So I bought this bike from a member of the older forum and gifted it to my wife as an engagement gift. She loved it. Well since then we got gentrified out of our neighborhood, married, had a kid, bought a house, and lots of life has happened. I did manage to get the bike running for her, but I was never happy with it in that it intermittently developed a mis and or high rev, indicated a vacuum leak.
So... that brings us up to the realities of our pandemic. I'm laid off and loving it. So I started a decent rebuild on the 125. I have a nice parts list that I will be buying from the UK, mostly an engine rebuild including the rods, pistons, and a bore. Obviously all seals while I'm at it. The wiring looks good. I have it all working, the battery charges, lights are good (working). So I'll clean up the frame, have my dad fix the left rear turn signal bracket that is bubble gum welded on, keep the build pretty basic. I'll apply some black spray paint to the frame to finish it. I want basically a stock bike here, I don't have any plans on touching the stock paint. The bike has seen some action and it is going to stay that way.
I took the old (not very original and falling off) seat cover off, that lead down a rabbit hole. The foam came off nice, it is in great shape! The pan is solid too, I'll braze up some spots and hammer it around a bit, but it's pretty solid. A new cover has been ordered. Getting that on will be a new experience. The aluminum trim strip and all that hardware isn't something I've done.
Here's a few pictures;
(https://i.imgur.com/nNLgq0I.jpg)
(https://i.imgur.com/3HmDt2U.jpg)
(https://i.imgur.com/Ucg7Ljx.jpg)
(https://i.imgur.com/25jQb3F.jpg)
I love the thimbles that are used as pistons in the 125's and 100's...
Enjoy your garage time!
Nice Chris. How many miles were on that one? Nearly all the 125s I've seen through the years have pretty low miles. Some are near mint but the majority look like they've been ridden 50K miles but show less than 3K.
Have you been able to source all the engine seals? I kind of recall from one of my searches years back that there were 1 or 2 seals that are NLA.
I'll be watching this one. Good luck!
The bike has just under 7k. It looks about right for 7k and 45 years.
There are a number of parts that have been sand blasted and then just put back on the bike, I think I'll touch them up in the media cabinet and then powder coat them silver. Not exactly original, but unless somebody has a stash of RD125 parts laying around I'm not sure I have too many options.
I have no idea about engine seals. Yamabits sells a seal kit, but I'll probably tear the engine down before ordering. Then I can compare to what they have on Yamabits.
I'm not trying for a show bike, I just want it to run nice, stop decent, and ride okay. It's a perfect size bike for my wife, and it should be a real hoot around the city.
Got a little further on the seat pan. Brazed some new steel to the sides where it was a bit thin, cleaned it up further. Going to paint it, glue the foam back on, and hope the seat cover shows up soon. I should have taken more photos, but the cylinders are in great shape. Almost perfectly round according to my equipment. I'll put some new pistons and rings in it, but I have no intentions of a bore, at most I'll throw some cross hatch in it with an extremely light hone. I got the engine all cleaned up as well as a number of other parts. I plan to do some light sanding on the frame and hit it will the paint. I spent the first half of the day doing my taxes so I got less done in the shop than I had hoped, tomorrow i'll try to get out there a bit and snap a few more photos.
(https://i.imgur.com/2qQG92a.jpg)
A few more photos. I have a nice collection of bits for the media cabinet. Going to clean them up and likely powder coat them. I'll need to find a new oven for powder coating as mine was destroyed in a flood... Sprockets, chain, and stainless engine bolt kit, silver/chrome powder, all ordered. I need to grab an impact screwdriver and then I can finish taking the engine apart. Once it's apart I'll finalize my order from Yamabits. I don't want to blast the entire frame, but I can't come to terms with cleaning it and painting over what's left. Maybe I'm being silly? I know lots just clean them up and hit them with the VHT or similar and get good results.
(https://i.imgur.com/IaVCPlu.jpg)
(https://i.imgur.com/ASvo3g2.jpg)
(https://i.imgur.com/FO8GCfk.jpg)
(https://i.imgur.com/8shEMy1.jpg)
(https://i.imgur.com/Rh92vQh.jpg)
That is going to be a fun errand runner!
Let's hope! Our grocery store is only like .75 of a mile away. So it would be a perfect little scoot for small items.
