backfire on startup?
Thread Starter
|
Road Warrior
Joined: Nov 2007
Posts: 1,641
Likes: 4
From: south of Boston
backfire on startup?
alright, i've got to say i'm not really surprised...but i don't like it
after a complete frame-off restoration i finally completed the bike....just waiting on a leather bare bones to complete the look
anyway, i tried firing it up today and BANG!...i got a mother of a backfire... like someone fired off a 12 gauge right next to my ear....was even a spark that shot out
console me, give me some suggestions about what could have caused it, offer me words of encouragement that it's okay to try and start it again....LOL
paul
after a complete frame-off restoration i finally completed the bike....just waiting on a leather bare bones to complete the look
anyway, i tried firing it up today and BANG!...i got a mother of a backfire... like someone fired off a 12 gauge right next to my ear....was even a spark that shot out
console me, give me some suggestions about what could have caused it, offer me words of encouragement that it's okay to try and start it again....LOL
paul
Thread Starter
|
Road Warrior
Joined: Nov 2007
Posts: 1,641
Likes: 4
From: south of Boston
hi pete.... can't be that...carb was a rebuild as well
and ride, i don't think it's that..... i rebuilt that engine, too... andrews 27 and new SE pushrods....had it in my basement for months doing the rebuild, and when she was complete, i made sure pushrods were on point with each stroke
i'm thinking it's because i inadvertently dumped a **** load of fuel into the carb by twisting the throttle completely open about 5 times before i started it.... wasn't thinking
and ride, i don't think it's that..... i rebuilt that engine, too... andrews 27 and new SE pushrods....had it in my basement for months doing the rebuild, and when she was complete, i made sure pushrods were on point with each stroke
i'm thinking it's because i inadvertently dumped a **** load of fuel into the carb by twisting the throttle completely open about 5 times before i started it.... wasn't thinking
Cruiser
Joined: Oct 2010
Posts: 239
Likes: 67
From: Erie, Co.
My 97 Heritage does this also, but only after the bike is warmed up. If I ride and warmup the motor and say I have to stop and get gas. It will backfire and it is Loud, women and small children crying and running in all directions. It's embarrassing as hell. The thing is it doesn't do it every time though. I have a new rebuild kit for the carb, going to try that and see if it helps.
Thread Starter
|
Road Warrior
Joined: Nov 2007
Posts: 1,641
Likes: 4
From: south of Boston
yah, i'm thinking the ignition timing...cause it did it again
don't think i had it at TDC on the compression stroke while adjusting it
and yes, gump...it is single fire...reverse the plug wires?
don't think i had it at TDC on the compression stroke while adjusting it
and yes, gump...it is single fire...reverse the plug wires?
Trending Topics
Elite HDF Member
Joined: Sep 2007
Posts: 4,468
Likes: 12
From: Bluffton, South Carolina
JSBRIDGEW,
Standard Harley ignition is "dual fire" which is a wasted spark ignition. The coil fires both plugs at the same time. Most aftermarket fire only one plug at a time, hence the term "single fire". So if you have the front wire going into the coil tower for the rear cylinder obviously the rear is is the wrong one too. This is the same as having some plug wires in the wrong place on your car, it can cause backfiring. Hopefully this makes sense. Changing the plug wires around is easier than rewiring the coil. Hope this helps.
Standard Harley ignition is "dual fire" which is a wasted spark ignition. The coil fires both plugs at the same time. Most aftermarket fire only one plug at a time, hence the term "single fire". So if you have the front wire going into the coil tower for the rear cylinder obviously the rear is is the wrong one too. This is the same as having some plug wires in the wrong place on your car, it can cause backfiring. Hopefully this makes sense. Changing the plug wires around is easier than rewiring the coil. Hope this helps.
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 Starter
|
Road Warrior
Joined: Nov 2007
Posts: 1,641
Likes: 4
From: south of Boston
ah....you are correct, mia
i installed a single-fire twintec that eliminates module and places everything in cone.... and in my ignorance i didn't bother to notice the plugwire configuration on the wiring diagram....just assumed it would be same as stock....damn
so...swapped the wires, and timed it properly according to comp stroke at TDC
should be good to go
i installed a single-fire twintec that eliminates module and places everything in cone.... and in my ignorance i didn't bother to notice the plugwire configuration on the wiring diagram....just assumed it would be same as stock....damn
so...swapped the wires, and timed it properly according to comp stroke at TDC
should be good to go