Sputtering/Misfiring

[SimpleMan_Omen]

When I traded for this bike I had a 200 mile ride back home on it. Halfway back it started sputtering and cutting out. I made it to a gas station to put in some fresh fuel and some carb cleaner additive. It ran fine the rest of the way home so I thought the issue was resolved.

Then I took it out to the store and it was doing the same thing but then it started to run smoothly with less power. When I stopped I noticed that the plug wire for the front cylinder had come off. After reattaching that I took it back out and had the same problem so it appears that the issue is only with the front cylinder. Today I put new plug wires on and it is much better but still stuttering a little when you get on the throttle and not consistently. If I get on it in lower gear from start it is more pronounced. If I roll hard on the throttle in 4th from 50-70 it generally does fine but will stutter a bit sometimes.

I wouldn't think the carb needs to be tuned since it ran great for about 100 miles but I could be wrong. I know nothing about the ignition systems on these things either (learning phase).

Ideas?

Everyone on here has been very helpful so far and I appreciate it guys.

 

[SimpleMan_Omen]

Clean the carb and the pet cock

They look good. Looking at the petcock from the cap opening the screen is shiny silver. I took the bowl off the carb thinking I needed to clean it but it is spotless with no gunk, trash, looks great.

 

[HMAN]

Replace, regardless of what they look like, the rubber caps on top of carb. You may have 1 or 2. You can buy silicon caps @ auto parts store. If they dry rot an crack, they suck air and will cause shitty performance. Jm .02
The higher end stutter may be air bleed in carb. Older Super G had a drilled .040 air bleed. Newer models have a screw in replacement simular to main and intermediate.

 

[SimpleMan_Omen]

Replace, regardless of what they look like, the rubber caps on top of carb. You may have 1 or 2. You can buy silicon caps @ auto parts store. If they dry rot an crack, they suck air and will cause shitty performance. Jm .02
The higher end stutter may be air bleed in carb. Older Super G had a drilled .040 air bleed. Newer models have a screw in replacement simular to main and intermediate.

I just had a look and there are two of them caps. One is zip tied on and has some dry rot. I'm going to bark up that tree today.

 

[HMAN]

I just had a look and there are two of them caps. One is zip tied on and has some dry rot. I'm going to bark up that tree today.

Always good to keep a few in the pack too, as they will sometimes pop off and disappear.....

 

[bdm7250]

Ethanol beats the snot out of rubber parts (fuel lines, carb o-rings, etc.) if you need to dig deeper to solve the problem I would suggest a carb rebuild, it is easy to do and really cheap piece of mind. Also try to run ethanol-free fuel...

 

[SimpleMan_Omen]

Low grade is the only ethanol free to be found around here and it says that the bike should only have premium.

I did swap out the rubber caps and it is doing a little better.

I think the next step is to retune the carb then do a rebuild if that doesn't work. My bike doesn't have a tach though. That fact has been irritating me anyway so I guess I'll just order one. That'll be a new project for me to figure out.

The ride to the parts store and back was fun though and the parts store guy was all about the bike so yay.

 

[SimpleMan_Omen]

Always good to keep a few in the pack too, as they will sometimes pop off and disappear.....

Thanks for the advice. I'll put some in my tool roll for that bike. Do you know what the blocked off ports are for?

 

[bdm7250]

Low grade is the only ethanol free to be found around here and it says that the bike should only have premium.

I did swap out the rubber caps and it is doing a little better.

I think the next step is to retune the carb then do a rebuild if that doesn't work. My bike doesn't have a tach though. That fact has been irritating me anyway so I guess I'll just order one. That'll be a new project for me to figure out.

The ride to the parts store and back was fun though and the parts store guy was all about the bike so yay.

https://www.pure-gas.org
The link is a useful site to find ethanol free locations near you..

 

[SimpleMan_Omen]

https://www.pure-gas.org
The link is a useful site to find ethanol free locations near you..

Thank you, that is awesome.

 

[bdm7250]

Low grade is the only ethanol free to be found around here and it says that the bike should only have premium.

I did swap out the rubber caps and it is doing a little better.

I think the next step is to retune the carb then do a rebuild if that doesn't work. My bike doesn't have a tach though. That fact has been irritating me anyway so I guess I'll just order one. That'll be a new project for me to figure out.

The ride to the parts store and back was fun though and the parts store guy was all about the bike so yay.

The Shell in Watkinsville has ethanol free 91 octane.

 

[bdm7250]

I believe all ethanol free is 91 octane at least around here it is and most stations have it, more likely than unlikely

Ethanol free comes in all grades, here we have 87, 89, 91 and 93 octane...all ethanol free.

 

[SimpleMan_Omen]

I believe all ethanol free is 91 octane at least around here it is and most stations have it, more likely than unlikely

Most of what I see when I stop at stations around here is low grade that costs more than premium with ethanol. They mainly sell it to people wanting it for small engine applications (rural area).

 

[HMAN]

Thanks for the advice. I'll put some in my tool roll for that bike. Do you know what the blocked off ports are for?

I would be guessing. Someone smarter than me will come along with the answer.