Sputter sound on low end?

[BuddyLee]

I recently received my bike back from being in the shop. I took it in initially for a carb clean, but came back out with a new carb heater, fuel filter, and spark plugs as well. The initial problem was that it was real sluggish and almost no top end at all (maxed out at 55ish mph). Now that I have it back it runs great on the top end, but the low end has problems. It seems from 20-45mph it has a sputter, and sounds pretty sick (not sure how else to describe it..) I do have cobra pipes if maybe back pressure could be the issue? However last year and the 3 years before that I haven't had a single problem with the bike and haven't done any modifications to the mechanics at all. It always has had some popping from time to time on decelerating, but not enough for it to ever bother me.

I know this problem is probably hard to diagnose without hearing it, but any ideas would be greatly appreciated! Still angry at the shop that said it was fixed and "how it is, is just how it is.."

[93gc40]

Sounds like you need a new mechanic, after you make this one finish, the job you paid him to do..

What bike?
When did you get the pipes?
What speeds are at issue, BY GEAR? 20-45 covers 3 gears on my bike.
1/4, 1/2, 3/4 or full throttle??

[BuddyLee]

Originally Posted by 93gc40

Sounds like you need a new mechanic, after you make this one finish, the job you paid him to do..

What bike?
When did you get the pipes?
What speeds are at issue, BY GEAR? 20-45 covers 3 gears on my bike.
1/4, 1/2, 3/4 or full throttle??

yeah!... $400 later it still isn't fixed and not enjoyable to ride.

2003 Shadow Spirit 750
Pipes came on it when I purchased it in 2007.
I initially thought it was only in 1st and 2nd. I took it out again earlier and realized even in 3rd it is an issue.
Throttle position is a good question. I know it is still a problem at 1/4 and 1/2, 3/4 I am not sure. I will have to get back to you. At full throttle it might sputter just for a second, but once it catches up and you begin to accelerate more the sputter goes away.

[93gc40]

What do the spark plugs look like? They white, tan, dry and black or wet and black? Is the issue worse in the first 15 minute of riding, and less noticable after 15 minutes? How much choke do you need on first start of the day?

[BuddyLee]

I will check the plugs when I get home. Problem doesn't change from 15 min to an hour at all. Choke is little to none on first start.

EDIT: After I thought about it, the shop told me to run a few tanks of b12 chemtool through it and it should clear it up...
So, I would think the plugs would be black correct?

[BuddyLee]

Plugs are black and wet. Part number: DPR7EA9

Just got back from a quick ride. I don't advise this, and i'm not sure if its even worth anything, but i shot a video for sound purposes. Didn't think to account for the wind noise, but hopefully you can make out the sound I'm talking about. It would be alot better if i could get a sound clip from a stop and then accelerate cycling through the gears (1st and 2nd is when it seems most prominent) but then i would not be able to pull in the clutch!
Sputter? -Video clip

Any thoughts or ideas would be greatly appreciated. Thanks!

[BuddyLee]

I have noticed that the sputter almost completely goes away when running with the choke pulled out just a little. I think overall it has gotten a little better, but it may just be that i'm getting more used to it..

[Scrapdog2grand]

are the plugs black and wet, front and rear cylinders?
and is that after running with the chock on?

[gdb069]

Originally Posted by BuddyLee

EDIT: After I thought about it, the shop told me to run a few tanks of b12 chemtool through it and it should clear it up...

You need a new mechanic. B12 is a carb cleaner and not a really good one. But they already cleaned your carbs so WTF. B12 is very strong stuff and should not be left in the system long as it will rot rubber. Take a look at the MSDS for B-12. I would not use this unless I was a very bad mechanic and ran it through the system as fast as possible so no chance for it to break down the rubber.

If they really did clean the carbs they need to tune and synch and your sputter will be gone.

G.

[BuddyLee]

Originally Posted by Scrapdog2grand

are the plugs black and wet, front and rear cylinders?
and is that after running with the chock on?

Yes, both plugs that I can get to without taking off the tank are black and wet. At the time of that post, that was without the choke on.

Originally Posted by gdb069

You need a new mechanic. B12 is a carb cleaner and not a really good one. But they already cleaned your carbs so WTF. B12 is very strong stuff and should not be left in the system long as it will rot rubber. Take a look at the MSDS for B-12. I would not use this unless I was a very bad mechanic and ran it through the system as fast as possible so no chance for it to break down the rubber.

G.

What cleaner do you suggest? What are your thoughts on the seafoam additive? I can see in full strength the b12 posing a problem, but when mixed per directions on the can I didn't know it could be so bad.

Originally Posted by gdb069

If they really did clean the carbs they need to tune and synch and your sputter will be gone.

The thought that the floats needed to be adjusted did cross my mind. Which I would think would eliminate the problem altogether, I just assumed that was standard in a carb cleaning... I can certainly say I will not being go back this mechanic... If i can ever get him to fix this problem first!

His reasoning for suggesting the cleaner AFTER he cleaned the carb was because "sometimes small deposits can get into the nooks and crannies deep inside that we cannot get to." When I told him that after a tank or two of his suggestion and if the problem still exists that I would be bringing it back, he said, "Well we can shoot some air through it to see if we can break up any deposits, but that's up to you as doing that could cause even more problems." (Thoughts on this "idea")

Another sidenote: Put 45 miles on today and the problem persists. I rode mostly all highway with the choke off. I did notice that on the slightest decel the pipes backfire extremely bad (also a sign of carbs needing synced?) and I have to pull in the clutch a little in fear of the whole neighborhood getting pissed off and tired of "that damn guy down the street with the busted shadow"...