Misfirin- bad gas?

[Perry]

Perry, has this bike sat for along time and you just purchased it or have you put many of the miles on it? You say no smoke, new plugs, runs good for about a mile then sputters or misfires. First, check for faulty tank vent, possibly creating vacuum in the tank starving it for fuel. Take off the gas cap and put your lips around the bottom part of the gas cap and blow and see if any air comes out the tiny holes or if it's plugged up. If you have an original gas cap with a little white colored plastic piece on the bottom of the cap unscrew this white piece put the cap back on and go for a ride. Second, check your pet cock the filter may be dirty, also, your gas tank liner maybe working loose and clogging the filter of the pet cock. If this doesn't help you will have to consider ignition issues.

I'm the original owner. I'd startbit up or take it for a quick ride, but it did sit without much exercise for a few months. The rear tire was getting slick and needed replaced, and I was busy. I always take into account that it only has two tires, so they should be good ones.

I like your suggestions. I should have checked in on the forum before I took it over there!

 

[chubs]

Going back to your original post, it sounds like the bike was running good till you put gas in it and then started having problems. I agree with the diagnosis of just bad gas being the main problem. Why didn't that shop do what you asked them to do ? I've seen unscrupulous people pull some really bad diagnosis's outta thin air to jack up a bill for something that a reputable shop would fix for free. My bet is water in the gas. (but then again, I could be wrong!)

 

[knothead]

Well the ticking you may be hearing is probably the tappet screen being a little dirty....i clean mine ever other oil change.....if it gets dirty it will restrict oil from the top end and make it have a ticking sound....and some still have a tick no matter whatbut you still need to clean it periodically

 

[Sven]

Push rod ticking is a tight valve usually. Piston tick you have poor compression if not material locking the rings as the snowball continues. Scope readings show aluminum melted on cast iron type cylinder bore is the tick. Normal hair type thick scratch lines in iron cast, yes. Silicone liners, not so much. That kind of welding effect, it more pulls the coating off the wall [I've seen] since it's mixed with silicone.

Tell them they are being watched. Report the leak numbers they tell you here. Back it up with a compression test. Recap:
Compression: We check this first so as to move on to the other two, or tail chasers are they.
Spark: This is up in the air. Two coils.
Fuel: Can't be fuel. One carb does not foul one plug and leaves the other alone. Back to comp or spark.

Edit:
And we play the odds of an air leak at the Y block... unless I have a look at the old plugs and rule an air leak out. And since you have a new set, there's another read as to pinpoint who.

 

[Sven]

Sven story... an ongoing problem at another website, guy is fouling #2 plug only. I told him fuel related. Others chimed in throwing all sorts of variables and missing the one wire theory. I explained it well before and still swapped coils and ignition to no avail. Have yet to hear back. Anyway, I'll toss in the same variable of the full ign system and see if it makes sense...

Say the ignition unit is 1-4 pickup and a 2-3 pickup on an inline 4-cyl eng. Say the wire connector only shows two wires in the connector. That still says one continuous wire showing both ends at the connector. If 1 fails, all 3 fail as well. How can the flow continue without the other wire that is stopped between a total of 2 pickups? Ain't gonna happen chasing one fouled plug. Then it's fuel related, not ignition but one of the 4 carbs/injectors.

Say dual coil is 1-4 and the other coil is 2-3 on a 4-cyl. Same wire in-wire out. Ign key to one side of the coil, pickup is the trigger and that side. Can't foul one plug if a dual plug fires once and out that thick Y of a braid split [inside] for both plug wires. Has to be comp.

Back to your variable. Since the ign setup was not mentioned, back to a single coil, dual leads, and dual pickups at the ign-system [if applies]. If wire in-wire out holds true, it's not the coil, not the ign, not fuel.

Bad coil lead?

 

[Perry]

Update- dropped the bike off with Mike at Lifestyle Cycles in Anaheim, Ca. They checked out the carberation and felt the original jets were undersized, so stepped them up one size. Then found the spark plug wire to that back plug was broken and replaced it.

The bike has never run better!

Thanks again to all you guys who weighed in. A little embarrassed I didn't find the bad wire in the first place, but all is good!

 

[Sven]

No, thank you, Perry. Come to find out, the 'story' was the guy was using aftermarket intake boots that caused a lean [heat expansion] condition after 20 minutes of riding. Pages later he mentions the intake boots were not stock... once he brought it to a shop and they caught it.