Bad timing,bad carbs or both?

1976xs

XS650 Enthusiast
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My XS seemed to be running better before I did the PMA and pamco. After upgrading to these parts the carbs have a bit of a sputter.

It sounded to be running OK but after I bought a timing light it was too far advanced and when I retarded it to what I thought was right the sputtering in the carb started.

It revs beautifully with the choke fully on but dies if you don't keep the rpm high, But trying to rev it up without the choke the sputtering worsens.

Also with it advanced a little to much the throttle seems to jam and stays high in the revs after I have wound it off.

I've been reading a few previous posts and hopefully this week I will pull the carbs off and give them a good clean. I think from reading they could be blocked.

I don't think anything should need adjusting??? Seeing as it ran fine before???

If you could help me narrow it down i'll be stoked.
:thumbsup:
 
Sorry for the hijack, 1976xs :eek: I'm struggling with the same issue right now.
PMA/cap and Pamco as well with all the advance parts from mikesxs. Mine likes to randomly cough through the carbs and pop out the exhaust at idle and part throttle low speed cruising. Pulls hard with no miss in upper RPM ranges. Starts third kick cold and first hot with no kick backs. BS34's with a 45 pilot and 140 main and Uni pods. I currently have the carbs removed and thoroughly cleaned the pilot circuit again. No real blockage found. I'm beginning to suspect timing. Is it possible that the timing is advancing way to early? I've got another set of springs on the way from Mikes so I can modify them. Cam chain and valve lash is good. Timing was checked with a light and seems to be spot on, however I have no tach to tell me when full advance occurs.

Once I get the carbs back together, I'll try running the ignition directly from a battery.

Any ideas or confirmations?
 
hey mate, i got the timing marks off this site

http://www.gofastforless.com/junk/Per-Mag-Alt-Instructions.pdf

a few pages down. and just used a file to score them on the bike.


I thought my timing was spot on to the marks but my old man said it sounded like it was to 'retarded' and after advancing it just a little bit it seems to sound better and doesnt cough or sputter anymore. havnt checked it against the marks again though.

thanks pete for the reply just my bad timing haha ;)
 
if you can make several marks on either side of where its currently set and with a light set it further retarded until it runs quite bad then slowly advance it until it runs good test ridding hard between each change and this should get you in the ball park also put new pugs in and check for little tiny black dots on the porcelain these are a good indicator of detonation before you can hear or feel it
 
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