Rejet to solve backfire? - Page 2 - VTXOA
 8Likes
Reply
 
LinkBack Thread Tools
post #11 of 24 (permalink) Old 06-02-2017, 12:48 PM
Senior Member
 
SeaSteve's Avatar
 
Join Date: Apr 2013
Location: Fredericksburg TX
Posts: 885
Garage
OKAY Harkon! (As I throw down the gauntlet of challenge) lol

I'm pretty sure I didn't have and exhaust leak after changing pipes and gaskets. And again to be clear, I didn't have a decel pop-pop-pop issue. It was one pronounced BOOM or PHUMF, depending on the pipes. What do think would cause this?

I also adjusted the A/F mixture and added a "small washer to the jet" (don't remember the mod name) with no change to the pop.

I'm gonna hit the highway like a battering ram, on a silver-black PHANTOM bike!
Meatloaf~Bat Out Of Hell

2002 1800 "S"
SeaSteve is offline  
Sponsored Links
Advertisement
 
post #12 of 24 (permalink) Old 06-02-2017, 12:58 PM Thread Starter
Senior Member
 
PoggiPJ's Avatar
 
Join Date: Jun 2009
Location: Gaithersburg, MD
Posts: 436
Garage
Quote:
Originally Posted by Harkon View Post
So if you can create a condition in your exhaust when you would normally see popping where the AFR in the exhaust is richer than 8:1 then you will effectively eliminate the much hated popping.
Thank you for your very thorough explanation. I did not know this, and I'm going to bookmark your reply for future reference.

So given I need to decrease the air volume Harkon, which way should I turn the A/F screw to accomplish this? Clockwise (in) or counterclockwise (out) ?

Regards,
Pete
Gaithersburg, MD
PoggiPJ is offline  
post #13 of 24 (permalink) Old 06-02-2017, 01:04 PM
Senior Member
 
Harkon's Avatar
 
Join Date: May 2010
Location: Calgary, Alberta, Canada
Posts: 4,915
Quote:
Originally Posted by SeaSteve View Post
OKAY Harkon! (As I throw down the gauntlet of challenge) lol

I'm pretty sure I didn't have and exhaust leak after changing pipes and gaskets. And again to be clear, I didn't have a decel pop-pop-pop issue. It was one pronounced BOOM or PHUMF, depending on the pipes. What do think would cause this?

I also adjusted the A/F mixture and added a "small washer to the jet" (don't remember the mod name) with no change to the pop.
I had the same issue with my 1800. It had V&H pipes on it, and I blocked off the pair system, changed the exhaust gaskets, did all of the ground fixes and so forth. The bike ran a lot better, but man, when those V&H pipes had an explosion, it sounded like someone was getting 12 gauged. I added the FI2000 and the decel popping disappeared entirely. I could manage it without buy keeping the throttle slightly cracked as I decelerated.

On a carbed bike, adding a washer under the needle speeds the transition from the idle circuit to the power circuit. It will run richer as the throttle progresses but at closed throttle the needle is relatively ineffective. You may have seen better results by bumping the pilot jet a number or 2. I don't know for sure as I never had a 1300, all I can say is that creating a rich condition to eliminate decel popping is an effective strategy and is done all of the time. For sure any point of fresh air ingress needs to be blocked though. Sounds like you did that.
SeaSteve likes this.


'12 Road Glide Ultra, Kuryakyn Alley Cat intake, Jackpot Super Duals header, Jackpot HiRoller mufflers, PV Tuner, Daymaker LEDs
Harkon is offline  
 
post #14 of 24 (permalink) Old 06-03-2017, 03:03 PM
Senior Member
 
Eazy-E's Avatar
 
Join Date: Sep 2006
Location: Destrehan, Louisiana
Posts: 7,195
Check your Vacuum line going to the air cutoff valve. Only vac line going to the carb. If it even has just a pin hole in the vac line, it with cause back fire. I would change all vac lines just to rule that out.
PoggiPJ likes this.


06 Tangelo Pearl 1300C ( Fastest Color)/ 2015 Harley Street Glide
http://www.bdscycles.com/
Eazy-E is offline  
post #15 of 24 (permalink) Old 09-26-2019, 09:01 PM Thread Starter
Senior Member
 
PoggiPJ's Avatar
 
Join Date: Jun 2009
Location: Gaithersburg, MD
Posts: 436
Garage
SOLUTION: Two years later, I finally had some extra time to work on my VTX. Combination of two things, although I think it was principally #2. I do still detect an occassional low, rumbing backfire, similar to what I can hear on my 2017 Indian Roadmaster.

