Hey guys, late last year I changed out my stock screaming eagle exhaust with a set of V&H Staggered Long Shots and put on an S&S Tear Drop Air Cleaner Kit. When that was done, the bike ran beautifully and a whole lot better than before the "upgrades".

I should say that my bike is a 97 FLSTC stock, other than specified above.

Anyway, recently the bike has been running very roughly, back firing through the carby (I think) when not under power - almost like the bike is running out of fuel which it isn't. It is hesitant and doesn't seem to want to go "until" the revs come up. It runs fine, or seems to, above 55 MPH when the throttle is open and maintaining speed. As soon as I let of the throttle, it back fires, jumps and kicks, hesitates as if it wants to just cut out. Al of this makes riding it bloody miserable and I am never certain what is going to happen when I try to accelerate away - will it go OR will it hesitate and stall - not very comforting.

Anyway - anyone have any ideas what is going on with it and what I need to do? I am seriously thinking about swapping out the factory carb with an S&S to match the Air Cleaner and so forth. That would also rectify my choke not staying open issue as well.

All and any advice appreciated - cheers.

 

Two things I'd check, the pick up sensor behind the timing cover and do an intake leak check. Can of brake clean with the little hose and give a few little shots at the intake manifold at the heads while at an idle, she drops you found it.

 

Pull the plugs and look to see if one is a different color then the other as in one brown and one black - the black one is part fouled and will back fire when at idle or low speed - also check if you have another set of plug wires just to be sure its not one of those

your changes have changed the type of intake and exhaust flow - both changes are performance adders - you did not add engine performance to complement the free flowing stuff you used its not happy about that yet is runs better

re tuning it post pictures of the spark plugs - first thing to do

 

Thanks guys appreciate the advice a great deal.

@johnjzjz I knew the exhaust and air cleaner stuff was going to have an impact, especially the exhaust - just didn't think it would make this much of a difference. To be honest, at the time I added that stuff I was also going to install an Andrews 27 Cam and associated items and was then going to get it properly tuned to everything - unfortunately life got in the way of that happening even though I still have all the parts.

Anyway, I have ordered some new parts - some of which you mentioned above - plugs and leads. NGK Iridium Plugs and Magnum Sterling Chromite leads. I also bite the bullet and bought an S&S Super E kit, something I have been wanting to do for awhile anyway.







Only annoying thing here is I have the air cleaner stuff already

 

Good advice above, looks like the kit you bought will solve any intake leaks if installed properly. Now would be a good time to also get cam( new lifters too) installed & change inner cam bearing if still original.
Original carb may have just got fuel circuits partial plugged to to old gas.

 

I have an Andrews 13 and an Andrews 27 Cam along with lifters and other associated stuff. Have to decide which cam to use (probably the 27) and then I will get it done. Right now, I just want the bike to properly so I can enjoy the limited riding season in New York State. Anything else can be done over winter when I can put the bike up and not be frustrated by that.

PS: How do you get email notifications of replies etc to posts ?

 

Click on username in thread who you wish to email/message, a small popup should show. Click on Email or PM to send a message.
As you probably know bike will need re-tune when adding cam.

 

Yep - and I honestly think a decent Tune Up (if I can find anyone who can do them any more) is probably needed now as well

 

Look toward the upper left at the dark banner. Click "User CP" then on the left under Settings and Options click "Edit Options." Scroll down to the 2nd box in the center and locate the drop down box for notification options.





The aftermarket air cleaner is likely what's wrong with your CV or more correctly, the carb/manifold seal. If not very careful and meticulous installing one, it's all too easy and convenient to move the carb out of place (in the manifold grommet) ever so slightly to make things line up for mounting the backing plate. They'll stay sealed a while but being out of line eventually takes it's toll. This is especially true if the grommet was not replaced at the time.

You won't have that issue with the S&S but if you don't install the manifold correctly on the heads, you'll never get it to run correctly. Get yourself a magnetic angle finder before you start. The magnet won't work on the aluminum but that's just what they call them.

 

Also...just for ***** and giggles, one of the simplest things to make sure of - is that your petcock is turned in the correct direction. Up (the long part of the little handle) is for standard running of the bike, horizontal is 'off', and down (again, the long part of the little handle) is reserve.