no spark on left side

Nate · Posted: December 22, 2005, 1:41 pm Post subject: no spark on left side

I just bought my 650 for 100 bucks. Put it in the shop and had the carbs cleaned, oil changed, and lubed up. I picked it up two weeks ago and rode it for a couple hours. I fell in love then i went and started it up the following weekend and the left side was back firing really bad. I took a look at the spark plug wire on the left and the conector was old (i believe stock). I called the local shop and he had one i picked it up and slapped it on and still the same problem. If i take the connector off and just hold the wire up to the plug it fires fine. Or if i only put the connector on half way it runs fine. What could be the problem? I'm new to the motorcycle world so any help would be appretiated.

mo650chopper · Posted: December 22, 2005, 7:44 pm Post subject: Re: no spark on left side

First off welome to 650rider.com! I don't know if you tried switching plugs from right to left to see if the problem moves to the other cylinder. It could be as simple as a bad plug. My guess is it will end up fuel related from my experience with my long setting XS650. What year is the bike?

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Replace the plugs, they're most likely fouled out. holding the wire back from the plug gives a stronger arc ,thus allowing the bad or fouled plug to ignite the mixture or the resister caps could be at fault too.

If the plugs are fouled,then start looking for sticking float needle and seat as Mo650Chopper has suggested...............Jack

Nate · Posted: December 23, 2005, 11:33 am Post subject: Re: no spark on left side

Its an 81'. Now that you mention it the guy at the shop told me that the plugs are easy to foul on this type of bike. Thanks for the info guys. Is there a special type of sparkplug or should i just go with the everyday plug for cars? I am new to the motorcycle game what and where is the float needle. I have the book for the bike i just dont know where to start.

Jack · Full Member Joined: Mar 15, 2005 Posts: 411

Being this is air cooled motor,the engine temperatures will vary and with this constant change most Auto plugs won't survive in my opinion. Get NGK BP 7ES plugs from a local motorcycle shop...............Jack

Nate · Posted: January 3, 2006, 12:16 pm Post subject: Re: no spark on left side

Back on the road. The engine is still smoking on the left side. I do not know anything about motorcycle engines to be trouble shooting it. But it's running agian thats a plus. Thanks for all the help Jack.

odw650 · Full Member Joined: Aug 05, 2005 Posts: 28

Sounds like the same problem I had, the intake valve was leaking on one of the cylinders. See if it blows air out the intake and if it will run one just one of either the cylinders. While it's running pull the spark plug boot on one side and repeat with the opposite side.

grizld1 · Posted: March 7, 2006, 11:48 pm Post subject: Re: no spark on left side

Careful about running on one cylinder; that can fry the TCI box on your scoot unless the disconnected plug wire's grounded. A dirty air filter can cause a rich condition and fuel-fouled plugs; that's the first thing I'd check (simple stuff first!). A leaking valve or bad rings will show up in a compression check. First set valve lash, as described in your manual. Then check compression or have it checked for you. If you have less on the left than on the right, you probably have either valve or ring issues in the top end. Another thing to look at before you get into the carbs is the petcock. If yours are stock, they're vacuum-operated, so that, in the "On" position, they shut off unless the diaphragm valve is opened by engine vacuum. They often fail, and don't shut off fuel flow. That can fill the crank case with fuel in a hurry, even with good float valves in the carbs.

blkshp725 · Posted: May 1, 2006, 8:06 pm Post subject: Re: no spark on left side

i can see that this post is very old but here I go anyway... I also am new to the motorcyle world, and i just bought my first bike month ago... 78 650 special.. Mine had real bad trouble starting so I got new plugs (from O'rileys) then it ran fine.... For a day, then it just seemed like it fired on one side.. Clean the spark plug ran good again, for a couple miles then just wanted to die.... I'm not sure what my engine is doing and from what I hear it could be a numerous of things... All this is happening on the right side though... I did try to change the plug boots"don't think thats what there called" but still no change, only wanted to fire on the one side... so know I confused..So I stripped it down to just wheels frame and motor... Don't know if the really fixed my problem but it sure felt good..

What Happened to 650rider.com?

Yamaha xs650