The 1955 YA1 Yamaha 125 (2T) restoration has finally started after lurking in the corner for many years. These bikes were also known as the Akatombo, or Red Dragonfly. Some say blasphemy against the Yamagods: "Leave it original." I think not:
(https://i.imgur.com/qncPegW.jpg)
Let the project begin! First order of business is get the motor out and apart - it took a week to nurse the cases apart since a couple pullers had to be engineered, and surprisingly most of the internals are serviceable; a good thing since NO parts are available, not even from Japan. Here are the cases after being stripped and the first pass through the parts cleaner:
(https://i.imgur.com/x6Zxrtt.jpg)
This is going to take some time. The bike spent 40 years in Hawaii at the first Yamaha Dealership in the United States, so the original finish has much surface-rust; the metal beneath is 100% sound and solid and amazingly straight.
The chrome will be a challenge as it didn't fare as well as the painted parts - the handlebars, rims, and exhaust system will take some heroic (read 'expensive') plating work.
Interesting history: the YA-1 was not only the first Yamaha, but it was also the first Yamaha race bike, having won the first race they ever entered, the 1955 Mount Fuji Ascent in Japan ... they finished minutes ahead of the pack. The YA-1 was produced from 1955 to 1957, and one had to be quite wealthy to buy one ... "the average starting salary of a college graduate (in Japan) was around 10,000 Yen, the YA-1's 138,000 Yen price put it well beyond the reach of most users."
There are less than 10 YA-1's in the U.S., and this is one of two 1955's - the actual count is unknown, but the other dated bikes are 1957's. The Yamaha Corporation was formed in July of 1955, and the date tag on this frame shows Aug-1955, so this is likely one of the oldest in existence.
Updates will be slow in coming - I estimate at least 1-year to finish (it is a very simple and basic bike), which probably means it will take at least 2!
Warren
Wow this is amazing! Can't wait to see this come together 👏
Cool project. It looks so much like a BSA Bantam DS1 or the Harley Hummer or DKW125 on which those were based after WW2. I don't suppose any parts would interchange if they were available.
I understand that the DKW was the motor everyone in the 50's copied - the Yamaha motor looks virtually identical on the outside right down to where the screw holes are located. Ironically all the engine bearings are German SKF's in weird fractional sizes that are obsolete. SKF used alpha characters instead of numeric and they (X-N's) did not supersede to anything either.
I found a video a while back of someone taking a DKW125 apart and inside the Yamaha looks exactly the same. I bet a lot of the parts do interchange, but they are rare too. I was lucky the YA-1 motor had very few miles and I think all the internals except seals are reusable. Crank and rod bearings are smooth and tight too. Whew.
Warren
WOW THATS AWESOME :olaf:
growing up dirt biking in SoCal in late 1960s, 1970s many bikes had Sachs motors in them. Penton, Zundap, Monark,and DKW among them. Some were directly licensed by German Sachs, some imitators that probably weren't. Eventually all of them became branded with KTM on the exact same engines. We all know how big the Austrian KTM conglomerate has become absorbing and buying out other brands.
Here's a link to a VMX swap meet site owned/operated by a guy named Mark Holloway who has an extensive collection of 1973/74 125 dirt bikes. If you look at the main page of this site you'll see a list of era 125s he's acquired and some he's still looking for- but many pictures and stories on his restorations on his collection. You can see how many bikes used the Sachs/KTM motors of the era. Might be a good place to expand options of different brands for parts interchangeability...
https://www.vintagemx.us/cgi-bin/swapmeet.cgi
Thanks for the link - sadly there many similar sites that never come up thanks to the commercialization and monetization of Google; I have a Forum website myself, and it has yet to show in direct searches on Google using the name of the site - I've recently moved to using DuckDuckGo or Bing; they list my site and it does come up on page 1 in searches.
I may try a wanted ad for YA-1 stuff, but suspect that what I need is a little old and too far out there. Mainly what I need is Yamaha specific like a lever perch, ignition switch and key, rubber bits like knee-grips and peg rubbers etc.
That site gave me an idea though, I might have something right up their alley to post: my wall-size Mark Brelsford 3D poster from 1973:
(https://i.imgur.com/F9MZWdz.jpg)
Thanks again for the info and link - much appreciated!
Warren
Warren
Have you seen the Yamaha Communication Plaza's Facebook page ? They're currently advertising YA-1 rubber spare parts for sale (seat / grips etc)
(https://i.postimg.cc/PfWBsxZF/YA-1.jpg)
Hey Brian,
Thanks for the pic and heads-up! I heard about 8 years ago that Yamaha was going to do a limited run of the soft-parts kit for the YA-1 (all in white), but I have never been able to find a source except for one dead-end. I searched the several hundred Yamaha groups for the 'Yamaha Communication Plaza' page, and goose-egged. Then I tried a few generic searches with no results. Where did you see the post? ALL the soft parts on my bike are shot or missing.
