bike shuts off after idling for short time

[shibby_cbs]

saw a post about this same issue in the old forum which was resolved but it didnt really explain what the problem was or at least i dont remember what it was. i know it did mention the ignitor and the pickup coils but not sure where to start. Aside from all that this is what is happening. after running for about 5-10 minutes the bike will stop running. when i try and crank it over to restart the bike it just cranks and cranks with no luck. If i let the bike sit for about 10 minutes or so it will start back up and i will be on my way. Now i did notice that every time the bike has shut off the temp needle is at about 3/4. As soon as the bike shuts off the fan turns on so it seems to shut off just before that most of the time. Any insight into what may be going on here?

[George R. Young]

Try with the gas cap open, might be venting issue. And it's easy.

[throb]

the temp needle is at about 3/4.

Where did it normally indicate before it started doing this?  This seems hot compared to where my gauge shows, which is only about 1/4 way off of cold.   Possibly an electrical piece on it's way out and cutting out intermittently now.  Could be venting issue like George says.   

[shibby_cbs]

i actually had tried that the first time it happend with no luck. when i recreated it in my garage the first time i had let it sit for about 10 min like usual but then thought about doing that...opend the cap and it slowly started to crank over as if it were getting fuel again after being starved. so i reset it up again and after it died again i pulled the cap immediately and couldnt for the life of me get it to turn over. So im wondering if it worked the first time ecause i lit it sit like usual before tryng it or of it was actaually the fix...is the vent in the cap assembly itself? and if so is there a procedure for cleaning it out or is it pretty straight forward?...also what about the vent in the back...anything to do with that?

[shibby_cbs]

Where did it normally indicate before it started doing this?  This seems hot compared to where my gauge shows, which is only about 1/4 way off of cold.   Possibly an electrical piece on it's way out and cutting out intermittently now.  Could be venting issue like George says.

the temp has always sat at 1/2 city riding and 1/4 on the highway. when it isnt getting any air flow at idle it goes up to 3/4 till the fan kicks in then it goes back down to about half. as far as electrical its possible as i was having intermitten shutoffs last year about once a month but was always able to immediately restart so it may not have been an electrical issue at all. It seems to consistent to be electrical as i can recreate it every time

[Steve in Sunny Fla]

The issue you're referring to turned out to be bad ignition pick-ups. hTH, Steve

[shibby_cbs]

The issue you're referring to turned out to be bad ignition pick-ups. hTH, Steve

so you think this could apply to the issue i am having...they seem almost the same. Also whats the best way to go about diagnosing the pickups?

[shibby_cbs]

BUMP!!!

[shibby_cbs]

anyone?...i dont even know what an ignition pickup is let alone where its at...and how would i know if its bad

[T Cro ®]

anyone?...i dont even know what an ignition pickup is let alone where its at...and how would i know if its bad

Is this a constant thing in that you can only get the engine to run in 10 to 15 minute increments right? Or does it come and go thus allowing you to ride the bike for longer periods of time? The pickups are under the pulser cover on the left side of the engine; there is a procedure for checking them in the Service Manual but you must be comfortable with the use of a multi-meter to do these test.

Are you sure that we are not dealing with a fuel starvation issue? Have you tried running the bike with the fuel petcock set to PRIME have you checked the carb drain screws after the bike dies out to make sure that you have fuel in the carbs?

[shibby_cbs]

Is this a constant thing in that you can only get the engine to run in 10 to 15 minute increments right? Or does it come and go thus allowing you to ride the bike for longer periods of time? The pickups are under the pulser cover on the left side of the engine; there is a procedure for checking them in the Service Manual but you must be comfortable with the use of a multi-meter to do these test.

Are you sure that we are not dealing with a fuel starvation issue? Have you tried running the bike with the fuel petcock set to PRIME have you checked the carb drain screws after the bike dies out to make sure that you have fuel in the carbs?

not quite sure if it is intermiten or not. It first happend while testing the bike in my garage after reassembling the cam cover. I was letting the bike sit on the center stand watching for oil leaks from the cover. was also making sure the coolant system was working correctly along with running the bike through the gears. Wile doing this the bike suddenly quit running. no spudder as if it were losing fuel. thought this was normal at first as i dealt with a small issue last year of the bike shutting off on me but was able to immediately start it up with no problem. The difference this time was after the bike shuts off i am unable to restart the bike for approx. 10 min. this never changes. After letting the bike sit i tried starting it again and it started up no problem so i chalked it up to a fluke. Well a da or 2 later i was riding the bike to get something to eat and on my way back to the house after about 7 min of riding she shut off while rounding a corner at an intersection. Same procedures applied...the bike just cranked and cranked with no results until i let it sit for about 10 min and tried and she started right up no problems. I have since been able to replicate this very consistantly in my driveway letting it idle for roughly 10 min. then it shuts off. One thing i have noticed is that the bike it always in the upper end of its heat range when it shuts off. Not overheating but in the process or just before the fan kicks in to cool the bike down. about 3/4 needle. Could the bike possibly be shutting off due to heat or are there no safety features such as this?. If there are could it be waiting for the bike to cool down before letting it start up again which is why i always have to wait. I have also considered a possible fuel issue as you mentioned but as of yet not checked the bowls for fuel after it shuts off which i will do now. As far as using a multimeter goes i am quite comfortable but dont have a manual to consult. does the clymer manual have the procedure?

