can some kind person explain to me relationships

[Boriqua]

So I was taking out the carbs to try cleaning again although I am in agreement with hillsy .. if it were dirty carbs it would be crappy all the time not just when it got hot but .. I am game for anything so I was taking them apart and discovered that I left 2 screws on the top of number 3 carb only hand tightened. I was fitting the bracket back in that holds the throttle cable and choke cable when I reinstalled the carbs last time and I guess I meant to come back and tighten them but when I went to take off the bracket just now I realized they were loose. I mean take them out with your hand loose.

I dont think that would cause my issue but ... Could it?

DSCF7442sm.jpg

I am going to drain my gas tank and strain the gas through a pantyhose and see if I catch anything. I am thinking I may remove the petcock and rinse the tank and screen and then reinstall before I go to clean the carbs again. Like I said. It fires right up first try on choke, lower the choke to half after about 20-30 seconds and idles fine after about 90 seconds. Runs perfect through every gear up to about 6500 rpm. Smooth as silk actually and my wife was very happy with our outing. Then after I last filled the tank .. once it hits proper operating temp it stalls out. I can restart only with choke and run it home only with choke.
alex

[Boriqua]

My coils look a bit on the rough side as do the contacts and I know I passed a tutorial or 2 that outlined how to test them. So maybe that is next. I read in some old archived posts that heat was affecting the coils and causing the bike to stall but none of the posts I read mentioned being able to start on choke and run it like I can. All the posts I read said that either the bike wouldnt start again .. and it was a charging issue and I dont think I have that .. or once they let the bike cool for 30 minutes it started right up.

[hillsy]

Have you opened the gas cap when the bike starts to run rough? That is the first thing you need to do.

[wymple]

Always, always, always get the electrics right 1st. If not, everything else is a clusterf*ck. To begin with, your coils are really sorry looking pieces and coils can do all sorts of things. They can be crap when cold, ok warmed up.....or do the exact opposite. Get some good coils & wires on it, paying attention to the resistor issue with them. How's the wiring on the rest of the bike? You may have insufficient juice TO the coils. You can check that out by running a hotwire to the coils off the battery or fusebox. If it doesn't puke when warmed up you know where the problem lies. As far as the carbs go, you said it ran fine the 1st few times. You may have something getting clogged up but they don't just walk out of adjustment.

[Boriqua]

crazy question .. I am using 3/16 prestone fuel line for my vacuum line from the petcock to the carb. It appears in cross section to be reinforced with cord but ... is there something else I should be using? Is the fuel line rigid enough? Seems thick enough that it wouldnt collapse but I have the tank off and figured I would ask.

I rinsed out the tank and the petcock screen and I am going to remount and head out tomorrow with the tank open and just a couple of gallons of gas and see what happens before I dig back into the carbs. I tightened up the two loose screws at the top of carb 3. May buy new coils just to have new coils.

[hillsy]

Don't ride with the tank open. You want to bring the problem on, THEN open the tank and see if it goes away.

Plus you don't want to die in a fire - guaranteed fuel will slosh out of your tank while you are riding.

Also there is very little vacuum coming from the manifolds to open the tap - your hose will not collapse.

[Boriqua]

Plus you don't want to die in a fire - guaranteed fuel will slosh out of your tank while you are riding.

Yea .. when your young going out in a blaze of glory its kinda crazy James Dean Cool. " Oh man did you hear .. Alex just blew up .. yup one minute there and next poof"

when Your old .. like I am ..and you set yourself ablaze ... you just look pathetically stupid like you had an AARP moment! " Guess he forgot about the whole gas combusting thing .. good thing he had life insurance."

[Boriqua]

Well I didnt get it to run right but I am encouraged because I was able to eliminate alot. I pulled the airbox and re attached everything and checked and double checked my boots. I must admit I was a bit more thorough. I installed new plugs and a new air filter. I had turned the mixture screws down half a turn to Richen but it didnt seem to like that. It wouldnt hold idle at all. I tried to run the bike with the gas cap on or off and to no effect so it isnt a vent issue. Came back and took off the tank again and turned the mixture screws up one half turn and I plugged the vacuum line and put the petcock on prime. Started right up and held idle at 1500 beautifully. I may have a petcock issue even though I just installed a new one but I will need to do more testing. Had it idling with a fan on it for about 5 minutes and during that time did the leak test with starter fluid and no air leaks. Idle speed didnt change.

I checked the plugs I pulled out which looked fairly new so I wasted 15 bucks on new plugs and they were all Tan and dry with no damage.