The kit was 'supposed' to be knee grips, seat-cover, handlebar grips, and foot pegs. I even tried contacting Yamaha Japan to no avail, and have been checking the Yahoo Japan auction site with no luck. If you could help me find that posting I would be forever in your debt! Well at least a few years.
I do have a copy of the parts book, but it's in Japanese too; the exploded diagrams help a lot.
Warren
Edit: I did find mention of the soft-parts kit on LinkedIn, but it was not optimistic...
"We've recently been getting a lot of requests for YA-1 parts from overseas. We went to a lot of effort to ensure that the colors remain authentic while making the parts with modern materials so they're more durable. We paid a lot of attention to the details and are proud of the results, so we hope they've been put to good use in YA-1s around the world.
*Sales have concluded, but interested parties may contact the Communication Plaza for more information."
Try this link Warren. Its a site I follow on FB. Their latest ad for YA-1 parts was only posted 5 days ago
https://www.facebook.com/YamahaCommunicationPlaza (https://www.facebook.com/YamahaCommunicationPlaza)
Good luck :clap:
Quote from: Yamanatic on May 24, 2024, 12:44:23 PMThanks for the link - sadly there many similar sites that never come up thanks to the commercialization and monetization of Google; I have a Forum website myself, and it has yet to show in direct searches on Google using the name of the site - I've recently moved to using DuckDuckGo or Bing; they list my site and it does come up on page 1 in searches.
I may try a wanted ad for YA-1 stuff, but suspect that what I need is a little old and too far out there. Mainly what I need is Yamaha specific like a lever perch, ignition switch and key, rubber bits like knee-grips and peg rubbers etc.
That site gave me an idea though, I might have something right up their alley to post: my wall-size Mark Brelsford 3D poster from 1973:
(https://i.imgur.com/F9MZWdz.jpg)
Thanks again for the info and link - much appreciated!
Warren
you're welcome. That site caters to all older dirt bike stuff (1989 cutoff) and it's free to join/post and he won't sell your info. :thumbs: Never hurts to put an ad up and see if any response. He does require some kind of price on 4 sale ads to limit fishing expeditions. Site doesn't get as much traffic these days, but he has a companion site of FB for those that like that. Have fun!
Quote from: Bryan H on May 25, 2024, 03:27:47 PMTry this link Warren. Its a site I follow on FB. Their latest ad for YA-1 parts was only posted 5 days ago
https://www.facebook.com/YamahaCommunicationPlaza (https://www.facebook.com/YamahaCommunicationPlaza)
Good luck :clap:
Hey Brian,
You are a star! I submitted the application to be entered in the Lottery for 1 of 5 sets they are going to sell. That would really set off the YA-1 Nicely!
I am not lucky in love or lotteries - the only lottery I ever won was the Draft, and the wife said yes to saying "I Do." :eek:
Thank you again and again, made my day to even try!
Warren
Good luck with that Warren. You've got to be in it to win it....or so the saying goes. Here's a couple of pics I took in 2017 when I was lucky enough to visit the Yamaha Communications Plaza in Iwata whilst on holiday
(https://i.postimg.cc/zB6XC4XD/100-0211.jpg)
(https://i.postimg.cc/0jS5cZbY/100-0212.jpg)
Fun trip! I understand there are lots of interesting bikes in Japan, unseen anywhere but there. Did you hit any bone yards? I can only imagine what might be in the rows way in the back:
(https://i.imgur.com/aTVBBvM.jpg)
I love that race-bike, but wonder of it was for mixed surface tracks or raced 2-up? The handlebars do not seem to go with the rest of it. Hard to crouch on the white seat and the rear-sets with the bars that far up.
Thanks for the pics - the first one is what I see in my minds-eye instead of the challenged pile in the garage.
Wow, only 1 Year since the YA-1 got dragged out of the corner! Going back to last year's comments, I did sign up to get one of the 'Soft Parts Kits' offered through Communications Plaza Yamaha Japan, and amazingly was one of the first 5 (they only produced 5 additional kits) requests, but when they contacted me to make the deal, the first question was my location; so much for that - the bike and owner had to be in Japan and Japan only, no where else, period =(. Oh well, I tried.
Since the RD350 project is finally done, I restarted the YA-1 resto in earnest, and have reduced the entire bike to a parts-book quality exploded diagram. I saved the wheels for last, knowing the spokes would be a nightmare; most everything has to be reused since just about everything is unique to the bike and there is no 'superseded,' to it. Also a true historical restoration favors marginal original to pristine replacement - getting the bike apart without destructive removals is crucial.
The front wheel took 2 full days to nurse apart, and today is day three on the rear with 12 spokes left. Thought I'd pass along a little insight on how to remove badly rusted stuck spokes; someday in the distant future there is a good chance a 2SW member may face the same challenge restoring a 70 year old RD or something.
