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Author Topic: Riddle me this????  (Read 4702 times)

Offline axeugene27

  • Posts: 1026
Riddle me this????
« on: Jun 23, 2012, 20:54:02 »
Been working on the bike all day and am perplexed. I was kicking at this thing all day wondering what was the deal. No go... I gapped the points set the timing, synced the carbs. adjusted air screw to 1.25 turns out. Could not get it to start. The spark does not look great kind of weak but it is there and it is blue. stopped for half hr and ate dinner came back and kicked it over started up. I quickly adjusted the air screw and set the idle. Had it running real nice for about 2 minutes. Then it sputtered and died. Would not kick over again..... I have had this thing do this a few times. I don't understand if the carbs are to a point the bike can idle well one day or even one minute and not start the next. This leads me to believe that 1. I am somehow flooding the engine. 2. the spark condenser is going bad and the spark is only good sometimes. Any thoughts?
72cb350 barn burner build http://www.dotheton.com/forum/index.php?topic=37654.20
TITAN http://www.dotheton.com/forum/index.php?topic=53037.msg600706#msg600706
"it's better to have an ugly bike that runs well, than an pretty paperweight."
"bullshit goes a long way if you throw it right"

Offline Sonreir

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Re: Riddle me this????
« Reply #1 on: Jun 23, 2012, 22:00:44 »
CB360?
Sparck Moto - http://www.sparckmoto.com

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Offline Swapmeet Louie

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Re: Riddle me this????
« Reply #2 on: Jun 23, 2012, 22:14:59 »
Bowls were dry. They filled while you ate..
" an opinion form someone who knows not of which he speaks is worse than worthless" TEAZER


"Carb tuning is a black art. It's voodoo(sic), scientiology and comet worship all rolled into a pile. There's is no blue pill, it's a matter of taking the time and earning the bloody knuckles. " Swagger

Offline axeugene27

  • Posts: 1026
Re: Riddle me this????
« Reply #3 on: Jun 24, 2012, 02:07:56 »
n0 it's a 350 no the bowls were plenty full of gas all day. Took the carbs off like 3 times. Playing with idle stuff.n  It doesn't appear to be a flooding issue either as the plugs are pretty dry. I don't know maybe my battery is dying? You don't think a condenser would cause that issue?
72cb350 barn burner build http://www.dotheton.com/forum/index.php?topic=37654.20
TITAN http://www.dotheton.com/forum/index.php?topic=53037.msg600706#msg600706
"it's better to have an ugly bike that runs well, than an pretty paperweight."
"bullshit goes a long way if you throw it right"

Offline Swapmeet Louie

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  • Put some metal in yer eye....
Re: Riddle me this????
« Reply #4 on: Jun 24, 2012, 02:15:59 »
condensors dont prevent anything but voltage spikes. You can run without them  for a bit before you fry your points.
" an opinion form someone who knows not of which he speaks is worse than worthless" TEAZER


"Carb tuning is a black art. It's voodoo(sic), scientiology and comet worship all rolled into a pile. There's is no blue pill, it's a matter of taking the time and earning the bloody knuckles. " Swagger

Offline MotorbikeBruno

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Re: Riddle me this????
« Reply #5 on: Jun 24, 2012, 13:12:07 »
condensors dont prevent anything but voltage spikes. You can run without them  for a bit before you fry your points.

Didn't know that...not that I want to try, but good info to know.

If your plugs were dry...you aren't getting fuel.  If you kicked it over several times, and they aren't wet.....look into bowl heights?  Verify that pilot passages are clear? Will it fire up with a little ether?  If so. Its fuel related.

