YZ125 Updates

[r4brightred]

I'm making a few changes on my YZ for the upcoming season. I thought I'd share a few pictures. I'm switching over to Shinobi water cooling, as well as a Noguchi cylinder and pipe. It should be running pretty soon. I haven't been able to find an authentic radiator yet so for the time being I'm using a 1981 YZ125 radiator. The radiator mounts are made from heavily modified headlight brackets and spare parts. I still have a lot of work to do.  I'll put up some more pictures as I make more progress.

[LWC82PE]

What class can you run this in with that head?

[Rossvickicampbell]

they were available at the time so shouldn't change running class.

[KTM47]

I'm assuming the bike is a Pre 78 as it wouldn't be legal in EVO.

[LWC82PE]

I thought these aftermarket watercooled kits were one of those items that although available at the time are not allowed in evo or pre 78 racing today?. Have things changed? Also the 81 radiator would certainly be an issue i would think?

[Tomas]

No offence but the cylinder  head and the bike with the radiator straped to the front looks ugly. Original yz looks nice on the other hand 

[80-85 husky]

top effort I say....cool mods

[r4brightred]

I'm working on the hose routing now. I'm also getting the pipe in position because I have to
make some modifications to it. The plan is to race this at Unadilla in June. Pre-75 class.
The straps for the tank seem to work well for holding the hoses in position. This is my first attempt
at rebuilding Thermal Flow shocks. So far so good.

[Tomas]

When I work on shock absorbers I usualy use two blocks of hard wood with V cut outs(bit like V blocks) in them to clamp shock bodies  in a vice. That way you dont chew your shock body too much 

[r4brightred]

I've got the shocks done. New innards and a cosmetic clean up. Not show quality but presentable. After a great deal of cutting and filing, and heating, and bashing I have the pipe ready for a replacement stinger and flange. I hope to have a co-worker do the welding on the pipe in a few days. It's getting there.

[r4brightred]

I finished the bike and displayed it at the Supercross yesterday. Broc Glover looked it over and seemed to like it. He was nice enough to share some stories with me about his early days racing the DG Elsinore as well as with factory Yamaha. I'll be racing the bike in June. All I have left to do is decide between a original YZ internal flywheel ignition or go with a MX175 external flywheel ignition. It should be running next week. Thanks for taking a look at my old YZ.

[skypig]

Very cool project.
I doubt there would be many of those heads, barrels or pipes floating around!
Were they popular "in the day"?

[r4brightred]

From all I've read the Noguchi kitted bikes were super fast right up until they seized. Apparently the chrome bores failed quickly. At some point in the history of my cylinder it was sleeved. I had it bored to 2nd over, no chrome issues for me. As far as the Shinobi set ups, it doesn't seem like they caught on. Possibly the thermo-siphon operation didn't work well. Here are a few vintage pictures I've located of Shinobi equipped YZ125's and an ad from Shinobi.

[shelpi]

why has that YZ125X got a DT/MX clutch cover

[r4brightred]

Humble Yamaha was located in Texas. They had  MX, Trials, Flat Track, and Road Race teams. They would do a lot of experimenting with their engine combinations. This included running the earlier model 5speed bottom ends on the 1976 YZ125 and YZ175 models. The 439 was raced by Glenn Urquart.