Question about 1981 Yamaha XJ 650

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When idling engine spits back thru carbs

81 yamaha 650 xs special

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When was the last time you had the carbs synchronized? If they are not flowing the same it could couse this problem.

Posted on Jul 02, 2009

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You should check the valve clearances, camshafts timing and make a compression test on the engine too.
One or more of your inlet valves is/are either not closing entirely or they close but their stem is damage and it doesn't seal off the combustion chamber properly.

Posted on Jun 28, 2009


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I have a 1980 yamaha xs 1100 special, it sat in a garage for 3 years, i replaced the fuel lines, cleaned the tank, and replaced the plugs, how come it only idles when the choke is on and it sounds like a...

You probably have varnish build up in the carburetors, causing restricted air flow, and therefore the engine is running too lean, especially on the right side, and a lean running engine will run hot at the exhaust. It only idles when the choke is on because the choke creates a richer fuel supply. A can or two of commercial fuel cleaner through the fuel supply may get the engine's jet's orifices cleaned out. Otherwise, overhaul the carbs.
Hey, nice old bike, though. Good luck

May 20, 2011 | 1979 Yamaha XS 650 F

1 Answer

1980 Yamaha XS 650 special not charging

check the rotor magnet to see if the windings are shorted to the base use an ohm meter to check for grounding to the base.

Apr 04, 2010 | 1980 Yamaha XS 650 G

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I have an 81 yamaha 650 maxim that will only idle with the choke on


Mar 16, 2010 | 1981 Yamaha XJ 650

1 Answer

1980 XS650 Special II. Timing acts like it has jumped. Will run but won't idle.

carb may need overhaul-take apart n put in solvent-try ajustin idle speed 1st--inspec ign wiring-the timing is controlled by a computer box-may need new-1st chec batt condition-make sure connections r tite--secure a clymer manual for details n keep in touch I had 2 of these babies

Jan 26, 2010 | 1980 Yamaha XS 650 G

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How to take a starter off a 81 yamaha 650xs

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Nov 01, 2009 | 1981 Yamaha XS 650 H

1 Answer

Can't find Model number.

I checked with a local Yamaha Dealership. They found it.

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Aug 29, 2009 | 1979 Yamaha XS 650 F

1 Answer

80 xs 650 hesitation and exhaust "popping"

Most likely the carbs need cleaning and adjusting. You may want to richen the A/F ratio when you do it. They are set really lean from the factory. I would go 1/4-1/2 turn out on the A/F screw.

Jul 22, 2009 | 1979 Yamaha XS 650 SF

1 Answer

When warm will not stay running+leaks oil to the air cleaner

This is an XS 650, no? Sounds like you might have some piston ring blow-by (especially if its burning some oil), or possibly bad valve seal's'. The valves could be tight, so make sure the valve clearance is correct first, then compression test, and finally a 'leak-down' test.

If it is blowing by, it probably is fouling plugs and you will need more energy in the spark to fire, but this is a secondary issue, which will be eliminated with the fixing of the other issues. Good luck!

Jun 25, 2009 | 1981 Yamaha XJ 650

1 Answer

Engine idles with choke on only

You either have cracked intake boots/ manifolds or the idle circuit in the carb is plugged with stuff. Spray some brake cleaner around the intake manifolds (air box in place) and see if the idle picks up. If nothing happens pull the air box, fire it up and put your hand over the carb(s) to try to **** it through....rev it up...cover carb with hand...repeat. Next you're removing carbs and cleaning

Dec 17, 2008 | 1978 Yamaha XS 650 SE

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