Project 1976 Yamaha YZ400

craydds · 02-22-2013, 02:00 PM

I just bought a '76 YZ400! I know, it's a sickness. It seems to be all original and unmolested, except for the gas tank. (pics to come later). Seems rare to find an old dirt bike (or any old motorcycle) that has not been tampered with, or TRASHED. The gas tank has been painted flat black - possibly to hide some bondo repaired dents? We shall see. The rear shock has NO damping, none, it is gone. I'll do a shock rebuild search, see if anyone does rebuilds, or possibly can tell me how it's done. Yeehaw, another project!

edit: Is there a YZ400 thread? I did not do a search.

craydds · 02-23-2013, 04:18 AM

Let's start a Yamaha YZ thread to include ALL the YZ's. I now have two, a 1980 YZ50 and my brand new old '76 YZ400. Remember, they were the FIRST with the MONOSHOCK. That was so cool! Elsinores were nice, Suzooks were good (I had a 125 and a 250), but the YZ's had that monoshock.

heliyardsale · 02-23-2013, 06:11 PM

Ha! I bought the same bike last week! Here is mine stuffed in my car! I also have a 76' YZ100C and the YZ125X.

Bad photo of the clan!

heliyardsale · 02-23-2013, 06:14 PM

Here is my YZ125X

craydds · 02-24-2013, 07:27 AM

Quote:

Originally Posted by heliyardsale

Here is my YZ125X

Wow! That 125 is NICE. I like that gas tank for the 400 shown in the post above. I saw one on ebay but I was unsure about it. I got a Clymer's manual with my YZ400, it SUCKS - conflicting info, etc; I bought an "official" YZ400 service manual from ebay - a gamble, but shall see if it is any better. I see that Racetech can rebuild shocks, may give them a call: http://www.racetech.com/page/id/64 . Got the bike home yesterday and it FIRED on the second kick. Started doing some cleaning up, going to lube everything, etc. I need a rear fender... ebay again? The project begins. (I will get some pics today.)

craydds · 02-24-2013, 07:50 AM

Bought this manual on ebay - http://www.ebay.com/itm/260908536395...S:3160&vxp=mtr.

Dirt, ugly, but it's ALIVE:

craydds · 02-24-2013, 07:58 AM

Will get some things cleaned up, lubed, and adjusted today. Take it for an easy test ride in the desert. A 400 cc 2-stroke! Bet it will have AWESOME power.

heliyardsale · 02-24-2013, 11:27 AM

Lolls pretty good! Don't lose the silencer, they cost huge $$$ to replace.

craydds · 02-25-2013, 02:54 AM

Rear wheel off. Axle, dirty but in good condition otherwise:

Rear wheel is good:

Everything covered in many years of dirt. Rear monoshock bolt ready to come out:

Swingarm loose. Look at that "inner fender", it's a piece of rubber floor mat:

Another view of the rear "inner fender". Anyone have a source for the correct part? ebay? :

The front monoshock bolt needs to be removed:

That nut is too TIGHT. I cannot get it to budge. Any tips on how to loosen it?

crg infidel · 02-25-2013, 06:29 AM

First and foremost, Sweet Bike!!! That is gonna be a ton of fun!

It might be helpful to get some heat on that nut, but not so much you burn up your rubber. You could try a wet rag around the rubber bits, and a little propane torch to warm up that nut. (please be ready to put out fires; I'd hate to hear a horror story

)

I grew up with old ring-ding Yamahas, and they are great bang for the buck!

Good luck!

craydds · 02-25-2013, 10:16 AM

Quote:

Originally Posted by crg infidel

First and foremost, Sweet Bike!!! That is gonna be a ton of fun!
It might be helpful to get some heat on that nut, but not so much you burn up your rubber. You could try a wet rag around the rubber bits, and a little propane torch to warm up that nut. (please be ready to put out fires; I'd hate to hear a horror story

)
I grew up with old ring-ding Yamahas, and they are great bang for the buck!
Good luck!

I will try and work it loose this evening. Get out my torch... and fire extinguisher. Ha!

dooder · 02-25-2013, 11:01 AM

I can't tell from the pic... It's not reverse threads is it?
Cool bike!

craydds · 02-25-2013, 11:27 AM

Quote:

Originally Posted by dooder

I can't tell from the pic... It's not reverse threads is it?
Cool bike!

I thought about that. I looked closely, but I'm blind in one eye... can't see out of the other. I could try to thread a nut onto the exposed threads to verify right vs. left hand threads. I will double-check that this evening.
edit: I zoomed in close on the photo in iPhoto, threads look like right-hand. It is hard to tell, will check tonight.

adventuro · 02-25-2013, 06:11 PM

If nothing else works you could try a nut splitter, better than screwing up threads on the shock...btw I still have my 78 yz400 that I bought new.

craydds · 02-26-2013, 11:41 AM

Quote:

Originally Posted by adventuro

If nothing else works you could try a nut splitter, better than screwing up threads on the shock...btw I still have my 78 yz400 that I bought new.

I was ready to buy a nut splitter! But, I used penetrating oil and my torch - slightly scorched the rubber - and got the shock OFF:

It was really HARD to get that nut to bust loose and I did mess up the threads a bit. Nothing that a die can't fix:

Will clean up the shock and send it off to Racetech - http://www.racetech.com/page/id/64.

