Bike not starting

[Mike]

Finally got my carbs put back together and tried to start it. Nothing. Just cranks and cranks. Every once in awhile, it'll fire for a split second when I let off the starter button, but other than that, it won't fire. I've got the battery hooked up to my car to make sure it's not low on juice (the car isn't running). I pulled the plugs and laid them on the head, and they're sparking. The bike ran before I pulled the carbs, so I can't imagine that the timing is off or anything too major.

Thoughts?

 

[Mike]

Also - I pulled the line from the tank and turned the petcock to prime and gas did come out.

 

[mike_of_bbg]

Did you "bench sync" the carbs before you put them back on? If one of the throttles is completely closed, it's unlikely a twin can start on just one. If one is too open it probably won't suck in enough fuel.

Are you using choke or no?

How many turns were the idle screws out before you disassembled the carbs? How many did you set them to putting them back on?

 

[tkent02]

Every once in awhile, it'll fire for a split second when I let off the starter button, but other than that, it won't fire.

This is a clue, check the voltage to the ignition while the starter is turning. It sounds like the voltage is too low, so it's not sparking until you release the starter button.

 

[Mike]

This is a clue, check the voltage to the ignition while the starter is turning. It sounds like the voltage is too low, so it's not sparking until you release the starter button.

How would I do that? Like where exactly would I put the leads? I'll have to go pick up a volt meter tomorrow first

 

[tkent02]

The orange and white wire going to the coils.

 

[Mike]

This is the part of the thread where I am mocked mercilessly

Took the carbs off and saw the problem immediately. I had the throttle cable horribly tight and the butterflies where about 30% open with the throttle off. Closed that up and it fired right up.

NOW - it idles erratically and if I give it some gas, it dies. I'm assuming I just need to mess with the adjustment screws?

 

[Nessism]

4) ?

http://www.thegsresources.com/_forum/showthread.php?t=171846

 

[Mike]

4) ?

http://www.thegsresources.com/_forum/showthread.php?t=171846

Airbox is in place

 

[Mike]

One thing I will point out - I absolutely could NOT get those damn adjustment screws out when I was cleaning the carbs. They turn no problem, but getting them out of the body? Not happening. Other than that, I'm clueless.

 

[mike_of_bbg]

Did you dip the carbs? In what?

Yours is a twin so I'm not familiar with your carbs. The 4-cyl CV carbs have an o-ring under the idle screw, Berryman's or Gunk might well melt that.

 

[Nessism]

GS bikes are lean from the factory so they need to warm up before they will accept throttle. I assume the air filter is installed and the airbox lid is sealed up. You might want to set the pilot screws to 3 turns and see if that helps. Just so you know the bike won't run with plugged pilot jets and plugged choke tubes. Basically the carbs need to be spotless, you need fresh O-rings in the carbs, and you need fresh O-rings in the intake boots.

Good luck and hope this helps.

 

[Mike]

Pilot jets are brand new. All new rings in the carb (except for the adjustment screw).

Dipped both carbs in berryman's overnight.

Next step is to jb weld something to the screw to get it to come out (not permanently)

 

[Guest]

I used a tiny jewellers flat blade to get my mixture screws out.

Hard to describe, but I was able to slide it down under the lip of the head and "walk" it out. Tedious and painful, but being careful meant I didn't damage the new O rings either.

 

[Mike]

I'm wondering if I should replace the air filter as well. Maybe it got soaked and ruined when the airbox flooded with gas.

 

[Larry D]

It won't hurt to replace the air filter.

Since you didn't remove the idle air adjustment screws completely and dipped them anyway, I'm afraid the small oring has melted and gooed up the idle circuit which is why it's idling erractically. So, after you replaced the orings you had a couple small orings leftover ?

Are you saying that the screws will turn both in and out, but, you can't get them to come out of the carb body ? Most times you can just loosen them as much as possble and shake them out. There should be a small washer and, in your case, a melted gooey oring........It must be done or idleing will always be a problem. I don't think I'm doing anything this weekend if you want me to take a look.

 

[Mike]

It won't hurt to replace the air filter.

Since you didn't remove the idle air adjustment screws completely and dipped them anyway, I'm afraid the small oring has melted and gooed up the idle circuit which is why it's idling erractically. So, after you replaced the orings you had a couple small orings leftover ?

Are you saying that the screws will turn both in and out, but, you can't get them to come out of the carb body ? Most times you can just loosen them as much as possble and shake them out. There should be a small washer and, in your case, a melted gooey oring........It must be done or idleing will always be a problem. I don't think I'm doing anything this weekend if you want me to take a look.

Yep, the screws turn just fine and when I back them out all the way, I can hear it clicking against the last thread, it just doesn't want to come out. I bought some JB Weld this morning so I'm going to give that a shot, but if that doesn't work, I might just have to take you uo on your offer. Thanks!

 

[Larry D]

K. Just let me know. I never know what my wife has planned for me......I'll send you a PM with my cell number.

 

[Guest]

OK So now here comes another dummy. Were do I attach the meter when checking the ignition voltage? On the orange and white wires or each separetly and to ground? Also what should the voltage be? Sorry. Just not to good with the electrical stuff yet.

 

[BassCliff]

OK So now here comes another dummy. Were do I attach the meter when checking the ignition voltage? On the orange and white wires or each separetly and to ground? Also what should the voltage be? Sorry. Just not to good with the electrical stuff yet.