My buddy's blast cabinet has seen better days, the glass is damned hard to see through and the vacuum will hardly keep the dust down, but after a few hours of blasting and the use of his parts washer I got a decent job on a number of parts. The bonus being I bought a gigantic toaster oven off a college student. The thing couldn't have ever been used. It's clean as a whistle. The toaster oven in my household looks like a scorched earth policy took place inside it for the last 40 years. This oven should be perfect for powder coat, albeit, way too good for such things. They don't make them like this anymore. The thing probably weighs 20lbs..
(https://i.imgur.com/igmBaGK.jpg)
(https://i.imgur.com/ZSfcRI6.jpg)
(https://i.imgur.com/fM7skmM.jpg)
That new oven worked out great. I got the black parts powder coated, and they look really nice. I forgot how great the powder coating process is. So easy, one coat and parts look awesome. Up next are a few silver pieces to replicate what used to be chrome. Unfortunately I am back to work tomorrow so time for things I actually enjoy will be a lot less. But I have a good start and if I can keep chipping away at it this old girl it should be back together in a month or so. I also got the seat pan painted up (too big for my oven), so it's looking better. This week I'll get the motor apart and order those parts.
(https://i.imgur.com/DkBSiRc.jpg)
I coated these two bits in silver. They turned out great! The license plate mount was already sandblasted when I bought the bike, so the chrome was long gone. The brake rod was just nasty. I think the results are good given the humble goals for this project. I got the bottom end of the engine partly disassembled this evening. I'll keep chipping away on that. The forks, coils, and remaining wiring will come off the frame, then I'll start cleaning and standing on it. With some luck I'll get paint on the frame in the next week or ten days, then I can go for assembly of the chassis. I'll hopefully put my Yamabits order in before the end of this week, so a mid May fire up isn't too unreasonable.
(https://i.imgur.com/jitjOck.jpg)
(https://i.imgur.com/G0gcyi0.jpg)
Interesting project, good work so far...I'm in ;)
Sounds like you're fighting the urge to restore the frame....just do it, you know you want to.
Thanks!
As for restoring the frame, don't say that! hahah. I am fighting that urge, it's killing me. I just don't want to get saddled with a big cleanup project on it and then have this thing drag out for a month or two longer as a result. So I guess I am going to see how it cleans up with the plan to be just touching it up, but if it's not going to look okay then I'll blast it and paint it.
Quote from: sav0r on April 22, 2020, 10:30:36 AM
Thanks!
As for restoring the frame, don't say that! hahah. I am fighting that urge, it's killing me. I just don't want to get saddled with a big cleanup project on it and then have this thing drag out for a month or two longer as a result. So I guess I am going to see how it cleans up with the plan to be just touching it up, but if it's not going to look okay then I'll blast it and paint it.
A degrease and power jet wash should have it come out clean, derust solution where necessary, quick rub down with 120 grit and a double coat of primer and away... :)
Chris, the 125 will look great when you're done, and watch out for Colin; he's an enabler :wave:
Thanks for the moral support gentleman, it's always appreciated.
I ran into some trouble getting the crank cases split, basically I got them about 1/4" apart and now they won't budge. I have a clymer manual, one of those catch all types, but I can't find it anywhere. So I googles and Yamabits has this puller (pusher?). I won't be buying it, instead I'll find some junk out of the scrap bin and make one.
https://yambits.co.uk/rd125-crankcase-splitter-p-43610.html
The picture isn't very good, but the labyrinth seal o-rings are looking pretty shot. Maybe this is normal, but they look pretty gruesome to me. It doesn't look to me like there's a snowballs chance in hell they were actually sealing.
(https://i.imgur.com/C7V1Ru9.jpg)
I made this piece of junk pusher out of a piece of junk. It worked fine until I got a rod jammed up and then the pusher bent. I realized my error, moved the rod, and it all came apart. Unfortunately I don't own a press to press the crank out of the other case half, so I ended up driving to my fathers to do that. I took my boy with me, we hit the hot tub after working in the shop. We also tossed some helicoils in the perches so that the mirrors no longer fall off from looking at them. Speaking of mirrors, I only have one. I can't remember which side, I'll have to check. The seat cover is almost on too. Not ready for pics, but I am pretty happy with it so far.
(https://i.imgur.com/o3oUmed.jpg)
(https://i.imgur.com/mZAwf0C.jpg)
(https://i.imgur.com/ZXUKUUj.jpg)
Those internal seals do look nasty...when I say seals, I mean a gobfull of tigerseal or similar. The central seal is critical to good combustion chamber dynamics....I wonder how it ran?