Next step - I want to take the swingarm off. Same thing again - the swingarm bolt will NOT come out:

02-22-2013, 02:00 PM	#1
craydds ^OP Studly Adventurer Joined: Aug 2010 Location: Las Cruces, NM Oddometer: 993	Project 1976 Yamaha YZ400 I just bought a '76 YZ400! I know, it's a sickness. It seems to be all original and unmolested, except for the gas tank. (pics to come later). Seems rare to find an old dirt bike (or any old motorcycle) that has not been tampered with, or TRASHED. The gas tank has been painted flat black - possibly to hide some bondo repaired dents? We shall see. The rear shock has NO damping, none, it is gone. I'll do a shock rebuild search, see if anyone does rebuilds, or possibly can tell me how it's done. Yeehaw, another project! edit: Is there a YZ400 thread? I did not do a search. __________________ Ray ABC #12947 '75 R90S craydds screwed with this post 02-22-2013 at 02:02 PM Reason: thread?

02-23-2013, 04:18 AM	#2
craydds ^OP Studly Adventurer Joined: Aug 2010 Location: Las Cruces, NM Oddometer: 993	YZ thread! Let's start a Yamaha YZ thread to include ALL the YZ's. I now have two, a 1980 YZ50 and my brand new old '76 YZ400. Remember, they were the FIRST with the MONOSHOCK. That was so cool! Elsinores were nice, Suzooks were good (I had a 125 and a 250), but the YZ's had that monoshock. __________________ Ray ABC #12947 '75 R90S craydds screwed with this post 02-23-2013 at 04:19 AM Reason: ,

02-23-2013, 06:11 PM	#3
heliyardsale Always looking for Dirt! Joined: Feb 2009 Location: CNY.. Home of too many Liberials, yuck! Oddometer: 309	Ha! I bought the same bike last week! Here is mine stuffed in my car! I also have a 76' YZ100C and the YZ125X. Bad photo of the clan! __________________ An Alaskan bush pilot once told me "every great adventure begins with piss-poor planning" Heli (Doc Mike) heliyardsale screwed with this post 02-23-2013 at 06:17 PM

02-23-2013, 06:14 PM	#4
heliyardsale Always looking for Dirt! Joined: Feb 2009 Location: CNY.. Home of too many Liberials, yuck! Oddometer: 309	Here is my YZ125X __________________ An Alaskan bush pilot once told me "every great adventure begins with piss-poor planning" Heli (Doc Mike)

02-24-2013, 07:50 AM	#6
craydds ^OP Studly Adventurer Joined: Aug 2010 Location: Las Cruces, NM Oddometer: 993	YZ400 manual Bought this manual on ebay - http://www.ebay.com/itm/260908536395...S:3160&vxp=mtr. Dirt, ugly, but it's ALIVE: __________________ Ray ABC #12947 '75 R90S

02-24-2013, 07:58 AM	#7
craydds ^OP Studly Adventurer Joined: Aug 2010 Location: Las Cruces, NM Oddometer: 993	Will get some things cleaned up, lubed, and adjusted today. Take it for an easy test ride in the desert. A 400 cc 2-stroke! Bet it will have AWESOME power. __________________ Ray ABC #12947 '75 R90S

02-24-2013, 11:27 AM	#8
heliyardsale Always looking for Dirt! Joined: Feb 2009 Location: CNY.. Home of too many Liberials, yuck! Oddometer: 309	Lolls pretty good! Don't lose the silencer, they cost huge $$$ to replace. __________________ An Alaskan bush pilot once told me "every great adventure begins with piss-poor planning" Heli (Doc Mike)

02-25-2013, 02:54 AM	#9
craydds ^OP Studly Adventurer Joined: Aug 2010 Location: Las Cruces, NM Oddometer: 993	Need Monoshock Help Rear wheel off. Axle, dirty but in good condition otherwise: Rear wheel is good: Everything covered in many years of dirt. Rear monoshock bolt ready to come out: Swingarm loose. Look at that "inner fender", it's a piece of rubber floor mat: Another view of the rear "inner fender". Anyone have a source for the correct part? ebay? : The front monoshock bolt needs to be removed: That nut is too TIGHT. I cannot get it to budge. Any tips on how to loosen it? __________________ Ray ABC #12947 '75 R90S craydds screwed with this post 02-25-2013 at 03:47 AM Reason: spell

02-25-2013, 06:29 AM	#10
crg infidel n00b Joined: Aug 2012 Location: CRG Oregon Oddometer: 4	First and foremost, Sweet Bike!!! That is gonna be a ton of fun! It might be helpful to get some heat on that nut, but not so much you burn up your rubber. You could try a wet rag around the rubber bits, and a little propane torch to warm up that nut. (please be ready to put out fires; I'd hate to hear a horror story ) I grew up with old ring-ding Yamahas, and they are great bang for the buck! Good luck!

02-25-2013, 11:01 AM	#12
dooder Adventurer Joined: Jun 2012 Oddometer: 27	I can't tell from the pic... It's not reverse threads is it? Cool bike!

02-25-2013, 06:11 PM	#14
adventuro n00b Joined: Aug 2010 Location: mocksville nc Oddometer: 5	If nothing else works you could try a nut splitter, better than screwing up threads on the shock...btw I still have my 78 yz400 that I bought new.

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