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Oil pump answer

Richard Pitman

Veteran Member
Joined
Jun 1, 2020
Total Posts
2,526
Total likes
632
Location
Worcester, England
The CB200 oil pump has a larger diameter plunger than the 175 pump, which means that it displaces more oil on each stroke. The pump bodies and oil strainer are similar, in fact I think it's possible to bore out the 175 pump to take the 200 plunger.

Is it any better ? I don't know. I have fitted CB200 pumps to two of my 175 engines, after reading an old thread where Simo suggested this. That said, most 175 engines manage perfectly well on the standard pump. Regular oil changes and cleaning the centrifugal filter are probably more useful. One engine has done over 8000 hard miles with a 200 pump without problem, but back in the day I ran a 175 for 22,000 thrashed miles on the standard pump, just regular changes of Castrol GTX 20/50 car oil, without any problems.

I think that Honda 'upgraded' the 200 oil pump because of the way the cam and cam journals are oiled. On the 175, there are two oilways, one to each side of the cam, up the rear outer cylinder studs, into the right and left cam bearings, and from there into the cam. The 200 only has an oilway to the right hand cam journal, the oil then travels through the cam to the left hand journal. On the way through the cam oil also comes out through drillings to the cam followers. Maybe more oil volume is required to get enough oil to the left hand journal. Maybe hearsay, but CB200 cam bearing failures are not unheard of.

Also, the CB200 engine is slightly lower revving than the 175, so maybe oil flow at peak rpm is similar ?
 
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