Yamaha MX800V - Engine Speed Does Not Increase

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TROUBLESHOOTING
OTHER TROUBLES
ENGINE SPEED DOES NOT INCREASE
No. Checking steps Possible remedy
1
Check the spark plugs for dirt and check the spark plug
gap.
Clean, adjust, or replace the spark
plugs.
2 Check the air filter element for dirt. Replace the air filter element.
3 Check spark arrester, muffler and air filter.
Clean or replace spark arrester, muffler
and air filter.
4
Check the valve clearance.
(Refer to “ADJUSTING THE VALVE CLEARANCE” on
page 2-9)
Adjust the valve clearance.
5
Check the compression pressure.
(Refer to “MEASURING THE COMPRESSION PRES-
SURE” on page 3-1)
Too high:
Decarbonize the combustion chamber if
there is carbon deposits.
Too low:
Next checking steps.
6
Check governor setting.
(Refer to “INSTALLING THE CARBURETOR ASSEMBLY”
on page 4-5)
Adjust the governor.
7
Check the valve face and valve seat for wear.
(Refer to “VALVES” on page 3-26)
Resurface or replace the valve face and
valve seat.
8
Check if the marks on the crankshaft and camshaft are
aligned.
(Refer to “INSTALLING THE VALVE LIFTERS AND CAM-
SHAFT” on page 3-44)
Correct.
9
Check if there is seizure, wear, or damage on the piston,
piston ring, or cylinder.
(Refer to “PISTONS, CAMSHAFT, CRANKCASE, AND
CRANKSHAFT” on page 3-37)
Rebore or replace.
10
Check if the main passages, such as the carburetor assem-
bly, are clogged.
Clean the parts.
11
Check if there is air suction from the carburetor assembly
joint, gasket, or throttle shaft.
• Tighten the carburetor assembly nuts
securely.
• Replace the carburetor assembly joint
or gasket with a new one.