$150 1980 YZ100

Antarctica
Posts
14
Joined
10/13/2014
Location
Shady Side, MD US
Edited Date/Time 4/14/2015 7:34am
Hi -

I'm new here, first post. I'm also relatively new to dirtbikes, and just picked up my first at age 44. As a kid I had a ATC 110 that I rode like a banshee (as much as one can do that with an underpowered trike) all over hell's half acre and loved every minute of it.

So I found a guy getting ready to scrap two bikes this past weekend. I got them both for $150. Both were basket cases in the truest form and I had no idea if all the parts were there.

One is a 1980 YZ100. (I hope this forum auto-resizes photos)

The bike after some cleanup..


The gearbox and lower end after some (lots of) cleanup..


The head and cylinder..






So I've done a bit of research, but not a whole lot yet. the following site was useful in learning about restoring:

http://projectyz.jfn3.com/

The top end was removed from the lower when I bought it and there was some rust on the crank. Most of it cleaned up relatively easily, but I haven't split the case to do a thorough inspection. Everything looks fine to me, and frankly, I can't even tell why the PO would have opened it. Short of some gaskets, I'm thinking of putting it back together to see what happens.

Thoughts on what to do with this thing? I don't want to pour a bunch of money into it, just get it into decent riding shape. I can do nearly anything it needs on my own.

From what I can tell, the 100 is a bit of a bastard child. Parts availability is really poor in comparison to a 125. Right now, I haven't even found a gasket kit for it - plenty of stuff out there for a 125 though.

Ideas? What would you do with it?

I 5' 11'' and 220 ponds, so this thing is probably going to be undersized for me. That said, I'm not really going to race it or anything (although I'm not that far from Bud's Creek and that may be the best place to actually ride it given the absence of riding places in general in MD). Even underpowered for my size, it will probably feel a hell of a lot faster than the old 110 three wheeler!

Oh yeah, the other bike is a 100cc Indian/italjet:






I also picked up a 50 horse Evinrude for 40 bucks from the guy, so probably more projects than I need right now. All this 3 days after my first kid was born, and the wife didn't bat an eye!

Brent


|
AHRMA361
Posts
2487
Joined
4/1/2008
Location
NE, OH US
10/13/2014 4:50pm
Actually you have a 1981 YZ100 there. They are little screamers. Best of luck on the build. Keep us posted on how it goes.
Antarctica
Posts
14
Joined
10/13/2014
Location
Shady Side, MD US
10/13/2014 6:18pm
Wow - sure enough. The clymers I have lists the 3R2 designation as 1980, but it looks like they continued that through 81 also, vs having a different designation for each of the previous years. Looks like the only way to tell is the rest of the serial number. Thanks!

Brent
Foghorn
Posts
927
Joined
1/26/2013
Location
CA
10/13/2014 6:43pm
Good luck finding parts for the Indian. I had a 125 back in the 70's and parts were hard to find then.
10/13/2014 6:47pm
The tank decals scream 1981 as does the mono-x decal on the silver swingarm. Is that the stock shock?

The Shop

moore433
Posts
525
Joined
11/2/2011
Location
Denton, TX US
10/13/2014 6:50pm
My dad has my old yz 100 in his shed. It's been there for years! I believe it's a complete bike. He posts on here as "paw paw 271" I believe or maybe just "paw paw".
Antarctica
Posts
14
Joined
10/13/2014
Location
Shady Side, MD US
10/13/2014 6:59pm
The tank decals scream 1981 as does the mono-x decal on the silver swingarm. Is that the stock shock?
I'll check, but yes, I believe the shock is stock. From what I read about the 80 yz100 (and I need to double check the clymer's now that I know it's an 81), there appears just about nothing that can be done for service on it. Is there something else (aftermarket) I should be considering putting on it - that is still made, especially given my size (220)?

Brent
Antarctica
Posts
14
Joined
10/13/2014
Location
Shady Side, MD US
10/13/2014 7:02pm
Foghorn wrote:
Good luck finding parts for the Indian. I had a 125 back in the 70's and parts were hard to find then.
Yeah, not sure what I want to do with the Indian, if anything. I'm not even sure its even worth anything given its really just a rebadged italjet. There is another box of parts that came with it not shown in the above pics. I'll probably sort through it before I decide what to do with it.

Brent
10/13/2014 7:08pm
Works Performance will build you a shock for just about any bike or needs. YZ 100 shared a lot of parts with IT 175 which might help.
Kirk
Posts
1
Joined
12/6/2014
Location
CA
12/6/2014 12:20pm
New here too and just acquired a 1980 YZ100.

I have a 3R2 head and jug with a 1W1 bottom end, 1W1 is a 1977 YZ125. It all works together.

Kirk
Antarctica
Posts
14
Joined
10/13/2014
Location
Shady Side, MD US
4/14/2015 7:34am
So a bit of a followup on this bike. I put the motor together this past winter and got it fired up.

Damn this thing is loud.

Put it in gear and it promptly stalled despite the clutch being pulled in - it obviously wasn't disengaging. Had other projects get in the way for a bit, but poked around the net on the clutch and read that they can get stuck together it they are allowed to sit - which this bike definitely had done. About two weeks ago, I opening up the clutch and sure enough, found the plates more or less stuck together. Pulled them apart, buffed the steel plates, and put it together again. Fired her up, pulled in the clutch and put 'er in gear. Still running, let out clutch some - started to engage… all good.

So - a little aside. Let's revisit my first post. Note that the bulk of my riding experience was on a crappy little three wheeler as a kid. 4 Stroke. I'm aware of power band, but had never really experienced it…. Back to the regularly scheduled program.

So in the interest of getting the bike running, I had not reinstalled the air filter or air box yet. As I gave her some throttle and let out the clutch, I started easing across the back yard. OK all good. Started to give her a bit more gas to get going, but it hesitated a bit - probably because it was cold or because the aforementioned air filter and box had not yet been installed and the carb is probably out of adjustment for that condition.

Still bogging a bit I gave her a bit more gas as I turned onto my gravel driveway. And BAM! This little bike went ape! It took me about 50 feet to get the front wheel back on the ground. So that's power band I guess! Like a knife edge! Took it around the yard a few more times (no more wheelies thankfully) and parked it. It was a little bit too loud to keep running on a Easter Sunday.

What a blast this little bike is. Still not sure what I want to do with it, or if I even want to keep it. Like I said - I don't even know any places to ride other than Bud's Creek in MD. But it sure has been cool to see this bucket of parts come back to life!

Brent

Post a reply to: $150 1980 YZ100

The Latest