How fast can a spark plug foul up?

[Paul's Zuki]

My plight is fighting spark plugs fouling up prematurely. So about 200 miles ago i was having ignition issues then isolated it to a loose wire, then sparks plugs not firing. Everything is wired correctly by the way. Now back the 200 miles ago, I found that the plugs weren't firing or at least #1 #3, I did a coil swap and that didn't work, then I put in a working plug and whad'ya know it sparked. So I replaced all four with new ones and went on with my business riding. a few days ago, the motor starts running crappy and feels like not all cylinders are firing. I check again..........and #3 (new plug) is fouled out. What gives? what could be causing the plugs to just give out? Any Ideas?

OH it's a 1978 GS550e

[nofear18667]

multiple reasons could cause this issue.

1. to cold of a plug, if you are using what factory recommends on a modded bike you might need a hotter plug

2. carbs might need to be cleaned, to rich of a fuel air mixture can foul your plugs, being that you are having this problem with #1, and #3 this seems more likely then the first option

3. Oil might be leaking into #1 and #3 is it a wet foul or dry foul wet means it is either really rich or there is oil on it smell it to get a better idea on the cause

4. Now this last thing that I can think of I hope is not the case but do a compression test and a cylinder leak test if #1 and #3 differ from #2 and #4 then you might have big issues

[tkent02]

My plight is fighting spark plugs fouling up prematurely.

Fouling at any time is premature.
GSes don't do that, unless something is drastically wrong.

[BassCliff]

Hi,

Sounds like a bad petcock.


Thank you for your indulgence,

BassCliff

[Paul's Zuki]

multiple reasons could cause this issue.

1. to cold of a plug, if you are using what factory recommends on a modded bike you might need a hotter plug

2. carbs might need to be cleaned, to rich of a fuel air mixture can foul your plugs, being that you are having this problem with #1, and #3 this seems more likely then the first option

3. Oil might be leaking into #1 and #3 is it a wet foul or dry foul wet means it is either really rich or there is oil on it smell it to get a better idea on the cause

4. Now this last thing that I can think of I hope is not the case but do a compression test and a cylinder leak test if #1 and #3 differ from #2 and #4 then you might have big issues

Thanks this is a great starting point. Will work on checking all of these. I read somewhere online, but it was refering to 8 cylinder vehicles that being to rich may be causing it. I will say this, I do have straights on it with pod filters and 100 main jets. maybe some adjusting of the carbs would help? I just recently rebuilt the whole motor and compression was pretty good, but I will check it anyways. 32yr old motor, you never know......

[Guest]

If you have straight pipes and pods, you have drastically changed the jetting requirements. If it was running perfectly as a stock set up and then you changed to what you have, it still wouldn't be easy. If you started with a bike that wasn't running well and changed from stock, well good luck, because that throws a lot of guess work into a difficult situation.

[SqDancerLynn1]

78 petcock vacuum is hooked to #3 carb. Check the petcock vacuum line for fuel

[1_v8_merc]

Plugs can foul in a matter of minutes if you're running super rich.
My 750 went threw a set every Ride...until I leaned-out the fuel screws.

[Guest]

Plugs can foul in a matter of minutes if you're running super rich.
My 750 went threw a set every Ride...until I leaned-out the fuel screws.

More than likely this is the problem.

[nofear18667]

Thanks this is a great starting point. Will work on checking all of these. I read somewhere online, but it was refering to 8 cylinder vehicles that being to rich may be causing it. I will say this, I do have straights on it with pod filters and 100 main jets. maybe some adjusting of the carbs would help? I just recently rebuilt the whole motor and compression was pretty good, but I will check it anyways. 32yr old motor, you never know......

regard less of cylinders rich fuel settings can cause it. straights, pods I am guessing you did carb work, do you have a carb sync tool seems like you did some work to the bike so I would guess that you probably don't have motor issues the fact that you know that you have 100 mains tell me you have gone into the carbs... if they are synced then I would say to go thru the carbs again I know that is probably not what you want to hear but I have had it to where I thought everything was right had problems took them back apart hit everything with a can of carb cleaner and sure enough it fixed the problem, when going thru check that all jets are the same between the four carbs.

[nofear18667]

This might help if you don't already have

http://www.carbtune.com/

http://www.carbtune.co.uk/colortune.html

I have both love them
these will help you tune your carbs to the mods on your bike, you have a idle air jet, main jet and pilot jet that all play a fuel air mixing part at different throttle positions so there is more then your main jet that needs to be dialed in This Should Fix Your Problems
Happy Tuning

[nofear18667]

78 petcock vacuum is hooked to #3 carb. Check the petcock vacuum line for fuel

also very posible

[1948man]

Float levels too high?