Hi,

Here's some collected material from my little website (feel free to have a look, link in sig):

Testing The Ignition System
by Mr. Matchless

Properly localizing a problem with the ignition is sometimes a bit confusing and the following below should of assistance:

• Basic test, remove spark plugs. Fit them to the plug HT leads and ground them to the engine. Turn engine with starter and see if plugs spark. If any one spark plug does not spark swap it out. If the spark seems good on all 4 plugs, the ignition system is very likely in order. If spark is not present or very weak proceed with the following tests.
• Remove the tank, left side cover, seat and signal generating unit (pickup) cover at bottom right of engine.
• A good habit is to check the coils and igniter to see if they do not get very hot once the ignition is switched on, as this will most likely be the indication of a failed component of faulty connection or wire.
• If the spark is weak but present, inspect the HT leads and plug caps. Suspect coil wires and spark plug caps, or voltage at the coils and thus the battery condition. It could also be due to coils with partially shorted windings, but do not jump on this cause immediately, and they may get hot.
• Overheating coils with no spark may also be due to them getting a permanent full ground either from a faulty igniter or a grounded and pinched wire. Disconnect the coil plug connectors and proceed with tests.
• Measure the battery voltage directly across the battery terminals. If lower than approximately 12.6V first charge battery fully before proceeding.
• Next measure voltage over the coil connector plug, orange/white wire and the battery negative terminal. If lower than 12 Volt inspect the wiring for poor contacts and localise cause of voltage drop.
• Again measure directly across the battery, but pull off the spark plug leads to prevent engine from firing and swing with starter. While starter is turning the voltage should stay at least above 11 Volt. Also swing the starter with the headlights on to see that the voltage does not drop significantly at the coils while the starter plus headlights load the battery, which could prove that even if your battery is fully charged, it cannot give full or sufficient current and is on its way out or your starter may be drawing excess current (usually unlikely if starter is spinning at full speed) and pulling the battery down. If it drops much lower, charge battery fully or have it load tested and replaced if faulty.
• If all is well up to here you can assume your battery and the positive feed to your coils are in good order.
• With the coil plug connectors disconnected, use an ohm meter and measure the resistance of both windings on each of the coils. Exact resistance measurements are not too important, but continuity of the windings close to the approximate resistance values given indicates that the coils are in good condition. It must be noted that it is possible for the coils to only show up a fault when at higher operating temperatures, but this does not happen frequently.
  Ignition coil resistance:
  Between the two HT plug caps of the same coil, secondary HT winding, approximately 30 - 35 K ohm
  Between the orange/white and white on the first coil and orange/white and black/yellow on the second coil, primary winding, approximately 2-5 ohm. If this test is within limits you likely have two good coils.
• Locate the igniter and disconnect the plug with the blue and green wires coming from the signal generator (pickup) at the right bottom of the engine. Test the resistance across these wires coming from the signal generator pickup coils, it should be approximately 250 - 360 ohm. If this is in order you have proved the pickups and the wires to be good.
• The little back box or igniter is now tested as follows. With the ignition on, kill switch on, test for 12 Volt DC between the orange/white and the black/white wires in the plug going into the igniter. This proves that it is getting the correct voltage.
• The next step is to prove whether the igniter is powering your coils. Remove all 4 spark plugs and connect the HT lead caps to a spark plug #1, #2, #3 and #4 which is grounded and located to enable you to see the spark. Ensure all the connector plugs are back in, except the one with the green and blue wires from the signal generator.
• To simulate the small voltage generated by the pickup coil, prepare an ordinary 1.5V dry cell with two wires red for positive and black for negative. Connect the negative black wire from the dry cell to the blue wire on the connector plug going into the igniter. Switch on the ignition and kill switch to power the igniter and briefly touch the red wire from the dry cell positive to the green wire connector going into the igniter. You should see a spark on plugs #1 and #4 when you touch the wire and on #2 and #3 when you remove the wire. If this works your igniter is in a working condition.
• One other check that is often overlooked. Run the bike at night with all lights off in a dark area and check that no sparks are jumping from the HT leads to the frame or tank. If so they may need replacing.
• At this stage if all tests have passed you MUST get a spark at all the plugs when everything is reconnected and the engine is turned with the starter.
• If a spark that was previously missing has mysteriously appeared, have a very good look at your wiring and connectors, as something may be making intermittent contact and corrected itself temporary when you moved the wires.
• If there is a spark, but the engine will not fire, it could be due to ignition timing, valve timing or fuel problems. Ignition timing and valve timing problems are more likely on a bike that has not run yet after being disassembled and more unlikely to be the cause if the bike was not taken apart and was running before.
• A quick test with a few drops of fuel directly into the cylinders before replacing the spark plugs and then trying to start will prove it to either the fuel system or ignition system.
  1. If the engine then starts and runs for a few RPM's the ignition is correct and you need to look at the fuel and carburettor side.
  2. If the engine does not fire, but occasionally gives one load pop through the carburetors or even exhaust, it may be igniting when the valves are open, the valve timing may be a problem, cam chain or swapped wires from pickup - plugs firing at wrong time.
  3. Other reasons could be extremely low compression, too tight valve clearances, thus not closing fully (usually unlikely on all cylinders at the same time, but plausible), carburettor faulty or dirty, fuel line, filter or petcock faulty. Filter can cause an airlock if not positioned properly to allow free gravity feed.
  4. Then finally the ignition timing must be set properly. At less than 1500 RPM connect a timing light to #2 or # 3 spark plug and check that the timing marks line up for 2-3 on F, then move to #1 or #4 spark plug and check that marks line up for 1-4 on F. Check the advance by pushing revs up to 2350 RPM and the timing marks should both line up on the 45 mark behind the signal generator mounting plate through the sight hole at the top. The three mounting screws can be loosened and the mounting plate can be moved slightly in the elongated holes to meet this.

Also feel free to start your own thread instead of hijacking another's. That way the proper information gets disseminated to the correct requester. If several different people are having different issues in the same thread it can be hard to tell what advice pertains to which issue.

Thank you for your indulgence,

BassCliff