Exhaust popping after installing sportster mufflers - Honda Shadow Forums : Shadow Motorcycle Forum
Reply
 
LinkBack Thread Tools
post #1 of 32 (permalink) Old 03-12-2017, 12:17 PM Thread Starter
Member
 
Join Date: Jan 2016
Posts: 231
Garage
Exhaust popping after installing sportster mufflers

I have a 1985 Honda Shadow VT700

I recently installed the Harley Davidson 65842-07 mufflers. they are about 19" long, and have about a 6" perforated, glass pack like section in the middle

Long story short the rear cylinder is popping a bit(it always has, just was very muffled before...)

So I tried turning the idle screw out a half a turn (1/2) but it was already kinda far out, 4 1/2 turns (if I recall correctly)

So can I turn it a little further out? would 5 1/2 or even 6 be too much?

Or is it time to shim the needle?

Or a complete rejet?

ericfx1984 is offline  
Sponsored Links
Advertisement
 
post #2 of 32 (permalink) Old 03-12-2017, 12:34 PM
Senior Member
 
Join Date: Apr 2008
Location: Palatine, IL
Posts: 9,750
4 turns is pretty much max. You should check to make sure the exhaust isn't leaking anywhere and possibly the intake leaking.

jpr1968 is offline  
post #3 of 32 (permalink) Old 03-12-2017, 12:38 PM
Member
 
Join Date: Dec 2012
Posts: 171
My rule of thumb with carbs is (mind you, this is just 'my' rule of thumb, not to be confused with what works for others):

If I need to go more than 3 1/2 turns out from lightly seated to get what I need from the pilot screw adjustment then, I am going up 1 size on my pilot jets. You have 42 slows right now, that would take me up to 45s so that I get my adjustability back.

I do this because on most carbs, starting engagement of the threads of the pilot screw/carb body interface until fully seated is almost always 10 turns.

If you set your pilot screws at 5 or 6 turns out, think about how much thread engagement you have at that point (a couple of turns).

Have you synched your carbs and made sure you have no air leaks in the carb/head interface?


John
cyclejohn is offline  
 
post #4 of 32 (permalink) Old 03-12-2017, 12:57 PM Thread Starter
Member
 
Join Date: Jan 2016
Posts: 231
Garage
Quote:
Originally Posted by cyclejohn View Post
Have you synched your carbs and made sure you have no air leaks in the carb/head interface?


John
Well I have tried spraying starting fluid around the carb boots while it was running/idling and didnt notice a change in rpm

As for synching my thought has always been if they are not been separated there is (normally) no reason to sync then up, as they SHOULD be synched to begin with... of course if they get are separted synching is absolutely required
ericfx1984 is offline  
post #5 of 32 (permalink) Old 03-12-2017, 03:03 PM
Senior Member
 
swifty2014's Avatar
 
Join Date: Oct 2014
Posts: 4,968
Garage
If you just recently removed the factory mufflers with the crossover expansion chamber you will notice much more popping. Mine does it a lot and I just got used to it. Sort of reminds me of the thought that loud pipes save lives. Maybe decel backfire may save my butt. LOL

But the mixture screws will come out a certain distance and then have no more effect on the adjustment because the tapered need is out past the orifice and has little change in opening.

As far as syncing the carbs it is always a good idea to check it because I know how worn my old 30 year old linkage is and it doesn't want to keep an even setting because of the wear.

Only a biker knows why a dog sticks his head out of a car window.
1983 750 Shadow
From the past=
1951 Cushman scooter
1962 Honda 305 Dream
1965 Honda 305 Dream
1971 Honda 175 scrambler
swifty2014 is offline  
post #6 of 32 (permalink) Old 03-12-2017, 03:04 PM
Senior Member
 
swifty2014's Avatar
 
Join Date: Oct 2014
Posts: 4,968
Garage
I was going to include a photo of the mixture screw tip=
Attached Thumbnails
Click image for larger version

Name:	Capture.PNG
Views:	46
Size:	10.6 KB
ID:	199914  

Only a biker knows why a dog sticks his head out of a car window.
1983 750 Shadow
From the past=
1951 Cushman scooter
1962 Honda 305 Dream
1965 Honda 305 Dream
1971 Honda 175 scrambler
swifty2014 is offline  
post #7 of 32 (permalink) Old 03-12-2017, 07:53 PM Thread Starter
Member
 
Join Date: Jan 2016
Posts: 231
Garage
Quote:
Originally Posted by swifty2014 View Post
If you just recently removed the factory mufflers with the crossover expansion chamber you will notice much more popping. Mine does it a lot and I just got used to it.

I mainly notice it after I come down to around 4,000 rpm, no throttle and a fairly low gear... pop... pop... pop So you are saying this is normal?
ericfx1984 is offline  
post #8 of 32 (permalink) Old 03-12-2017, 10:23 PM
Junior Member
 
Join Date: Mar 2017
Location: Kingsport, TN
Posts: 9
Garage
Be careful with the popping. I heard a story where the off deity policeman working security Ata rally drew on a biker when the bike backfired!
James15 is offline  
post #9 of 32 (permalink) Old 03-12-2017, 11:25 PM
Senior Member
 
swifty2014's Avatar
 
Join Date: Oct 2014
Posts: 4,968
Garage
Mine will pop, pop, pop for 20 or 30 feet on a hard decel. I believe it is because these bikes use 2 spark plugs per cylinder and they fire on each stroke of the rotation. There is only one pickup for the pulse generators and no cam position sensor to tell the ignition on which stroke it is. So it fires on the compression and the exhaust strokes causing the flame to ignite any unburned fuel. With the factory designed cross over chamber it balances some of the the exhaust pulse and quiets it.

Only a biker knows why a dog sticks his head out of a car window.
1983 750 Shadow
From the past=
1951 Cushman scooter
1962 Honda 305 Dream
1965 Honda 305 Dream
1971 Honda 175 scrambler
swifty2014 is offline  
post #10 of 32 (permalink) Old 03-13-2017, 01:45 PM Thread Starter
Member
 
Join Date: Jan 2016
Posts: 231
Garage
Went to the carb jet kits website. They had a kit with 125 and 45s plus shims for $27 shipped to my door

Also how can I be certain that my slide springs are right?

ericfx1984 is offline  
Sponsored Links
Advertisement
 
Reply



Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda Shadow Forums : Shadow Motorcycle Forum 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









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



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



Posting Rules  
You may not post new threads
You may not 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