kobra's 1985 RZ350NC2 basket case restoration

Got a customizing or restoration project? Discuss it here

Moderator: rztom

Message
Author
User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#211 Post by kobra » Sun Jan 13, 2019 2:57 am

Thanks guys!!! One less extra part to worry about...

I got the first thing put back on the frame - the fork clamps! I used All Balls tapered roller bearings. Everything went smoothly until I went to install the bearings and they felt super rough. Wtf? Took me a second to realize what was happening. There was a small protrusion next to the bearing race that was making intermittent contact with the bearing cage. Dremel to the rescue!

Tiny bit of material removed (like .010") that was scraping against the bearing cage. Then had to thoroughly clean and blow out the steering head of metal dust.
Image


Clamps installed loosely. These tapered roller bearings like to be run as loose as possible to eliminate clunking but NO MORE. Any more and they create stiff steering which negatively affects handling.
Image


While tweaking out in the garage I noticed the open ends of the subframe. They are interesting because they have no drain holes at the bottom. So I made some plugs cause why the hell not. To the spinny thing...
Image


It's times like these that buying the 100 pack of o-rings from McMaster 9 years ago comes in handy.
Image

Image

User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#212 Post by kobra » Sun Jan 13, 2019 4:24 am

Rebuilt the petcock today. A few findings:

-I knew the knob that was on there didn't look stock. The previous owner must have lost it and put on this thing. It's all sorts of wrong, and going straight into the trash. It looks like I can get the original knob still... but this looks like a fun opportunity to make a custom knob from aluminum! It should be pretty easy.

-I can confirm that the K&L 18-2730 repair kit fit perfectly. It even includes the large o-ring for sealing the petcock assembly against the fuel tank. It does not have the bowl gasket as mentioned above, so I will get that from Yamaha. Thanks brraapp for the tip!!!

-Overall the condition looked pretty good. The filter has a kink in it but I don't think it matters. I didn't try removing the filter as it seems pretty stuck on there. Has anyone removed one of these? The only reason would be to clean inside better, but it's probably fine.

-The faceplate was bent so I straightened it on a piece of rod stock. There is some minor corrosion on the surface but sanding it would mean removing the screenprinted labels, so I might just leave it. It's kinda hidden anyway.

-The outlet for the fuel line was attached to the fuel line not the petcock. Does it just press in there? Is there an o-ring/clip/sealant to hold it in there and seal?

Image

Image

Image

Image

Image

User avatar
JonW
Posts: 9716
Joined: Sat Oct 10, 2009 4:33 am
Location: Sydney
Contact:

Re: kobra's 1985 RZ350NC2 basket case restoration

#213 Post by JonW » Sun Jan 13, 2019 6:35 pm

Yep the filters pull out.
My Projects:
see them all at www.2smoked.com

80 XT500 Supermoto!
81 RD350LC Resto
82 RD 421 LC Hybrid
82 RD 250 '51L' YPVS LC
83 RZ350 LC2 Resto
85 RZ350 F1 Resto
84 RZ500 Resto
86 RZ350 F2 Hybrid

Like Watches? Try www.PloProf.com and www.DeskDivers.com

User avatar
brrrappp
Posts: 240
Joined: Tue Sep 18, 2018 10:21 pm
Location: New Hampshire USA

Re: kobra's 1985 RZ350NC2 basket case restoration

#214 Post by brrrappp » Sun Jan 13, 2019 7:29 pm

The tapered roller bearing is the same as a wheel bearing for a car, a trailer or a Harley. The directions from "all-balls" say to smear some grease on the bearing face, THIS IS WRONG!!!!
You need to pack this type of bearing with grease (see below how too link). The tapered bearing will hold a lot of grease- at least an ounce or two each bearing. If you have ever "packed" a wheel bearing for a car or trailer axle, you know this to be true. There are bearing packers you can buy that look like two cones with a grease fitting OR you can fill the palm of your hand with grease and drive the open edge of the bearing into your palm with a scooping motion, repeatedly all the way around the bearing until it wont take any more.
Once you have the bearings packed as fully as possible then you can install the lower bearing on the stem and assemble the steering. The steering stem does not have a torque spec in the Yamaha manual. I usually over-tighen it then rotate the steering back and forth a bit, then back-off the and re-tighten until it is just to the point of steering resistance.
Use a waterproof grease like Mercury 2-4-c or Mercury high performance extreme and you will never need to disassemble this again.

How to pack a wheel bearing by hand:
https://www.youtube.com/watch?v=BhL1uAp_WCw
A modest "high" can be obtained by listening carefully to the sound of a 2-stroke hitting the fat part of the powerband while inhaling cool fall air tainted by the exhaust scent of VP-C12 and Golden Spectro, mixed at 24:1.

User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#215 Post by kobra » Sun Jan 13, 2019 7:43 pm

oh yeah, I packed the crap out of it. I learned how to do it from watching that old show "TRUCKS!" and he did a similar thing.

edit: Regarding the petcock - I found that the fuel outlet spigot pulling out is a common issue on this era of Yamahas. It's a strange design - there are no retaining features other than friction. Apparently FJ600's were known to leak and catch on fire due to this spigot falling out, and the fix is to either epoxy it in place, or safety wire it in place so it can still rotate but not fall out. Here is an example of one someone sells that is safety wired (though I'm not sure why anyone would buy that since it takes 2 minutes to do yourself). I might start with the safety wire trick until I realize its final "resting" direction, and then fix it with some retaining compound.

