HELP!!

eli98 · New Member Joined: Mar 25, 2007 Posts: 3

I am having problem after problem with my 78 XS 650. First the engine wouldn't run. Fixed that then the electrical had a very hard to find short, fixed that. Now the engine runs but poorly. It back fires and has no power. If you hold the throttle open patiently (in one spot) it will fire and sounds like a shotgun going off. I am losing patience. I checked the points, plugs are new, and I've switched the coils side for side. I have also checked the valves for free movement and clearance (although I don't know the actual tolerance so I could use that if you know it.) As well I tore down the carbs and gave them a good cleaning, but I believe they still could use a carb kit. It appears to have good compression but my comp. tester broke a while back so again its only an estimated guess. I am not sure what else to try. It runs so rough that at an idle on the center stand it will vibrate out the garage in a couple of minutes. ANY IDEAS ARE APPRECIATED AND WILL NOT GO UNTRIED.

76xs · Posted: March 25, 2007, 5:15 pm Post subject: Re: HELP!!

You need to check the compression. It may have a burnt valve. But first i would make sure the point gap is correct and check the timing. Putting in new points will change the timing.

jayel · Posted: March 25, 2007, 5:18 pm Post subject: Re: HELP!!

.006mm intake .015mm exhaust, hows the timing? hows the spark plug wires? these bikes are well known for poor electrical connections check them all including switches, what color of spark do you have at the points? yellow and lots of sparking bad condenser, sharp and blue condenser is ok, as far as vibrating unless you have it set on a piece of carpet or a rubber mat it will dance out the door even if it's running smoothly

tudawgs · Posted: March 25, 2007, 6:56 pm Post subject: Re: HELP!!

check the output on your charging system

eli98 · New Member Joined: Mar 25, 2007 Posts: 3

The condensor may be nfg, I recall yellow and lots of spark, what are the points to be gapped to?

jayel · Posted: March 26, 2007, 7:40 am Post subject: Re: HELP!!

0.3-0.45mm (0.012-0.018 in.) make sure the condenser is connected between the points and coils should have two leads one for each side also check condenser ground.

eli98 · New Member Joined: Mar 25, 2007 Posts: 3

condensor ground is good. the points, and valves are gapped to spec. Compression runs 150 #'s in three strokes on either side. Guessing that is tolerable. I am going to remove the carbs and rebuild them. Is there any carb kits I should look for or any that I should steer clear of? I purchased a set of cone air filters off ebay, and am wonering what to do with the pcv hoses fromn the head? Can I block them off? Should I let them puke pollution into the atmosphere? Also I have removed the mufflers off my bike(not that they were doing much but rusting there anyway) and straight piped my bike, what should I be doing to balance this change out? (other than buying earplugs!!!)

kingwj · Posted: March 28, 2007, 6:41 pm Post subject: Re: HELP!!

eli98 wrote:

Also I have removed the mufflers off my bike(not that they were doing much but rusting there anyway) and straight piped my bike, what should I be doing to balance this change out? (other than buying earplugs!!!)

By low octane gasoline and drop the size of the jets by 2. That way the bike will detonate and not give XS riders a bad name.

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