Explosion on Start-up
Thread Starter
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Road Captain
Joined: Jan 2012
Posts: 713
Likes: 235
From: Florida
Explosion on Start-up
2002 Road King classic FLHRCI with 95" crate engine Andrews 37 cams
Stage 1 (pipes and air)
Recently I have noticed when starting the bike I get an explosion out the pipes before it starts. Bike runs fine, just that explosion on startup.
Pipes are "Wild Pigs" out of Holly Hill Florida and have been installed for 10? years. Air is a K&N filter nothing special
Any comments would be appreciated.
Stage 1 (pipes and air)
Recently I have noticed when starting the bike I get an explosion out the pipes before it starts. Bike runs fine, just that explosion on startup.
Pipes are "Wild Pigs" out of Holly Hill Florida and have been installed for 10? years. Air is a K&N filter nothing special
Any comments would be appreciated.
Stellar HDF Member
Joined: Sep 2020
Posts: 2,428
Likes: 2,869
From: Southeast
My 06 RKC would do that once in a while if it didn't start on the first try. As soon as it would start to wheel around on the second attempt, BANG! Neighbors loved it. 
I bumped the timing a little and it hasn't done it since. I've got a T-max ecu, EFI, so I can do cool stuff like that. LoL
Maybe timing is the issue, maybe not. I figured it was so retarded at a very low RPM (250rpm) to make it easier to crank when hot, but when it got near TDC - it would light it off while the exhaust was still open? I bumped it a bit and it hasn't done it since. My .0000002.
Good luck!
I bumped the timing a little and it hasn't done it since. I've got a T-max ecu, EFI, so I can do cool stuff like that. LoL
Maybe timing is the issue, maybe not. I figured it was so retarded at a very low RPM (250rpm) to make it easier to crank when hot, but when it got near TDC - it would light it off while the exhaust was still open? I bumped it a bit and it hasn't done it since. My .0000002.
Good luck!
Road Master
Joined: Nov 2018
Posts: 922
Likes: 898
From: Upstate NY
Your mixture is fat. All that extra unburned fuel gets dumped into the exhaust and on the 2nd or 3rd spark it (from starting) it lights the mixture and gives you that explosion. Im willing to bet your bike is set up for running on the top end (wide open throttle) and is running advanced timing. Either bring the timing back a few degrees or cut back on the fuel mixture a bit. If you are not mechanically inclined.....leave it alone. Check your spark plugs and make sure you arent running 'foul' rich and leave it be.
Thread Starter
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Road Captain
Joined: Jan 2012
Posts: 713
Likes: 235
From: Florida
Guys, Thanks for the comments. The engine has not had any work on it, other than spark plugs, in 50K+ miles so if the mixture or timing is off then something is going phooey.
Could a sensor be going bad. If yes, which one(s). I don't know enough about engine stuff to competently diagnose which one(s).
Thanks again
Regards,
John
Could a sensor be going bad. If yes, which one(s). I don't know enough about engine stuff to competently diagnose which one(s).
Thanks again
Regards,
John
Grand HDF Member
Joined: Jan 2012
Posts: 4,458
Likes: 2,876
From: Oklahoma
Hot start or cold start, or the same either way? I would suspect a seepy injector. If you wait for the full prime before starting, when hot, try starting as soon as you turn on the switch. Perhaps some Sea Foam, Techron, or fuel treatment of your choice would be a help to clean a dirty injector.
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Road Captain
Joined: Jan 2012
Posts: 713
Likes: 235
From: Florida
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Road Warrior
Joined: May 2007
Posts: 1,434
Likes: 384
From: Arkansastan
Tensioners stock or hydraulic conversion? My 2003 did that all the time, it was gear drive. Never seemed to bother anything but it let everyone know it was starting!
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Road Warrior
Joined: May 2007
Posts: 1,434
Likes: 384
From: Arkansastan
OK, I was thinking maybe if it had standard tensioners, if worn, they might have been messing with timing or something.