Kudos for taking on the engine rebuild btw.
After closer inspection, it looks like one o-ring was probably sealing. The other definitely was not. The spring was out of the right side crank seal and just floating on the crank. That probably wasn't helping things.
The bike ran as recently as last summer, but it certainly had issues. The one carb was rotten when I got the bike and i never got that side to run with that carb. So I replaced the intakes with DT intakes and fitted Mikuni knockoffs, the right side then would fire, but it never ran consistently. See the video below. If after a rebuild I still can't get it tuned consistently I'll likely buy real Mikuni's, but I'll cross that bridge when I come to it.
I'm considering building the crank myself. How hard can it be (famous last words)? We used to build our own karting engines and had great success doing so, but we never pressed our own cranks, a friend of ours always did it for us. I'm just not too keen on waiting 6 weeks (or worse) for somebody else to do the crank for me, and maybe it will be a learning experience.
https://www.youtube.com/watch?v=i_FZBOtluvE
do it, ive done mine as you know. not too hard, just be patient
man i -hate- vertically split twin cases. main reason i gave away that ds6 i had.
Alright, I'm going to do the crank myself. Should be fun! I'd say I'm not a fan of vertical split cases after this, they never bothered me with the karting stuff. Of course those engines didn't require press fitting everything.
I was looking for this book tonight, I found it obviously. It's from 1972, but seemingly the information is pretty on the nose. Lots of neat information on Yamaha twen 125's in there. Apparently in race trim they revved 3k more than in street trim. I think it's good for 10k or something in stock form. :eek:
(https://i.imgur.com/IzI8oAk.jpg)
Inside the book I found this memorandum, I must have stashed in there back before we moved as I found the book in one of few remaining moving boxes. Vaughn was one of my best buddies, we raced together from about 12 years old up until his death (we are very similar in age). He jokingly liked to be called Ace, always had it stenciled on his race cars, and he was one hell of a wheel man. He was the smoothest driver I have ever seen, I have never figured out how he managed to look so effortless on the race track. He passed away from complications due to a motorcycle crash... Godspeed, Ace.
(https://i.imgur.com/kUOi8Fg.jpg)
Sorry for the buzz kill. Anyways, here's the crank. It's pretty cute.
(https://i.imgur.com/VtnGApQ.jpg)
Here's the transmission. Gears looking pretty typical for Yamaha transmissions of the era. The teeth looking grainy likely a product of hobbing. They wouldn't stand up to any modern inspection, but with the 8hp this bike will produce I'm sure they have quite a bit of life in them.
(https://i.imgur.com/dZ2PVH2.jpg)
And one half of the case, it's got some sludge in there. Not much else of interest to see really.
(https://i.imgur.com/fuZTlr3.jpg)
Quote from: sav0r on April 26, 2020, 11:16:33 AM
(https://i.imgur.com/C7V1Ru9.jpg)
Is there just a piece that slides in between the cases on top of the lab seal? Is all the black goo on top of the lab seal to seal the piece that slides in there?
Weird design. Makes sense for a single cylinder engine, but for a two cyl is looks a bit hokey. Still a pretty cool little motor though.
I dont mind vertically split cases, but I always had problems getting a YZ250 gearbox back in place. Need extra fingers and a bag of elastic bands.
The lab seal has an O-ring on the outside and it is housed inside a part called the Crank Cover. The photo shows the top of the crank cover. The crank cover has a 2-pc seal on the outside. That black stuff almost looks like the cover seal has started to break down or dissolve. There's also a "filler" part that drops in on top of the cover on those 2 pins.
Quote from: sav0r on April 27, 2020, 08:30:13 PM
Apparently in race trim they revved 3k more than in street trim. I think it's good for 10k or something in stock form. :eek:
FYI, the redline on a RD125 is 10.000 RPM. While the US version did not come with a tach, some other regions did come equipped with a 12,000 RPM tach from the factory. Part # 396-83540-00-00. I've always dreamed of retrofitting mine. The tach boss on the front right corner of the case is present on the US RD125B but would need to be drilled. Sourcing the parts would be tough because the gauge is hard to come by, especially in nice shape.
The seals are breaking down alright, basically crumbling.
Of course the gasket set from Yamabits went out of stock sometime in the last few days. So I'll have to search around for one.
Not sure if you've sourced seals yet but here is some recent info that I compiled in my notes. The prices are from large vendors and just for reference, and not the Yamaha MSRP. The left crank seal is NLA but there are alternates according to info I found, 93102-20447-00 is supposed the be the same and is currently available.
