Fuel is definitely a possible problem in Mexico, and will make the bike run very poorly.

Howqever you also say you adjusted the points twice, but haven't adjusted the timing. Ouch, that's a no-no - adjusting the points DOES change the timing and WILL cause problems. Correct drill is to adjust the points to within specs and then set the timing, either static or with a timing light. Static is easy on points systems.

Re carbs, they must be adjusted AFTER everything else is just right, and then only very very slightly. Tiny adjustments can make a big difference. 1/4 turn on one of the adjusting screws is major.

I suspect a good tune and possibly a fresh tank of gas will make a big difference.

RE: the tapping sound - if it's a light "tick-tick" it's probably valve adjustment or rocker arm end play, neither of which is fatal. If it's a deep knock, bad news. VERY unlikely to be a crank problem though, more likely worn pistons. Not super expensive to repair, and can probably go a long ways left alone.

Cranks on these are almost indestructible. 200,000 miles isn't unusual.

Get to a good mechanic! Contact the Valle de Bravo HU Community, Juan is away but will be able to point you in the right direction. Also any of the other HU Communities in Mexico will be worth contacting if they're nearby, they'll be pleased to help out.

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Grant Johnson

Seek, and ye shall find.
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One world, Two wheels.
www.HorizonsUnlimited.com

__________________
Grant Johnson
Seek, and ye shall find.
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Inspiring, Informing and Connecting travellers since 1997!
www.HorizonsUnlimited.com