Author Topic: Bike suddenly dies/loss of power/fuel line ?  (Read 675 times)

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Offline burgundysquare

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Bike suddenly dies/loss of power/fuel line ?
« on: August 20, 2012, 05:30:32 PM »
I was traveling from LA to San Diego the other night and the bike was running fine the entire trip. I was cruising at 70mph, around 6500rpms for 70+ miles. As I pulled off the highway to fill up again, I start to slow off the ramp and the bike just cuts out. Almost as if it was out of fuel. I fill up the bike and it cant kick over. I eventually barely get it to start, but now there is no idle and it will only rev to 4000rpm and get me about 40mph. I proceed to take surface streets home since it was late and it suddenly makes a loud 'pop' and the bike seems fine again. It's worked like a charm since.

Im getting ready for a trip to SF on this bike in less than a month and do not want the same thing happening, and my first thought was that the 40 year old fuel lines were clogged. I thought that I had better just install a simple fuel filter. And as always I tried to fix something that wasnt broken and got myself into trouble. The main fuel line going from the petcock to the carbs ripped when I tried to remove it (seems it needed to be replaced anyways), but now that I have removed that main line, how do I go about putting a new one on?

Do I need to take apart the entire carb assembly to get to the bottom nipple? Are there any tricks or tools to getting to that bottom nipple? Im hoping that I dont need to spend an entire weekend to take the assembly apart to simply replace one simple fuel line and install a filter. Lastly, does anyone have other thoughts on what might have been my problem earlier?

Thanks all.
« Last Edit: August 20, 2012, 05:32:04 PM by burgundysquare »

Offline BobbyR

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Re: Bike suddenly dies/loss of power/fuel line ?
« Reply #1 on: August 20, 2012, 06:14:41 PM »
It would help if you tell people the model and year since they are different and we have experts on all models and years.

For fuel line you may want to try TYGON tubing. It does not kink easily, can make good bends, and is self clamping.

One thing that does happen a lot is a plug wire gets loose, arcs, or the plug caps go bad. These bikes use waste spark so 1-4 and 2-3 fire in pairs. If one cylinder in a pair does not fire, the other one does not. One may have dropped and came back so you got a backfire.
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?

Offline burgundysquare

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Re: Bike suddenly dies/loss of power/fuel line ?
« Reply #2 on: August 20, 2012, 06:43:59 PM »
It would help if you tell people the model and year since they are different and we have experts on all models and years.

Sorry about that. 1974 350F. I thought I had added that.

One thing that does happen a lot is a plug wire gets loose, arcs, or the plug caps go bad. These bikes use waste spark so 1-4 and 2-3 fire in pairs. If one cylinder in a pair does not fire, the other one does not. One may have dropped and came back so you got a backfire.

This might be the problem. One of my plug caps is ripped apart and Ive been meaning to replace it, but as a 20-something year old, money is tight and things (usually) only get fixed when they are REALLY broken. A friend told me to check to see if Im am getting a spark, how would one check this? Start the bike and carefully lift each cap to see if it arcs across to metal?

Offline BobbyR

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Re: Bike suddenly dies/loss of power/fuel line ?
« Reply #3 on: August 20, 2012, 06:59:17 PM »
A ripped cap can do this, try running the bike in the bark and look for small arcs. Wiggle the wires while you look. NGK plug caps are pretty cheap. I would check online for prices when you get a couple of extra bucks.
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?

Offline BobbyR

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Re: Bike suddenly dies/loss of power/fuel line ?
« Reply #4 on: August 20, 2012, 07:01:02 PM »
You can get TYGON fuel line at a shop that repairs lawn movers, snow blowers. They use it a lot.
Dedicated to Sgt. Howard Bruckner 1950 - 1969. KIA LONG KHANH.

But we were boys, and boys will be boys, and so they will. To us, everything was dangerous, but what of that? Had we not been made to live forever?