Cobra jet kit install troubles for 06 1300c

[eaglefan2000]

I have a Honda Vtx 1300c 06.
I bought Cobra Speedster Longs for it and a Cobra Jet Kit. Using stock air cleaner.
I have tried to install to cobra's directions (Installed all parts with 85 jet at 2.5 turns and it burns rich.
Tried adjusting the mixture down in increments to 1.75 turns and is still rich(black spark plugs and black inside pipes.
Took it to a tech I know to help and lowered the jet to the 80 and it would break up at around half throttle on up. Shot starter in at this point and motor revved so it was probably lean at that point.
Tried putting in bigger jets till the throttle would not break up at almost full throttle. Sounds good right!
Ran it for about 30 miles and started missing. Pulled a plug and it was black again.
The closest we got is when we put back in the stock needle and spring and have the 90 jet installed at 2.5 turns on the mixture screw. Still black.
The next thing I can try is to keep lowering the jets till it burns right but then it will break up like it’s lean again. What am I doing wrong? Is there not enough air flow using the stock air cleaner?

[2dobies]

I'm sure a lot of people will chime in on this one, but when I changed my pipes and left the stock box I only did the SCAR method with two shims and the bike is running perfect. Plugs are a light chocolate color and no hesitation. Never touched the a/f screw. Oh, and I cut the piston spring down, but that has nothing to do with it.

[lzt0d2]

I personally don't know much about adjusting the jets and such, but
I do know that the information exists. For that combination...try
Main Jet = Stock
Shim = Yes, 0.05
A/F turns = Stock setting

More information located at http://vtx1300tips.com/VTX1300TIPS.htm#REJJETTINGSPREADSHEET (http://vtx1300tips.com/VTX1300TIPS.htm#REJJETTINGSPREADSHEET)

Good luck!

[eaglefan2000]

Thanks for the info. Will try to shim it. Just took it out and ran the piss out of it. 1st gear to 40mph 2nd gear to 80mph a couple of times and checked plugs. They were starting to clean up. Looks like I was riding too easy and shifting too early. Wanted to sound like the Harleys and run it low to hear the exhaust crack through town. I still want to try and get it set up for lower but will try the shims 1st to see if I can ride lower RPM's and burn clean.

[Retro Rich]

eagle,

If you have the stock airbox and filter you didn't need to re-jet at all with just the pipe change. The Stage 1 kit from Cobra doesn't have a main jet that is equivalent (they are all smaller) than your stock main jet (Keihin 195). The Keihin jets and DJ jets are measure differently (i.e.-a Keihin 195 equates to a DJ 208). I recc. you put the stock main back in there with stock needle, you can put one .02 shim in if you want and have stock pilot (Keihin 55). Start with your A/F at 2&1/2 turns, you may end up turning it out (i.e.-richen the mixture a little) like an 1/8 or 1/4 of a turn past that with just the pipe change. If you shim the needle, trim the "tit" on the needle holder cap in 1/2 so it can move freely/wiggle.

Your bike won't run as well with that jet kit in there as it will with your stock parts. The stock Keihin parts you have in there are superior IMHO to anything DJ has. If you start changing out things at the airbox, we'll discuss different shimming and/or jetting.

Hope this helps.

RR

[eaglefan2000]

OK. I did what you said Retro. Used a little bit bigger shim though. .025. Trimmed the tit that holds down the needle. I am now experiencing backfiring. I turned mixture screw out 1/4 turn and still same thing. Cleaned plugs before and they look allright. Giving it hell down the street doesn't break up at all and runs great all but the backfiring. Does running lean cause it to backfire? Can you explain this? Backfiring should be unburned fuel that gets ignited on the next cycle. Right

[eaglefan2000]

Backfiring on Decel. Sorry for not adding this to the last message.

[Charlie D]

check your pipes and make sure they have not loosened up.

standard is torque go for a couple hundred miles and retorque

[eaglefan2000]

Not the exhaust. Only happens on deceleration. Also can anyone tell me what exactly does trimming the tit do.

[2dobies]

Not the exhaust. Only happens on deceleration. Also can anyone tell me what exactly does trimming the tit do.

Trimming the "tit" gives the stock needle the free play that it needs. If you used a shim and didn't trim it it would make the needle too tight. Only trim half off though so the spring can still grab on. After you put it all back together the needle should wiggle freely, depending on the number of shims used.

[eaglefan2000]

Here's an update.
I went up to 2 shims @ .025 each. Put Mixture screw back to stock @ 2.5 turns and the backfiring went away. Ran it for a while and all seems great. Doesn't break up at all. No smoke. Used to give a puff of smoke. Someone in another forum said he was getting black boogers. It wasn't quite that bad but now it's gone. Will check the plugs in a couple. Thanks to all. This can be closed.

[razorbak57]

Glad it worked out for ya. Got some great techs on here!

[Kidd]

I have the same problem with my 1300 VTX. I installed Cobra slip on mufflers with stock carb. It started lagging in mid speed. Motor was running hot. I added a Cobra jet kit..stage one. Now it running so rich I closed the A/M screw all the way just to get it close to running right.
Tomorrow I'll try putting the stock jet and needle back in and just add another turn to the A/M screw and see if that will help.

Glad I found this post.

Thanks Razor

[eaglefan2000]

Update to this. Started burning rich again after a while. Replaced spark plugs with NGK's recommended in the manual and still a little rich but better. Ended up taking out a shim and richening the mixture an 1/8th of a turn. Oh yeah, make sure the choke tube is pushed all the way in on the top of the carb. It is now running pretty good but it is winter and might have to be leaner for the summer. If so then I will get K & N filter for more air and go from there. Runs like a raped ape 4 now.

[wren]

If you still have a shim in there with that stock airbox that would be why yer still a little rich. Once you put the K&N in there you could get away with that one shim.

[eaglefan2000]

I have Cobra Long pipes with 1 shim under needle and turned 2 & 5/8th turns and is really good now but this is Winter and cold winter air is dense and will lean it out a bit. 1 shim at 2 & 1/2 turn gave backfiring on decel ( too lean)this is why I have it where it is.

[wrangler]

RR..... I just did the Bub juggers and the BAK on a 05 1300C. Haven't touched the Carb yet but getting ready to. Any base line suggestions?
Out
wrangler

[wren]

I have Cobra Long pipes with 1 shim under needle and turned 2 & 5/8th turns and is really good now but this is Winter and cold winter air is dense and will lean it out a bit. 1 shim at 2 & 1/2 turn gave backfiring on decel ( too lean)this is why I have it where it is.



Are the PAIR valves still in there?