Engine & Transmission
The Honda CT90 engine was built for decades with variations of it still being used today on the reintroduction of the modern trail 125. Our support focuses on the semi-automatic clutch version produced for the CT90 models between 1966 - 1979 that use a single overhead cam, single cylinder engine at 89.5cc with a 4 speed constant mesh transmission. The CT90 variants of the 89.5cc Honda engine also featured a unique dual range transmission allowing for low range torque for off-road riding and high range speed for on-road jaunts. One last unique feature of the CT90 and C90 models were that they use a centrifugal auto clutch mechanism versus the manual clutch used in the S90 and CL90s. The CT90 was surpassed by the CT110. A common misconception is that the CT110 engine is simply an enlarged CT90; however, each engine has its own unique castings and design. Engine and transmission parts from Honda CT90 family of bikes include Allen bolt kits, drive chains, gasket kits, cam chains, clutch discs and more.
- How to set the Valve / Tappet Clearance on the Honda CT90 / Trail 90
- How to set the Cam Chain Tension on the Honda CT90 / Trail 90
- How often do I need to change the oil on my Honda CT90 / Trail 90?
- What engine oil should I use on my Honda CT90 / Trail 90?
- How often should I lubricate and inspect the drive chain on my Honda CT90 / Trail 90
- What size drive chain do I need for my Honda CT90 / Trail 90?
- What is the valve adjustment / tappet clearance specs for the Honda CT90 / Trail 90?