QuestionI have a 1970 trail 70 that has no spark. All the wiring and switch seem okay, but I can't find the ignition coil so I can ohm it out. Is there an easy way to get at it without taking the whole cover off? The battery is new and the points are good. Bike was stored for quite a while before I got it. Thanks.
AnswerJim, before you get too deep into this, clean the points and gap them out to about .012"-.016", so they just open at the F mark alignment on the flywheel/case.
This is a magneto ignition so clean points are critical. The battery is just for the lights.
go to: http://www.powersportspro.com/Partsfish/Login.asp
and sign up and log in, find the HONDA m/c option and then use the CT70 trail 70 microfiche images for some guidance. Coil looks like it is bolted into the frame inside the hollow section. Access to the wiring is probably through the battery box cover, with battery removed. Early S90 machines had the coils bolted to the top of the engine cases, so you had to drop the motor to change a coil or condenser. The magnetos have everything but the coil all in one place.
In general, the lack of spark (tested with a new plug!) can be traced to dirty point contacts, too little point gap, bad condenser or rusty magnet section of the flywheel. IF you have to pull the flywheel, get the proper flywheel removal tool! The condenser is soldered into the point plate under the flywheel. MAKE SURE the KILL switch isn't grounding out the spark, too!
Check the resistance value of the spark plug cap, while you are checking things. Should be around 5k ohms. Honda coils seldom fail.... FYI.
Bill Silver
