I read this service bulletin;
Bulletin#: 73 H-16 Date: Oct. 20, 1972 Bike(s) affected: H1, H2 Subject: Oil pump modification Action taken: PROBLEM: There is a tendency for some three cylinder models to smoke excessively from one exhaust pipe. On the H1 and H2, it is usually the right cylinder that is affected. CAUSE: This problem has been traced to faulty O-ring seating in the oil pump end cover. After installation, the two O-rings inside the cover shrink approximately .1 to .2mm in diameter. This shrinkage allows oil to seep around the seals and into the end cover chamber. From this point, the excess oil is pumped to the right cylinder which is serviced by the end cover orifice, resulting in smoking and premature sparkplug failure. It should be noted that other symptoms may indicate oil pump malfunction, such as right hand piston seizure. This may be caused by oil being forced back into the main pump body through defective O-rings. As a result, the right cylinder is starved for oil, and this situation will eventually lead to seizing. CURE: To remedy this problem, the oil pump end cover has been redesigned to prevent oil seepage. A. The radius in the end of the cover has been decreased in depth to give the O-rings less "squish" space. B. The bottom radius has been eliminated. C. The internal diameter of the chamber has been decreased from 14.0±.1mm to 13.7±.05mm to compensate for shrinkage. D. A slight shoulder has been added to the chamber base to further compress O-ring.
Seems like an old pump sitting around would also leak these O rings, even if modified. So, how do I know if my H2B pump was modified, and which section do i remove? Also, my pump is a 4 port H2B type, but it says H1 on the cable arm. Worried my pump will not work right and I won't know it until damage has been done to the motor. I have not put oil in it yet so seems like I need to check it out.
_________________ 1974 Kawasaki H2B 750, 1981 Yamaha XV750 Cafe, 1986 Kawasaki KDX200, 2003 Honda XR100, 2004 SDG140. 2006 Ninja 500R Turbo intercooled fuel injected.
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