Loose cam chain. The 253FMM features an automatic tensioner, but the spring or tensioner wedge can wear out over time.
: The 253FMM utilizes a timing chain. Over time, the chain can stretch and require adjustment or replacement. This procedure should be performed according to the specifications for the Honda CD250U.
: Documentation covers the four-stroke, air-cooled, parallel twin-cylinder layout with 233cc-250cc displacement. Interchangeability
Yes, the timing chain and valve clearances are similar, but the 253FMM has unique quirks:
The Mechanic’s Bible: Why You Need the 253FMM Service Manual (And How to Use It) 253fmm service manual
For complex internal repairs, the Honda Rebel 250 Service Manual is the most accurate substitute for technical specs and assembly steps.
233cc or 249cc air-cooled, 4-valve (SOHC or DOHC variants), 5-speed or 6-speed transmission.
Clean/replace air filter; inspect carburetor synchronization. 3. Valve Clearance Adjustment Procedure
Whether you are shimming the shift drum, lapping the valves, or simply changing the oil for the 50th time, consult the manual. It costs nothing to download but saves you hundreds in exploded engines. Loose cam chain
If experiencing fuel overflow or starvation, verify the internal carburetor float height.
A detailed ML250-4 Engine Parts Catalogue provides exploded diagrams of the 253FMM cylinder head, crankcase, and transmission.
Warm up the engine to operating temperature (ride for 10 minutes). Park the vehicle on a level surface.
To help you get the exact data or guide you need next, please consider the following options: Over time, the chain can stretch and require
Loose valve clearance. Adjust immediately.
Excessive carbon scale on the piston crown and combustion chamber acts as an insulator, retaining dangerous levels of heat. Excessive Engine Noise
Reinstall the clean screen, spring, and cap. Replace the drain plug washer if flattened, and torque the drain plug to .