1997 BMW F650ST to F650R: Enduro Hellride Conversion

Re: 1997 BMW F650 El Diablo Hellride

Maritime said:
This thing gonna be your ride at the thaw? It looks like when you get it done it will take you anywhere!
Not sure I will have it done by Thaw or not. The plan is to have it done, tho. I hope it can do most of the terrain at Thaw, that's for certain.
 
Re: 1997 BMW F650 El Diablo Hellride

Shit the rate you are moving it will be LOL. unless you hit $$ road blocks and that would suck, but it happens to all of us.
 
Re: 1997 BMW F650 El Diablo Hellride

https://youtu.be/UEJpBgh2Dfk
 
Re: 1997 BMW F650 El Diablo Hellride

Yeah, that XL tank is spot on.

Spanish for a fighting chicken ;D
 
Re: 1997 BMW F650 El Diablo Hellride

XL600r seat fits perfectly. Side covers will certainly be made from fiberglass, although I’m considering doing vacuum molded plastic.

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1997 BMW F650 El Diablo Hellride

In some not so excellent news, we’re looking at a motor showing only 70 psi compression. It sat for two years, so maybe I’m lucky enough to have stuck rings. It definitely smoked and it definitely put some oil on the plugs. It definitely got really hot.

I needed to find TDC, but without pulling covers, so I can put compressed air into motor for a leak down test. These motors have a dimple in the crank at TDC to lock the motor during valve work and whatnot. The special bolt is really just a bolt with a rounded tip. In my case, that’s the fuel tank bolt...

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This bolt is removed, and gets replaced by the rounded tip jawn...

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Then I rotate the motor until I can feel the piston at the TDC on the compression stroke. A screwdriver works here...

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Once it’s at TDC, I crank the special bolt down about 1.5 turns and I’m locked in place.


Next, hook up the compressed air to a spark plug hole. To do this, I have the hose from one of my compression testers rigged up to utilize the quick fitting on my air hose. It’s as simple as pullling the Schrader valve out...

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Hooked it up in a plug hole...

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Then raised pressure to 90 psi. I wasn’t getting much at 30psi, which is why I turned it up. No air out the exhaust or intake ports, but a bunch of air out the oil filler and I even got some oil out the breather tube...

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Pretty much puts us at bad or stuck rings, barring any other hidden surprises.




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Re: 1997 BMW F650 El Diablo Hellride

This is never going to work.








I'm in.
 
Re: 1997 BMW F650 El Diablo Hellride

What's the availability of oversize pistons for that lass?

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Re: 1997 BMW F650 El Diablo Hellride

Hurco550 said:
What's the availability of oversize pistons for that lass?

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Good question. So far, I haven't seen a one. Just replacement jugs and pistons, and rings.
 
Re: 1997 BMW F650 El Diablo Hellride

irk miller said:
Good question. So far, I haven't seen a one. Just replacement jugs and pistons, and rings.
Is it a nikasil barrel?

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Re: 1997 BMW F650 El Diablo Hellride

irk miller said:
could well be fine with fresh rings then

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Re: 1997 BMW F650 El Diablo Hellride

Hurco550 said:
could well be fine with fresh rings then

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Yeah, that's what I'm thinking. Amazingly, the valves don't seem to leak. I actually expected the exhaust valves to be roasted. It was stored outdoors and the airbox was partly fucked with. So good chance condensation got into the cylinder.
 
Re: 1997 BMW F650 El Diablo Hellride

irk miller said:
Yeah, that's what I'm thinking. Amazingly, the valves don't seem to leak. I actually expected the exhaust valves to be roasted. It was stored outdoors and the airbox was partly fucked with. So good chance condensation got into the cylinder.
Be a good/ cheap place to start. Re lining barrels can get a little spendy

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Re: 1997 BMW F650 El Diablo Hellride

Weren't they Aprilia engines? You may find tuning parts/barrels/big bore kits on sale advertised as being for Aprilia which may fit.
 
Re: 1997 BMW F650 El Diablo Hellride

The bore is beautiful. Looks like I should get by with a set of rings, a head gasket and a base gasket. The valves don't leak one iota.

This is a really pretty motor. Dead simple and well engineered.

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The hardest part to pulling the top end was getting the cylinder head off. It was about 3mm short of clearing the long studs, so I put a block in-between the jug and head and removed the studs.

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