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post #1 of 18 (permalink) Old 04-08-2009, 12:49 PM Thread Starter
 
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Nubbie needs help

I just got an 84 Yamaha FJ600. I replaced the Starter Relay as needed, and it started up, but couldn't hold an idle level and eventually was unable to keep from stalling.

Now when I try to start it, the starter cranks, but it doesn't get going. If I let it do that long enough, it seems to backfire once and then i stop.

This is my first bike, but I'm pretty good w/ mechanical stuff. I think it might be flooded, and needs a carb cleaning & balancing. Does that sound right? And if so, do I need to take the carbs off to drain the bowl? Also, WTF could be causing that backfire and is it related?

Any help would be greatly appreciated.

Thanks,
Mark
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post #2 of 18 (permalink) Old 04-08-2009, 05:29 PM
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Try new plugs and change out the gas if it's old!

A few ccs short of a full litre.
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post #3 of 18 (permalink) Old 04-08-2009, 06:24 PM
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Start with mac's approach, its easier than a carb cleaning and balance. Those would be my next approaches.

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post #4 of 18 (permalink) Old 04-09-2009, 07:25 AM Thread Starter
 
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Quote:
Originally Posted by mac020 View Post
Try new plugs and change out the gas if it's old!

Thanks, that was the next thing I was gonna do. Is there an easy way I can check the floats to make sure that they're not gas-logged? And does anyone know where I can get a manual for the Mikuni BS 32/34 carbs?

Mark
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post #5 of 18 (permalink) Old 04-09-2009, 07:35 AM
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My old bike's carbs were covered in the bike's service manual, including settings for floats. Not the case for you?

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Dragging knee is for the track, and dragging tail is for the lot. --Kane Friesen

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post #6 of 18 (permalink) Old 04-09-2009, 08:37 AM Thread Starter
 
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I bought 2nd+ hand. I don't have the shop manual. You know what else I'm looking for? Does anyone make an inline quick-connect fuel valve? I want to be able to quickly disconnect my fuel tank w/o making a mess. The petcock doesn't have an "off" position, so I'm looking to make a little mod.
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post #7 of 18 (permalink) Old 04-10-2009, 09:34 AM
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The petcock is prolly vacuum actuated. That may be your problem.

A few ccs short of a full litre.
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post #8 of 18 (permalink) Old 04-10-2009, 01:30 PM Thread Starter
 
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Well, I changed the plugs and oil, and charged it up. It starts up just fine and holds an idle while standing. Once I get goin, it seems to starve for gas, regardless of what position the choke, or idle screw are in. It putts along until it hits about 3k, then it has FULL power. I accidentally did a little wheelie the first time it happened. Then it revs up to about 5-6k and just sits there, regardless of what i do to the throttle. Then after about 5-10 seconds it goes back down.

I'm thinking I still need to balance the carbs, but I'm hoping I don't have to rebuild them. Any idea why I can't seem to go off the line?

Thanks,
Mark
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post #9 of 18 (permalink) Old 04-10-2009, 03:02 PM Thread Starter
 
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Ok, so in my exploration of the carbs (ie taking them off) I didn't clamp them back onto the boots which lead to the engine. I'm assuming that since the vacuum tube comes from there that this lack of a seal was one of the issues. So I put that back together correctly and it has a lot more power off the line, but it's still fluctuating a lot, especially still sticking when it hits a high rev. And I think i noticed a leak from one of the carb bowls.
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post #10 of 18 (permalink) Old 04-12-2009, 02:04 PM Thread Starter
 
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Well thanks to everyone who helped me out on this one. I got the bike up and running well enough to get out onto the highways. I'll probably post another thread sometime next week when I start to run into more problems.

Mark
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