Question about 1979 Yamaha XS 650 SF

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Xs650 one cylinder lean

One cylinder plug is lighter by far than other cylinder leen cylander
also backfires. 1982 xs650.

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I had the same bike.there is a rubber line that connects the two carbs together.the carb with the lighter lean sparkplug is the one being feed by the other carb with the darker richer sparkplug with the fuel line connected to it i bet.

Posted on Mar 08, 2009

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I have a gpz750 1982 that starts well but wont run on all 4 cyl either no1 or no2 wont join in popping and backfiring

Could be dirty / bad fuel but that should have affected all cylinders. It could also be a pinched fuel line to the cylinders. Sorry can't be more helpful

Jan 03, 2016 | Motorcycles

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My S50 backfires when I close the trottle.

The motor is running too lean on the popping cylinder. A best (but most expensive) solution would be re jetting both carbs. However you can cheat this problem by setting the air screws richer (further out). Try 1 turn out at first. More than two should not be necessary. Adjust both carburetor needles to better balance the cylinders. The needles may have a plug covering them. Remove and discard this. These needles are located below the throttle cable attachment point on both carburetors.
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Remove swingarm on yamaha 650

Hi, Anonymous for this scenario you will need your service/owners manual if you can't find the first and best tool you ever bought for your Yamaha, despair not, for a mere $0 you can download another one. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
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Mar 10, 2013 | 1982 Yamaha XJ 650

1 Answer

My 1982 Honda 200e starting missing about a month ago, sometimes it will backfire, it runs but poorly, plug was black. Had the fuel changed, carb cleaned and still the same!!

With any naturally aspirated motor, aside from timing, your fuel/air mixture is crucial at part-throttle as well as at wide-open throttle and off-idle. Sounds like your running too lean on the top end and too rich at part-throttle and off-idle. You should focus on either preliminary adjustments to your carbs; rebuilding or replacing them. You may also consider re-metering and re-jetting your carbs.

Jun 07, 2011 | 1974 Honda CB 200

1 Answer

Just wondering if this I need to replace the oil filter on my 1982 yamaha xs 400 with YICS or can i just lean it with kerosene?

Change the filter. Oil under pressure flows through it. This weakens the filter material. Cleaning with kerosene just abuses it more. If the filter tears or bursts after an oil change, you will soon be seing a light smoke coming from the muffler caused by unfiltered oil abraiding the pistons, rings and cylinder walls. Soon it will be heavy smoke and oil fouled spark plugs. Really, filters don't cost THAT much. They are really cheap compaired to a top end job.

Jul 23, 2010 | 1982 Yamaha XS 400 Special

1 Answer

Backfiring when throttling back or on over-run downhill

hi,this is quite common on big v-twins,it is normally caused by a leak in the exhaust system(gaskets or clamps)this allows air to enter the exhaust system which then leans out the mixture inside the pipe,when the next hot exhaust pulse arrives from the cylinder,the lean mixture inside the pipe is ignited causing a backfire,check all the exhaust joints and the manifolds,where the pipe exits the cylinder,and make sure they are all tight and leak free,your problem should then go away,but in saying that,you will always get some exhaust popping on most v-twins,hope this helps

Feb 02, 2010 | 2005 Hyosung GT 650

1 Answer

Bike missing and backfiring... put new plugs in 2001 ace 750

I'm trying to think away the possibility of a burt vave. Have you run the valve adjustment? Carb adjustment is very critical, Too lean will cause backfiring or stumbling and too rich will cause deccel popping at the exhaust. One other thing, Vacuum leaks screw everything up so it wouldn't hurt to ck all the vacuum lines make sure of no cracks or loose fits. Safly, you may need to just run it out and hope for it to clear up.Make sure the plug wires are not laying on anything. Take some electrical spray cleaner and rinse og the top of the coilnd the plug wire. I'll keep thinking on this and if I stumble on anything I'll you know. Ned

Nov 13, 2009 | 2001 Honda VT 750 DC Shadow Spirit

1 Answer

I have a trike with a yamaha xs650 front end .is

You should be able to get a brace by measuring tube diameter with a micrometer and spacing of tubes. That is what I did for my 1982 Honda 500 Deluxe since not many stock parts are available for that year.

Sep 22, 2009 | 1976 Yamaha XS 650 C

1 Answer

1982 yamaha XS650SJ motorcylcleSignal light problem.

If this is really the XJ650 (in-line 4-cylinder engine) then yes - go to to order the XJCD set. If it is the XS650 (vertical twin) then you should get the Yamaha service manual or go to or

Feb 18, 2009 | Yamaha XS 650 H Motorcycles

1 Answer

I ran one of my carbs too rich and blew the left piston.

Hi fixx it
With the XS650, if you blew a hole in a piston, it has been  detonating on that cylinder, probably too lean more than anything. 
 There are some great forums out there that you can get access to with lots of information about the XS650. I own one myself, and have used this forums to rebuild my bike. 
for parts check out Mikes XS
for great advice on any dramas you are having
  650 Garage
  650 rider.
 The motors are easy to get out of the frame. One man can lift the engine, though I would recommend having someone hold the bike for you whilst getting it out.  I do have a link for a workshop manual somewhere, will get back to you shortly with that also.
happy to talk to you more about your classic bike. I love XS650's and ride one every day:)
regards robotek

Jan 04, 2009 | 1979 Yamaha XS 650 SF

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