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The Garage Motorcycle Related Discussion (Yamaha XS650, other makes and models, and anything else motorcycle related including tools and gear)

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Old 01-06-2012, 10:38 PM   #1
noears
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Default Bike wont fire, Considering setting bike on fire.

Hi, Im new to this site, all the way from New Zealand.

I bought an xs650 special 1978, it has done 19,000k's since new.

I have recently chopped and hard tailed her,

The build is basically finished, Using the original wiring loom it has now been re wired with a few bits changed to the loom,

Before the chop the bike started first pop.

I have a new tank and am running one "on/off" petcock that T's into both carbs.

Original tank had a petcock with prime on each side feeding both carbs separately.

Im running k&n air filters.

What do I do with the two lines that went from the petcock prime to the engine/carb?

What do I do with the two breather lines that went from the top of the engine to air box?

I have new spark plugs and occasionally the engine will back fire, but wont actually fire up, the spark plugs are practically bone dry when I check.

What would have changed with the carbs before and after the chop to make the bike now not run?

Thanks!
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Old 01-06-2012, 10:48 PM   #2
XSJoel
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Default Re: Bike wont fire, Considering setting bike on fire.

Man I would give up and ship it my way, I will make sure to set it ablaze for you good and right.
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Old 01-06-2012, 10:51 PM   #3
noears
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Default Re: Bike wont fire, Considering setting bike on fire.

Haha Classic! The only thing stopping me from setting her ablaze is the countless hours I have poured into her!
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Old 01-07-2012, 01:15 AM   #4
noears
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Default Re: Bike wont fire, Considering setting bike on fire.

Problem sorted.

I capped off the prime lines and opened the breather lines,

Then swapped the left spark plug lead to the right spark plug, and the right lead to the left, and we have ignition.

My bike is running, time to start build some quieter pipes.
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Old 01-07-2012, 01:15 AM   #5
Splexin
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Default Re: Bike wont fire, Considering setting bike on fire.

Haha the title of this thread is priceless

The other day I couldn't get mine started for the life of me, nearly had an asthma attack kicking it to death. Carbs were flooded. Came back a couple hours later and started right up


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60 MPG is very, very good gas mileage, almost too good.
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Old 01-07-2012, 01:24 AM   #6
noears
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Default Re: Bike wont fire, Considering setting bike on fire.

Haha, Thanks Splexin,

Before I changed the leads over I attempted to kick start the bike so more power would be going to ignition and what not,

15 mins later im shirtless keeled over out of breath and sweating like a crazy man.

So glad I decided to leave that starter motor on!
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Old 01-07-2012, 07:07 AM   #7
jayel
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Default Re: Bike wont fire, Considering setting bike on fire.

Quote:
Originally Posted by noears View Post
Problem sorted.

I capped off the prime lines and opened the breather lines,

Then swapped the left spark plug lead to the right spark plug, and the right lead to the left, and we have ignition.

My bike is running, time to start build some quieter pipes.
prime lines? air barbs on the intakes? interconnect them with some vacuum line, smooths out the carb balance... breathers run 3/8th (10mm) hose back to rear of engine pointed at chain for free chain mist oiler


I actually read this post and now my comment makes absolutely no sense.
Where are we going and why are we in this handbasket.
Hobbies... Avoiding hard work and pain
1987 XLH1100, 1980 XS1100, 1978 SR500, 1980 Yammahopper, 1966 Aermacchi/H-D M-50
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Old 01-07-2012, 04:38 PM   #8
oldbiker
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Default Re: Bike wont fire, Considering setting bike on fire.

hi,,, because i,m in australia,,,, we are nearly brothers ,,, and so,, if you pallet it and send it toooooo me i,ll be nice tooo it and it can socialize with my xs650,,,, it won,t be on its own only trying tooo help ease the pain,,, regards oldbiker
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Old 04-04-2013, 11:14 PM   #9
pristic
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Default Re: Bike wont fire, Considering setting bike on fire.

Quote:
Originally Posted by jayel View Post
prime lines? air barbs on the intakes? interconnect them with some vacuum line, smooths out the carb balance... breathers run 3/8th (10mm) hose back to rear of engine pointed at chain for free chain mist oiler
Hi jayel,

umm, I NEVER thought about that but now wondering, would using little inlet block off caps vs putting a hose from one to the other... would that really balance the carbs at all?
I have the inlets with the barbs... would putting a hose between them help?

Cheers,
Peter
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Old 04-05-2013, 08:53 AM   #10
SINKING78
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Default Re: Bike wont fire, Considering setting bike on fire.

Yes. If you have an open vacuum port on the carbs, run a line from the breather ports to each carb. I did this with my Mikunis and it made all the difference in the world. A vacuum leak will make any engine run like poop.
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Old 04-07-2013, 10:09 AM   #11
Clarko
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Default Re: Bike wont fire, Considering setting bike on fire.

Quote:
Originally Posted by noears View Post
Problem sorted.

I capped off the prime lines and opened the breather lines,

Then swapped the left spark plug lead to the right spark plug, and the right lead to the left, and we have ignition.

My bike is running, time to start build some quieter pipes.
Does swapping plug wires on these bikes make a difference? I was under the impression that both plugs fire at the same time. Or does that only apply to electronic ignition?
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Old 04-07-2013, 10:31 AM   #12
5twins
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Default Re: Bike wont fire, Considering setting bike on fire.

That only applies to the electronic ignition. You can't swap the wires on the points ignition or the timing will be off. In the case here, the plug wires were installed wrong to begin with so swapping fixed them.


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