URAL Motorcycles 2000 -10 series, Repair Manual, Page: 168 / 193

9.3 Carburetors
For US import models, the current carburetors for 650 cc machines are dual Keihin Seiki
32 CVK -type carburetors, which have been certified for compliance with US EPA
requirements.
NOTE: Technical information concerning the Keihin Seiki carburetor is proprietary, and
alteration of the carburetor system in any way would violate the E.P.A. approval of the
URAL motorcycle. For these reasons, we are unable to provide any information
regarding the tuning of the carburetor system. Please treat the carburetor as a sealed
unit with no user-servicable internal parts.
Carburetor Function
The function of a carburetor is to deliver a combustible air-fuel mixture to the engine.
however, in order to be effective, it must first break the fuel into tiny particles (in the
form of vapor) and then mix the fuel with air in a proper ratio so it can burn without
leaving excess fuel or air.
Troubleshooting
When the carburetor setting is not correct, various irregularities in engine performance
are noticeable. These irregularities can be traced to two basic causes.
When air-fuel mixture is too rich
•
The engine sounds dull and idles roughly.
•
Engine stalls when enricheners applied.
•
Engine performance grows worse as it heats up.
•
Removal of the air cleaner improves engine performance somewhat.
•
The exhaust gases are sooty.
•
The spark plug is fouled (black wet deposit around electrode).
When air-fuel mixture is too lean
•
Acceleration is poor, noticeable lack of power at full throttle.
•
The performance improves when enricheners closed.
•
Engine RPM fluctuates.
•
Engine overheats.
•
Spark plug burns (blistered white insulator).