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Ebay was fun on this project...I found a ton of new parts cheap and collected for a year and a half until I had everything to build the bike. I found NOS cables, front rotor, brake lever, Answer Radialite sprockets. I paid 30 bucks for a rusted DG pipe that I cleaned up. I used all Moose bearings/seals/brake pads/air filter. Pro Wheel rims.
If I was concerned about performance Pro Circuit still makes a pipe and silencer and some port work can make these keep up with the RM/CR/KX. One of my buddies raced 80 Expert from 89-91 on them and used PC motors and Suspension. Barrs Competition on the East Coast was another company that I think is still in business and was known to build good YZ 80s.
I went from this bike to a 89 KX 80 and immediately picked up speed and went from Beginner to Intermediate in about a year...I remember my Dad asking me then if I thought I could go back and ride as fast on the YZ 80...and I told him I could....but for some reason I didn't think I would have been able to progress that fast if I'd stayed on a Yamaha...something about getting on the KX 80 made me figure out riding and pick it up quicker.
It was a sentimental project for me because I'll have a replica of my first race bike and I'm really nostalgic about that time period when I started racing. My kid doesn't ride much and I figured it would be a cool project for him to help work. Until he can learn to ride this YZ 80 right....keep it on the pipe.....use the brakes...and jump with good technique...I see no reason to spend 3-4K on a new 85.
I had a 1985 Barr Competition engine in my KX125 back in the day. Yes it ran awesome...broad power band. Your not alone with the nostalgia. I have collected several of the bikes from the 70s/80s I either had, or wanted. I race them in SSVMX.
Thanks
That’s a WMX 250 but I do have a 125 (an 88 and 83). They are my main hobby and I’ve been racing them in the Northwest for the last 4 years. I get rid of the Dellorto and use Mikunis off the modern Italian Husqvarna 125/250s. The YZ was the first Japanese bike I’ve restored.
86-87 front disc, boxed swingarm, new gas tank and shroud, significant motor revisions were long rod plus cylinder and porting changes. Basically a copy of the 85 KX80 powerband.
88-92 head and flat top piston otherwise BNG
The pipe design changed quite a bit, look at the shape of the 86-92 vs 83-85. Engine basic design is just a water cooled 81 YZ80.
Popular here through 87, forget it once the 88 KX and 89 RM came out. Motor was easy enough to make fast enough. 33mm damper rod forks atrocious. Unless you were small or a beginner, all of the other bikes did most things better. 89 CR80 was 7 mph faster top speed, and that was with the YZ having 15/46 gearing.
They spent at least three years testing what became the 93 YZ80...
Drilling out the airbox, like quarter sized holes, and using fine mesh helps it breathe better. There was a heavy duty shock spring available, I remember we got it from dealer. We also had problems with stripped shift shafts.
I remember we got my 88 or 89 as a leftover for not much more than a thousand dollars or something. We had a little backyard track that the neighbors would tolerate me putting in laps on with the super quiet S-II silencer, but I liked how the blown out stock one sounded and would swap it. Cops would be there in 10 min every time.
Pit Row
There was a good thread on Planet Minis where a couple of guys were building old YZ80s and one mentioned he had the hot porting specs for those motors. It may be worth reading through and trying to get in touch with that guy, not sure if he is on Vital:
http://planetminis.com/forums/2-stroke-pitbikes/166079-82yz80j-also-83-…
I’ve built plenty of bikes that I just thought were cool and weren’t the fastest....unless you really want to do the YZ for some sentimental reason or challenge it’s going to be hard to beat the CR you’ve already got.
wpark89....I bummed this wasn't fast model...but I too have saved a few slow bikes for the niftyness or sentimental purpose. I raced a 85 rm125 briefly that year....pretty bike...but I clearly remember being passed on a straight during practice by a little kid on a white/red 85 YZ80 !...That's when I KNEW that RM was slow..
Looking at the cylinder....I see some room for improvement,,maybe even some boyesen boost ports. I appreciate any and all help to find the connecting rod,piston kit, silencer
I used a Pro X rod kit. Part number is 03.2104 (84-92 YZ 80) they don’t come up on the Pro X site but I found one on eBay.
You can still get a silencer from DG, but I don’t think the new DG quality is anything like the parts they sold in the 80s. The pipes aren’t bad but in my opinion the silencers are cheesy. I’d get a PC silencer if it will work with the DG pipe. I’ve seen nos Answer silencers on eBay and DynoPort is an option.
Just for fun I went through the Loretta’s Vault. 87/88 there were decent numbers of YZ 80s. By 92 there were only a couple of them in the results...and only in the 7-11 stock class. The last fast mini rider to have top 10 results on a mod YZ 80 was Matt Maximoff in 1990. Might be worth it to find out who built his bikes. For some reason Michigan kids kept racing them when nobody else was.
I have no experience with Mitaka parts. Just research and be careful, a lot of aftermarket companies have the years wrong for fitment. I used the chaparral site a lot and you can look up part numbers and then also see what models that part is used on.
FYI Friday I saw Pro Circuit has 87-92 YZ 80 pipes on sale for 100 bucks. Only the plated version is available, but it’s a great deal.
FYI I just saw that Pro Circuit has 87-92 YZ 80 pipes on sale for 100 bucks...only the platinum, but it’s a great deal.
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