Oil pump; 5.5 bar vs. 4.5 bar; counter-balance shaft compatibility - K-Bikes.com - Excellence in Motion
 
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post #1 of 5 (permalink) Old Aug 12th, 2019, 3:14 pm Thread Starter
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Oil pump; 5.5 bar vs. 4.5 bar; counter-balance shaft compatibility

Hello to K-Bike folks;

I'm new to the forum. I own and ride an '87 K75 and an '06 K1200s.

There is something that has me puzzled on the K1200 that I hope someone here may be able to shed some light on. First of all, I am moderately well informed on the bike; I have done my share of research and have gotten to know the machine fairly well. I have actually posed this question to a long time BMW Tech; to his credit, he said that he really does not know the answer as opposed to giving me some BS.

I have some internal bits that I am going to be putting/changing on the K40 this winter( K1300 Clutch and thrust adapter ). From my old hot-rod days, oil pressure was never a bad thing so I would also like to change out oil pump. My understanding is that the 5.5 bar pump configuration is a 26/24 tooth drive/driven arrangement with a high pressure relief setting in the pump itself with existing being 25/25.

The parts fiches I have seen indicate that the 5.5 bar pump must be used with the later, 2011-on counterbalance-shafts. These are unrelated systems. Has anyone had the chance to look at the setup(oil pan and clutch cover removed) to verify if there is an interference that would be caused by the drive chain on the 5.5 bar pump on the K1200 counter-shaft? Is there something else that I'm not considering?
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post #2 of 5 (permalink) Old Aug 12th, 2019, 4:03 pm
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You are right in your assumption: Counterbalance shafts and oil pump/sprocket have nothing to do with each other.

The 5.5 and 4.5 pump are virtually the same (same housing). The 5.5 will fit plug and play as long as you have the correct drive sprocket and oil pump sprocket combination.
Chain stays is the same....

Let us know how it runs.
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post #3 of 5 (permalink) Old Aug 12th, 2019, 4:18 pm Thread Starter
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Thanks Patrique. It seems a stretch for me to believe that BMW would specify a completely unrelated part as being necessary....but....
I will be finding out for myself when I have the chance to check it out when its apart.

I'll do that; I'll go back to this post and document what i found with the changes.

The plan is actually to put a oil pressure sender on the motor and affix a permanent oil pressure gauge before the changes so that I will have numbers before and after. Besides, I'm a sucker for gauges.
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post #4 of 5 (permalink) Old Aug 12th, 2019, 5:44 pm
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Quote:
Originally Posted by Bronco View Post
Thanks Patrique. It seems a stretch for me to believe that BMW would specify a completely unrelated part as being necessary....but....
I will be finding out for myself when I have the chance to check it out when its apart.

I'll do that; I'll go back to this post and document what i found with the changes.

The plan is actually to put a oil pressure sender on the motor and affix a permanent oil pressure gauge before the changes so that I will have numbers before and after. Besides, I'm a sucker for gauges.
I would also be interested in your results...
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post #5 of 5 (permalink) Old Aug 14th, 2019, 11:01 am
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I too changed the oil pump to the higher capacity one. I didnít notice that the counter balancers were also recommended with the change. I found two on eBay for $50. Why BMW recommends this change? I think they saw a problem or potencial problem with the higher pressure on the bearings the lobes rides on. The newer ones have a small oil relief hole in the lobe to allow oil to flow through the bearings and out the lobe.
I have not installed the counter balancers yet. I had just done the pump which meant draining the oil and coolant all over again. So far the bike has not exploded!
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