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post #1 of 10 (permalink) Old 03-20-2012, 12:55 AM Thread Starter
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Backfire

Whenever I let off the throttle I get backfire or at least popin'. It's not as bad after it's warmed up but it never completely stops. I've ran a can of Sea Foam through it and didn't help.

Any ideas where I need to start?
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post #2 of 10 (permalink) Old 03-20-2012, 12:58 AM
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Originally Posted by hbhobby View Post
Whenever I let off the throttle I get backfire or at least popin'. It's not as bad after it's warmed up but it never completely stops. I've ran a can of Sea Foam through it and didn't help.

Any ideas where I need to start?
Have you backed out the idle adjust screws to 2-2.5 turns out (total)?

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
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1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

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post #3 of 10 (permalink) Old 03-20-2012, 01:42 AM
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Search Coasters or Marbling in the versus. Either of these options may help reduce the backfire. I did a complete "earshave" and that helped to greatly reduce mine.. You can also check for leaks in the exhaust system.. Use a cigarette and follow your exhaust and see if the smoke is disturbed. Could need to replace the crush gaskets.

X2 on the idle adjust screw on the side thats popping..

goodluck!

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post #4 of 10 (permalink) Old 03-20-2012, 06:00 PM
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There is nothing wrong with the bike. It is mostly just annoying. Most of us take measures to reduce or totally eliminate the popping by doing as described above. But if you can live with it, leave it alone.

02 honda sabre 1100
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post #5 of 10 (permalink) Old 03-20-2012, 08:13 PM
Crap, I WAS in 5th gear.
 
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If marbling or coastering doesn't help, report back as the group has been through this before, many times.
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post #6 of 10 (permalink) Old 03-22-2012, 01:04 AM Thread Starter
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Thanks guys. I messed with the idle screw. It seemed like it was more than 2.5 turns. I warmed it up and tweaked it a little more. The popping is not as bad.
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post #7 of 10 (permalink) Old 03-22-2012, 05:48 PM
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Actually it isn't the idle adjust screw you need to adjust, but the idle mix screws or pilot jets, one on each side of the bike, often still covered with a tin cap that you have to pry off before you can get to them. The 750's are known poppers and usually you can marble the reed valves and quiet the bike down considerably. I did this alone to mine and never touched the idle mix screws and got rid of the really loud popping on decel. Your mileage may vary...

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post #8 of 10 (permalink) Old 03-22-2012, 06:58 PM
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Quote:
Originally Posted by fergy View Post
Actually it isn't the idle adjust screw you need to adjust, but the idle mix screws or pilot jets, one on each side of the bike, often still covered with a tin cap that you have to pry off before you can get to them. The 750's are known poppers and usually you can marble the reed valves and quiet the bike down considerably. I did this alone to mine and never touched the idle mix screws and got rid of the really loud popping on decel. Your mileage may vary...
My Canadian bike never had any of the emission crap on it and had coasters installed at the factory. It still pops loudly upon deceleration.
If it bothers me when I finally get to ride again in a few weeks, I will turn the idle mix screws out a bit.

Gordon

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Last edited by OlHossCanada; 03-22-2012 at 07:01 PM.
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post #9 of 10 (permalink) Old 03-22-2012, 07:05 PM
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My UK bike is the same OlHoss
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post #10 of 10 (permalink) Old 03-22-2012, 09:47 PM
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Quote:
Originally Posted by fergy View Post
Actually it isn't the idle adjust screw you need to adjust, but the idle mix screws or pilot jets, one on each side of the bike, often still covered with a tin cap
Those are what I was referring to above.

The usual fare is to back them out 2 - 2.5 turns, depending on side.

1986 Kawasaki Vulcan 750
NGK Iridium Plugs #7803/DPR7EIX-9
Duralast Gold ETX15 AGM Battery
Coastered & Shaved
TOC MCCTs
Metzeler ME880 [110/90-19, 170/80-15]
Balance Dampers Replaced
Tuxedo Mod
Rebuilt Forks w/ Progressive Springs
V&H Cruzers
VN750.com Grill Cover
Meanstreak Seat
Emgo 23-92411 Handlebars
MOSFET FH012AA R/R


1990 Kawasaki Vulcan 750

1998 Honda VFR800 FI

2014 Honda VFR800F

1989 Pontiac Firebird Formula 350
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