 backfiring while riding
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Joined: Aug 2010
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so i finally re-jetted the bike.
125main and replaced the 42pilots with 42 pilots and did 3 turns out.
tors-uni filter- top of air box removed.
the bike started right up and ran great for about 200 miles.
so i am riding home yesterday and at the stop light the bike died. srarted rigt up but would not idle without a little throttle. as i rode the bike would back fire as i'm riding...not on decelerating. the whole bike had a vibration like it was not running right.
i checked all the rubber plugs and they are all ok.
where do i start:
pull the spark plugs check the coils.
how do i check to see if the mixture is correct without taking it to the dealer.
thanks
If it isn't broke, I haven't messed with it.
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Re: backfiring while riding
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Joined: Jan 2005
Posts: 4,932 Likes: 2
Loquacious
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Loquacious
Joined: Jan 2005
Posts: 4,932 Likes: 2 |
we should do this every weekend!
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Re: backfiring while riding
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Joined: Aug 2010
Posts: 476
Adjunct
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OP
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Joined: Aug 2010
Posts: 476 |
i hope it is that simple...i'll put in some sea foam and see if that helps.
If it isn't broke, I haven't messed with it.
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Re: backfiring while riding
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Joined: May 2007
Posts: 1,354
Learned Hand
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Learned Hand
Joined: May 2007
Posts: 1,354 |
That just about sounds like how my bike ran with the missing squirrel condom. Are you sure they are all there?
Blue/White 2007 TBA, Thruxton needles, Unifilter, AI removed, Polaris Bellmouth, Bubs, Nology Coils/wires, Lightbar, Ricor Intiminators, Hagon Nitros, Tall Sissy Bar w/luggage rack, Dart flyscreen & Lowers. 130 Mains, TrueGel Battery MG12-BS.
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Re: backfiring while riding
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Joined: Feb 2007
Posts: 23,248 Likes: 64
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,248 Likes: 64 |
Did you adjust the mixture or did you just set it to 3 turns? If I read your post right you went from 42 to 45 pilots (typo of 42 to 42?) With your set up 3 turns is probably rich. This shouldn't cause your backfire condition but may add to it and would cause the idle problem. Does sound like a vacuum leak possibly.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: backfiring while riding
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Joined: May 2007
Posts: 6,432 Likes: 1
Worn Saddle
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Worn Saddle
Joined: May 2007
Posts: 6,432 Likes: 1 |
Quote:
That just about sounds like how my bike ran with the missing squirrel condom. Are you sure they are all there?
Seems about right, that's just what I was thinking, too. Could be a dry rotted cap that's not obvious.
A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)
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Re: backfiring while riding
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Joined: Aug 2010
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the condoms were the first thing i looked at. i think i will shot gun them and replace all.
42 to 42 is what i did. this bike was owned by an extreme motorcycle enthusist and had gone less than 3000 miles in 5 years. i figured the polits might have been a little clogged as my gas mileage was 38mpg. the mains were 118 and i changed them to 125. yes i did 3 turns out, since i was running a uni and no cover.
it sux not having a bike...my klr is down with a bad rear tire...the tread is trying to leave the case..
Last edited by motorat; 05/11/2011 2:25 PM.
If it isn't broke, I haven't messed with it.
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Re: backfiring while riding
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Joined: Apr 2007
Posts: 3,063 Likes: 8
Loquacious
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Loquacious
Joined: Apr 2007
Posts: 3,063 Likes: 8 |
Take a close look at both carb rubbers that join the carbs to the intake manifolds. Check the rubbers under the clamps. Those often crack and cause a vacuum leak that is hard to see.
12 Rocket Roadster
03 Bonneville America
69 BSA Firebird Scrambler
73 Yamaha TX 750
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Re: backfiring while riding
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Joined: Apr 2009
Posts: 639
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Hidden fuel filter could be a good thing to clean too, if you don't have an aftermarket on there already.
Blue/White, Battery Relocated, 155/45's, AI removed, Cocktail shakers
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Re: backfiring while riding
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Joined: Aug 2010
Posts: 476
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thanks for the replies. it was one of the condoms. right side big crack on the inside. when i went to remove it it fell appart. i replaced all of them and have a couple spares.
love the $1.89 fixes
If it isn't broke, I haven't messed with it.
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Re: backfiring while riding
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Joined: May 2007
Posts: 1,354
Learned Hand
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Learned Hand
Joined: May 2007
Posts: 1,354 |
Joe,
I had the same problem about a month or so ago. I was going to go with new squirrel condoms, but Z suggested using the vacuum hose, from the removed AI pump, and run it from one nipple to the other. After cutting a shorter piece from the leftover hose, it fit perfectly and has been running very well. I will still get a couple of spare condoms to keep in my bag o'stuff, just in case I lose the hose.
Blue/White 2007 TBA, Thruxton needles, Unifilter, AI removed, Polaris Bellmouth, Bubs, Nology Coils/wires, Lightbar, Ricor Intiminators, Hagon Nitros, Tall Sissy Bar w/luggage rack, Dart flyscreen & Lowers. 130 Mains, TrueGel Battery MG12-BS.