User avatar
brrrappp
Posts: 240
Joined: Tue Sep 18, 2018 10:21 pm
Location: New Hampshire USA

Re: kobra's 1985 RZ350NC2 basket case restoration

#216 Post by brrrappp » Mon Jan 14, 2019 3:49 am

held together with bailing wire, bubble-gum, and duct tape?
A modest "high" can be obtained by listening carefully to the sound of a 2-stroke hitting the fat part of the powerband while inhaling cool fall air tainted by the exhaust scent of VP-C12 and Golden Spectro, mixed at 24:1.

User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#217 Post by kobra » Mon Jan 14, 2019 4:30 am

WD40 when I want it to move, and duct tape when I want it to stay. haha..

User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#218 Post by kobra » Tue Jan 15, 2019 2:57 am

I spent some time on the cylinder head. There were some fine grooves in the surface maybe .001-.002" deep so I lapped it smooth on the surface plate. I also lapped the YPVS logo. It appears the factory just kind hit it on a belt sander. The surface is not perfect so I couldn't lap it entirely on the surface plate, and had to do a little by hand instead using a flexible piece of wood as a sanding block. Started with 240 and finished with 600, looks alright!

Image

Image



Then I got to thinking... all this work on the cylinder head, and I never really checked the cylinders themselves... Due to the studs it's not possible to lap the surface perfectly smooth. And I am pretty scared of removing the studs... How perfect does it have to be? There are a few small scratches on the head side, and one gouge on the base side. I'm not really experienced in this area of what's normal or what needs work.

I uploaded the close-up pics here - each photo can be zoomed in. Would definitely appreciate some feedback! Thank you
https://imgur.com/a/iLlfnSJ

User avatar
pdxjim
Posts: 30
Joined: Sun Dec 30, 2018 9:24 pm
Location: Portland, Oregon!

Re: kobra's 1985 RZ350NC2 basket case restoration

#219 Post by pdxjim » Tue Jan 15, 2019 4:43 am

You can't really lap the mating face on the cyl even with the studs out.

Just spray the head gasket liberally with Permatex Copper Spray before assembly and you'll be fine.
Wasting time on 2T forums since the dawn of the internets. RD350LC, TDR250, KH400, 300XCW. Looking for an RZ350.

User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#220 Post by kobra » Tue Jan 15, 2019 4:53 am

Why is that? Run the risk of messing it up? It looks like it would be flat with them out, at least on top.

User avatar
brrrappp
Posts: 240
Joined: Tue Sep 18, 2018 10:21 pm
Location: New Hampshire USA

Re: kobra's 1985 RZ350NC2 basket case restoration

#221 Post by brrrappp » Tue Jan 15, 2019 10:54 am

You can pull the studs and do the top of the cylinders. Or leave it alone.
OEM head gaskets will generally seal the minor imperfections you have at the top of the cylinder. The copper spray wouldn't hurt.
You can use a thin coat of Yamabond 4 (or similar) on the base gaskets to ensure a good seal.
OR go "all-in" bust the budget and ship the top half of the case, the cylinders and the head to a reputable 2-stroke performance machine shop. Get the surfaces matched and clean up/match the transfer ports at the same time. While they are at it you can have the squish properly machined.
A modest "high" can be obtained by listening carefully to the sound of a 2-stroke hitting the fat part of the powerband while inhaling cool fall air tainted by the exhaust scent of VP-C12 and Golden Spectro, mixed at 24:1.

User avatar
pdxjim
Posts: 30
Joined: Sun Dec 30, 2018 9:24 pm
Location: Portland, Oregon!

Re: kobra's 1985 RZ350NC2 basket case restoration

#222 Post by pdxjim » Tue Jan 15, 2019 2:04 pm

kobra wrote:
Tue Jan 15, 2019 4:53 am
Why is that? Run the risk of messing it up? It looks like it would be flat with them out, at least on top.
Yeah, sorry. You *can* lap the top of the cyl with the studs out. As I said, not really needed as the gasket and sealer will seal even with minor imperfections.

The bottom is difficult (without machine tools) because of the basic shape. Also not crucial as the gasket will seal even if it's not perfect.

Can't accurately do the squish without assembling the engine first, tho.
Wasting time on 2T forums since the dawn of the internets. RD350LC, TDR250, KH400, 300XCW. Looking for an RZ350.

User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#223 Post by kobra » Tue Jan 15, 2019 2:13 pm

Oh yeah, regarding squish. I haven't taken off more than a couple thou from stock but I'm curious about measuring it anyway. I've seen plenty of procedures to check it but I am wondering how you're supposed to check it without ruining the head gasket. It's a one time use thing isn't it?

User avatar
pdxjim
Posts: 30
Joined: Sun Dec 30, 2018 9:24 pm
Location: Portland, Oregon!

Re: kobra's 1985 RZ350NC2 basket case restoration

#224 Post by pdxjim » Tue Jan 15, 2019 9:38 pm

Use an old head gasket to measure squish, then use a new one for final assembly.

Verify thickness is the same while you have it all apart.

While pattern gaskets are good for everywhere else, I'd recommended OEM Yamaha for the base and head gaskets.
Wasting time on 2T forums since the dawn of the internets. RD350LC, TDR250, KH400, 300XCW. Looking for an RZ350.

User avatar
kobra
Posts: 170
Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#225 Post by kobra » Tue Jan 15, 2019 9:56 pm

Ok, I think my old head gasket is trashed but I'll take a look. I have all new Yamaha seals and gaskets for the entire engine.

Post Reply