Engine Shut-Off when Warmed up

[Cybergrizzly]

Got a problem with the engine. I live in the tropics so when I say starting the engine cold is at 90 degrees Farenheit. The engine starts ok with the choke and I adjust the choke immediately to lower the rpms. The bike runs ok when cold but when it gets to normal operating temperature and I stop at a light, the engine shuts down. If I rev the engine everything is ok but letting the throttle off and the engines shuts down. Tried to adjust the idle speed knob but it revs the engine and somehow the engine begins to lower the revs and eventually shuts down.

The engine used to run just fine about a couple of months ago. I cleaned the air filter. The spark plugs are new as I replaced them about 5 months ago.

Any ideas?

Al

1998 Vmax: Progressive front shocks and ZX14 masters/levers. Everything else is stock.

 

[Diablotin]

Where in the tropics are you leaving? Just curious

Sent from my GT-I9100 using Tapatalk 2

 

[MaxMidnight]

Will it keep running if you add a little choke?

I would start by cleaning out the idle jets.

 

[naughtyG]

It sounds like you need to do the 'shotgun' carb cleaning method (search for it here) as your pilot circuits are most likely clogged up.
The other possibility is poor battery charge - do put a voltmeter across the battery terminals and see what voltage you get on idle, and what it rises to when revving up. Should be well over 12V at idle, and over 13V revving up.

 

[Cybergrizzly]

Diablotin: Republic of Panama (Central America).

MaxMidnight/NaughtyG: Found a detailed procedure here (http://vmax.lvlhead.com/tips/shotgun.htm) for the shotgun carbs cleaning procedure. Gotta remember my old days when I used to disassemble carbs in our cars with my Dad. Old times. Nowadays is all fuel injection and computers.

MaxMidnight: Not sure which are the idle jets. Will the shotgun cleaning procedure include cleaning of the idle jets?

NaughtyG: Battery is new and is kept under a trickkle charger. Bike starts without a problem and strong, but will check connections to be sure.

:ummm:

 

[jfeagins]

If it runs good under normal conditions w/o choke, and only begins dying after full warm up, it most likely is NOT the idle circuits, and I doubt the shotgun proceedure is going to make too much difference. It won't hurt to ensure they are clean.

My bet is on the charging system. When the fan kicks in, and that CDI box is starved for a full 12.6 or greater voltage, we all know what starts happening.

Check your charge rate AFTER the fan kicks in to be certain the bike's voltage remains in the 13.25, or greater, range. I'm betting it isn't.

 

[Diablotin]

Might not be related, but couldn't it be a fuel pump issue or rust issue?
I just saw my buddy few weeks ago, having to stop every now and then because the carbs were not getting enough gas due to a clogged fuel line.

 

[sdt354]

If it runs good under normal conditions w/o choke, and only begins dying after full warm up, it most likely is NOT the idle circuits, and I doubt the shotgun proceedure is going to make too much difference. It won't hurt to ensure they are clean.

My bet is on the charging system. When the fan kicks in, and that CDI box is starved for a full 12.6 or greater voltage, we all know what starts happening.

Check your charge rate AFTER the fan kicks in to be certain the bike's voltage remains in the 13.25, or greater, range. I'm betting it isn't.

+1. most probable issue. And very common on our bikes. There are lots of threads
on fixing this issue here.
Steve-o

 

[Cybergrizzly]

jfeagins: The engine dies way before the fan kicks in. I will check the voltage, though.

Diablotin: That's one thing that also popped into my mind. Being thinking of replacing the gas filter also.

I will also check the CDI connections. I remembered now that when I replaced the battery, I unscrewed 2 connectors (CDI or Coils?). One of them didn't have a gromet surrounding the spark plug cable and I just re-inserted the cable and screw back the connector. Maybe it is not making a good connection down there. I will remove the seat again to check that one.

 

[naughtyG]

Check your voltage for charging first - it'll be easier to just fix that if it turns out it isn't charging properly!

 

[Cybergrizzly]

I'll check both, the connection with the CDI/Coil and the charging system. Either way, I have to remove the seat and both things are just there. Thanks.

 

[Cybergrizzly]

Got a problem. I started by doing the shotgun carb cleaning. I decided to remove the air box completely and now I cannot reinstall the airbox because I am unable to reattach the filter hose that attaches underneath. Is there any trick to do it. I cannot fit my hand to push the hose into the airbox fitting.

On the other hand, I think 2 jets were clogged. I started the engine and it seems to work fine but it was too late last night to keep it working to verify that the engine would not die or to check the voltage.

 

[Cybergrizzly]

Never mind. Figured out. Still pending, the tests.

 

[Cybergrizzly]

I haven't had the time to test the bike, yet. I do have a couple of questions, though.