Offline Swapmeet Louie

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Re: Riddle me this????
« Reply #6 on: Jun 24, 2012, 13:23:36 »
Dude, I'm not trying to make you feel like any less of an enthusiast. But honestly, I've bought so many bikes where the p.o was selling it because they were un sure on how to use a pet cock with a prime setting. And if the bowls are dry it takes several minutes to work. If not given enough time, one would kill there battery try to start it. I know a cb 350 doesnt have a prime. But, when the bowls are dry, it will take a few minutes to fill. Especially if your petcock is not flowing at maximum potential. It really is the only reason for it not to fire if everything is dialed and your battery had a good charge.
" an opinion form someone who knows not of which he speaks is worse than worthless" TEAZER


"Carb tuning is a black art. It's voodoo(sic), scientiology and comet worship all rolled into a pile. There's is no blue pill, it's a matter of taking the time and earning the bloody knuckles. " Swagger

Offline MotorbikeBruno

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Re: Riddle me this????
« Reply #7 on: Jun 24, 2012, 13:52:28 »
Dude, I'm not trying to make you feel like any less of an enthusiast. But honestly, I've bought so many bikes where the p.o was selling it because they were un sure on how to use a pet cock with a prime setting. And if the bowls are dry it takes several minutes to work. If not given enough time, one would kill there battery try to start it. I know a cb 350 doesnt have a prime. But, when the bowls are dry, it will take a few minutes to fill. Especially if your petcock is not flowing at maximum potential. It really is the only reason for it not to fire if everything is dialed and your battery had a good charge.

I agree. I was giving one more option...as I was hoping the original poster had already figured the petcock into play. If he has not, the easiest thing I do is run the bike without the tank to verify this. I do this on all the bikes that come into the shop, so that I know MY carb cleaning was done correctly, if there's a problem it's usually the owner's gas tank that is the problem.  Get a small funnel, hook it up to the gas line and  watch the gas go down until it stops.  If it never stops...and you are pissing fuel everywhere, you know that's an issue, if it stops, then the floats/needle are stopping said fuel. At which point if the plugs are still dry, you have a float setting/ jet setting/ or just plain dirty carbs.  I have to use the prime feature on my KZ550 every time I start it if it's been sitting for more than a day.  I installed clear fuel filter and can verify fuel is going in that way. 

Offline axeugene27

  • Posts: 1026
Re: Riddle me this????
« Reply #8 on: Jun 24, 2012, 20:05:09 »
No offense taken louie I have done dumber shit than that before.  Just to clear things up I have clear line/ with inline filters and brand new mikuni carbs The petcock has been cleaned and fuel flows freely though both lines.I can see the inline filters are full of gas  Also every time i take the bowls off the carbs they are full of gas so idk seems like that is not the issue. It acts like it's flooding but the plugs are not wet I don't get it. Those carbs are new so they can't be dirty Unless some gunk escaped the filters and clogged a line somewhere. I don't think so though I ordered some variable jets so when i put those in I will try spaying out all the passages with carb cleaner. I don't know man I had it running today and even rode it for like 10 min acts like it's rich I say that because when i loose power at around 3k rpm it doesn't improve with choke. Pulled plugs when i got home and they were black with soot. Let it sit another couple minutes wouldn't start. WTF. IDK maybe it's the gas tank vent or something. Even if it's running rich it shouldn't flood out and if it was flooding the plugs should be wet right? I kind of think it's a fuel starvation thing at start up I will check the float height but in a brand new carb i don't see how that can be off unless the spec height isn't right for this machine????
72cb350 barn burner build http://www.dotheton.com/forum/index.php?topic=37654.20
TITAN http://www.dotheton.com/forum/index.php?topic=53037.msg600706#msg600706
"it's better to have an ugly bike that runs well, than an pretty paperweight."
"bullshit goes a long way if you throw it right"

Offline Big Rich

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Re: Riddle me this????
« Reply #9 on: Jun 24, 2012, 21:36:08 »
Mikuni carbs have their own float height - regardless of what they are mounted to. And the height can be set at Mikuni, but due to handling in shipping it can be off when they arrive at your door.

If you think it's running dry, pull the inline filters off, check you gas tank vent, petcock filter (if installed), and the carb vent tubes. All of these can restrict flow to the carbs. Sooty plugs are caused by the air/fuel mix being off - which isn't always jetting. Dirty air filters, timing, weak spark, etc can all throw you a loop.