78 YZ-100

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3/30/2017 3:22 PM

Here is my almost completed 100.
I know what you are think. " Why build a 78 when you can build a 82-83 which is a much better bike"?
Well, simple, I feel like the 82-83 are cheater bikes with their link suspension.Photo

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Swapped out the front forks for a set off a 1979 IT 175, I went from 32mm to 26mm and another inch of travel. rear shock was built by Works performance and added another 1" of travel so I have 8" on both ends. Eric Gorr did the engine. Added a bigger set of reed valves to give it more low end. Pipe pics to follow. That was a lot of work!!! Sand sand and sand!

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"Whatever makes your mother cry is worth doing"

3/30/2017 3:47 PM

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Finished the pipe last week. Had to take one dent out. Then sanded it down and re-blued the welds and wiped it down with WD-40. The silencer is a Bill's. found it on E-bay. had to cut the mounting bracket off and make a new one that wasn't so long. now have to make anew pipe back to the pipe then weld it up and it's done. Just need to put the seat cover on but that is going to take some work. Couldn't find the right foam so I had to buy a seat foam for a 77 YZ 125 and cut it down. Same with the cover. Need to cut it down to fit. Had to buy all new spokes and re lace the wheels. it was a job.

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"Whatever makes your mother cry is worth doing"

3/30/2017 4:14 PM

Nice!!

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3/30/2017 5:37 PM

Beautiful!!!!!

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3/31/2017 8:58 PM

Reminds me of Team Dynamic. Awesome.

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4/1/2017 4:34 PM

Nice bike! make yourself a folding shifter if you cannot buy one!

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5/5/2017 3:02 PM

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DONE! Time to go burn some laps!!!

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"Whatever makes your mother cry is worth doing"

5/5/2017 3:21 PM

What a beauty, nice job Spankey.

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There's something happening here, what it is ain't exactly clear.

5/5/2017 9:56 PM

Great job. Awesome bike!

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5/5/2017 10:03 PM

Very nice. Should be a fun ride.
Greg

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5/6/2017 3:54 AM
Edited Date/Time: 5/6/2017 4:01 AM

Wow, beautiful bike. Lots of terrific detail and just the right amount of personal "style" from stock. The re-blue of the pipe was a good call; made it stand out. How long was the process (entire bike)?

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5/6/2017 10:37 AM

Outstanding!!! Love it!
That era of 100cc racing was good times.
Enjoy!!!

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If you don't crash once in a while, you're not going fast enough.

5/8/2017 1:08 PM

Since73 wrote:

Wow, beautiful bike. Lots of terrific detail and just the right amount of personal "style" from stock. The re-blue of the pipe was a good call; made it stand out. How long was the process (entire bike)?

Once I got the engine and frame back it was about 8 months.

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"Whatever makes your mother cry is worth doing"

3/4/2018 5:40 AM

Great build, I’m doing a 79, what rims and spokes set did you use

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3/4/2018 9:42 AM

Steve Hughes wrote:

Great build, I’m doing a 79, what rims and spokes set did you use

Ditto.

I'm doing an 83 125 and can't find anywhere for black excel rims.

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3/4/2018 10:12 AM

Steve Hughes wrote:

Great build, I’m doing a 79, what rims and spokes set did you use

1983YZ125 wrote:

Ditto.

I'm doing an 83 125 and can't find anywhere for black excel rims.

Unless you are dead set on Excel, you might try Full Circle Racing. A buddy of mine just got them on his '84YZ125 and they look amazing. http://www.fullcircleracingltd.com/vintage-mx-rims-and-spokes.html

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3/4/2018 1:44 PM
Edited Date/Time: 3/4/2018 1:58 PM

Quote OP "I know what you are think. " Why build a 78 when you can build a 82-83 which is a much better bike"?
Well, simple, I feel like the 82-83 are cheater bikes with their link suspension
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Yes like it! and also the cantilever series were also of a great racing period, for many of us I expect... before the bikes started going mono.....so if you can take something to later YZ100 on the track, then all credit to you sir! Lovely bike and super job.

I raced a 1979 YZ100F and also a 1981 YZ100H, the '79 was actually really fast, seemed as quick as the '81 version possibly but think the '81 version generally felt better handling..and sort of more nimble. It may have been because it was abit fresher than the 79F though. May have tired the '79F out abit after 2 years of racing it. The '79F was quick though to me and think this '78E was pretty much the same? Love your bike and brings back great memories of those years and times racing.

