Timing basics

[evk88]

Hey guys I have an 86 xs650 running the stock ignition box. I blew the motor and since have replaced it with a 79 xs650 motor. The bike won't start and will backfire. Is there a timming differance?

 

[I am Carbon]

Hey guys I have an 86 xs650 running the stock ignition box. I blew the motor and since have replaced it with a 79 xs650 motor. The bike won't start and will backfire. Is there a timming differance?

Hey evk I will start welcome to the site.
They didn't make the ole xs650 in 86. up to 84
in 79 it probably me with points may have come with tci.
if it has stock tci 80 to 84 nothing to time
When at idle 1200 rpm timing should be at 15 tdc at 3200rpm 40tdc
maybe you can help us help you by showing pix of your engine open the left side cover over the crank and the left side one between the valve covers.
that way we can see what you have going on.
you can post pix using the attachment below when you post.

 

[XSLeo]

If you swapped the 79 engine into a Bike with a TCI ignition, I assume you removed the alternator from the TCI engine, then you reinstalled those parts on the 79 engine.
If mounted right then the timing is right.
Is your battery fully charged, the TCI doesn't like low voltage. My 81 runs great as long as the battery voltage stays up there. Drop to around 12 volts and it gets weird. Idles fine but won't rev up.
Leo

 

[Marlin72xs]

Ooops! Wrong thread

 

[Marlin72xs]

You probably fixed it already, but...

Did you check to see that the insulating washers on the points are in the proper place?
Did u check the wires attached to each set of points? R they rubbed out in the back?
Is the metal spade tip touching the back plate?
How old are the wires? Did u try twisting the plug wires (clockwise) into the coils?

 

[Orion61]

Do any of you guys do house calls in Iowa? Thanks for all the great information.
I love these old Girls with breaker Points and everything is made out of Metal.
I have a Suzuki C50 Touring bike, side covers and even FENDERS are made of plastic, It was my Brothers bike and he willed it to me when he passed away..
But in my eyes I wouldn't even THINK about rebuilding it, A 2 ring Piston motor?? reeks of throw away.
My Boulevard will be on my Estate sale unless my Son decides he wants it, but he has already called dibbs on the XS....My Pride and joy..

 

[Gabe]

I have a 1980.x S650 and it seems to sputter in first and second gear any idea what would cause this?

 

[XSLeo]

Gabe The 80 used the TCI ignition, I doubt the ignition is your problem. If it sparks then it's probably ok.
Sounds like dirty carbs to me. www.amckayltd.com/carbguide.pdf has the carb info you need. Read it, Print it out, read it. Read it a few more times. Once you start to understand what your reading use it to tear down, clean, inspect your carbs, Pay particular attention to the choke and idle circuits. Once you get things clean and inspected you can determine if any parts need replacing. Usually just the gaskets need replacing.
The guide also list the specs you need so you can adjust things as you reassemble.
There is also a "Tuning for Mods" section. The same tuning procedure applies to stock bikes too.
Leo

 

[TwoManyXS1Bs]

With a TCI ignition, there's also the weak trigger magnet syndrome.
Do a forum search on "rare earth magnet"...