#1, I pulled out the carb just enough to not require disconnecting the water hoses. Dropped the float chamber, opened and cleaned the fuel pump and vacuum diaphragms, both the main and idle jets. Blew out all the fuel pathways with compressed air. Cleaned out all varnish.

#2, I also found that the petcock diaphram had ruptured, resulting in drawing fuel into the vacuum line. I replaced the entire petcock assembly for about $112. In my uneducated, layperson opinion, This is what most likely was causing extra fuel getting into my system and going KAPOW in my pipes almost every time I decelerated.
Blaine C likes this.

Regards,
Pete
Gaithersburg, MD
PoggiPJ is offline  
post #16 of 24 (permalink) Old 10-05-2019, 11:26 PM
Junior Member
 
MrAnudo's Avatar
 
Join Date: Dec 2003
Location: Parker, CO
Posts: 24
How timely - I was literally going to post the same question. I have tried just about everything on my 1300c.

Background - I recently took off stock pipes, replaced with V&H. New crush gaskets (twice removed since they're cheap and new ones placed) - did the washers under the acorn too. No change at all. I've tried monster baffles and then replaced with quiet baffles. Literally no change - so pressure made no difference. I've monkeyed back and forth with the AF mix - I can make it pop more... but not less.

Just did the pair valve removal. But STILL no luck. Still backfires on decelerations. Also - I am experiencing what is uneven acceleration when first twisting the throttle - a little hesitation. Had you experienced the same?

The petcock assembly replacement is interesting - and look pretty easy. Where did you get yours?

2006 VTX1300C - Bloodstone Red (Maroon)
MrAnudo is offline  
post #17 of 24 (permalink) Old 10-05-2019, 11:40 PM
Senior Member
 
Hans&Feet's Avatar
 
Join Date: Jun 2005
Location: Conyers/McDonough, GA
Posts: 10,657
Garage
Check the Air Cutoff valve diaphragm.

Expensive little sucker.. Cover, spring and diaphragm/valve
Fill it with RTV??? Rubber tire tube to make a new diaphragm??

14 VALVE SET, AIR CUT 16048-MZ8-H00 In Stock $84.02 $65.02

Look up MR VTX Carb 101 for carb teardown pix.
PoggiPJ likes this.

2005 1300c Red, Mustang seat, HK 2.5 straights. Leds for safety-front & back. 194,184 VTX miles
Hans&Feet is offline  
post #18 of 24 (permalink) Old 10-06-2019, 12:16 AM
Junior Member
 
MrAnudo's Avatar
 
Join Date: Dec 2003
Location: Parker, CO
Posts: 24
Just ordered - will give it a go - thank you!

Update: replaced the ACO and still same exact symptoms. Hesitates on initial throttle roll on. Backfires on decel. Like a firecracker

To date:

1. Desmog - no change
2. Replaced all vacuum hoses - no change
3. Reseated exhaust - no change
4. All new plugs - no change. And the ones I took out looked great
5. Sea foam - no change
6. Replaced ACO - no change



Does it matter that I’m at altitude in Denver?
PoggiPJ likes this.

2006 VTX1300C - Bloodstone Red (Maroon)

Last edited by MrAnudo; 10-09-2019 at 09:20 PM.
MrAnudo is offline  
post #19 of 24 (permalink) Old 10-07-2019, 11:37 AM Thread Starter
Senior Member
 
PoggiPJ's Avatar
 
Join Date: Jun 2009
Location: Gaithersburg, MD
Posts: 436
Garage
Quote:
Originally Posted by MrAnudo View Post

The petcock assembly replacement is interesting - and look pretty easy. Where did you get yours?
I picked up mine at PartsFish, for $116. So far I've ridden it about 98 miles, with just one, solitary POP.

Regards,
Pete
Gaithersburg, MD
PoggiPJ is offline  
post #20 of 24 (permalink) Old 10-07-2019, 11:40 AM Thread Starter
Senior Member
 
PoggiPJ's Avatar
 
Join Date: Jun 2009
Location: Gaithersburg, MD
Posts: 436
Garage
Quote:
Originally Posted by Hans&Feet View Post
Check the Air Cutoff valve diaphragm.

Expensive little sucker.. Cover, spring and diaphragm/valve
Fill it with RTV??? Rubber tire tube to make a new diaphragm??

14 VALVE SET, AIR CUT 16048-MZ8-H00 In Stock $84.02 $65.02

Look up MR VTX Carb 101 for carb teardown pix.
Hello Hans! It has been a long time. I decided to purchase the entire petcock, because for a little bit more it would also include a new filter screen, and also since the front of the valve is riveted, I couldn't check the condition of the plastic diverter and so didn't want to chance that it was damaged.

Regards,
Pete
Gaithersburg, MD
PoggiPJ is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the VTXOA forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome