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Jrm1290
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Joined: 04/08/2016
Posts: 1

Hi everyone,
I'm a new owner of a 1974 R90/6. When I bought it there was a little smoke from the left exhaust, but now it's a lot. It burned a little oil before and now it burns a lot. I picked the bike up for a great price, so I'm fortunate to have a budget that allows me a lot of options and my question is what would you recommend? I'd like to fix any and all common problems in one fell swoop and if there's some improvements that can be done (for example high compression pistons + Mikunis?) what would you recommend? Ultimately I care more about reliability than a few extra ponies.
Thanks in advance.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6427
It can be common for oil

It can be common for oil smoke to come from the left exhaust because the side stand is used extensively. Oil can work past the rings on the downhill cylinder and then it's smoked out when started. It usually goes away after a few seconds. Parking on the center stand can help with this. Also, not putting the bike on the side stand immediately after shutting the engine down. Sitting astride the bike for a few seconds and/or tilting to the bike to the right can help drain oil back into the sump.

If it's not that scenario, then you probably should consider a compression test and a leak down test to help isolate where the problem is in the engine.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Marcus
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Joined: 04/05/2016
Posts: 3
If it were me I'd dive in on

If it were me I'd dive in on a Siebenrock 1000cc upgrade kit!!!!

Careful, there's a difference between /7s and the /5s & /6s in regards to the diameter of where the jug fits into the block. The /7s are slightly larger.

Other than that you can use your same heads and carbs. That is unless you need valve work or you want to upgrade to Mikunis...

Cheers and happy wrenching!

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6427
The '76 /6 models had the

The '76 /6 models had the 99mm engine case openings as well. BMW was gearing up for the change with the /7 and they introduced the larger opening for the September 1975-on bikes.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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