What were the differences for the YZ100's over the years of this period I wonder, if anyone knows? Obviously the 82 / 83 had the monoshock. The 78-81 YZ 100's always looked quite similar to me. Were there many differences if anyone knows for the 78-81 models?

I for sure would like a 82-83 but thinking about it... I would maybe even like a 78-81 even more!!

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Always was an excellent rider ...... at crashing usually

Moto Aspes, you know you want one

3/4/2018 4:02 PM

Blue-ing on the pipe welds??? Are you guys using a blue process that gunsmith would use on rifles? Or something else? Please explain.

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Larry Navarro - Spring,TX. Damm glad to meetcha!

3/4/2018 4:12 PM

""""Here is my almost completed 100.
I know what you are think. " Why build a 78 when you can build a 82-83 which is a much better bike"?
Well, simple, I feel like the 82-83 are cheater bikes with their link suspension."""

That's a pretty fancy rear suspension on that '78.....a lot nice than the stocker on my '83. IMO the '82-83 doesn't have advantage over any other 100. Rider skill prevails on these little rockets as I've raced against all of them, mono's and twin shock RM's.......and I've eaten plenty of dust from them. smile

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Larry Navarro - Spring,TX. Damm glad to meetcha!

3/4/2018 4:32 PM

Steve Hughes wrote:

Great build, I’m doing a 79, what rims and spokes set did you use

1983YZ125 wrote:

Ditto.

I'm doing an 83 125 and can't find anywhere for black excel rims.

Since73 wrote:

Unless you are dead set on Excel, you might try Full Circle Racing. A buddy of mine just got them on his '84YZ125 and they look amazing. http://www.fullcircleracingltd.com/vintage-mx-rims-and-spokes.html

Thank you, I’ll be calling them this week

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3/5/2018 6:09 AM
Edited Date/Time: 3/5/2018 1:33 PM

wfoyz250 wrote:

""""Here is my almost completed 100.
I know what you are think. " Why build a 78 when you can build a 82-83 which is a much better bike"?
Well, simple, I feel like the 82-83 are cheater bikes with their link suspension."""

That's a pretty fancy rear suspension on that '78.....a lot nice than the stocker on my '83. IMO the '82-83 doesn't have advantage over any other 100. Rider skill prevails on these little rockets as I've raced against all of them, mono's and twin shock RM's.......and I've eaten plenty of dust from them. smile

Thats interesting to know- I remember back then it seemed like the YZ100 (78-81) had the edge on the RM100 of the same period possibly on speed and grunt abit but the RM100 seemed to handle possibly better- especially if the kid riding it had Fox shocks on it or something, which a few did back in the day.

I remember really smacking into bumps on the YZ! The 79F defo felt more 'clunky and sort of heavier feeling' than the 81H- both were great bikes though- always wished I had tried an RM100 to compare them.

I want a 100 now! Don't think though we are so hot on racing 100's in UK though as you guys are in the States, where it seems quite popular from what I read on here.

Edit : Just also remembered the Gold DG heads for the 80 100G or 79 100F also poss.

Also we used these Red Mitsui Yamaha tank covers over here, they were a red sort of maroon colour- that seemed to become available around that time- these tank covers sort of made the bikes look quite trick(for the time) and also some kids put red fenders on also to match the Red Tank covers.... Not sure if you had the Red Tank covers over there but alot of us had them here. For some reason I think I prefer the small 78-79 sidepanels to the longer 80-81 models. Not seen one of those red Mitsui tank covers for years but back then were quite popular.

Such good memories of remembering racing those 100's in 79-81 for me! Great thread.

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Always was an excellent rider ...... at crashing usually

Moto Aspes, you know you want one

3/6/2018 5:40 AM

Your bike looks great, good detail. My bike was my brothers first bike purchase. Wish I had it today. Who did you purchase the new plastic from? Or did you polish up the old stuff?
I just got a 100 myself, a 1982. I have just been cleaning it up, no restoration plan yet.
Enjoy your bike.

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3/6/2018 9:32 AM

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I get what your saying with the cheater bike but why not throw the 81 swing arm under it like mine is setup?
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3/7/2018 6:05 PM

What are you guys running for reeds/ intake boot? I need both for my 79 100 and was wondering what other years or aftermarket would work?

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