Bike won't start...just replaced throttle cable

dinsy · Mar 28, 2006

Gday all again!

I took your advice and just bought a brand new throttle cable. It arrived today, i put it in, tried to start the bike and it won't start!

Once i had put the throttle cable in, when moving the throttle grip, it only moves a little and doesn't turn as much as it used to. I'm not sure, but the slider slides up to the carby lid doesn't it? If so, i can hear it touching the lid.

The slider is about 10mm (wouldn't know how many inches that is...there's 25mm to an inch. so it's a little less than half an inch) under the top of the carby...is it supposed to be down further? I couldn't push it down any more. (i didn't use great force though so i wouldn't break it.)

After tryin to kick it over many times and trying hill starts, it just goes "barrrrrr barrrrr barrrrr" and bogs down sorta thing.

Now there is fuel leaking out of the bottom of the valve thing on the underside of the carby. Is this because it's flooded or do i have major problems :(

Hope you guys can help me again!

Thanks

TimberPig · Mar 28, 2006

The slide needs to seat properly into the carb. Make sure the jet needle seats down into the needle jet correctly. If not, the slide will stick up like you describe. There is also a guide pin on one side that slides into a groove on the side of the slide. On the other side is a notch for the throttle stop screw that is used to set the idle RPM's.

If it is pissing fuel out the overflow, your inlet needle isn't sealing. Either dirt on the needle and seat, a punctured float, the pin backed out, or some other means is causing the valve to not shut off the fuel flow. To fix it, pull the float bowl, clean the carb, and make sure the needle and seat are clean, everything is correctly assembled, and sealing.

dinsy · Mar 28, 2006

thanks for helpin again timberpig :D

It's nearly midnight over here in australia so i can't check it out now, but will do tomorrow...will let you know how it goes.

Thanks again!

dinsy · Mar 28, 2006

okay, i took off the carby lid and reseated the slider and it went allt eh way in (the throttle now turns the right amount). Dunno how i screwed that up inthe first place! anyways...

Now that the throttle cable is in correctly, it still won't start...tried hillstarting, kickstarting...no luck. Just "barrrrr".

There's not any fuel dripping out of the overflow now either so the throttle cable must be seated correctly.

I'm hoping there isn't anything too wrong with it! Is it normal for motorbikes to play up so much or do i just have a dud! lol.

Thanks again!

JST122 · Mar 28, 2006

Try replacing your spark plug with a new one and see if that solves the starting problems. You may just have a fouled plug. Simple fix but often times it is just somthing as simple and small as this and you end up trying all sorts of more complicated repairs when all you need to do is swap a plug or something simple. Start there.

dinsy · Mar 28, 2006

rightio then, i got a spare spark plug so i'll give it a go...i'll try cleaning the current one first.

I was thinking it wasn't starting because it may need a top end rebuild, however i did some thread searching and found a test to push the kickstarter with your hand and i found that it's quite hard to push so there's compression there.

ps-the bike went before i replaced the throttle cable, however it's been sitting in the shed for about 2 months!

JST122 · Mar 28, 2006

I would just replace the plug with a new one rather than clean the old one. Sometimes you can clean them up and get it going again but when you're having as much trouble as you have had trying to start it, I would just replace it with a brand new one.

dinsy · Mar 28, 2006

Seems it was the spark plug...i don't have a new one atm, but i just cleaned the other one and it starts now.

There's 1 more problem; when it starts, it revs at full RPM. i've turned the idle screw both ways, however it makes no difference.

JST122 · Mar 28, 2006

Does it slow down after a few seconds or does it stay up at the high rpm? Change that plug as soon as you can it is possible that it is causing this issue as well. Once you change the plug if it still does it then it is probably a carb issue.

JST122 · Mar 28, 2006

Does it slow down after a few seconds or does it stay up at the high rpm? Change that plug as soon as you can it is possible that it is causing this issue as well. Once you change the plug if it still does it then it is probably a carb issue. I know you said that the throttle cable is seated properly but double check to make sure your throttle snaps back to fully closed after opening, there may be some binding holding the throttle open slightly.

dinsy · Mar 28, 2006

it stays up in the high RPM's...

What/where is the plug?

How do i double check to see if the throttle fully closes?

Thanks.

(you're probably thinking i'm pretty stupid! lol, but u gotta start somewhere!)

