New xs owner with issues, help please!

[Hooja]

Finally bought a 1977 650d, so can justify joining instead of lurking and I'm jumping in with both feet with a list of issues, a lot are covered in posts I've read but thought I'd post my specific probs and hopefully get it running right!
The bike is modified, all fairly recently:
Gas flowed head, lapped valves, electronic ignition, starter motor removed, 1.5" stainless headers, reverse cone mufflers. Vm roundslides with ramair foam pods.
All this was done by previous owner who swears it ran beautifully, was set up on rolling road with printouts to prove it.
Problem is I can't get it running right. It idles at 2000rpm with 4.5 turns out on mix screws.
I fatted around with mix screws, got it running to rich, fouled plugs and ended up on one cylinder. Got it back to working now but, like I say, high idle and I'm sure the screws are out too far already and fear fowling the plugs again.
Apparently it was set up for bell mouths ( velocity stacks) but is fitted with the foamies.
Any help would be great as I want to fall in love with this bike but am so far not very good friends with it.
Thanks in advance and hello!

 

[retiredgentleman]

Find the "Carb Guide" in the "Tech" section. Read it thoroughly.

There is a table that tells you what jets your carbs should have, if you have stock air boxes and stock exhausts. But, since everyone modifys the air filters and exhausts, you will have to determine the correct jets by the trial and error method.

Good idea to replace the needle jet O-ring, as that can cause a high idle. Mixture screws should never be opened up greater than 3.5 turns...................indicates a need to go to a larger pilot jet.

 

[XSLeo]

With the VM round slides the stock carb guide won't help much you need the VM 34-36 carb guide. www.amckayltd.com/vm34-36.pdf
I don't know much about the VM carbs but that guide should help.
Leo

 

[Hooja]

Cheers guys, will have a good read through.
The strange thing is, when the bike turned up it was idling around 1200 but conked out after half hour later and that's when the troubles started!
I can't think what else would cause it, assuming it has the correct jets?

 

[scabber]

Welcome to the site. I would check the timing and the advance mechanism to see if is operating properly.

 

[XSLeo]

If there was crud in the tank it can move to the carbs where it plugs jets and passages.
Leo