[T Cro ®]

I think that yes the Clymer manual has the same info as the factory manual. I think that the hot die out does sound like a bad pick up or a bad cdi but these are expensive parts that must be trouble shot carefully or risk spending money chasing your tail.

[shibby_cbs]

so i just let her run for 17 min with the petcock on prime with no shutoff. It ran through quite a few cycles of the cooling system. In past tests it had shut off much quicker than the time i gave it on this recent test. I am going to let the bike cool and try again with the petcock on run and just a note the tank cap is off so vent issues are not a problem. I will update with results as soon as i get them.

[shibby_cbs]

Ok just went out and did the test with petcock on run. Suprisingly she shut off after about 2 min. Wasn't even all the way up in the heat range but sure enough i was unable to restart so same as always. Checked the fuel level in the #1 carb and it seemed to be full. In light og this i think we can eliminate a fuel starvation issue. Whats next?

[timmerz]

Kinda sounds like you may have a vacuum issue there, or a petcock issue, at least....if the bike runs normally with petcock on prime but not on run, there's an issue...

[shibby_cbs]

Kinda sounds like you may have a vacuum issue there, or a petcock issue, at least....if the bike runs normally with petcock on prime but not on run, there's an issue...

fuel was getting to the bowls no problem

[MAN OF BLUES]

replace the vacume line that runs to the petcock...?
sounds like it is not keeping the diaphragm open. Having fuel in #1 does not mean it's working, all the carbs tie together, and fuel from #4 ccan be flowing downhill to #1....

[shibby_cbs]

replace the vacume line that runs to the petcock...?
sounds like it is not keeping the diaphragm open. Having fuel in #1 does not mean it's working, all the carbs tie together, and fuel from #4 ccan be flowing downhill to #1....

well i checked all 4 carbs and they were all filled with fuel. Also checked vacuum at the line and was fine

[MAN OF BLUES]

well i checked all 4 carbs and they were all filled with fuel. Also checked vacuum at the line and was fine

what do you consider fine? Did you remove it, inspect it, draw a vacume on it with one end plugged to be sure, while flexing it?

here

so i just let her run for 17 min with the petcock on prime with no shutoff. It ran through quite a few cycles of the cooling system. In past tests it had shut off much quicker than the time i gave it on this recent test. I am going to let the bike cool and try again with the petcock on run and just a note the tank cap is off so vent issues are not a problem. I will update with results as soon as i get them.

then

Ok just went out and did the test with petcock on run. Suprisingly she shut off after about 2 min. Wasn't even all the way up in the heat range but sure enough i was unable to restart so same as always. Checked the fuel level in the #1 carb and it seemed to be full. In light og this i think we can eliminate a fuel starvation issue. Whats next?

it takes 3 things to run:
spark
sounds like that is fine,
air
I dunno, pull the airfilter, and check it.
FUEL
You did 2 things at once during the one experiment, you ran it on PRIME, and had the cap open....
these are things Steve and I insist that you can only do one change at a time when anylizing problems you don't understand.

so, you can repeat the first experiment with the cap shut, or go further.

It may be a problem with the cap vent, but I cannot say without disassembling it in my hands. With that said, it sounds like a fuel dlivery issue.
The diapragm in the petcock will have a hard time overcoming the vacume if there is high pressure on the tank, but should still work...
that takes this down to the diaphragm. having fuel in the carbs, is NOT the same as having the CORRECT amount of fuel to keep the bike running. The bowls can partially re-fill, but still not be at a proper level to run correctly. You cannot discount this by saying you find fuel in the bowls.

Diaphragm, vac line, tank vent, and even possibly blocked carb breather tubes (the 2 clear tubes running up from the carbs, and along the upper frame, which allow the carbs to be open to atmospheric pressure, and fill correctly...they get blocked with spider egg nests at times...)
all in the order of the way I note them....

that's all I can offer.

[shibby_cbs]

I have already done a seperate test with just the cap open and the petcock on run with the same result

I have done a test with the petcock on prime with the same result

To test vacuum at the petcock i pulled the line off of the petcock and plugged it with my finger and it felt quite strong. I remember trying it in the past when the bike was running fine and it feels the same

Question: If the bike were being starved of fuel wouldnt it spudder instead of just shutting off clean...the bike goes from perfect idle to nothing instantly

Carbs were rebuilt with the full treatment by steve middle summer last year and bike was stored with full tank and fuel stabilizer

The fact that the bike ran fine with petcock on prime on the second test i believe was a fuke of some type as it shutoff on m earlier test with petcock on prime. Plus In the past after the bike has shut off ive switched the petcock to prime still being unable to start

Also the breather tubes were cleaned out last year but will check them again... but to me...and i am no expert but it seems to be an intermitten spark issue to me. I am going to go back out to the garage and replicate the shutoff and will pull the #1 plug and place an extra spark plug i have in there and test for spark...will let you guys know

and thanks so much for spending the time to go over this with me