1975 BMW R90/6 - Rocinante

ridesolo

You don't stop riding when you get old...
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Not sure what it's got to do w/ living in Ohio... I'll git r done one way or another.
 

ridesolo

You don't stop riding when you get old...
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Wow, those carbs were really gross.

You should check with the city/county you live in but many cities will have some sort of pop-up free hazmat drop off site every few months. I bring them everything from old solvent, to old paint and used cooking oil, some places will even let you drop off a couple tires.
Yeah they were really gross for sure. The second carb is about ready to be assembled and stashed away so I guess cleaning out the tank is next. Oh joy...

That I know of they only do an "old tires, old batteries, old paint, hazardous chemicals, etc" collection day every once in a while around here. I only recall a couple of them in the last several years.

(EDIT: Done.)

BMWR90038.jpg
 
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JerryAssburger

Been Around the Block
I used to have an old Chevy van I used to burn all kinds of chem-cleaner chemicals in, mixed with gasoline! Never ran well any way....
 

ridesolo

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Many people use to burn all kinds of things in old Chevy vans... oh, you're talking about burning chemicals in the engine!
 

teazer

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A gallon of acetone is enough to clean out the tank plus your lungs and leave you with all manner of cancers. Just saying...

Try to start out with a regular cleaner like Simple Green or one of the Zep products which are far less volatile and less toxic. The age old trick is to pour a handful of wood screws into teh tank and shake vigorously. I hear of people doing that and wrapping the tank in a blanket and putting it in the tumble drier but that sounds a bit brutal to me.
 

ridesolo

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I put about a half gallon of the acetone through it and the gasoline sludge appears to have been dissolved. It's now sitting with some cleaner stuff in it and it looks to me like maybe the BMW factory liner has started coming off. It isn't terribly rusty in there, though, so I'll just have to see how things go. If I continue w/ some more cleaner and chain and there isn't any more sludge and solids it may be ok.

The front brake master cylinder is as clean as a whistle (inside) and appears to be working perfectly. That means the caliper is probably toast. It's tempting to not rebuild or replace it and just go directly to a big brake conversion. I'll have to have a discussion w/ @Hurco550 about that.
 

ridesolo

You don't stop riding when you get old...
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More brakes is more better
Very true. Looks like I'm going to switch to @Hurco550's original R90 caliper until everything is sorted out w/ the thing. At least I won't scare myself trying it out going up and down the alley behind the house. Once I get it sorted out I'll look at big brakes.
 

ridesolo

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I just got done cleaning the tank. It sat w/ the cleaner stuff in it over night and I'm confident that gasoline and acetone residue are gone. More cleaner went in w/ a hunk of chain and then swish and shake, swish and shake. Finally I rinsed w/ lots and lots of water, both w/ the chain and then w/o. The last bunch of water came out very nearly clear. Looking inside I don't see rust but it does look like red liner BMW put in at the factory has largely chipped up and come out. I'll do a search to see if there are good instructions on how to get rid of what's left.

Then I left the old shop hair dryer run down into the tank on high air/low temp for over an hour. The dryer nozzle fills the neck and there was a good flow out both bungs. (I'll go out in a bit and put more air through it for a while just to make sure.)

BMWR90038.jpeg


Here's a pix of much of the sediment that came out of the tank. It looks red like rust could, but I put a magnet down into it in several places and no metal particles stuck to it so I'm sure this is all liner bits and, perhaps some amount of dirt collected since 1975.

BMWR90039.jpeg


For now, once I'm sure it's dry inside I'll close the cap and put corks back into the bungs and hope it doesn't flash rust.
 
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ridesolo

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I did a bit of spit n polish before stashing it away. Pretty good looking for what is suppose to be a close to 40 year old paint job.

BMWR90040.jpeg


BMWR90041.jpeg
 

ridesolo

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Looks phenomenal
Thanx, buddy! It reassures me that there's lots of good lurking under all that dirt and old gasoline! I don't expect showroom perfect from a bike that's nearly 50 years old, but I'd be very pleased if I don't have to do much painting to have it look like a healthy survivor. Like many (most?) of these w/ the master cylinder under the tank the frame tube there is paintless and rusted. I'll clean that up, mask it off, and spritz it as necessary and there may be a few other spots, but mostly it's looking like some patient clean and shine work will make it presentable. I am thinking, though, that the spokes will probably have to be replaced, I think that's too many spokes to sandblast and repaint. I'm considering black spokes, what do you think? The rims on these aren't shiny nor are the hubs so I think black would look better than chrome or stainless.
 

doc_rot

Oh the usual... I bowl, I drive around...
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Nice save on that tank looks mint! The best way to get the tank liners out is with paint stripper. Just went through that nightmare with my GSXR. obviously the chances your paint will be destroyed are high, so its a last ditch effort.

