At low rpms (3000 and below) I can hear my carb backfire with my exhaust. Its driving me nuts.. what could be going on. Oh, Its the front cylinder thats doing that. It has good power at crusing speed but, it has slow deacceleration. If anyone has a idea what to do let me know. 1999 vulcan 750 with 15,000 miles...James

Sounds like you may have an exhaust leak. Check the clamps and exhaust gasket. Have you done any work on it recently, or did it just start backfiring?

It just started backfiring...I noticed a downgrade of performance for a while so i had started putting fuel cleaners in every fillup. Then oneday i noticed the carbs popping and the exhaust as well.

It just started backfiring...I noticed a downgrade of performance for a while so i had started putting fuel cleaners in every fillup. Then oneday i noticed the carbs popping and the exhaust as well.

There is a little vaccuum line on the right carb, Mine was backfiring and i took it off and put a little cap on it. that made a big difference. now it only back fires when i am coasting down a hill st high speeds. :) (40mph and up)

It could also be an exaust leak like the guy said above.

putting cleaner in it every fill up is too much, it could be doing an odd burn cycle on to much cleaner, that will also wear the exaust and give you a leak.
try waiting for a mo. then put half a can of seafoam and run it at speeds of 40mph up to 80 fast, that will clean out the carbs, or just do a maintance on the carbs. u can also check the air fuel mixure... there could be alot involved and there could be one easy thing.

I got the krackles too. On every deaccelleration like forth of July. I'm trying to pretend it's intentional but no one can see my convincing look through my helmet. I just try to speed home and go in the bat cave. I read on line here that putting marbles in the vent tubes might help. I can't find the artical. Anyone out there tried it with success?

I read on line here that putting marbles in the vent tubes might help. I can't find the artical.

I haven't done it, but HERE'S (http://www.vn750.com/forum/showthread.php?t=1083) the thread from the Vulcan Verses that might help ya.

The easiest thing is to go through the exhaust system and check for loose nuts on both the exhaust pipe and the manifold on the cylinders. If these are loose and leaking air into the system, you will get the pops that you describe and no amount of cleaner or Sea Foam will fix it. It takes about 10 minutes of time to check. Why futz with esoteric solutions if it's that easy?
The vacuum line on the right carb goes to the evaporative fuel recycling system. It creates a low pressure that allows gas fumes to be sent to a charcoal canister rather than venting into the air. If this is causing the popping, there is a problem somewhere in the system.

I posted this on another forum (the wrong one) so I will repost here;

I marbled my bike today. Made a HUGE difference! I only get a slight pop from the rear cyl. when suddenly coming off the gas. I may have to consider the carb screw adjustment next. One thing I don't want to do is sacrafice reliability for silence. Any help or cautions anyone can give about carb adjustment? I read other posts here about how to do it, but one question I have is; are the lead-covered screws actually on the side of the carbs instead of the bottom as I have read? Looks like the same thing, but much easier to get to. The carbs are Kleihns.

Also- is there a written procedure for relocation of the R/R? I still think I am cooking it with my goat belly.

Thanks.

Here's what I posted on another thread:

If you look in the gallery under mods, you'll see my r/r relocation. I went to Home Depot and got:
6" heavy duty Strong Tie - usually back in the lumber dept. Just a plain straight one
1/2" U-bolt (strange enough, it fits our 1" pipe). That's in the miscellaneous nuts and bolts section.
2 nuts and to fit the old r/r bolts - take one of the bolts with you to match it to the right size nuts.
Some shrink wrap tubing that will fit over the U-bolt (isn't necessary, but protects the paint on the frame from the U-bolt. The shrink wrap is in the electrical section where the voltmeters are.
If you don't already have one, a drill and drill bit the size of the original r/r bolts. The U-bolt should fit through the same size hole.
Oh, maybe some washers and locktite.

Now, make it look like mine.

You'll need to take the battery out and dislodge the battery box just enough to remove the r/r. It's probably best to disconnect all the plugs from the various devices connected to the battery box before trying to move it. The starter solenoid comes out of its rubber mount, so no need to disconnect anything there.

With the r/r removed, place it towards the end of the Strong-Tie, and mark the hole locations with a permanent marker. While it's there, lay the u-bolt on its side at the other end of the Strong-Tie and mark where the holes need to be drilled for it. Then install the r/r to the Strong-Tie using the original bolts, and the two nuts(and washers) you bought, and a little lock-tite so you won't need to worry about it coming loose. Next, take the heat shrink tubing (if you opted for it), and place over the u-bolt, then heat with a lighter or something really hot so that the chrome part is fully sheathed.

Stick the u-bolt end of the assembly between the frame and plastic fender piece right above the left passenger footpeg as shown in my pics, and plug in the r/r. Take the u-bolt and put it over the frame and then through the Strong-tie, and install the washers and nuts, making sure to have a little locktite on them. Adjust for best looks.

Any questions?

I Have A Small Leak Where Exhaust Mounts To Head. Have Read About Getting New Gaskets For Exhaust From Judge. Were Can I Find These Gaskets.

If you're talking about the exhaust pipe to the manifold, then your Harley Davidson dealer.

Here's what I posted on another thread:
With the r/r removed, place it towards the end of the Strong-Tie, and mark the hole locations with a permanent marker. While it's there, lay the u-bolt on its side at the other end of the Strong-Tie and mark where the holes need to be drilled for it.

I did the relocate but am not entirely happy with the mount. I am not sure what a Strong-Tie is but may copy yours if I can find the tie.

Go to home depot and ask them for the strong-tie. or go to strongtie:

http://www.strongtie.com/products/connectors/HRS-ST-FHA-PS-HST-LSTA.html

something like this in 6 inches

First I degoated and had some backfire. Then I adjusted carburetor fuel mix and had less backfire. Next step was marble and got worse backfire. Does that mean I need to open carburetor fuel mix more. I am at 2 1/4 LS and 2 1/2 RS .Right side is worse then left.