[sambroom]

I know this is a pretty common question, but I think I have done everything, and I cant seem to stop the backfiring on de-accel. I have:

resealed the Cobra headers with new press washers
rejetted the main jet from 185 to 195

what else can be done to get rid of backfiring? I rode it for a bout a month like this last season, and all of this season. The power seems alright, there is no hesitation and it is consistent on the highway. I just cant seem to get it to stop backfiring! :banghead:

I heard from a local guy that de-capping the airbox might help, but I dont get how... it seems like that would just lean out the fuel mixture.. Maybe I should go up a size for the main jet? adjust the needle? Help!

 

[MPD193]

Did you remove the PAIR valves? Did you retorque your bolts again on a cold engine? This should be done after the engine and pipes get good and hot and allowed to cool completely.

Bigger jets wouldn't hurt. Most run 210-215.

 

[sambroom]

Thanks. I didnt remove the pair valves. I guess I cant see a reason why not because Utah doesnt test motorcycle emissions. I'll do that next. I put the pipes on warm, but re-tightened after running it for 10 minutes (I thought I must not have sealed well enough because of all the backfiring) I'm confident I have a good seal. I live and ride at pretty high altitude. VTX1300s sold in my area all came with a 185 Jet. Jets are cheap though. I guess it couldnt hurt to throw in a bigger one if removing the pair valve doesnt solve the backfiring. Thanks a ton! Any other ideas?

 

[jstar61]

Add a washer or two under the header bolts. Flanges are thinner than stock and acorn nuts can bottom out before they actually torqye down the gasket.

 

[MPD193]

If you're gonna rejet, get the factory pro kit and de-cap or mod the airbox. None of this is necessary with just new pipes, but you will thank the Cafe later. At the top of the 1300 forum, there is a sticky thread of "answers to common questions". You should find info on all the part numbers you need and links to how to rejet, pair mod, etc.

If you run into any problems, post a new question and someone who has been there will explain how to do that.

Maybe CharlieD or Gonzo will chime in and have better advice for carb settings. I know what works for me, may not work for you and that just because it works for me is not the way you have to do it.

Edit: Good call on the washers John

 

[hawkvtx]

The pipes aren't seated. Put washers on the exhaust bolts.

 

[sambroom]

Thanks a ton! Here is the order of the things I plan to do: 1. add washers under the acorn nuts on the headers. 2. remove pair valves+ clean carb since I'll be there anyway... 3 if I still dont like the way its running, de-cap the airbox, adjust the a/f screw out, jet to 210, adjust needle back two notches... Sound about right??

 

[dnice]

Let it backfire...sounds cool.

 

[Donut]

Thanks a ton! Here is the order of the things I plan to do: 1. add washers under the acorn nuts on the headers. 2. remove pair valves+ clean carb since I'll be there anyway... 3 if I still dont like the way its running, de-cap the airbox, adjust the a/f screw out, jet to 210, adjust needle back two notches... Sound about right??

Careful not to brake the studs off when adding the washers. That is where your popping is coming.
Add the block off plates when doing the par removal Don't just plugs the hoses.....
Decap and add K&N filter , it's waterproof.
Jetting.., FP stage 1 or 3 jet kit. In my opinion only.
58 or 60 slow jet
215 or 220 main
Glen's a/f adjuster
Needle clip on 4 notch from blunt end ( on F/P needle)
A/f set 1-3/4 turns out.

Next go and have a good time riding.

Doug

 

[Bassdude404]

Get the issue with the backfiring fixed before doing anything else...Start doing too many things at once and you're just chasing your tail, not accomplishing anything...

 

[jstar61]

^^^^^What Bill said...

 

[sambroom]

Hey thanks Donut and Bassdude. I plan on making sure my seal is tight on my pipes and trying it out. Thanks for reminding me to be careful about the studs. I actually broke one on my XR 400 before. That was a pain. I figure its about time to pull the plugs and check the mixture--and adjust the carb accordingly. If it still pops, I'll remove the pair valve. I'm also planning to do the same de-cap bassdude posted a couple of years back, and also the scar mod Doug recommended. Thanks a ton for the replies! I have been getting help from you two for over a year... I just only decided yesterday to get a membership! :cheers:

 

[sambroom]

ill do the decap and scar last

 

[sambroom]

hey one more question, I when/if I remove the pair valve I am certainly going to do the job right and not just plug hoses, I originally planned on making the cover plates myself, but I was wondering if rather than removing the reed valves from the valve covers, if I could just plug them where the hose now connects... So get rid of the hoses and the T, but plug and keep the reeds? any reason why this shouldn't work?

 

[MPD193]

Also agree with Bassdude and Jstar. Do you fixes one at a time and you'll have less problems to chase down if something goes awry. Fix the gasket problem first and then the Pair valve if you want and you want to use the block off plates if you choose too. Something about condensation build up if you don't.

I said earlier that most all of the mods and rejetting are unnecessary with just new pipes and just because it works on one persons bike doesn't mean it must be done on all bikes.

 

[RBull]

hey one more question, I when/if I remove the pair valve I am certainly going to do the job right and not just plug hoses, I originally planned on making the cover plates myself, but I was wondering if rather than removing the reed valves from the valve covers, if I could just plug them where the hose now connects... So get rid of the hoses and the T, but plug and keep the reeds? any reason why this shouldn't work?

Much easier to buy the block off plates with the dimple in them.

From everything I've learned here; your pipes are popping to due the pair valves. My OE pipes would do this some and after installing the plates with dimples it's gone away and also has a deeper sound.

 

[hawkvtx]

popping on de-cel if from the pair system the backfiring is your pipes not being seated.

 

[Bassdude404]

Blocking off the inlets has the possibility of moisture building up in there and then going into the exhaust system...Can't remember when exactly, but a few years back one member here tried to "shortcut" that mod and ended up rusting out a brand new set of aftermarket pipes in less than a year's time...Just do it right the first time...

 

[sambroom]

Blocking off the inlets has the possibility of moisture building up in there and then going into the exhaust system...Can't remember when exactly, but a few years back one member here tried to "shortcut" that mod and ended up rusting out a brand new set of aftermarket pipes in less than a year's time...Just do it right the first time...

Yikes! Plates it is then. No rusty pipe for me...

 

[puzzle]

i just ordered plates as well http://www.vtx-parts.com/honda-vtx-fury-1300-1800-pair-valve-cover.html