TimberPig · Mar 28, 2006

Here's some reading for you
Carb Link

The behaviour you are describing points towards a lean condition. A plugged carb or an air leak are the likely causes. Since you stored your bike for a couple months, I'd start by cleaning the carb, as it is likely plugged.

dinsy · Mar 28, 2006

could you please tell me what a plugged carb means?

Thanks

ps-i read that guide just before actually when doin thread searches. Are there any better guides out there with perhaps pictures to help explain?

Also, is cleaning the carb a simple procedure?

CRguyStan · Mar 28, 2006

Dinsy,
It may be that the throttle cable is preventing the slide from dropping all the way down. Twist the throttle a few times to half way and release the throttle. You should hear a distinct metal tapping when the slide is forced back down by the spring inside each time. If not rip it back apart and try again.
Stan

TimberPig · Mar 28, 2006

When gas sits, it starts to break down, especially in hot temperatures, and when exposed to air. This turns the gas into resins that will plug up the fine passages in the carburetor. thus preventing the fuel from floowing through them correctly. When this happens, the reduced fuel flow produces an air fuel mix with too little fuel in it, and the bike runs lean. When this occurs, your engine runs hot, and can begin to melt the piston, and leads to an engine seizure.

Cleaning the carb is not very hard, but does requires some common sense to avoid damaging anything. You need some commonly available hand tools (screwdriver, 6 mm wrench, etc) to pull the carb and tear it down. You also need some carb cleaner, and a compressed air source. Basically you take it apart, place the rubber parts aside (carb cleaner damages them), hose out all the passages with carb cleaner, and blast them all out with compressed air. Make sure not to lose anything, make sure everything is good and clean before reassembly, and put it all back together correctly. Here's an exploded view to help you
KX 80 Carb

dinsy · Mar 28, 2006

CRguyStan said:
Dinsy,
It may be that the throttle cable is preventing the slide from dropping all the way down. Twist the throttle a few times to half way and release the throttle. You should hear a distinct metal tapping when the slide is forced back down by the spring inside each time. If not rip it back apart and try again.
Stan

To tell the truth, i can't hear a noise when it drops back...only noise is the handle bar grip goin back to the original position.

I'll pull the slide/carb bit apart and have another go...

*********************************************

Thanks again timberpig...i hope you're wrong about having to clean out the carby as it sounds a little complicated and i don't have enough spare cash to get it done by a shop. Are you sure that this can't be fixed by adjusting all the different bolts? (ie idle screw, and throttle bolts)

TimberPig · Mar 28, 2006

dinsy said:
To tell the truth, i can't hear a noise when it drops back...only noise is the handle bar grip goin back to the original position.

I'll pull the slide/carb bit apart and have another go...

*********************************************

Thanks again timberpig...i hope you're wrong about having to clean out the carby as it sounds a little complicated and i don't have enough spare cash to get it done by a shop. Are you sure that this can't be fixed by adjusting all the different bolts? (ie idle screw, and throttle bolts)

If its gummed up and needs to be cleaned out, the adjustments will do nothing.

Get the throttle adjusted correctly first. It's probably easier to pull the carb out, as you can see if the slide is seating or not. If it is hanging up, it will keep the throttle open, hence the revving. Normally 2 months won't gum a carb up, but its been known to happen, so I wouldn't discount it either. You need to get the throttle operating 100% correctly first, before chasing other issues. Cleaning the carb now ensures that not the cause, but may not be needed. It isn't hard to clean a carb, and I certainly wouldn't pay a shop to do it. Simply disassemble, lay the parts out, clean it, and then reinstall the parts in reverse order. It's a half hour job to tear a carb down and reassemble, unless its really dirty.

Focus on the throttle though first. If its not closing fully, you need to fix that before worrying about anything else.

dinsy · Mar 28, 2006

Thanks, i think i'll leave this job for the weekend so dad can give us a hand as well.

JST122 · Mar 28, 2006

If you dont hear the slide drop all the way back down when you release the throttle from the open position then this is probably your problem and it is less likely that it is a dirty carb. The throttle is just sticking slightly open because the slide is not fully seating when you release the throttle. Either the slide is getting hung up within the carb or it is binding somewhere along the line. Did you lubricate the new cable before you installed it? It may be getting hung up on the rubber sheath if not and you need to disconnect it from the carb end and use some cable lube on it. The reason I say disconnect it from the carb prior to lubing the cable is because you dont want cable lube gumming up your carb when it runs down the cable and causing new problems. When I was referring to the plug earlier I was talking about the Spark Plug. Before you tried cleaning it, it wouldnt even start, now it starts but revs high. Go get a new spark plug and try that before you go tearing apart your carb and everything else. If it still revs high after a brand new gapped properly plug is installed then try troubleshooting the cable and cleaning the carb from there.

