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Author Topic: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.  (Read 10092 times)

Offline advCo

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Over the winter I picked up this F650 ST. I had been wanting a newer, more reliable bike that I can use as a daily while I wrench on the vintage stuff. The seller disclaimed that it had some milky oil, and after doing some research on these bikes I narrowed down the possibilities to a faulty water pump seal, or a blown head gasket.

Once I got the old girl home, she looked pretty clean. About 50k miles and the motor should be barely broken in. The bike actually included all the original paperwork, and the maintenance records since new.

Besides the obvious coolant leak issue, a few cosmetic issues, leaking fork seals and some pretty thin brake pads will all get addressed.

Offline advCo

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #1 on: Jul 19, 2018, 02:22:17 »
So I cleaned the carbs and fired her up to get the oil circulating so I could drain it and see what’s what. No bueno. Looked like a melted Frosty mixed with soot and poo.

I decided to start with the simpler solution and replace the water pump shaft and seal, despite the fact that the maintenance records said it was done fairly recently. The water pump seal is basically a 20k mile maintenance item on these motors and from everything I can tell is the only crux of the Rotax lump.


Offline advCo

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #2 on: Jul 19, 2018, 02:26:04 »
After the water pump is done, I changed the oil and test ran the bike again just to get it warmed up. It looked ok in the OIF tank but draining out came the same frothy mess.

So into the motor we go. It’s a pretty straightforward motor and game apart pretty easily. Once I got the head off, it was pretty clear that the culprit was the head gasket.

Offline advCo

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #3 on: Jul 19, 2018, 02:36:16 »
A pile of parts were ordered including new circlips, rings, a set of kibblewhite valves and seals, base and head gasket, etc.

I ended up replacing the thermostat since the PO had deleted it for some reason that is beyond me.

The whole top end went out to a local machine shop that builds racing motors. Cylinder and piston clearance measured within spec, and the original cross hatch could even still be seen on the barrel.

Machinist surfaced the mating surfaces between the head and cylinder. They pulled vacuum on the head and cylinder,  skimmed about .003” off between the two surfaces, cut in the new Kibblewhite valves and shimmed the valves. I need to pop the valve cover off and check the clearances before I run it.

The last few months I’ve been building a new kitchen in our house from scratch and coming up to the home stretch on that project. So I hope to get back on this as soon as that’s finished.

Currently, the motor is back together, just needs the carbs installed and it’s ready for a test fire.

Offline trek97

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #4 on: Jul 19, 2018, 08:25:43 »
WOW, sorry for your troubles.  But looks like its going your way now!!!    8)

Offline Maritime

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #5 on: Jul 19, 2018, 09:30:10 »
That oil is nasty, but you'll sort it out I am sure.
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Offline canyoncarver

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #6 on: Jul 19, 2018, 14:39:14 »
She'll be like new. 

Online Jimbonaut

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #7 on: Jul 19, 2018, 14:44:39 »
Sweet man, we can embark on our “restorations” together and see how the plans of mice and men unravel


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Offline Brodie

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #8 on: Jul 19, 2018, 19:52:01 »
I love the look of a fresh milled head.
What is your plan for the styling of the bike?
I'm not sure, but don't ask Brodie.

Way to many build and half done projects to list here.
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Offline Hurco550

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Re: 1997 BMW F650 ST Bluebird - Repair, maintain, ride.
« Reply #9 on: Jul 19, 2018, 20:35:33 »
Yisss! I'm in

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