Figured lets try a ride and as I was backing it out of the driveway the minute it hit about 208 on the dash gauge .. Stall! *&$^#%%$@

Now I have had a couple of air cooled bikes over the years and I know 208 isnt nearly overheat temp so I am pretty sure I am not overheating .. But .. I am pretty sure I have eliminated everything from gastank through combustion. The carbs are good, mixture and adjustment while not perfect is pretty good and when the bike makes spark it runs well. So .. at least I can stop sweating the delivery system. Now ...??

Coils? I just don't see the connection though between being able to run it home with a partially open choke and the coils?

[chuck hahn]

The vacuum comes off carb 2 and goes to the small nipple on the petcock If thats not hooked to the petcock the petcock will not function right. Secondly if the vacuum from carb 2 isnt capped in such cases as the petcock is a manual operated one .....such as a Pingle... then youve got a massive vacuum leak and the bike wont run right either..follow me???

[tom203]

Let's rule out the new petcock as a problem.....
There have been reports of new petcocks not functioning right, so test yours. Get some vinyl tubing to fit on petcock's vacuum fitting (the little guy). With petcock in "on" position, disconnect fuel line and using jar underneath outlet, suck on the vinyl tubing, fuel should flow. Stop sucking, fuel should stop flowing. Now move petcock to "pr" spot, fuel should flow without sucking.
I'm confused about where you left your mixture screws ... Two turns out from gentle bottoming would be my minimum to start.

[Steve]

I had turned the mixture screws down half a turn to Richen but it didnt seem to like that. It wouldnt hold idle at all.

If you turned the mixture screws IN, you did not richen the mixture, you LEANED it out. This was explained in post #12.

Also mentioned in that post: the bike will run much easier on a rich mixture than it will on a lean mixture. Set the screws a bit rich just to make sure that a lean running condition is not your problem, then diagnose from there. Three full turns out. That is three full 360-degree turns. I have to say that because I was trying to help a member several years ago who insisted that he was doing "three turns out", but his running symptoms still sounded lean. I hopped on my bike and rode about 2 1/2 hours to his place to see what was going on. Started turning the screws in, counting as I went. Got to 1 1/2 turns in, they bottomed out. He was thinking that a "turn" was one "flip" of the screwdriver without changing your grip. Turned the screws out three full turns, it purred like it was supposed to.

.

[Boriqua]

Ugh .. I know it was laid out but I obviously still didn't get it. But ... I spent about 20 years designing and building things and have created hundreds of cad drawings for others to build from and know the difference between 180 and 360 degrees so they are at a true 2.5 turns out. Not trying to sound smug because I would rather say I figured it out and all is well but just want to eliminate that as a possible trouble spot.

Right now they are at 2.5 turns and it starts and runs beautifully ... right up until it gets to 208 degrees temp as measured by the gauge. I dont know that making the mixture more rich will help that but I will try it in the AM.

I have eliminated the petcock and for the most part the carbs as an issue since it starts and idles well .. right up until it gets warm/hot

My wondering now is tight valves or coils... but I will admit I dont have a damn clue so thank you to everyone for your input. That epiphany is going to come from someones post and I am thankful for the comments.

[JJ]

I have eliminated the petcock and for the most part the carbs as an issue since it starts and idles well .. right up until it gets warm/hot

My wondering now is tight valves or coils... but I will admit I dont have a damn clue so thank you to everyone for your input. That epiphany is going to come from someones post and I am thankful for the comments.

I don't think the valves will cause the problems you described, but if you haven't adjusted them, you should. Actually, that should be the first maintenance item you do on these old bikes.

I'm thinking either the coils or igniter box failing when they get warm, but I'm surely no expert on them.

[Steve]

I will agree on the valves not being likely suspects. The valves almost always tighten up on these bikes. The 16-valve bikes like yours are the occasional exception. Once in a while, a locknut will come loose and who knows which way the valve will adjust itself then. Anyway, tight valves make the bike hard to start when cold, then easier when warm. That is not your reported problem, so I do not suspect valves, at least not tight valves.

If your bike is running well with the mixture screws out at 2.5 turns, then 3 turns won't help much. You can test the mixture when the bike is warm by blipping the throttle and observing the response. If it revs quickly and cleanly, then returns to idle, that's great. If lags a bit on the way up then hangs there, not wanting to come back down, it's running lean, turn the screws out about 1/4 turn and test again. If it revs rather readily, but drops below the set idle speed and comes back up to it, it's running a bit rich, turn the screws in about 1/4 turn and try again.

.

[hillsy]

Sounds like it might be coils breaking down as they get hot, but I'm not sure you've totally ruled out the fuel delivery issues.

Take off the tank and sit it up on a bench. Get a length of fuel line and attach to the tap, then route this into a bucket or fuel can. With the tank full (or close to), turn the fuel tap to prime and let it drain out with the cap sealed. If there is a venting problem the fuel flow will stop after a few minutes. If it doesn't, and the flow is fine then move on to checking the coils / igniter.