New build will not start.

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GoSlowJoe

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Oh great wizards of the XS 650 community, I humbly ask your assistance.
I have spent hours pouring over threads, trying to find nuggets of knowledge which may leave me in the right direction. ..

I have a 1975XS 650 with a 1977 engine. Bought it in boxes two decades ago. Finally got it together a nice straight tracker…
PMA from Hughes handbuilt
Removed Electric start
Electronic ignition from mikes XS
High output coil from Mikes XS
Original, mechanical advance
No battery – big capacitor
5K plug caps
NGK BP7ES plugs
Straight pipes with internal baffles from drag specialty 1.5 inch
mikuni VM 34 carburetors with pod air filters
Needle Jett 159, P5
needle 6f9 - clip in middle groove,
pilot jet 25
Main jet 190
Mixture screws turned 3/4 turn out

I have cleaned the carburetors and set the float height to 24 mm. Synched slides to 5/32” when throttle closed and they open at the same time.

The coil and electronic ignition are brand new.

I have a nice, bright, blue spark at the plug

I have a good engine and chassis ground.

A compression check shows 120 on both cylinders, cold after six kicks.

I even pulled the cylinder head cover to make sure the timing chain hadn’t skipped. Everything is in alignment. And cam chain tensioner is correct.

If I kick it like crazy, it will pop occasionally maybe even a small backfire. Yesterday I did get it to fire up, 10 seconds… but had to keep the throttle halfway open to keep it running and then it stalled and I could not restart it. Plugs black after that…

I am hoping that my carburetor settings are just way off… Or that my starting procedure is causing it to immediately flood or something…

Any guidance and wisdom that you could bestow upon me, would be greatly appreciated!

HELP!
 
GoSlowJoe said:
Oh great wizards of the XS 650 community, I humbly ask your assistance.
I have spent hours pouring over threads, trying to find nuggets of knowledge which may leave me in the right direction. ..

I have a 1975XS 650 with a 1977 engine. Bought it in boxes two decades ago. Finally got it together a nice straight tracker…
PMA from Hughes handbuilt
Removed Electric start
Electronic ignition from mikes XS
High output coil from Mikes XS
Original, mechanical advance
No battery – big capacitor
5K plug caps
NGK BP7ES plugs
Straight pipes with internal baffles from drag specialty 1.5 inch
mikuni VM 34 carburetors with pod air filters
Needle Jett 159, P5
needle 6f9 - clip in middle groove,
pilot jet 25
Main jet 190
Mixture screws turned 3/4 turn out

I have cleaned the carburetors and set the float height to 24 mm. Synched slides to 5/32” when throttle closed and they open at the same time.

The coil and electronic ignition are brand new.

I have a nice, bright, blue spark at the plug

I have a good engine and chassis ground.

A compression check shows 120 on both cylinders, cold after six kicks.

I even pulled the cylinder head cover to make sure the timing chain hadn’t skipped. Everything is in alignment. And cam chain tensioner is correct.

If I kick it like crazy, it will pop occasionally maybe even a small backfire. Yesterday I did get it to fire up, 10 seconds… but had to keep the throttle halfway open to keep it running and then it stalled and I could not restart it. Plugs black after that…

I am hoping that my carburetor settings are just way off… Or that my starting procedure is causing it to immediately flood or something…

Any guidance and wisdom that you could bestow upon me, would be greatly appreciated!

HELP!
Click to expand...
I would first check ignition timing with a strobe lamp.
 
Bruno_c said:
I would first check ignition timing with a strobe lamp.
Click to expand...

Yes I have the same view as Mr Bruno But I would move it ( ignition ) step vise in increments noticing any changes Kickback to advanced or shooting in the exhaust to late

Is it a waste spark ignition if not other mix ups is possible

Is the 3/4 turns right for these carbs Mixture tt is more for BS 34 I would consider fatten it for now.
 
image.jpg

The electronic ignition module is set to the middle of the range per the manufacturers installation instructions.
 
