This site uses cookies to help us provide quality services. Using our services, you consent to the use of cookies.

[Forum] Help with Honda ST70'S

Neil Larratt: Hope someone can help. I have recently purchased 2 ST70's both in very poor condition. Both motors had water in them and the top ends are completely shot. I know that honda at some point used different valves and pistons in these motors, The 1 head has valves with the 5.5 mm valve stems and these were bigger valves, this head also has the cast "combustion skull". The other head has the smaller valve stems (5mm) and the combustion chamber is aluminium and is part of the head casting. I am aware that pistons with different "deck heights" (Gudgeon pin hole higher, ring grooves higher)were used, not really sure what I need to source piston-wise, the frame engine numbers are 1. Light Blue - seems to be original color with all original stickers - Frame ST70- 557666, ENGINE NUMBER ST70E - 135485 2. Light Gold colour (under black overspray) Gold seems to be original colour, Frame number - st70- 5565661, engine number ST70E- 133674. Did some motors have different rod lengths? How do I determine what I have and what I need to purchase in terms of pistons? Can the be interchanged ? Any information appreciated. Regards, Neil
Frank: Hi Neil, You should try to head over to Search for you model ST70, and you should be able to find complete charts and part numbers based on your frame/engine numbers. For instance here:  See the frame numbers (ST70-137314 ~ 152908) at the top of the screen.
Peter: There is also info here:

Feel free to post a comment if you want to add something to the discussion!

Please log in or register for free to comment!