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Author Topic: newbie ques. on carbs.  (Read 940 times)

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Offline famoussas1

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newbie ques. on carbs.
« on: October 28, 2009, 05:00:58 PM »
ok, took my bike out today, i am totally new to this, bikes, hondas fours, etc. took bike out and think im having running rich/lean probs. but unsure. bike runs fine, but if i twist the throttle to open it up, i can kill the engine, am i flooding it out or is it starving? took off air filter, ran it that way, a little better but still bogging out. air filter smells like gas. im unsure and dont wanna fix something that isnt broke, but i know this is related to the carbs. do they need to be adjusted/sync'd?
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Offline Industrial Cafe

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Re: newbie ques. on carbs.
« Reply #1 on: October 28, 2009, 05:05:26 PM »

edit:
If you whack it open like a new bike it creates a lean condition because the throats are wide open and the engine isn't turning fast enough. sounds like "BAAAW"
 the 78 750 has an accelerator pump

be easy on the old girl

« Last Edit: October 28, 2009, 05:17:36 PM by Industrial Cafe »
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Offline Industrial Cafe

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Re: newbie ques. on carbs.
« Reply #2 on: October 28, 2009, 05:10:22 PM »
list your model and current mods
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everything I say is pure speculation and
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Offline famoussas1

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Re: newbie ques. on carbs.
« Reply #3 on: October 28, 2009, 07:29:24 PM »
well not so much opening it up in that way, but when im in first, shifting to second, or second to third...its bogging. was cruisin around 30 mph & it wouldnt open up more more than that.


just got it a couple months ago, no mods from what previous owner said, stock 74 cb550.  havent had the time to rip into it, was gonna use the winter for that.

he said he cleaned the carbs, & gave me an old set after he rebuild the old ones...ran awesome when i test rode it and a few weeks after that. since then its been draggin a bit. any help would be appreciated...im lost here  :(
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Offline ekpent

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Re: newbie ques. on carbs.
« Reply #4 on: October 28, 2009, 07:37:01 PM »
Is the gas tank nice and clean inside or do you see some rust and crud.Clean carbs go fast with a dirty tank,drop a float bowl and see if there is any crud in the bottom that could mess with your jets.Good tune-up sounds in order ;D
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Offline jeepster

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Re: newbie ques. on carbs.
« Reply #5 on: October 28, 2009, 08:28:49 PM »
Quote from: ekpent on October 28, 2009, 07:37:01 PM
Is the gas tank nice and clean inside or do you see some rust and crud.Clean carbs go fast with a dirty tank,drop a float bowl and see if there is any crud in the bottom that could mess with your jets.Good tune-up sounds in order ;D

+1

If there is crud in the tank you can get an inline fuel filter to keep debris out of your carbs. Check the FAQ for typical rich/lean symptoms. Before tearing apart the carbs you can try replacing the air filter if it's old/dirty and clean out the screen in the petcock (might not have one on that bike) and in tank filter, also check to see if the tank vent is open...
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Offline the technological J

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Re: newbie ques. on carbs.
« Reply #6 on: October 28, 2009, 10:35:40 PM »
just throwing it out there could ur timing be way off some how?have u done the 3000 mile tune up it worth the hour and a half or so it will take u (the first time then it comes quick) check your spark plugs.. if u dont know how old they are its well worth the 13 or 14 bucks to get new ones
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Offline TwoTired

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Re: newbie ques. on carbs.
« Reply #7 on: October 28, 2009, 10:46:07 PM »
You cannot snap the throttle full open from idle.  It will simply wheeze and most likely quit.  It is the nature of mechanical slide carbs that don't have accelerator pumps.  It should take up to 1/2 total throttle travel and accelerate gracefully/briskly.

If you have the stock air filter ...
(I just love it when people post problems with no details about bike that's been subject to changes for  the last 30 years...not.)
...it must be new or clean as new.  Almost always, if the stock filter is more than a year old, it's time to renew it.

Nobody gets to complain (and get sympathy) about how these old bikes run until after a complete and thorough tune up per scheduled maintenance every 3000 miles.
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Offline greasy j

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Re: newbie ques. on carbs.
« Reply #8 on: October 28, 2009, 11:10:12 PM »
the air cleaner could be dirty since it runs better without it. I'd say you're running rich. but what do I know.

also, sometimes it's something really simple like the intake hose is cracked/not on all the way, or the float bowl isn't completely snapped in. in that case it would be leaking, though.
« Last Edit: October 28, 2009, 11:14:20 PM by greasy j »
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Offline Industrial Cafe

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Re: newbie ques. on carbs.
« Reply #9 on: October 29, 2009, 10:45:33 AM »
heh, TT you sound like you've seen this before.
 ;D


I think you need to pull your main jets and see if you can see though them.
 I bet they're gummed up a bit.
  I use a dental pick sharpened on a belt sander then sanded and polished so it doesn't damage the port.
 also check your emulsifiers on the jet tubes if there are any on the 550.

edit:a full tuneup sounds like a fine idea
« Last Edit: October 29, 2009, 10:49:47 AM by Industrial Cafe »
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everything I say is pure speculation and
I have no idea what I'm talking about  ._.

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Offline famoussas1

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Re: newbie ques. on carbs.
« Reply #10 on: October 29, 2009, 01:18:14 PM »
thanks to everyone. i put new plugs in it recently, but thats all. time for a tune up. wanted to ride it a few more weeks til winter or it gets cold, but i think i have to do these things now..maybe just put it up for winter, cuz i had some plans for it. just gotta find the time.

ill get a new air filter, change oil, re check plugs, then look at carbs...hopefully that takes care of it all. thanks again.
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