Starting issue.... Weak spark

I just finished building the bike and I am getting a weak spark. Has a new gel battery, custom 4-2 exhaust, carbs cleaned and rebuilt, stock air box. She cranks over strong. Battery sits at 12.13 volts with ignition on. I held a finger up to every plug end( which has rajah ring terminals) and receieved a shock. When I hold a screwdriver up to each ring terminal, there is no arc off the plugs. Not sure where to start here.... Is there a proper way to go about checking the starter circuit relay or ignitor? Solenoid puts out 11.94 volts upon cranking. Any direction would be appreciated for order of elimination before I start swapping out parts. 1981 xj650. coils are original and everything was functioning prior to tearing it down. I have done nothing to the wiring but relocate the igniter, rectifier, and starter circuit relay.

Bike in question...

 

I jumped the selenoid to remove that from equation. Also, we are sure the starter and generator is clean as new?

 

Did you put the spark wires on the correct order? If you get "shocked" which I wouldn't do too much by the way.. then you should get ignition.

Try some starter fluid, a quick spray in the air box, if she fires you know you have a fuel issue.

 

I assume the starter is fine since the motor turns over when I jump the solenoid. Is this not so?? I'll get a sound clip later today but it sounds like its not getting any spark or fuel.... It doesnt even choke on itself when being cranked long enough. I know for a fact it is getting fuel and I can feel air being pushed out both mufflers but the spark is fairly weak. Compression is solid due to a leak down test prior to tearing everything apart and the motor was not touched(aside from building the exhaust). I feel like it has something electrical at play here but I'm not very apt in the process of elimination.

 

Thanks krs14. I'll try that when I get off work. Also, can we elaborate a little on the importance of the kill switch? I have it routed temporarily but I'm deleting it since I have a new pull throttle installed from Lossa engineering. From what I can tell, there are three wires... Two ( red with a white tracer ) which control the kill switch. I'm guessing this is a loop for positive. Turn the switch left or right and the loop is disconnected. The other wire is blue and controls the start button, yes? My current start button is located on the left side cover(visible in the photo and jumps the solenoid with a loop. What will have to be done with the red/white tracer and blue wires in order to delete the stock right control box?

 

Are the plugs new? As KrS said if you're getting shocked, you have voltage. If the plugs aren't arcing then this would be your next step. Also are you checking for a spark at the plugs in a darkened area? Will be easier to see.

 

Also that's a neat looking bike.

 

Plugs are about half a season old and I cleaned off what little carbon buildup they had after checking for spark. And thank you.

 

Ok so I put starter fluid in and she fired right up. Idle raised super high(like 2 1/2-3k) and I shut it off. So now it would seem its a fuel issue...

 

Ok here's a video. I let it warm up for about 10 minutes and then took it for a test ride. This is after returning and it still acts exactly the same. The choke is non existent as it dies imediately when I try to use it. I have to hold the throttle open(as you can tell from the video) to keep it running. There is a huge power loss. The power band is extremely smooth but it feels like someone cut down the power to 1/3 what a stock xj650 feels like. My initial thoughts are to check the stator. Headlight brightens with reving. Thoughts?

http://www.youtube.com/watch?v=rd9t6j1T ... ata_player

 

Have you checked for a vacuum leak.....you can check it with some carb cleaner sprayed around the carbs, boots ect....if the idle increases then you have found it. Also it sounds like you might have a exhaust leak.

Kenneth

 

I was just going to say your exhaust sounds funny, like it's straight pipes or something. that would lead to a bit of a tuning issue.

 

No exhaust leak, new mufflers and the pipes are air tight 4-2. Just did a compression test Cyl. 1:120 Cyl 2: 105 Cyl 3: 50 Cyl 4: 62. I believe this would explain the power loss. Looks like valves are in my near future.

 

Yeah, that sucks. But now you know what's causing it. :cry:

That's also why it's so important to make sure your valves don't get too tight.