Honda 1999 vt 750 cd has carb issues...installed cobra 2in drag pipes no baffles..installed jet kit to match...but still backfiring when let off throttle...

The carbs are running lean you need to richen them up and your back firing will stop.

hi the air box and exhaust restrict the air movement through the cyclinders to match the jets in the carbs. i have bikes that you can remove baffles or airbox with no problem, others are so finely tunes that it is impossible to run the bike without the restriction. the easy option would be to get a jet and air filter kit. then if you need to restrict air flow any (hopefully you wont need to) you could very slightly raise the inlet/outlet valve gaps to the maximum amount which will open the valves for a slightly shorter time. you could also restrict the exhaust by using large washers on the exhaust gaskets. similar to those used to restrict a bike.

I have a 2007 Honda Shadow Sabre VT1100 and I also put after market pipes on it from Vance and Hines. I also have to keep it choked when first starting and sometimes even hold the throttle a bit while it warms up. The bike has two carburetors and the best solution I have found by lots of asking around of mechanics and bike folk is to get it rejetted through Dyno Jet. It is meant for bikes with after market exhausts and much less back pressure from the lack of those stiffling baffles in the stock pipes. I have also noticed the power loss in the middle torque range and backfiring because of the bike running in a lean condition. The Dyno Jet website is a good place to find the correct set and corresponding part number, but then I suggest finding a cheap place online so you avoid retail price :) Hope this helps. Oh, and don't forget to buy two kits...we have two carburators in our bikes.

The most common reason for backfiring is lack of back pressure from changing the exhaust. To compensate for the flat spot you get you put in a jet kit. This leaves the possibility of more unburned gas getting into the exhaust. Honda uses Kei Hin carbs with a fuel shut off diaphragm to help limit this condition (backfiring) by turning off the fuel to the carbs during deceleration. Even stock exhaust can pop or backfire. Typically it is caused by air getting into the exhaust either past the copper o-ring gaskets in the head or leaking muffler connections from the head pipes to the mufflers. Try replacing all the exhaust gaskets and you should minimize this condition.

to start with you need to purchase a jet kit. it will come with instructions. the stock needle is non adjustable. also you need bigger jets.

did you change the exhaust and air filter? if not, you should. bike is running rich. lean it out a little and you'll be alright.

Check for exhaust leaks that could let cold fresh air into the pipes,test plug wires for ohms resistance, maybe replace plugs.Could it be one of your coils has a crack that only shows itself when chilled?(try to spray silicone on the suspect coil when it is missfires, if this helps stop it fron cutting out replace the coil.(maybe even go back to your prefered jets then) If a relay is weak they can be temperature sensative as well.

Probably the idle jets are set too lean. From what I have read, the factory settings are often wrong. Drill out the plugs and adjust. If you use the right size drill you can get in with a small screwdriver and make the adjustments without totally removing the plug. This eliminates the possibility of losing the adjustment screw, which can happen if the plugs are not there.

Best thing to do is put in a Cobra stage 1 jet kit. You will be amazed at how much better the bike runs.

they are not stock, just call your local Honda shop ask for the parts desk, tell them what you want. They will help you get the right carb parts. without vacuume gauges you might just pay for the work to be done,

just make sure you rejet the carb all bikes come from the factory on the lean side to meet epa standards etc. if you dont rejet you'll actually lose some power and have nasty backfires as well take the time to put a jet kit in i personally recommend dynojet easy to install and comes with suggestions for your application