kobra's 1985 RZ350NC2 basket case restoration

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tacky1
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Re: kobra's 1985 RZ350NC2 basket case restoration

#226 Post by tacky1 » Tue Jan 15, 2019 10:11 pm

You can reuse OEM head gaskets, Ive taken mine apart 4 to 5 times and reused it and no probs, I spray a little copper spray and all good.

This is how I measure all my squish clearances, This way you get a more accurate measurement.

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1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1984 GPZ750 Turbo
1989 VFR750R RC30

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kobra
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Re: kobra's 1985 RZ350NC2 basket case restoration

#227 Post by kobra » Thu Jan 17, 2019 3:22 am

Well that's reassuring :)
Picked up some Permatex copper spray sealant today.


Okay, another question. The saga continues...
I pulled out the shift drum, shift forks, etc. so that they are not in the mix when I sandblast. Kind of a pain getting those phillips head screws out. I made sure to use heat first rather than risk twisting them, and also used a manual impact driver.

Anyway, I pulled the shift drum out and that needle bearing kinda feels like crap. It's not chunking but definitely doesn't feel smooth, and is pretty loose. The drum itself is not a polished bearing surface so the rollers feel gritty running over it. I noticed the other end doesn't even have a bearing. Now, how critical is this one? The drum basically just indexes with very little force on it, so maybe this is normal...

brrrappp
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Re: kobra's 1985 RZ350NC2 basket case restoration

#228 Post by brrrappp » Thu Jan 17, 2019 8:42 pm

I would replace the bearing since you already have it all apart.
Yamaha shifting has always been kind of "notchy." Some others might describe Yamaha shifting as having a "positive" feel. After years of riding Yamaha's almost exclusively, the first time I rode a Honda while wearing boots, I thought I missed a shift because it was so smooth!
My point is that Yamaha obviously didn't think this was too important. The shift drum rides in an oil bath. The shifting action is always smoothest right after an oil change. Anything you can do to reduce friction there will make it feel better but you can only do so much to improve the action with out getting into custom work elsewhere.

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kobra
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Re: kobra's 1985 RZ350NC2 basket case restoration

#229 Post by kobra » Thu Jan 17, 2019 9:17 pm

brrrappp wrote: Thu Jan 17, 2019 8:42 pm I would replace the bearing since you already have it all apart.
Yamaha shifting has always been kind of "notchy." Some others might describe Yamaha shifting as having a "positive" feel. After years of riding Yamaha's almost exclusively, the first time I rode a Honda while wearing boots, I thought I missed a shift because it was so smooth!
My point is that Yamaha obviously didn't think this was too important. The shift drum rides in an oil bath. The shifting action is always smoothest right after an oil change. Anything you can do to reduce friction there will make it feel better but you can only do so much to improve the action with out getting into custom work elsewhere.
Apparently the banshee guys will turn down the shift drum and put different bearings. They also replace the shift star follower with a bearing rather than the little jiggly roller that is stock, and these mods are supposed to tighten it up and smooth it out a bunch.

I stumbled on an old post here from JonW saying the stock bearing is nasty feeling even when brand new. Guess it doesn't matter too much... haven't heard of any failures because of it.

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Re: kobra's 1985 RZ350NC2 basket case restoration

#230 Post by brrrappp » Thu Jan 17, 2019 9:39 pm

You can probably find lots of creative ways to lighten the action. Softer shift return spring, round the tops of the shift star, polishing or hi-tech coatings for the drum grooves, transmission shafts and shift shaft. I think someone even sells a kit to place a bearing in the case or case cover where the shift shaft rides.

I can feel a big difference (good) in shift action simply by running Bel-Ray light viscosity gear oil. I think it's now called Bel-Ray 80w GearSaver Transmission oil.

tacky1
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Re: kobra's 1985 RZ350NC2 basket case restoration

#231 Post by tacky1 » Thu Jan 17, 2019 9:42 pm

A really good mod is to grind the shift Star. I do this with all my bikes. Just google banshee shift star mod.

https://www.youtube.com/watch?v=as-48SLsPDs
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1984 GPZ750 Turbo
1989 VFR750R RC30

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kobra
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Location: Bay Area CA

Re: kobra's 1985 RZ350NC2 basket case restoration

#232 Post by kobra » Fri Jan 18, 2019 12:34 am

Hrmm, I am wary of modding that shift star without ever riding it in stock form. To be honest I can't say I've ever had a problem with any bike's shifting except for my old BMW with a rotax motor - it wouldn't clutchless shift no matter what!

I do however want to replace these god-awful phillips head screws with some socket heads!