BTW I recently looked up the MSDS for acetone and was blown away that is relatively benign compared to most other solvents. its a "2 - Moderate" for health, and It is currently not listed as a carcinogen. Its become my go-to solvent because of this.

My .02 on the spokes - painted nearly any color can look good as long as they are painted separate and assembled, and the nipple is not painted.
 

Hurco550

Keep er' Between the Ditches
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Thanx, buddy! It reassures me that there's lots of good lurking under all that dirt and old gasoline! I don't expect showroom perfect from a bike that's nearly 50 years old, but I'd be very pleased if I don't have to do much painting to have it look like a healthy survivor. Like many (most?) of these w/ the master cylinder under the tank the frame tube there is paintless and rusted. I'll clean that up, mask it off, and spritz it as necessary and there may be a few other spots, but mostly it's looking like some patient clean and shine work will make it presentable. I am thinking, though, that the spokes will probably have to be replaced, I think that's too many spokes to sandblast and repaint. I'm considering black spokes, what do you think? The rims on these aren't shiny nor are the hubs so I think black would look better than chrome or stainless.
There's definitely a sweetheart of a bike under all that grime. Also, I 100% say we re lace those wheels with fresh spokes. Could be this winter after you've ridden it a bit. The wheels and hubs maybe send out to @irk miller for vapor honing and you'll have a real nice set of hoops.
 

ridesolo

You don't stop riding when you get old...
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Nice save on that tank looks mint! The best way to get the tank liners out is with paint stripper. Just went through that nightmare with my GSXR. obviously the chances your paint will be destroyed are high, so its a last ditch effort.
Thanx! Yeah, not sure what I'll do w/ the rest that's in there. Problem is if you look at 100 different internet comments about it you get 100 different sure fire ways to fix it.
My .02 on the spokes - painted nearly any color can look good as long as they are painted separate and assembled, and the nipple is not painted.
Appreciate the input/opinion!
 

ridesolo

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Looks phenomenal
AND looking at everything else I think that the front fender has the potential to clean up as well. The rear fender looks like it will be good but not fantastic and the side covers look almost like new. So, all in all, that part should be great. The Wixom bags are about like the rear fender; good but not fantastic and the S fairing is good except for a chip right next to the headlight opening. I'm not sure whether to attempt to match and touch it up or to just leave it as character/patina.
 

irk miller

You've been mostly-dead all day.
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I just got done cleaning the tank. It sat w/ the cleaner stuff in it over night and I'm confident that gasoline and acetone residue are gone. More cleaner went in w/ a hunk of chain and then swish and shake, swish and shake. Finally I rinsed w/ lots and lots of water, both w/ the chain and then w/o. The last bunch of water came out very nearly clear. Looking inside I don't see rust but it does look like red liner BMW put in at the factory has largely chipped up and come out. I'll do a search to see if there are good instructions on how to get rid of what's left.

Then I left the old shop hair dryer run down into the tank on high air/low temp for over an hour. The dryer nozzle fills the neck and there was a good flow out both bungs. (I'll go out in a bit and put more air through it for a while just to make sure.)

View attachment 236089

Here's a pix of much of the sediment that came out of the tank. It looks red like rust could, but I put a magnet down into it in several places and no metal particles stuck to it so I'm sure this is all liner bits and, perhaps some amount of dirt collected since 1975.

View attachment 236090

For now, once I'm sure it's dry inside I'll close the cap and put corks back into the bungs and hope it doesn't flash rust.
Rust is non-magnetic to paramagnetic, so it will not stick to a magnet like sheet metal.
 

Maritime

Over 10,000 Posts
That looks a lot like the 18 year old old gas that came out of the CB, I thought it was rust but really was the glazed gas. After I got it all out the tank was clean as a whistle under it all.
 

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