engine number - PLEASE HELP ME!!!!

Hi all, im new to all this forum stuff so not sure if anyone can help but thought i would try you highly mad for it honda st fans...

I have a (complicated) 1971 honda st50. It wont spark, and think its the coil. I cant order a new coil as im not sure what year my engine is...
I think its got a st70 engine with a C90 carb! Anyways would anybody be able to decode this engine number to give me an idea of the engine and year of it?

ST70E-
115286

Any help would be much appreciated. Thanks.

hi steve, and welcome i think all st70 coils are the same i could be wrong but all mine are the same, Has the frame been powder coated or painted? I had a bit of jip with body work earths as for engine it sounds like a very early one but waynus will have more idea ps i got one of my coils from wemoto!

good luck! lee

great stuff, thanks for that, really appreciate the help. its painted, and still on the original colour (i think). The earths seem fine, good contact. i first started having problems when it was getting hot. Then it wouldn't run until it cooled down. Now it wont run at all. Could that be the coil? Should i just order a coil for a late 70's engine then?

I absolutely love it - really funky looking bike and loads of fun. but only managed to use it for 3 days!!...gutted

hi steve, check points and condensor first, condensor can break down when warm lee

condensor: when braking down, you should notice tiny sparks between the points. Easy to replace, but make sure it doesn't get hot while soldering!
points: check for wear, are they surfaces perfectly flat and timed correctly?
coil: check if there is still resistance (Ohm) all condensors should fit, just get a pre '80's 6v type. Even the 12v types should work.
OEMs are pretty expensive but are still the best ones.
Cables: check for wear and short circuits.
ST70E: old type engine. 6v, most likely the flat Hitachi ignition. Reliable but slow.
Spark Plug: no need for checking / repairing here. Just get a new one, NGK 6 will do the trick. Just make sure you set the gap right, and tighten it correctly.
Spark plug cover: when in doubt, replace it with a good one (NGK) which is weatherproof.

If you want to check the spark plugs condition, look at the colour of its tip and corrosion. Dismount the spark plug cover and hold the wire against the frame. See if you get a spark.

Good luck!!!

Nice one, that was a very informative reply. Thanks for that. Im starting to really like this website!!

The points and condensor are like brand new. Timing is set up perfectly. Already replaced the spark plug.
Im going to order a new coil, then try it. Fingers crossed it will work.

Thanks for all the help guys.