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No. 1 and 2 plugs fouling and wet

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

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OK folks bear with me.

I have to replace the number 1 and 2 plugs about every 100 miles, less if I use a lot of choke. When I do, they are black, and drenched in gas. On the highway, I can go hundreds of miles with no problems.

I had the coils checked about 5 years and 15,000 miles ago. Compression is good. I have rebuilt and synched the carbs, the boots were pliable, and in good shape and I replaced the boot o-rings.

I rebuilt the petcock last year.

Where I was lazy in rebuilding the carbs was:

1. I didn't check the float levels.
2. The main needle jets (the big ones in the sliders) were off to one side on cylinders 1 and 2. Not centered. It feels like there are some springs or something to keep them straight. Maybe one busted?

Those are the only things I can think of that would cause the fouling plugs. Would they? And that frequently? Or is there something I'm missing?

Another thing...
All of my plugs are black. How far can you lean out the mixture before you can't lean it anymore? Will the screws come out, and you can't put them back in again?

If you can help me out, that would be great. Thanks.

-istp ](*,)
 
check the connections to the coil in question--clean thm even if they dont need to be cleaned.
Put an ohm meter across the primary and secondary sides of the coils and tell us the reading you get/got hmmm/goot

Well let us know what happens.
 
Well I am not the pro but there are things I have learned that I can help you with.

First, the needles leaning to the side is by design. There are little nipples in the metal plate that goes between the needle seat base and the slide that are there to make it lean like that. The idea I was told is so that the needles are always touching the inside of the tube. This is to help with vibration.

If your OK on the highway but not at low throttle then your pilot circuit may be way rich. But before you go any of those places you have to do what Scotty said. If you have a weak spark your not going to fix anything until that is fixed. And the fact that it is 1 & 4 both makes me thing Scotty is most likely right on. I'll bet it is bad spark. Like he said, check that first and report back. I just wanted to chime in to share with you about the leaning needles.

Keith taught me that :D
 
I must have been tired when I wrote that last night. #-o

I have a 1979 GS 750. That might help.

And it's cylinders 1 and 2 (the ones on the left from the rider's vantage point), not 1 and 4.

Also, I put in an Electrex regulator/rectifier about 6 years ago.

Thanks for the info on the needles hoomgar. That makes sense.

-istp
 
If it is 1 & 2 then a bad coil is less likely and if still spark related would be do to wires/connections. Check spark. If good move onto carbs. Now I think it does sound like rich pilots.
 
I've backed off the pilot screws 2 1/4 turns so far. To lean them more seems a bit much, but maybe I'll just back the hell out of them, and see what happens.

I'll double check the spark, too.

So do I just idle the motor, and hold the plug against the head? Seems to me I've seen that done before.

Anyone else's ideas?

-istp
 
To check spark I put the cap on a removed plug and hold it to the side of the block with a pair of insulated pliers and then crank the engine. If you remove all the other plug wires the engine wont start that way. But you can test them all one at a time then and see any descrepencies.

If it is your pilots that are running rich I would think that reducing the fuel pilot screw would be preferable to the addition of air via the air screw. 79? These are VM carbs in there right? If so you have pilot fuel screws. Although I believe they are pluged in the 79? You may need to drill them out.

Hoom is petering out here, Earl, Keith, somebody... bail me out man! :lol:
 
Take a voltage check at the coils then clean the kill switch and retake the voltage.

Check the float height as it will run rich at a lower rpm, at high rpm it may just be enough to kept the plugs from fouling.

Check your choke circuit, it may be leaking.

Also what size jets are you running?
 
If they are CV carbs backing the pilot screws out richens them. Most of the time 1 - 1 1/2 turns is about all that's needed if the circuit is clean. If the tips are worn at all then backeing them out only compounds the problem. If you can get the screws all the way out check the condition of them. Float height could very well be your problem.
 
The jets are just the stock size, whatever that is. And they're VM carbs.

Looks like I have some fiddling around to do. If nothing works, then don't you guys worry, I'll be back. :lol:

-istp
 
istp said:
The jets are just the stock size, whatever that is. And they're VM carbs.

Looks like I have some fiddling around to do. If nothing works, then don't you guys worry, I'll be back. :lol:

-istp
Click to expand...

I figured they were VM's on that year. I am pretty sure that EPA laws made them cover up the pilot screws with plugs by then so in order to adjust/check them you will need to drill those out if that is the case. If it is the plugs are just little disks forced into the hole. You can take a small drill bit and wrap tape around it so it is only about 1/8" or so showing. then drill carefully into the center and adjust until you can see through. If you knick the screw under it a little bit it wont hurt. Then you can pop it out with a scratch awl or whatever.

Good luck!
 
cylinders 1 and 2 you say??? can't possibly be the coils (could be wires though)

you didnt check your float heights??? (but they dont go out of whack on their own unless your floats leak and are full of fuel, or maybe its the float valve thingies?)

1 and 2, thats on the left side of the bike right?
lemme guess, your bike spends a lot of time on the sidestand... (ie: leaning left)

i know, im a genius... you know what to do...
 
If these are CV carbs, the manual sez not to adjust the pilot mixture screws for US models. I'm no expert either, but it sounds like you've been adjusting them quite a bit. Now there isn't a reference to put them back to original.

I would consider turning them all until they seat, then out three full turns. This is where mine all seemed to be set. While you're at it, take them all the way out and clean the needle and the passage with carb cleaner and compressed air - I had some corrosion (or something) in one of mine.

For what it's worth,
Ace.
 
I checked my spark. Just fine at idle.

The only thing I'm not sure about now is float height. If that's OK, I'll be back with more questions.

It's a Canadian bike by the way, with VM carbs which I drive daily.

-istp
 
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