honda trx 70 cdi unit acting up

[oneroom42]

i,ve been dealing with a 1986 trx 70 which starts and runs great one minute and the next it doesnt have spark. after replacing the coil and spark plug and unwrapping the wire harness to look for any issues, i find nothing. oh and i cleaned all the electrical components in the stator. the only thing that has my full attention is the cdi box. i put a new one in and it doesnt work at all. its a universal one so we all know how that goes. anyways if i unplug and plug in the original cdi unit a few times it will than get spark. after a ride it will lose spark again. has anybody ever experienced any issues with the cdi box on anything? what is inside it that goes bad but yet still works sometimes?

[Thorpe]

Just had the same issue with a US90, and it was a dirty ignition coil ground....

[oneroom42]

i made sure mine was really clean cause i thought that was the problem, not so lucky for me.

[oneroom42]

took the flywheel off and the stator was filthy. cleaned it and spark returned for a few rides, then no spark. removed the flywheel again and took a wire brush to everything. seems to be fine now!

[just ben]

happend to me this past weekend. it was the stator but that was a tecate and pretty well known for that

[jensenracing77]

most (but not all) aftermarket CDI units that will work on the TRX 70 need the wires switched. the plug that only has 2 wires in it are the ones that need switched. i am not saying that is the deal with yours but if i was betting....

[jensenracing77]

also, ground the wire going to the neutral start switch.

[Mosh]

i,ve been dealing with a 1986 trx 70 which starts and runs great one minute and the next it doesnt have spark. after replacing the coil and spark plug and unwrapping the wire harness to look for any issues, i find nothing. oh and i cleaned all the electrical components in the stator. the only thing that has my full attention is the cdi box. i put a new one in and it doesnt work at all. its a universal one so we all know how that goes. anyways if i unplug and plug in the original cdi unit a few times it will than get spark. after a ride it will lose spark again. has anybody ever experienced any issues with the cdi box on anything? what is inside it that goes bad but yet still works sometimes?
My brother was having this exact same issue a month ago. Same bike even. It would run for a few, then lose spark. If you squeezed the CDI with pliers it would get spark again.
He got an aftermarket new CDI and the same thing. No spark. So he hose clamped a bolt on the old CDI to squish the case together and get it to run. It ran a few days then acted up again.
He decided to put a Piranha 90 cc engine in it. When I pulled the stator and chain cover off the 70 engine, the pick up coil had rattled loose and was hitting the flywheel.
I am sure that was the issue, in conjunction with CDI. May want to pull your starter cover and look.
In the end it was almost cheaper to drop the 90 engine in it with a new harness and carb, and get more power, VS fixing the stator and pickup coil and buying a CDI.