Runs but dies when warms up?

[Brian556]

Hey guys,

My motorcycle sat for about 2-3 months without use and when I went to put it back in service it ran fine. I drove it home about 60 miles no problem and then it sat for about another week. When I started it back up I took it around the block a few times and after it warmed up it died on me and would not restart until it sat for a few hours. It has no problems starting but it just dies and will not restart after it gets hot. Can you give me any suggestions or information on why this might be happening?

Thanks,

Brian

[Ibsen]

Welcome to the forum Brian.

It could be several things, but first, when you get to the point where the engine won't start, check if there is a spark on the plugs. You don't have to screw out the plugs, just use a spare plug and check if ther is a spark on all four cylinders.

[Volker_P]

Hi Brian,
welcome here!
In case you can't restart because it does not or only slowly crank when its hot, it is most probably a weak battery. Although it may crank perfectly when cold.
In case it cranks, maybe it gets not enough fuel. Maybe the tank vent or the fuel cock (there is a filter screen inside the tank) is blocked. You may pull the hose and check how much is coming out of the fuel cock. You shold drain about one liter for the vent check.

[Brian556]

Yesterday I decided to take a look at it again. The bike starts fine and idles without a problem. I then take it for a ride and it runs fine for a few minutes and then starts to backfire and wants to die. It will restart but will die almost immediately if I don't keep giving it gas.

We took out the spark plugs and they are already filled with carbon after I had just sandblasted them the other day. The spark plugs were also not hot where they would be sparking. I did the spark test and it looks like I am getting spark but some cylinders seem to be sparking more than others. The spark plugs also smelled like gas. Is it possible that it is dumping too much fuel or that there is not enough spark?

Thanks for your help so far,

Brian

[Ibsen]

A few things that might be the problem.

Fuel air system:

A dirty air filter element. A choke mechanism that is hung up and fails to open the choke butterflies fully when you push the choke knob down, floats that fails to close. And if you haven't done so, drain the old fuel and put fresh fuel on the tank. Fuel don't last long when stored.

Electrical:

A weak spark caused by bad plug wires or plug caps, bad wire connectors for the coils and the ignition system, bad coils, bad IC igniters, low power on the battery or a failing charging system.

Start by checking the simple things first. Since it ran good before you parked the bike, I'm pretty sure the solution is simple.

[Brian556]

I have been pretty busy lately and I have not had much time to look at the bike. I am going to order new wires, caps, and plugs since all of that stuff seems pretty aged on my bike. I noticed here http://www.z1enterprises.com/catalog.aspx?pid=CB650-1980-IG0 that they have wires with a suppression core and wires with a copper core. Which one should I order? Also, are there any other good websites for wires?

Thanks,

Brian

[Ibsen]

On my bike they have a metal core. But the European model are using the resistor type spark plugs, so there is no need for the supression core wires.

[Chris]

I looked all over eBay and I can't find that store that had a complete ignition tune up set advertised. I know that's where I saw it. They had wires, caps and plugs and you could also add oil and air filters for a few dollars more. The wires even came in custon colors if you didn't want black. I think they were Accel wires. I wish I could've found that for you... sorry.

As far as suppression wires go, I think that's only to stop electrical interference that might screw with your radio or on board computer... oh wait, you don't have either of those on your bike I believe what Ibsen was thinking (correct me if I'm wrong) was that if you don't use resistor-type plugs, you need resistor caps? Hey, life is a learning game and I'm learning with the rest of you, but I'm pretty sure that suppression refers to 'electrical noise suppression' and not resistance.

[Ibsen]

You are right Chris, the resistor spark plugs, the resistor plug caps and the suppression wires all serve the same purpose, and as you said, to avoid disturbance on radio and TV signals. And not only on your vehicle, but more important, on everybode elses radios and TV's.
The downside with this is that all these resistances will also increase the resistance in the coil secondary windings, and reduce the power, and the spark, on the spark plugs. Test has shown that the spark won't be reuced too much, but it could be sufficient to give you starting trouble on a cold morning. And that's why I belive you don't need a supression, or resistance in the plug wires if you have it in the plug caps, or the spark plugs.

http://www.ngkntk.co.uk/technicaltips/resistorplugs.asp

[Chris]

Ok, so I was really only half right because I didn't really know what resistor plugs/caps were for Thanks for straightening me out with the link. So only one component, either the plug OR the cap(boot) should be of the resisitor type, but not both? And the construction of the wires themselves shouldn't matter either way unless you're concerned about electrical noise? I ask because it seems to me that if you have a resistor cap(boot) AND a resistor plug it would be too much resistance and you'd get a weak spark. Sorry if that sounds a little redundant but I just want to be clear on this when I replace my own wires

Thanks, Ibsen


Also, according to an NGK chart I saw, it looks like the D8EA plugs that we use here in the states are not resistor-type plugs (for those of you that are reading along and wondering what you have on your bike).

Have you ordered your plugs and wires yet, Brian? I wonder which combination would be more cost effective... standard caps(boots) with resistor plugs, or resistor caps(boots) with non-resistor plugs?

[Ibsen]

Yes, one resistor should be sufficent. But I must admit, I have got both resistor plug caps, and resistor plugs on my bike.
But that is how the 650 came over here in Europe thogh, and I can't see why they did. In US you got them with the non resistor plugs.

[Chris]

Hmm, I guess maybe the best thing to do would be to keep the stock setup on the bike. Thanks again.

[Brian556]

Well, I was about to order the wires from that website and it says that they are temporarily out of stock. Can you guys recommend another website that would have the wires?

Thanks

[Chris]

Did a quick search and all I could find is these NGK wires with resistor caps at Cyclewareables. Looks like they're $19ea. http://www.cyclewareables.com/pages/sparkplug_caps/sparkcaps.htm Oh yeah, and they're also bright red.

[Brian556]

Well, I just installed the new plugs, caps, and wires. The bike ran better during the time it was actually running but it still died on me once the bike got hot. After it died on me it would not restart.

I removed the carburetors and I'm going to inspect and clean them because the bike needed that anyways. I'm starting to think it has something to do with the charging system because when I let it sit and cool down I can go back later and it will restart.

Any ideas?

Thanks,
Brian