CT70 No Spark
- Thread starter xr75
- Start date
Oldfishguy
Member
Do you have a battery installed? The circuit needs to be completed, meaning old battery or new one needs to be installed.
Hope this helps.
Hope this helps.
kirrbby
Well-Known Member
Check out this thread. Post #9. http://lilhonda.com/webboard/f6/no-spark-after-installing-replacement-wiring-harness-15543/
theraymondguy
Well-Known Member
Spark at points is a sign of a weak / failed condenser. Time to rebuild that stator plate Honda Trail Bikes
Enginedoctor
Well-Known Member
dude thats so weird. Comparing apples to avocados here, On the little briggs and tec points setups, a condenser going bad is like winning the unlucky lottery. almost never happens. On the trail 70, seems so much more common. i don't know what it is. maybe the location, or even physical size of the condenser that makes it so prone to failure. multimeter to check the impedance between the isolated side of the condenser and it's body would be a good tool here. ZAP
Long Crapper
Member
Sometimes it can be as simple as the sparkplug wire not getting a good connection to the sparkplug cap and you have to cut a little of the rubber off the end of the wire and screw the cap back onto the plug wire. Althou that was probably the first thing you checked.
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Another issue that easily overlooked is fouled breaker points. It only takes a light (and I do mean light) oil film to prevent spark and some breaker assemblies are factory-coated to prevent oxidation on the shelf. A few light swipes with 600-grit paper and a little cleaning solvent can make all the difference.
I agree with enginedoctor's assessment of the condensers on these motors. Not many of them fail but far more than I've ever seen with any industrial/lawnmower type engine. Overheating during the soldering process can be fatal, too.
First thing I'd try is disconnecting the stator plug from the main harness and running a test lead from the primary ignition coil of the stator to the HT coil input. That takes the bike's wiring and keyswitch out of the way, isolating any potential problem (assuming you still get no spark) to the stator assembly, coil, plug and coil ground. OTOH, if you get spark, then you'll know the problem is in the harness or keyswitch,
I agree with enginedoctor's assessment of the condensers on these motors. Not many of them fail but far more than I've ever seen with any industrial/lawnmower type engine. Overheating during the soldering process can be fatal, too.
First thing I'd try is disconnecting the stator plug from the main harness and running a test lead from the primary ignition coil of the stator to the HT coil input. That takes the bike's wiring and keyswitch out of the way, isolating any potential problem (assuming you still get no spark) to the stator assembly, coil, plug and coil ground. OTOH, if you get spark, then you'll know the problem is in the harness or keyswitch,
I ran a jumper wire from the stator black wire to small coil wire and get no spark. The coil is brand new the spark plug and cap are brand new, the stator coils are brand new with new points and new condenser, the rectifier is also brand new. Where is the engine ground where the 2 bolts go through the frame. Thanks
All of the electrical components, are grounded to the chassis...at least they're supposed to be. That includes the engine. Only way you could have a non-grounded HT coil is if the frame was freshly painted, or PCd. Grounding is easy enough to verify with a continuity tester.
At this stage of your diagnostic process, I'd be looking for something on the stator plate (in no particular order):
Clean the points, verify the wiring is right (i.e. the inuslator washer is in the right place, nothing shorting-out against the stator plate), check the primary coil with an ohmeter. If that all checks out, not much left to do but throw a new condenser at it.
HTH...keep us posted.
At this stage of your diagnostic process, I'd be looking for something on the stator plate (in no particular order):
- bad condenser
- bad primary coil
- shorted primary lead to the points
- fouled points
Clean the points, verify the wiring is right (i.e. the inuslator washer is in the right place, nothing shorting-out against the stator plate), check the primary coil with an ohmeter. If that all checks out, not much left to do but throw a new condenser at it.
HTH...keep us posted.
darrel gunderson
Active Member
Is the coil grounded to the frame? Sent a freshly rebuilt and tested engine to a customer and had the same problem. He had the frame powder coated and did not know to scrape the frame for a good coil ground? Cleaned the area and great spark!! HTH
Frame is original has not been repainted. I put the new coil in but didn't look at the area it mounts to it doesn't look like there is any surface rust there looks pretty clean. I did run an additional wire from the coil mount to the engine to make sure it was getting grounded. If the compression is low or the valves aren't adjusted properly would that cause a no spark problem?
theraymondguy
Well-Known Member
Using an ANALOGUE meter (rare any more, vintage), all of the coils on this bike should read ~ 1 ohm. If you have a digital meter, the secondary side of the igntion coil (spark plug wire to frame) will read ~ 8 kOhm, add 5 kOhm if your reading through the spark plug cap (13 kOhm).
With the dmm the primary side of the coil will read ~ 3 ohms. Low compression and poorly adjusted valves will result in poor combustion, but are NOT a factor in a no-spark situation.
For $80 in parts, you can replace the ignition coil and all the gubbins on the stator plate...
cjpayne
Well-Known Member
It should still have spark at the sparkplug, if the sparkplug is grounded to the engine. Even new sparkplugs are sometimes bad. I always keep 2 or three around and one in my toolkit, just in case.