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kobra
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Re: kobra's 1985 RZ350NC2 basket case restoration

#233 Post by kobra » Sat Jan 19, 2019 11:22 pm

Couple random questions as I make progress...
-Should I lubricate the head studs that are installed into the cylinder? ARP says yes, but only with the correct lube. Seems to me like it would just help them from getting so stuck if this ever comes apart again, and won't affect torque spec during install.
-Is it recommended to gently sand the reed valve cages (rubber part) to improve sealing? I am installing TDR reeds. If so any tips on doing it right?

RuZty
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Re: kobra's 1985 RZ350NC2 basket case restoration

#234 Post by RuZty » Sun Jan 20, 2019 6:32 am

kobra wrote: Sat Jan 19, 2019 11:22 pm Seems to me like it would just help them from getting so stuck if this ever comes apart again, and won't affect torque spec during install.
That is incorrect, when tightening a fastener most of your effort goes into overcoming friction in the threads and under the nut or head of the bolt. You will reach the specified torque at a lower clamping force (tesile load) in the fastener with dry threads. Lubrication reduces the friction, resulting in a higher and more consistent clamping force for the same torque. A bolt or stud will twist slightly under the torque (like a torsion spring), cyclic and thermal loading will allow that to unwind, hence the spec to retorque after a heat cycle.

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kobra
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Re: kobra's 1985 RZ350NC2 basket case restoration

#235 Post by kobra » Sun Jan 20, 2019 2:35 pm

RuZty wrote: Sun Jan 20, 2019 6:32 am
kobra wrote: Sat Jan 19, 2019 11:22 pm Seems to me like it would just help them from getting so stuck if this ever comes apart again, and won't affect torque spec during install.
That is incorrect, when tightening a fastener most of your effort goes into overcoming friction in the threads and under the nut or head of the bolt. You will reach the specified torque at a lower clamping force (tesile load) in the fastener with dry threads. Lubrication reduces the friction, resulting in a higher and more consistent clamping force for the same torque. A bolt or stud will twist slightly under the torque (like a torsion spring), cyclic and thermal loading will allow that to unwind, hence the spec to retorque after a heat cycle.
I'm referring to the part of the stud that goes into the cylinder, which pretty much is fixed once you tighten them down. Seems like a tiny bit of some lube might keep them from seizing in there so bad. I don't plan on lubing the top threads or the nut for the exact reasons you mentioned.

brrrappp
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Re: kobra's 1985 RZ350NC2 basket case restoration

#236 Post by brrrappp » Sun Jan 20, 2019 3:34 pm

I guess the question is...... does it matter if the stud loosens or becomes over tightened due to the lube.
Example: 1) when you go to remove the head retaining nuts and the stud comes out with the nut attached....
Example 2) When you torque the head nuts and the stud tightens further instead on the nut on the stud....leading to the threads in the cylinder being stripped.

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Whymee
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Re: kobra's 1985 RZ350NC2 basket case restoration

#237 Post by Whymee » Sun Jan 20, 2019 4:26 pm

Lube the threads of the stud before you install them in the cylinder. I usually coat the first 1/4 of the total length of the threads. I use motor oil or anti-seize.

If your stud comes out of the cyl. when you loosen the nut, that tells you that someone never tightened the studs tight enough, or the head nuts have galled. If the stud tightens in the cylinder when tightening the head bolts, you have not tightened the stud enough. The stud will bottom out in the threaded hole in the cylinder when you tighten it.

The head is only torqued to 18 ft. lbs. Not like your are torquing on a 429 CJ Ford head.

Put a small dab of oil on the head bolt flange that faces the washer and the threads. Much more constant torque.
2.5 RZ350's
2018 Grom
2017 KTM 390
2017 FZ-10
1973 RT3
1974 TY250
plus many others

brrrappp
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Re: kobra's 1985 RZ350NC2 basket case restoration

#238 Post by brrrappp » Sun Jan 20, 2019 5:14 pm

Good read on how and why fastener torque.

https://ridermagazine.com/2005/11/15/th ... fasteners/

basically it says
Oil yes.
No Synthetic or heavy oils, molly paste, teflon.
Too slippery = too high a torque value. No lube might lead to not enough.

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Re: kobra's 1985 RZ350NC2 basket case restoration

#239 Post by gpaddict » Mon Jan 21, 2019 12:19 am

Pretty sure torque specs are called out as clean and dry unless otherwise specified!
tuned to Paris Hilton specs............rich and retarded!

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kobra
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Re: kobra's 1985 RZ350NC2 basket case restoration

#240 Post by kobra » Mon Jan 21, 2019 4:11 am

Been tweakin out more trying to decide which screws to buy. I'd like to buy from McMaster since I can get exactly what I want, but the only downside is I end up with 25-100 of each thing. So the idea with this is to determine which screws can cross over in terms of length and style so I can use the same screws in several areas.

A lot of the screws are rusted, stripped, or missing, and some I want to replace simply because socket heads are nicer than phillips in most cases.

Here's the chart so far. If I have the energy to flesh it out it might be a useful contribution to the forum.
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