1975 Commando 850 restoration

Larry S

VIP MEMBER
Joined
Apr 15, 2020
Messages
132
Country flag
One week ago I brought home my 1975 850 Commando Roadster. I got this bike for free, well almost free. All I had to do was repair a garage door and the bike and clean title were mine. A couple of other caveats were that I wouldn’t part the bike out or sell the bike and that I would restore it to the best of my ability. The widow and former owner also gets first ride when I get it on the road. Wish me luck on my project.

When I brought the bike home the engine was seized so I pulled the plugs and poured diesel fuel into the cylinders. While that was working it’s magic I removed the seat, tank, side covers, oil tank, carb, fenders, turn signals, tail light assembly and headlight assembly. After doing that I turned my attention to the seized engine. I put the transmission into fourth gear and rocked the rear wheel back and forth, over and over until I thought I felt a slight movement. Finally I got it free! What a great feeling that was! I drained the engine oil and it looked and felt brand new.

This bike has been sitting since 1980 or so with fuel in the tank and the tank is full of gunk and rust. Getting this clean is my weekend project. Tips?
 
Last edited:
Joined
Dec 28, 2009
Messages
3,668
Country flag
$pend a fortune seeing as you got it almost for free. Grease everything and of course the layshaft bearing change up.
 

gortnipper

VIP MEMBER
Joined
Nov 11, 2013
Messages
3,218
Country flag
Welcome!

Inspect the bores, as they are likely in need of a hone since the rings stuck to them so badly.

Check out the rebuilds section of the forum, and read up.
 

Esmerela

VIP MEMBER
Joined
Jan 9, 2017
Messages
215
Country flag
One week ago I brought home my 1975 850 Commando Interstate.
This bike has been sitting since 1980 or so with fuel in the tank and the tank is full of gunk and rust. Getting this clean is my weekend project. Tips?
Hi Larry

I use washing soda and electrolysis method its simple and effective on rust and gunk link to video below. Good luck with your project.

 
Joined
May 11, 2010
Messages
2,397
Country flag
I've done three tanks this way. It is slow but it works. But the old dodge of using a battery charger as a power source is getting harder because modern ones don't seem to work and the old ones burn out it after a few days.

And in general, take copious amounts of pix from all angles before you get too far. Most useful at reassembly time.
 
Joined
Apr 4, 2020
Messages
52
Country flag
Agree with Onda take hundreds of pictures before you take it apart from all angles. I did and it has paid dividends. I stripped an 850 Interstate which seemed pretty much standard.
Good luck
 

grandpaul

VIP MEMBER
Joined
Jan 15, 2008
Messages
11,117
Country flag
This thread needs to go in the Projects section, with LOTS OF PHOTOS!
 

Esmerela

VIP MEMBER
Joined
Jan 9, 2017
Messages
215
Country flag
I've done three tanks this way. It is slow but it works. But the old dodge of using a battery charger as a power source is getting harder because modern ones don't seem to work and the old ones burn out it after a few days.

And in general, take copious amounts of pix from all angles before you get too far. Most useful at reassembly time.
Hi
Regarding the power supply : A computer power supply works really well black and yellow cables on a HDD plug my t160 tank below power from a pc power supply.

 
Last edited:

jaydee75

VIP MEMBER
Joined
Jul 2, 2012
Messages
743
Country flag
I had great success removing the rust from a tank with Evap-o-rust product. Clean as a pin without taking any metal off.
Jaydee
 

concours

VIP MEMBER
Joined
Dec 29, 2011
Messages
4,310
Country flag
I’ll be the guy that gets rotton tomatoes thrown.
Those romantic old stories (yes! You proved them true) of using penetrating weasel piss to free up stuck old engines.....
Well, maybe a vintage make & break or something, but....
The rust that held it is still in there.
It MAY start, MAY run....
But the iron oxide, which is harder than everything in there, WILL destroy parts. Quite costly parts.
I recommend (if you have the skillset) removing the head & cylinder to inspect. If you find no problem, you’ve lost $50 worth of gaskets.
It may save you thousands.
 
Last edited:

Larry S

VIP MEMBER
Joined
Apr 15, 2020
Messages
132
Country flag
This thread needs to go in the Projects section, with LOTS OF PHOTOS!
As soon as I figure out how to post pics, I’ll do so. I’m a newbie at this computer stuff so bear with me. I’m still figuring out this great website. I’ve been reading threads on here for a couple months now but have never posted. I’d put this thread in Projects section if I knew how. Moderator?
 

Larry S

VIP MEMBER
Joined
Apr 15, 2020
Messages
132
Country flag
I’ll be the guy that gets rotton tomatoes thrown.
Those romantic old stories (yes! You proved them true) of using penetrating weasel piss to free up stuck old engines.....
Well, maybe a vintage make & break or something, but....
The rust that held it is still in there.
It MAY start, MAY run....
But the iron oxide oxide, which is harder than everything in there, WILL destroy parts. Quite costly parts.
I recommend (if you have the skillset) removing the head & cylinder to inspect. If you find no problem, you’ve lost $50 worth of gaskets.
It may save you thousands.
No rotten tomatoes for you! As soon as I get something to eat I’m going to do just that, pull the head and cylinder for inspection.
 

Richard Tool

VIP MEMBER
Joined
Aug 3, 2019
Messages
520
Country flag
So where the h_ll was I when they were handing out free Commandos ? LOL - good for you . Best of luck and let’s see pics .
You will need to be VIP member to post pics directly or else you need a photo hosting site . I use Imageshack .
 
Joined
Jan 5, 2019
Messages
1,672
Country flag
Be sure to run some inline filters for a period after the electrolysis is over because the silt doesn't all rinse out easily. At least it didn't for me, although it's almost down to nothing now after 1 1/2 years which I'm good with.
 
Top