Trouble getting it running......

awdswag

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I have an 81 Yamaha XS400 and I cant figure out why it quit running. In the fall it became harder to get to started until it wouldnt start at all. It turns over and gets fuel but no ignition. I replaced spark plug/wires/battery, and rechecked all of the connections on the bike. If i take the plug out and ground it to a frame it will spark but if I just hold it without grounding it wont spark at all..Can anyone give me some suggestions on this. Ignition coils maybe, Starter Solenoid ? lemm know thanks guys!!
 
If i take the plug out and ground it to a frame it will spark but if I just hold it without grounding it wont spark at all..Can anyone give me some suggestions on this.

yep, you touch the spark plug to ground you get a spark! that's how it works.

BTW running the bike without grounding the spark plug can break the cdi unit as cautioned in the manual!
 
Sparks plugs normally will not spark unless grounded. A few things to try. Spray some starting fluid into the carb throat and see if it will start. If so, you problem is probably carb/fuel related. Perform a compression test. No/very low compression means no start. Try starting while hooked up to a battery charger. If is starts easy it's probably a weak battery or poor charging circuit.
 
i would just do a general check of all wire connections, many of the stock bullet connections loosen with time. i was amazed how many melted and loose connections i found when i took apart my wiring loom
 
If the carbs have not been cleaned in a while might be worth checking.
 
A few things to check

0) Does it turn over? Possible battery failure, solenoid failure can be checked by jumping the connection with a heavy wire / screw driver
1) How do the plugs look? Are they fouled up? Do they indicate lean condition?
2) Do you have a fuel filter? Is it clogged?
3) Does it start if you spray a shot of start fluid in the carbs - If so likely fuel delivery problem

If it where my bike the first things I would verify is battery, fuel flow, etc. If it was getting harder to start this indicates fuel delivery or spark problem. Check the gapping on the plugs make sure they're not fouled.

If that doesn't work next steps are to pull the carbs and rebuild them, even a basic float bowl cleaning can do amazing things.

-cf
 
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