitive. 1 grain of sand will completely throw your bike out of wack. i guess it's just one of those "most obvious" kinda problems that people tend to forget.
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post #18 of 22 (permalink) Old 11-23-2007, 11:43 AM
 
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check the covers, o-ring sometimes gets stuck up there.

-a|ex
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post #19 of 22 (permalink) Old 11-24-2007, 01:41 PM
 
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Not to be contrary or a devil's advocate, but everything said in the first post points to an ignition problem. The motor dying instantly, the dying when pulling in the clutch, and starts in first, but won't start when cruising all points to something (safety switches, ignition switch, coils, spark plug wires, etc) preventing a spark from getting to the plugs. And by the way, I personally know that Honda's spark generator can go bad and leave you with no spark advance, and possibly with no spark.

The rubber boots things and those white velocity stacks appear to be on the air filter side of the carbs. Any leaks on this side of the carbs won't affect air mixture, only letting in unfiltered air. Your picture of the air cleaner side of the carbs shows four air bleeds (those brass jets). Not familiar with your carbs, but one or more lets air into the idle mixture, one or more lets air into the choke mixture, and one or more lets air into the vacuum chamber on top of the carbs.

I think now is the time to take one of those black chambers off the top of one carb (watch out for the spring) and see how clean the piston and piston walls are. One reason it runs well at high rpm may be that the pistons/walls are so dirty the piston stays wide open (doesn't come back down), so the bike is always running on the fully open main jet.
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post #20 of 22 (permalink) Old 11-24-2007, 04:20 PM Thread Starter
 
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I'm having the carbs cleaned. We looked at them and saw a little junk in the cover for the float bowls(?). He's also going to put a new needle and spring in the carb for me for $25.

I'm probably going to borrow a friends multimeter and check the eletrical.
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