90 fxrs carb backfire
Thread Starter
|
4th Gear
Joined: Aug 2010
Posts: 8
Likes: 0
From: Lake Arrowhead,CA
90 fxrs carb backfire
my bike runs great..but when I'm out to the store and it sits for a few minutes
it will back fire thru the carb when I start it and unseat the carb causing a major vACUUM LEAK. I have to tear it all apart to reseat the gasket to the intake . I've already check for vacuum leaks while bike is hot , none found. Any suggestions?
it will back fire thru the carb when I start it and unseat the carb causing a major vACUUM LEAK. I have to tear it all apart to reseat the gasket to the intake . I've already check for vacuum leaks while bike is hot , none found. Any suggestions?
Dirt don't hurt
Joined: Jan 2011
Posts: 21,062
Likes: 4,547
From: Haslet Texas
Coughing through the carb is an indication of a lean condition.
What jets are you running??
If you had an S&S it bolts to the manifold so there is no chance of it coming loose.
Just a thought!!
What jets are you running??
If you had an S&S it bolts to the manifold so there is no chance of it coming loose.
Just a thought!!
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
Idle jet is probably too small, go up a size and try again.
Grand HDF Member
Joined: Apr 2007
Posts: 3,714
Likes: 3,037
From: Brighton, MI
It also sounds like something is not right with your gasket. I think your saying the carb to manifold seal becomes unseated when it backfires?
Replace that seal and check alignment of the carb. Is the carb mounted properly with no play, gaps, or movement to that seal at the carb to manifold?
I agree with the others, your slow/idle jet is lean. Pick up a couple of sizes larger than what you have. If your stock is 42, then get a 45 and or a 46 in there. YD
Replace that seal and check alignment of the carb. Is the carb mounted properly with no play, gaps, or movement to that seal at the carb to manifold?
I agree with the others, your slow/idle jet is lean. Pick up a couple of sizes larger than what you have. If your stock is 42, then get a 45 and or a 46 in there. YD
Road Warrior
Joined: Oct 2011
Posts: 1,376
Likes: 36
From: Round Rock, TX
That's what I was thinking. If the backing plate is installed correctly, no way it can come loose.
Cruiser
Joined: Aug 2010
Posts: 181
Likes: 13
Trending Topics
Seasoned HDF Member
Joined: Dec 2010
Posts: 7,736
Likes: 1,524
From: Coromandel Peninsula New Zealand
About the carb coming unseated....what do you find when you take it apart or are you assuming it came loose because it works when you take it off and put it back on again???
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
Thread
Thread Starter
Forum
Replies
Last Post