Is that one below serviced and operates as i should there is a bushing to lubricate not mentioned in service documents so often
Springs can also be weak

Original, mechanical advance
 
GoSlowJoe said:
I have spent hours pouring over threads, trying to find nuggets
Click to expand...
If you've searched for your XS charge ignition, there's several threads discussing problems with them: they have lots of problems, particulalrly when paired with a Capacitor. My suggestion would be to (at least temporary) replace the capacitor with a battery of 12volts, 6+AH capacity, rotate the ignition module counterclockwise a small amount (retarding) and try it that way. Given all your mods, you've introduced a lot of variables, but I do think the ignition is the most likely suspect.....
 
GoSlowJoe said:
I cleaned the advance mechanism. I lubed the shaft and bushings and make sure that everything moves freely. Any other thoughts?
Click to expand...

Mr JP has something there

I have not seen the instructions for the ignition installation ..or what type it is
But since you have spark ..it should make some noises ..
As mentioned I would try to change ignition positions --- being in the middle now
I would move it to end points both directions se what happens
And perhaps use A wood stick in the spark plug hole checking that any ignition mark's line up with the piston TDC

The battery have been a solution finding the problem before
 
jpdevol said:
If you've searched for your XS charge ignition, there's several threads discussing problems with them: they have lots of problems, particulalrly when paired with a Capacitor. My suggestion would be to (at least temporary) replace the capacitor with a battery of 12volts, 6+AH capacity, rotate the ignition module counterclockwise a small amount (retarding) and try it that way. Given all your mods, you've introduced a lot of variables, but I do think the ignition is the most
Click to expand...
I checked rotor markings with piston TDC. I will try the battery instead of a capacitor and see if that helps! I’ll report my findings!
Thank you!
 
XS charge question?
Should the rotor be flush with the sending unit? My rotor sticks out 4mm, enough to see the edge of the magnets… I’m thinking that’s not correct…
 
IIRC there was a thread on here that mentioned the difference in the nut and threads showing and it was normal?
 
GoSlowJoe said:
XS charge question?
Should the rotor be flush with the sending unit? My rotor sticks out 4mm, enough to see the edge of the magnets… I’m thinking that’s not correct…
Click to expand...
I think what JP's referring to is that a search here on the forum will show you that the XS Charge ignition you're try to use is mostly junk. At least that's the conclusion a lot of forum members have come to...


1691551815097.png
 
Eureka! Thank you Jan_P!!!
Once I started, going through the form again, looking for issues with the CHARGE XS electronic ignition… I stumbled across the thread that mentioned having to widen the adjustment range on the flange. While running an external battery (another Jan_P recommendation), and modifying the flange to allow an extra 5° of movement, she fired up! I have now set the timing! I then went back and remove the external battery and reinstalled the capacitor, and she still fires right up! Oh, my goodness! Thank you so much, I was putting a dent in the side of my toolbox, beating my head against it!

Any suggestions on who builds a high-quality electronic ignition? I have trust issues with this Charge XS system…
 
GoSlowJoe said:
Eureka! Thank you Jan_P!!!
Once I started, going through the form again, looking for issues with the CHARGE XS electronic ignition… I stumbled across the thread that mentioned having to widen the adjustment range on the flange. While running an external battery (another Jan_P recommendation), and modifying the flange to allow an extra 5° of movement, she fired up! I have now set the timing! I then went back and remove the external battery and reinstalled the capacitor, and she still fires right up! Oh, my goodness! Thank you so much, I was putting a dent in the side of my toolbox, beating my head against it!

Any suggestions on who builds a high-quality electronic ignition? I have trust issues with this Charge XS system…
Click to expand...
Hugh's CDI system:

https://www.hughshandbuilt.com/product/complete-xs650-cdi-system/

1691719765246.png
 
Might be worth google info on Boyer Bransden .. It is a company that has been around and have support.
It is not the highest quality and dont like under or over Voltage
Not sure if it is possible with a capacitor only .

Looks something like that

https://www.ebay.com/itm/314703190426
 

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