bad juju in my motor xj650

[erikphoto]

1982 yamaha xj 650

If you own one I am looking for help.

The symptom on both bikes is the same...the bike will be running fine and then lose power. It feels like one or more of the cylinders is not getting fire. Checked the spark and it looked weak.

Anyone else get this?

[totalmotorcycle]

to the community! I moved your message into the Garage forum as your post was technical help.

I own the same motorcycle and I haven't had that problem myself, I have done a few things along the way that you might try.

I have 54k on mine.

- I replaced both coil packs with newer ones
- Replacing all 4 spark plugs every 6-12 months
- Triming off the tip of the plug wires
- Getting new spark plug caps
- Using NGK plugs only
- check your airfilter

It could also be a carb issue if you haven't cleaned and checked your carbs (floats, needles, jets) in a long time.

Also check the compression of the engine.

There are a few suggestions to keep you busy. Always try the cheapest/easiest ones first.

Mike

[BuzZz]

How long do they (so we're talkin' 2 bikes here, right?) run fine before they crapp out? If they just seem to power out, with no other bad noises or such, it is possible that the fuel tanks are not venting. How long this takes to happen depends on how much gas is in the tank, less gas=more air space and longer run times before it starves for fuel. Next time try popping the cap loose when it loses power. If it comes back online, that's the problem.

If not.... maybe try looking for a power drain/lose in the ignition system.

[totalmotorcycle]

BuzZz has it right, that gas cap can get plugged up a bit.

BTW, is your Seca cold blooded (doesn't like to start when it's cold out)?

Mike