First thing was to mop the business end of the spokes down with Liquid Wrench (actually PB-Blaster) a half a dozen times over a week or two to free things up. A good wheel stand and a bar stool helps. Buy a couple of the best full nipple-width spoke wrenches you can; a short one and a long one if possible. Add good tunes and a pinch of Indica PRN(as needed)!
(https://i.imgur.com/cIH1ILd.jpg)
(https://i.imgur.com/Mmi03F7.jpg)
Verify that the nipple squares have not been brutalized first, then give it a try. If the nipple doesn't move at all, the nipple has corroded to the rim; I have a small brass hammer to firmly tap the nipple from both sides a few times, and if really stuck give the screwdriver end of the nipple light angular hits with a fine drift - just stay away from the end of the spoke area.
The tricky part now is to not torsion-break the spoke; at this point it doesn't matter which way it breaks loose; hearing that 'pop' is music to the ear. I start with about a 20-degree twist back and forth, and stop at 30-degrees. More penetrating oil, and sometimes hitting the end of the spoke wrench holding tension will do it; worst case a little heat sometimes help.
I find that 45-degrees is about the limit of twist before the spoke breaks. If and when it finally comes loose, even just tiny bit, start working the nipple back and forth further and further until the threads free up - it might only take a few back and forths or 20 times, but it will loosen; this step saves fighting the nipple all the way off.
The last 12 spokes have been successfully removed - all the spokes and nipples are salvageable; all 72 came loose!
Warren
OK, Enough with the spokes - must be time for some fun stuff; motor work! Solving Nipponese motor puzzles is better than a night at the movies. There is nothing on the intricacies of YA-1's assembly beyond history and color, but, they are very close to an exact copy of the '49 to '57 DKW RT125, probably the most duplicated motor ever - the BSA Bantam, Russian Minsk, Polish Sokol and SHL, Harley Hummer, and of course, the Yamaha YA-1. Lots of DKW vids and the only obvious difference inside the cases is the shifter mechanism design.
First, the gearbox. The 4-speed transmission is a marvel of simplicity; the mainshaft carries the clutch on one end, and the drive sprocket on the other. The countershaft is more an idler shaft that handles the gear reductions. The shift mechanism is a bit of a mousetrap but well made, similar to the mechanism used in YDS motors but fully contained inside the cases. Luckily everything inside was in excellent++ condition including the bearings and bushings.
The gear and roller bearing sitting in the crankcase goes on the drive end of the main-shaft, then the drive sprocket mounts on the splines. Can't see the gears very well so it was moved aside for pics. That arrangement mounts to the left case prior to assembly. A couple of the lipped seals (especially the drive sprocket shaft) ended up being obsolete, but eBay pulled through - a European seller had one and only one, and it should be here by next week.
No Phillips-head screws in the entire motor; all Cheese-head with straight slots. Star washers go under all the case screws. The cases are Yamabonded together with no gasket.
(https://i.postimg.cc/6TnHt2tM/DSCN2408s.jpg) (https://postimg.cc/6TnHt2tM)
(https://i.postimg.cc/QHq0K2B5/DSCN2409s.jpg) (https://postimg.cc/QHq0K2B5)
Speaking of Crankshafts...
After hitting the International market to source the rather unique engine oil seals (India and China), I'm finally down to installing the crank and closing the cases. Going by both the parts book and the way the motor came apart, there are 0.012" thick, bearing-OD diameter flat shim-washers that go between the outer flywheels and the mains. With the washers installed, they basically turn the mains into partially sealed bearings (they fit the bearing faces flush - see pics).
The only oil supply to the bearings would be through the feed holes at the base of the transfers. Yamaha could have intended the washers act as oil retainers, but it wouldn't seem enough oil would pool there in the first place. Given that Yamaha didn't continue using the full-coverage washers on future 2T cranks, I decided to take 6mm off the washer radiuses, thereby exposing the races.
Note: The removed bearings were nasty dirty but functional.
Even though this engine is a direct copy of an RT-125 DKW, Yamaha's fingerprints are all over it, and some of the evolution/development of future engines is apparent. One thing noticed was the un-characteristically minimal crankcase volume; besides the 8mm's between flywheels, there is only 0.013" clearance on either side of the crank and 0.10" difference radially - almost like they didn't want the crankcase to contribute to charge volume. IMO, the mains need as much exposure to circulating pre-mix as possible given the space.
Here are the 'before' pics:
<img src="https://i.imgur.com/jRB922M.jpg" title="source: imgur.com" /> (https://imgur.com/jRB922M)
<img src="https://i.imgur.com/3f4lGw5.jpg" title="source: imgur.com" /> (https://imgur.com/3f4lGw5)
Considering the bike will only see a few hundred miles (maybe), the purist in me says leave everything 100% stock and original as possible - I digress...
Warren
that's interesting. the triples would oil in the sane way with 'slingers' and def held in the sludge. it also made premixing on the h1s kind of a no go w out modding the crank