1987 Yamaha Big Wheel 80 project

[BK911]

Picked this up pretty cheap, but it is beat to heck!



Sounds like she wants to start, but I got tired of trying.
So now she is torn all apart while I order all the bearings, brakes, seals, etc...

While i have it torn down this far, I am thinking of doing something with the engine.
At a minimum a re-ring kit, but maybe take it all the way down and replace everything?
Would it be worth boring 0.5, 1.0 or 1.5mm and spending $100 to get an oversized forged piston?

About an hour to get
From this:


To this:


Now what to do with this?

[Tim Hancock]

I think I would have got it running first so that I knew what to fix. If it were me, I would not tear the engine down completely if it did not need it. I would just fix what is broke so you don't end up with a ton of money into it.

[Schumi]

That is so cool.

I had a Yamaha Moto4 80cc as a kid. Lots of memories. Lots of injuries. I remember it having a 4-speed gearbox... but no clutch? I don't remember how that worked.

[matt711]

That is super cool, I pretty much learned how to ride in the dirt on a BW.

[Nostril Cheese]

I remember these. I begged my dad to buy me one when I was a kid.

I'd clean out the carb at the very least. Following that, maybe new rings and hone the cylinder. There's not much to these engines.

[BK911]

Originally Posted by Tim Hancock

I think I would have got it running first so that I knew what to fix. If it were me, I would not tear the engine down completely if it did not need it. I would just fix what is broke so you don't end up with a ton of money into it.

I thought about that before I started wrenching, and now you have me thinking about it again.
Maybe do everything but the engine then put her back together and see what I have?
Its just so hard not spending an extra $100 to bore and raise compression.

A ton of yamaha money is definitely lighter than a ton of porsche money!
Total investment should be less than $600 including bike, minus any engine mods.
Not a perfect restoration, but a dirt worthy restoration.

[Tim Hancock]

I spend most of my free time cleaning up/restoring things that are not worth a bunch of money and I enjoy doing it. That said.... I just typically do not replace parts that are still serviceable/restorable which is why I like to get old junk running first prior to ripping possibly still good parts off and ordering new replacements.

Example:
I just found and bought a 2006 $3000 tow behind self-engined 60" mower with a couple bad spindles for only $250 (I essentially stole it).

Some folks would buy a new battery, (3) new blades , (3) new complete spindle assemblies, (3) new belts, carb rebuild kit, muffler, new air filter, new spark plug, new tires, new fuel filter etc. Nothing wrong with doing all that, but it would mean throwing away many parts that still had serviceable life left in them and would make my $250 "good deal" not as good of a deal. Instead I replaced only the bad $3.00 ea bearings, cleaned the air pre-filter, changed the oil, charged the battery, sharpened the blades, welded a few deck cracks and I am good to go.

[herr_oberst]

^ Tim, I've seen your work, I'm betting there was a nice paint job too. Can't imagine you welding and not protecting the bare metal!

[Joe Bob]

Are the tires still available?

[widgeon13]

My son had a 350 that I rode some.

[BK911]

I know you guys were dying for an update, so...

Fresh paint on swing arm and forks, touch up por-15 on frame, all new bushings and bearings:




New bearings, refreshed brakes, new tires:



Trying to get her done by the 22nd because I have friends coming in.
Drunken relay races around the yard.

<$500 total so far not including beer.

Cylinder has slight damage but I dont have time to fix her properly. So just a simple re-ring until my buddies leave. Then probably bore her out and mill the head slightly.

[Eric 951]

Cool bike. Back in my steady riding days one of my cohorts had a BW 350. Those and the Honda Fat Cats were interesting machines.