I need some help

[bout_it_4real]

i have a bandit 02 bandit 1200 engine that backfires only in 2nd gear when im really getting down own here hard why does this happen only in 2nd gear??????????  These are the things it has on it it has its orginal carbs which is bandit 1200 carbs, factory slip on scorpion pipe, stage 3 dynojet kit and i removed the pair system off of my engine some of you may know it as the air valve solinoid/assembly. This bike runs well fast as hell but only when riding do i hear the little back fire noise every now and then and when i get on her hard out of first gear into secon it sounds like a gun shot the rest of the gears or fine. the carbs have been cleaned and alsosynchronized so what can i point the finger at thats causing the lound 2nd gear backfire.

[bout_it_4real]

oops im sorry i meant to say it has factory headres and a aftermarket slip on scorpion pipe if this will help...

[txbanditrydr]

..... i removed the pair system off of my engine ....

Check to see that all the vacuum hoses are plugged off - there's one on the pair valve itself that requires plugging and maybe it worked loose.

[bout_it_4real]

much apperciated but the pair valve is no longer on the bike anymore i took it off and pluged the main holes from the pair valve lines that are located down by the exhaust headers.

[txbanditrydr]

Pair valve has 5 hoses.... one to each cylinder and a small vacuum hose from the petcock vacuum hose.  That's the one I was thinking about may have started leaking.

[bout_it_4real]

doesnt the petcock one go on the gas tank cuz thats where i have it hooked up  and i also have my breather hose that usually connects to the air box running to nothing and its open because i have k&n air filters on it?

[txbanditrydr]

The vacuum line that runs to the petcock should (or did) have a tee installed between the carb and the petcock.  This tee had a vacuum line that ran to the pair valve.  I forgot about the breather hose so I guess there's a total of six lines to the pair valve.

[bout_it_4real]

so what should i do with these lines or the line plug it up. i noticed there is a space right in the middle of the carbs where it looks like a carb vac hose use to be it resembles the 2 on the left and right of it is this suppose to be missing or should i maybe plug this line in the center of the carbs up as well?

[txbanditrydr]

Carbs 1, 2 & 3 (left to right as you're sitting on the bike) should have caps on the vacuum ports used for carb sync procedures.  Some people will install a short (5-6") piece of vacuum line on each with a plug on the end to may carb sync easier.  The #4 carb has the main vacuum hose hooked up all the time except during the sync.

Bottom line... all vacuum lines have to be plugged or connected to something and all vacuum ports have to be capped or have a line run to them.  In the end I have no idea why there's popping going on - my pops a ton on decel (stage one & slip-on) but I'm still running the PAIR.  Good luck.

[bout_it_4real]

hey man i really apperciate  you taking the time out to explain all this to me you've really been helpful so i guess what ill start doing is pluging off the lines from my carbs that arent running to anything i know for sure i have 3 of them 2 of them are the ones that use to run over tom the factory airbox that i no longer have. So one again thanx..

[Slider]

I have a 98 with a Yoshi slip on and it pops in 2nd too but only when I'm using the engine for braking -especially when decending a steep hill. I know that there is air leakage where the Slip On joins the stock pipe, since it sometimes spits out condensation when starting.
Since I have enriched the low end jets for better driveablity at low speeds... I believe that the fuel air mixture is not totally burned or something... hence the popping.

Well, who gives a hey? I don't think it's doing any harm. Enjoy the popcorn. 

[asskickinpeanuts]

Mine pops good on decel, especially hard engine breaking (stage 1 kit (I think), D&D slipon, stock headers).  But, I like it.   (I know im goofy, if that helps!) 

[txbanditrydr]

Plugged off my PAIR valve recently... all popping is gone.  I kinda miss it in a way but I've noticed some changes for the better.