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Re: backfiring while riding
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Joined: Feb 2005
Posts: 2,839 Likes: 3
Loquacious
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Loquacious
Joined: Feb 2005
Posts: 2,839 Likes: 3 |
by running that hose as you described, it will also sinc the carb's. it is a good way to go. 
ENJOY!!!!! NEWT!!!!!
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Re: backfiring while riding
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Joined: May 2010
Posts: 5,720
Check Pants
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Check Pants
Joined: May 2010
Posts: 5,720 |
Quote:
by running that hose as you described, it will also sinc the carb's. it is a good way to go.
Interesting, anybody verified that with a vacuum gauge?
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Re: backfiring while riding
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Joined: Mar 2009
Posts: 12,964
Stickman Yogi
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Stickman Yogi
Joined: Mar 2009
Posts: 12,964 |
Quote:
by running that hose as you described, it will also sinc the carb's. it is a good way to go.
It will? But the throttle bodies could still be out of adjustment.... 
Live to love, love to live.
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Re: backfiring while riding
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Joined: May 2010
Posts: 5,720
Check Pants
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Check Pants
Joined: May 2010
Posts: 5,720 |
Just seems that if bridging the carbs are such a hot idea, why didn't they come that way? Never seen any high performance dual carb applications on hot rods, bridged like that. Anybody know different, I'm listening.
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Re: backfiring while riding
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Joined: May 2007
Posts: 1,354
Learned Hand
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Learned Hand
Joined: May 2007
Posts: 1,354 |
This is where I got the idea from Z: Squirrel Condom ThreadShe's been running fine since the change. Took a long ride up to Snohomish, a couple of weeks ago, and rode with Z, Karen and Rocket Bob. I rode her down to Chehalis last weekend for the Triumph get-together. She ran fine. Of course, having said that, she'll probably do something "interesting" the next time I take her out...
Blue/White 2007 TBA, Thruxton needles, Unifilter, AI removed, Polaris Bellmouth, Bubs, Nology Coils/wires, Lightbar, Ricor Intiminators, Hagon Nitros, Tall Sissy Bar w/luggage rack, Dart flyscreen & Lowers. 130 Mains, TrueGel Battery MG12-BS.
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Re: backfiring while riding
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Joined: May 2010
Posts: 5,720
Check Pants
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Check Pants
Joined: May 2010
Posts: 5,720 |
I perused that thread way back when, just wondering if you lose a little fuel delivery velocity with a bridged manifold, hell, maybe you gain some by scavenging? Like our exhaust crossovers are supposed to accomplish. I was hoping some engineer would chime in.
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Re: backfiring while riding
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Joined: May 2008
Posts: 740
Adjunct
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Adjunct
Joined: May 2008
Posts: 740 |
I use the hose bridge method instead of SC's. I think it runs smoother that way. Its also easier to find a piece of tube on the road if you need it and the tube seems to last longer than the SC's.....FWIW
Bill.
"I spent a lot of money on booze, birds and fast cars. The rest I just squandered."
-George Best
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Re: backfiring while riding
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Quote:
by running that hose as you described, it will also sinc the carb's. it is a good way to go.
How's that?
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Re: backfiring while riding
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Joined: Feb 2007
Posts: 23,248 Likes: 64
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,248 Likes: 64 |
It will help equalize the vacuum but it will not sync the carbs.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: backfiring while riding
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Quote:
It will help equalize the vacuum but it will not sync the carbs.
How would it even do that?
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Re: backfiring while riding
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Joined: Feb 2007
Posts: 23,248 Likes: 64
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,248 Likes: 64 |
The vacuum line is open between sides and bleeds vacuum from one side to the other. Just theory, I have never measured it or even done it but have seen it. I choose to balance mine.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: backfiring while riding
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Why would one want airflow going anywhere but through the carb bore?
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Re: backfiring while riding
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Joined: Dec 2006
Posts: 7,028 Likes: 8
New Tires
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New Tires
Joined: Dec 2006
Posts: 7,028 Likes: 8 |
My 76 T140V Bonnie has a tube between the carb manifolds, I think it's stock, but I've had the thing for 30 something years and can't remember.
Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats.
H. L. Mencken
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Re: backfiring while riding
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Joined: Feb 2008
Posts: 2,671 Likes: 15
Loquacious
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Loquacious
Joined: Feb 2008
Posts: 2,671 Likes: 15 |
Quote:
My 76 T140V Bonnie has a tube between the carb manifolds, I think it's stock, but I've had the thing for 30 something years and can't remember.
Did it also connect to the carbs?
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Re: backfiring while riding
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Joined: Feb 2007
Posts: 23,248 Likes: 64
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,248 Likes: 64 |
Quote:
Quote:
My 76 T140V Bonnie has a tube between the carb manifolds, I think it's stock, but I've had the thing for 30 something years and can't remember.
Did it also connect to the carbs?
It connected the intakes just in front of the carbs, I have seen that too.
I never said I wanted vacuum going anywhere but through my carbs, that is why I choose to balance.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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