Motorcycle starts but dies thirty seconds later

[massimofinance]

My Honda elite 80 has 242 miles and sat with old gas for years. I cleaned the gas tank, replaced the electric choke by starter, installed a fuel filter, replaced the fuel tank petcock and cleaned the carbs four times, taking it off the bike and cleaning it all. It starts right away and runs great for thirty seconds then dies. It then will start but the second you touch the gas it dies. It will start fine immediately but you can't give it any gas. So weird. I'm so frustrated at this point. Any ideas?

 

[gm280]

Well it is obvious your problem is a fuel delivery issue. So ignition and everything else is ruled out. Sounds like once it uses up the fuel in the fuel bowls, it stops. So if it is a gravity fed fuel system, I would look at some type restriction in the fuel lines from the tank to the carb(s). If it is fuel fed via a fuel pump, then that would be my first thing to test. I realize you stated out clean the carb(s) a few times. But did you disassembly them, or merely spray some carb spray on them? I would certainly install some new carb kits in them after totally disassembling them and cleaning them very well. JMHO

 

[robert graham]

Maybe that petcock has a little filter/screen in it that's plugged up with junk from old gas?....or petcock is not opening correctly...take it off and blow some air thru it to be sure it's not restricted....

 

[GA_Boater]

Pop off the bowl on the carb. Any gas?

Check the vacuum hose to the petcock for cracks. Also check for vacuum leaks.

Can you rig a temporary tank to bypass the tank and petcock?

 

[Bob_VT]

2 stroke or 4 stroke? Those 80's have tiny orifices on the carbs. Is the carb together correctly....... I have seen people flip parts and or rotate them and they still fit together

 

[Scott Danforth]

Pull the carb apart. Run a fine wire thru every passage. Once the carb is clean reinstall.

Then pull your fuel tank. Pull the petcock and clean it. If there is any rust in the tank (common problem in old honda mopeds/scooters with metal tanks - yours may be plastic) the tank will need to be cleaned.

What I do to clean rusty metal moped tanks is fill it with a 20:1 solution of muriatic acid or vinegar, dump in a handful of misc small screws and washers. Put the cap on, and shake the tank vigorously for 30 minutes.

Pour out the rusty goo, repeat as needed, neutralise the tank with soda ash and water. Then fill with used motor oil overnight. Pour oil out, rinse with gas, the reinstall.

 

[gm280]

^+1 perfect advice!

 

[shaw520]

All good advise above ,...Ill ad that your symptoms also replicate an air intake leak.

 

[GA_Boater]

Why starting a new thread is usually not a good idea and counter-productive, look at the links. I do believe most of the hints above have been tried.

Cleaning The Carb

Cleaning The Tank

 

[massimofinance]

thanks everyone- you gave me some great tips.

 

[Pusher]

You can hook a clear vinyl hose up to your carb's fuel bowl drain plugs. This is an easy way to test the fuel level and your floats. It's also a good way to see if your bowls are running dry when the bike dies.

 

[massimofinance]

So after re adjusting the valves (They were too tight) and spacing them per the manual it's doing the same thing. Starts for just thirty seconds then starts fine but dies after five seconds or so. The tank is clean and I added a new fuel filter so I know good gas is getting to the carb. I pulled the carb again and took it apart. Seems clean but I am going to remove all the seals and drop it into a chem dip bucket. I'll post back once I put it all back togeer. And sorry about starting anew thread I thought since my problems were continuing I should do that.

One question. How you test for an intake leak or a vac leak? While the fuel filter is filled up with gas I do noticed that the gas coming from the tank is a fast drop instead of a steady stream.

 

[gm280]

Is your tank vented properly? If air can't get in, gas can't get out. JMHO

 

[shaw520]

There two things you can do imediatly to determine weather you have an intake leak;
1. Once you have it running, spray carb cleaner on all intake mating surfaces/gaskets,.. If there's an intake leak you will hear an increase in rpm's.
2. Once it's running you can partially close the choke flap, or partially block the air intake at the carb to see if engine runs longer.

 

[GA_Boater]

Has the compression been checked? I don't remember reading about that.

 

[robert graham]

So after re adjusting the valves (They were too tight) and spacing them per the manual it's doing the same thing. Starts for just thirty seconds then starts fine but dies after five seconds or so. The tank is clean and I added a new fuel filter so I know good gas is getting to the carb. I pulled the carb again and took it apart. Seems clean but I am going to remove all the seals and drop it into a chem dip bucket. I'll post back once I put it all back togeer. And sorry about starting anew thread I thought since my problems were continuing I should do that.

One question. How you test for an intake leak or a vac leak? While the fuel filter is filled up with gas I do noticed that the gas coming from the tank is a fast drop instead of a steady stream.

A fast drop is not good...either a fuel restriction there at the tank or a fuel cap vent plugged or not venting.....

 

[GA_Boater]

When you tear the carb apart, how much gas is in the bowl?

I don't think you have enough vacuum to the petcock to open it to flow fuel.

The dripping gas with no vacuum to the petcock doesn't mean much. It's like filling a straw with water and holding a finger over one end. Moving your finger a little to allow air will let it drip out or pour when open.

Have you tried bypassing the tank and petcock with another way to supply gas to the carb? An quart oil jug can be rigged or an empty lower unit lube jug with the tapered nipple will work too. Just cut the bottom off the jug and put some gas in it and a hose from the nipple to the carb.

Have you tried with the tank cap off?

 

[WIMUSKY]

After the chem dip, air down the carb really good. Use the attachment with the rubber tip and stick it in all the passages you can find. And some that you can't........ Doesn't take much to block up a passage way.... Tank needs to extremely clean...

 

[dolluper]

Take air breather off carb ...start her up put your hand over carb ttottle opening runs you have intake leak...take your hand off dies ..intake leak

 

[massimofinance]

thanks all, It was the carb- I didn't chem dip it, but cleaning it a sixth time (!) seems to have done it. I think now I just need to adjust the carb because it doesn't keep idle. What an adventure...