FruDaddy · Mar 28, 2006

Another thought, make sure the cable is adjusted correctly, if it is too tight, it will not allow the slide to seat. Put some slack in it and see what happens.

TimberPig · Mar 28, 2006

Where do you get your theory that a spark plug can make it rev up at idle? The plug will not cause that issue. A bad plug will make it not start, or start hard, but there is simply no way for a plug to cause it to rev up. It's highly likely that the throttle cable is holding the slide open. He needs to get the slide sitting on the bottom of the carb, then adjust the cable so it just starts to lift the slide when the throttle is turned.
Dinsy, you did adjust the cable when you popped it back in didn't you? If not, loosen the nuts on the throttle cable at the carb top, and adjust the cable until the slide is sitting on the carb bottom with the throttle closed, then adjust it to where the slide just begins to lift, then lock down the adjuster nuts.

dinsy · Mar 28, 2006

TimberPig said:
Dinsy, you did adjust the cable when you popped it back in didn't you? If not, loosen the nuts on the throttle cable at the carb top, and adjust the cable until the slide is sitting on the carb bottom with the throttle closed, then adjust it to where the slide just begins to lift, then lock down the adjuster nuts.

Well, i've tried to adjust the cable...which way should the nut be...screwed all the way in (like it already is) or only screwed in a little bit? Also, the adjusting bolt near the grip, that is also screwed all the way in.

I'm not really understanding what you mean by: "loosen the nuts on the throttle cable at the carb top, and adjust the cable until the slide is sitting on the carb bottom with the throttle closed, then adjust it to where the slide just begins to lift, then lock down the adjuster nuts."

How do i know the slider is on the bottom? You can't see in there!

TimberPig · Mar 29, 2006

Put as much slack into the cable as possible. The carb end adjuster needs to thread into the carb top, and the grip end needs to thread into the throttle housing. Then you back the carb end of the cable out, until it just begins to lift, and lock the nuts down to hold the setting.

To check if the slide is sitting on the bottom of the carb, you need to pull the carb out of the airboots. Since it is already out, it also makes for an opportune time to give it a cleaning just in case. If you can't hear the slide hitting bottom when the carb snaps back after releasing the throttle, then its not closing fully. If the throttle isn't closing fully, and the cable is not correctly adjusted, the bike will not idle correctly until the cable is correctly adjusted.

JST122 · Mar 29, 2006

TimberPig said:
Where do you get your theory that a spark plug can make it rev up at idle? The plug will not cause that issue. A bad plug will make it not start, or start hard, but there is simply no way for a plug to cause it to rev up. It's highly likely that the throttle cable is holding the slide open. He needs to get the slide sitting on the bottom of the carb, then adjust the cable so it just starts to lift the slide when the throttle is turned. QUOTE]

I am assuming you are refering to my comments. My point is not to theorize that the plug is causing his high reving problems but rather that his plug is shot and needs to be replaced and he should work methodically and replace one thing at a time since the plug is a simple fix I say get that problem sorted out and then troubleshoot from there. I also believe the slide is stuck slightly open thats why I asked if he had lubed the cable to ensure that it wasnt binding and said that if he didnt hear the slide seat when he releases the throttle, that this is most likely the problem either that or as mentioned earlier, there is not enough slack in the cable to allow the slide to seat. I wasnt trying to discount your advice to clean the carb my point is just that before he goes tearing that thing apart with little experience it would behoove him to take care of the simple fixes first and continue to troubleshoot as neccessary. Chances are you can fix your problem without getting too complicated.

CRguyStan · Mar 29, 2006

Dinsy,
It is very possible that you have the wrong cable length as these come in various overall lengths, and various lengths of usable cable (ie how much excess is outside the casing). If this is too short your cable will never work.
I would start with the basics, take the cable loose from the throttle assy (even if this means unhooking from the carb). After doing so make sure the carb end is installed to the best of your knowledge, now you should be able to hear the slide seat when you pull the cable end and release. Also make sure the spring is pushing the slide back down. Only when all this checks out, attach the throttle end, this will let you know if your cable is close to the right length.
I got a replacement cable from an aftermarket, did not measure it against the old one and it was way off so I did the above to verify the issue.

Bike won't start...just replaced throttle cable

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