More issues, 2 and 3 not running

[Guest]

I have had nothing but trouble on the bike since I stopped riding it and started modifications.

Carb 4 leaked gas after putting the tank back on the bike. So I took it apart and checked the float level. It was good. Saw some crap in the full holes so I decided to do a full dip again.

Had trouble with the float needle holder thing, they wouldn't come out. With extreme pressure they came out but the o-rings were shot. I ordered and installed new o-rings from Robert.

Put everything back together, added temp tank, and gas came out carbs 1 and 2 and the vent tube between one and two. I don't know what that means, but after a little time the leaking stopped and it would hold gas. Added more gas and let it sit and no leaking out of the carbs. No leaking for days with gas in the temp tank.

Put the carbs back on the bike hooked up the temp tank for testing and it leaked out the vent tube and out of the carbs. Then it stopped and held gas.

After I cleaned up all the gas I decided to see if it would fire up. It did and much better than before since it wasn't flooding out. I started to tune by ear with the mixture screw. No changes with carbs 2 and 3 closed or out many turns. The exhaust from those two carbs was only warm to the touch. Both are getting a nice spark. Luckily this time no gas went into the oil.

One other thing I did while I was waiting for the carb dip is the coil relay mod. I followed Basscliff's method. Don't know if that has anything to do with my new issue.

I am pretty stumped and frustrated. Between gas leaking then not leaking and 2 and 3 not firing, I have no idea what to do next. Any suggestions would be appreciated. Thanks.

[MisterCinders]

What kind of compression do you have?

Did you check the plugs on 2 and 3? Are they wet?

[Mop Bucket]

What kind of compression do you have?

Did you check the plugs on 2 and 3? Are they wet?

Last time I checked compression was good. I can check again. How do I know if it is wet and what does that mean? Does the gas get it wet?

By the way, very nice looking bike!

[Mr.Midas]

There should be some dry carbon residue(from coal black to light tan in color) on the plugs if they are firing. The dry residue will return quickly after a thorough cleaning if the plugs are firing. A plug that isn't firing won't look much different from when it was cleaned/replaced, and is usually a little wet from all the unburned fuel that has been pumped through the non-combusting chamber and into the exhaust.

Remove the plugs and compare the firing plugs to the non-firing plugs. Clean them all thoroughly with carb or brake cleaner and get down into the gap around the insulator tip with a toothpick.(or just get a new set if they are really crusted up)

Make sure all the flammable solvents have evaporated before attempting to check spark output.


With the plugs still removed, connect them to the suspect coil wires and briefly engage the starter with the kill switch in the run position while keeping the plug grounded to the engine(watch out for gas fumes and the possible shock hazard).

If you don't see or here a spark, double check with a different plug. If no spark, then there is likely something wrong with the coil, or the points/ignition isn't triggering the coil properly.

With all the plugs still out, swap the 2-3 points/ignition wire to the known working 1-4 coil and test for spark with a plug in one of the 1-4 wires to verify the points/ignition is actually triggering the coils.


Good Luck!

[tom203]

You said you had good spark to 2 and 3 , so this is likely a carb issue. I assume you replaced all float needle seats with new o-rings and set float levels for all four carbs- not just #4 ??? Did you inspect needle/seats for excessive wear- they might not seat well once engine is vibrating, even if they hold pressure overnight .

[Mop Bucket]

Thanks for the help I pulled the carbs and pulled the float bowls. #3 was dry and #2 was 3/4 full. I messed up #3 trying to replace the orings on the float needle holder thingy. I will replace the float needle on #2 and the float needle holder thingy on #3. I hope that fixes the issue.

[Mop Bucket]

Much better results from changing out the parts. The carbs no longer leak gas! The bike idled well. Still have some issues. Carb #2 doesn't seem to be running much and turning the mixture screw did not have an affect on idle. The muffler was warm to the touch out of carb #2. It did warm up after awhile but I was still able to touch it with my hand.

Still need help making sure all are firing. Not sure if temperature is a good indicator of an issue but I assume so. I am guessing either the float is still off even though I measured or the butter fly is not synched to the others. I will pull them again and check the above.

Anyone have any other ideas on what to check?

[MisterCinders]

Again, you should check for spark by grounding the plug against the engine. That will rule out (or confirm) any connection, cap, coil issues.

I would also check your ignition timing, assuming it is adjustable on that bike. Even though your problem ties to a single cylinder, I found that a timing adjustment helped when I had problems on my No. 3 cylinder.

[Mop Bucket]

The spark plugs are getting sparks. I will swap out plugs just in case.
I took the carbs off again and checked the float and needles on carb #2. I swapped the needle on #2 and adjusted the float a little so it would allow more gas in the bowl. I bench synched the carbs.

Fired it up and let it run for awhile. carb #2’s muffler was about 50-70 degrees cooler than the other three. Again the mixture screw didn't seem to have any effect on #2. The bike seems to idle, rev, and sound great.

Is there a good way to tell if it #2 is firing?

[tom203]

Pull spark plug wire off #2, does it still 'idle,rev and sound great"?

[Mop Bucket]

Pull spark plug wire off #2, does it still 'idle,rev and sound great"?

Great idea! I did pull it to check spark and it seemed to run great but wasn't really paying attention. I will check it out when I get home. I also ordered the colourtune see through spark plug, hope it’s not a gimmick.

[IanDMacDonald]

Are they hooked up properly?

Hey-

Just a shot in the dark, but, did you check to make sure the coil wires are hooked up in the proper sequence? Kind of sounds dumb, but, I had my wires hooked up wrong, not allowing my cylinders to run properly. Left coil fires the 1 & 4 cylinders, and the right coil runs the 2 & 3 cylinder on my '82 GS650L. Just a thought.

[Mop Bucket]

Hey-

Just a shot in the dark, but, did you check to make sure the coil wires are hooked up in the proper sequence? Kind of sounds dumb, but, I had my wires hooked up wrong, not allowing my cylinders to run properly. Left coil fires the 1 & 4 cylinders, and the right coil runs the 2 & 3 cylinder on my '82 GS650L. Just a thought.

Thanks, I believe they are on the correct plugs. Correct me if I am wrong, the wire closest to the plug is connected to that plug. The wires are in kinda like a Y shape from each coil.

PS I used to think putting carbs on was like giving birth. (never gave birth, but the first time I pushed and pulled for about two hours. Never sweat so hard in my life.) Then I read a post were someone used something to push them on. I used a racheting tie down. The carbs go in almost with no effort.

[Dave8338]

Are you using a nurse tank or the bikes' tank, hooked up with the petcock and vacuum line for the #2 carb? If not...is the vacuum port on the #2 carb, capped? Can you get it to fire with a little starting fluid in the #2 carb, when the bike is running? Have you done a valve adjustment yet?

[Mop Bucket]

Issues are solved!

The leaking was due at first to something got into the carbs from my painting exploits. Then they started to leak because the orings I had in there were too big or something and it took extreme force to get the float needle seats out. The extreme force bent the seats so the needles wouldn't move. Luckily I had a spare set of carbs. Leak fixed.

Next I took all the bowls off to see what gas was doing. Carb #2 was flowing great. So the issue wasn't the needle or no gas in the bowl. Checked the float level and the float looked good. I took apart the carb and blew air through everything. Air blew through everything great. Checked the needle holes and other tubes and they were all clear. Didn't see any issues so I but it back together and put it back on the bike.

Fired up the bike and shazam all cylinders are firing. Just need to tune it a little and I should be able to ride it… after I put everything else back together.

Thanks for the suggestions and hints.