I removed the air box and the side caps caps, then I proceeded to unscrew the idle screw but it remains in its hole and the instructions says the screw/spring will pop out when injecting the carb cleaner from the top of carb jet. Well, I did that but almost all if not all of the spray came out from a side jet and not from the idle screw hole. Did it on all 4 carbs and it was the same. Two of the side jets were clogged but were cleaned after a couple of sprays. Now, did I do something wrong or should I have continued to inject the spray and try to force the idle screw out ? I know that the instructions calls for compressed air but I would imagine that carb cleaner would do ok. Or not? After cleaning the side jets, I just went ahead and screwed the idle screws back in.

Will do tests tomorrow afternoon.

 

[Cybergrizzly]

Well, finally I was able to test the Max without avail. Still having the same problem, the engine starts ok, idles ok while warming up and getting up to running condition. Onces it gets there and the temperature begins to rise, the engine begins to run rough until revs get below 1,000 and finally dies. This happens before the fan kicks in.

Checked the voltage while running ok and it is at 14.7 volts. Once the engine begins to get rough, voltage needle begins to flicker. When the fan kicks in, voltage drops to 13.6 volts but flickering until the engine dies.

I really thought idle would fix with the "shotgun cleaning". Any more ideas? Tomorrow I will re-check all connectors that I had to disconnect when replacing the battery, I doubt any bad connection but will check. I don't ride the bike much, will a full throttle ride on the highway help ?

Things done during the past 2 months, before this problem:

Changed battery
Changed throttle cables (push & pull)
Installed trickle charger cables and charger
Changed clutch and brake masters & levers to Kawi ZX14
Reinstalled clutch & brake master switches (working ok)
Bleeding front brake lines
Bleeding clutch line

 

[Miles Long]

Well, finally I was able to test the Max without avail. Still having the same problem, the engine starts ok, idles ok while warming up and getting up to running condition. Onces it gets there and the temperature begins to rise, the engine begins to run rough until revs get below 1,000 and finally dies. This happens before the fan kicks in.

Checked the voltage while running ok and it is at 14.7 volts. Once the engine begins to get rough, voltage needle begins to flicker. When the fan kicks in, voltage drops to 13.6 volts but flickering until the engine dies.

I really thought idle would fix with the "shotgun cleaning". Any more ideas? Tomorrow I will re-check all connectors that I had to disconnect when replacing the battery, I doubt any bad connection but will check. I don't ride the bike much, will a full throttle ride on the highway help ?

Things done during the past 2 months, before this problem:

Changed battery
Changed throttle cables (push & pull)
Installed trickle charger cables and charger
Changed clutch and brake masters & levers to Kawi ZX14
Reinstalled clutch & brake master switches (working ok)
Bleeding front brake lines
Bleeding clutch line

Just reviewed this entire thread. My thoughts -
- Can't imagine that any of your "things done" could be responsible for your current problem.
- The voltage when warmed up, 13.6, should be more than enough to keep the bike running at idle.
- I would re-visit that Shotgun cleaning procedure, this time making sure to remove the idle screws, thereby allowing complete cleaning of the orifices and needle seats, washers and o-rings. To remove the screws, if they won't come out with spray, try this(worked for me) - using a tight fitting piece of rubber tube inserted in the top idle port, blow using lung power to dislodge the screw, making sure it doesn't fly out completely, using your finger over the side port or a helper with a rag.
Another method, if the above fails, is to use a drinking straw (or equivalent piece of hose), inserted in the side port and over the head of the screw, to hopefully help it release, as you blow from the top. Lung power may not even be needed, if the straw or hose is a tight fit, and you are able to turn it c.c.w. while pulling slightly. The straw method was first mentioned by a late forum member, Roy Carter - R.I.P.
- Did you change the fuel filter yet? Or drained each carb bowl to check for debris in the gasoline? Also, if this is a fuel starvation issue, caused by a poor performing pump (when hot), you could try this - with the bike "cold" (or as cold as it gets in Panama) turn the ignition on, listen for the clicks as the pump fills the bowls. Don't start the bike. Then drain each bowl into a measured cup, noting the volumes of each. This should also be a very rough check of proper float setting. Then close each drain, start the bike, let it get to the point where it stumbles and dies. Then check each bowl for gas content, of course without first turning on the ignition.
- Probably also wouldn't hurt to clean and re-gap each spark plug.
Cheers!

 

[Cybergrizzly]

Mmmmm, interesting thoughts. I have an air compressor with tank, I could use it to blow at low pressure making sure to put my finger over the idle screw hole. Small blows. I didn't check the gas filter, that's a good one. Will check the rest.

Thanks.