HM Spark Plug Cap on CT70's


Well-Known Member
From what I have seen, NGK was the king of spark plug caps ("noise suppressors"), and most bikes have NGK or unmarked caps from the factory, but I have run across two HM winged caps. Was there a particular year/model that Honda released with the HM caps? Or would they of been all dealer add-ons?


Well-Known Member
I wonder if it's a year thing or is it like the tires,they used what their supplier had? My 50 built in 9-69 has the original NGK cap. My 10-69 70 has the exact same cap but I am the second owner so I cannot be 100% sure it's the original. My '74 TL 125 is an all original bike but I'm at least it's 3rd owner. It has a HM winged cap. That seems odd since the winged logo goes so far back in Honda's history that you'd think the HM would be on the older ones and the NGK on later bikes. What year have you found the HM caps on?


New Member
Great question. I had the pleasure of taking a really close look at an untouched 1 owner survivor CT 70, June / 1970 production H bike over the weekend. That bike had the HM spark plug cap and the owner is certain it came off the assembly line that way.

Another detail that stood out was the fuel reserve line from the tank to the carb. It had a ribbed texture to it and the normal fuel line was smooth. The ribbed line had a red stripe that ran lenthwise, the smooth line had red writing and part numbers. I'm guessing it was an easy way for the assembly line worker to know where to hook up each line to the carburetor since the other end is buried once the tank is installed. Pretty cool detail that I hadn't seen before.