Honda TRX ATV Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
New here seeking wisdom. I have here an 87 trx250 that I have never seen running. It has no spark. Ignition coil is new, cdi is new along with another new cdi on the bench to rule that out. Exciter coil tested within specs at the high side of 200 ohm but the pulse generator tested at 296 ohm and spec is between 330 and 360. Exciter is putting out around 5v dc while cranking. All wires and connections seem good and tight. My question is, with the pulse generator being out of spec cause a no spark issue? Any ideas or thoughts appreciated.
 

·
Super Moderator
Joined
·
4,642 Posts
The exciter coil puts out AC voltage and the coil is connected to the AC Voltage regulator - you might have a bad voltage regulator, but most likely its a bad alternator stator. Bad stators are the most common problem regardless of the meter measurements. I relate - a friend of mine was trying to get spark on his 200 - he was using my meter and my manual - the only part that tested good was the stator - after installing a new pulse coil, CDI unit and primary coil - still no spark - installed a new stator and got spark - changed back the original coil, pulse coil and CDI box and still had spark - turns out the only bad part was the only part that tested good.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #3 ·
Yes its ac. Ment that haha. Anyway, got a new used stator that everything measures right in the middle of acceptable specs other than pulse generator is still below the 330 minimum. Still no spark. Question still stands if the pulsar would cause now spark being below 300 ohm reading. I have a new one on order. Out of ideas on everything now
 

·
Super Moderator
Joined
·
4,642 Posts
Bad ignition switch (not breaking the connection between the Black wire with the white stripe and ground (the green wire)).

Black wire with white stripe shorted to ground anywhere from the CDI unit and either the handlebar kill switch or the main switch.

Try this - unplug the main switch from the wiring harness - jumper the red wire to the black wire on the wiring harness half if the main switch connector (this will power up the electrical system) - crank the engine - if you get spark, the main switch is bad - no spark, unplug the black/white wire from the handlebar kill switch - spark, bad kill switch - still no spark, cut the black/white wire at the CDI unit (leave the wires long enough to solder back together later) - still no spark, bad Exciter coil, bad pulse coil or problem in wiring.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #5 ·
Bad ignition switch (not breaking the connection between the Black wire with the white stripe and ground (the green wire)).

Black wire with white stripe shorted to ground anywhere from the CDI unit and either the handlebar kill switch or the main switch.

Try this - unplug the main switch from the wiring harness - jumper the red wire to the black wire on the wiring harness half if the main switch connector (this will power up the electrical system) - crank the engine - if you get spark, the main switch is bad - no spark, unplug the black/white wire from the handlebar kill switch - spark, bad kill switch - still no spark, cut the black/white wire at the CDI unit (leave the wires long enough to solder back together later) - still no spark, bad Exciter coil, bad pulse coil or problem in wiring.
I think i did check for a short in the black/white wire. When i first checked all wiring i did find one plugged straight to ground. I did fix that. I'll check your procedure tomorrow after work and post findings. Thanks.
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #6 ·
I got a few minutes in the garage and tested the switches. Everything checks out good bypassed. Still no spark. I cant get a reading from the pickup coil at all. Tried a known good coil also. It seems that something is cause ing the pickup coil to not tell the cdi to fire.
 

·
Super Moderator
Joined
·
4,642 Posts
Wiring, neutral switch, pulse coil and flywheel is all that's left - have you checked the TDC mark? If the flywheel key sheared, it could put put the flywheel far enough out of time that you would not get a spark. Is the neutral light on?

With the spark plug out, use a soda straw to check the position of the piston. With a wrench on the flywheel not, turn the crankshaft till the piston is at TDC - check that the"T" mark on the flywheel is visible in the inspection hole on the alternator cover.
 
1 - 7 of 7 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top