RIGHT
Crank, R SW-28-40-8 Yamaha 93103-28011-00, ~$8.00
Primary gear O-ring Yamaha 93210-180A6-00 (93210-18023-00) , ~$2.35
Kick start SDO 15-26-6 Yamaha 93109-15001-00 OIL SEAL, ~$4.60
LEFT
Crank, L SD-20-40-8 Yamaha 93102-20117-00 OIL SEAL, SD-TYPE, Not Available
Seal markings: ARS SD 20 40 8 - 1 GS
Interchangeable Parts:
93102-20010-00
93102-20117-00
93102-20231-00
93102-20447-00, ~$6.10
Sprocket SD-28-44-7 Yamaha 93106-28043-00 OIL SEAL, SD-TYPE, ~$7.00
Shift Shaft SD 12-22-5 HS Yamaha 93102-12321-00 OIL SEAL, $6.15
Thanks, SoCal. I'll have to check those seals out.
I got the seat more or less done tonight. I'm okay with it. The seat cover quality is decent, fit ended up a bit asymmetrical (hardly visible in photos but after wrestling it for an hour it's obvious to me), and the material just isn't all that stout. It's a huge improvement over the old cover though. So i'm calling it a win!
(https://i.imgur.com/b5K2czW.jpg)
(https://i.imgur.com/4H2k5uB.jpg)
(https://i.imgur.com/leEOaYX.jpg)
(https://i.imgur.com/ujrvcBB.jpg)
(https://i.imgur.com/HOP8A9Z.jpg)
That'll do ...nicely. And, considering your overall approach and restoration level you hope to achieve is a realistic outcome. Good progress...sav.
That seat cover job looks great to me; I'd let you do a cover for me in a heartbeat! And now I know I'm not the only one who uses old socks as shop rags!
Thanks for the compliments dudes. I appreciate it!
I got the parts from Yambits yesterday. 5 days from the UK to Pennsylvania. Incredible service!
The frame painting is under way (sorry for the awful photos). Crank pressing tools are in design. I have a huge load of shocks for customers right now, I have to get them finished, then I'll machine the crank tools. I worked over our Lisle hone and will be honing the cylinders in house. I reached out to Chuck as well as others, these tiny cylinders don't have the luxury of getting serviced at any old shop. Luckily the bores are straight and fairly clean, honing them up .25mm should be a breeze.
(https://i.imgur.com/93ttPXY.jpg)
(https://i.imgur.com/ptk6swu.jpg)
Also, I machined this absolutely ridiculous shift lever for my 350 (I dont have a thread for it and wont start one for a shift lever). I could have fabricated something much simpler, for way less expense, but I wanted a learning experience. So I present the worlds most expensive RD350 shift lever. 97% removal rate and each billet is like $30 in material, and I fucked it up 4 times before getting it right. I've been testing a new machine control software and that is in part responsible for me just throwing cash down the toilet as I need to test it out. Things went wrong at times, but I am happy ultimately. The result isn't perfect but things are looking promising.
(https://i.imgur.com/wh6LQfF.jpg)
(https://i.imgur.com/ZmBBCSz.jpg)
A little better shot of the frame. I think I'm offically done painting it. The paint I used sure took a while to let go of the tack, but it's pretty good now.
(https://i.imgur.com/P5yKGN2.jpg)
I honed the cylinders yesterday. They came out quite nice, very straight, though they are both a tad loser than I wanted. I'm sure they will run just fine though. To get my hone to fit I had to find some short stones, to find short stone I decided to just mill them short. My face mill took a beating, it will be okay though.
(https://i.imgur.com/FNAAMbb.jpg)
I'm thinking I am going to wet sand the tank, side covers, and head light with some 1000 grit or something fairly light and then clear coat them. Anybody know what type of clear coat will be friendly with the stock paint?
Quote from: sav0r on May 19, 2020, 10:07:38 AM
I'm thinking I am going to wet sand the tank, side covers, and head light with some 1000 grit or something fairly light and then clear coat them. Anybody know what type of clear coat will be friendly with the stock paint?
Not sure on compatibility with your existing paint (one problem with using adhoc rattle-cans) but a petrol resistant clear coat is essential and a 2pack is that.
An auto paint supplers will offer a rattle can option which has a shelf life, but will set like a gun applied 2pack.
I have access to a paint booth and can apply automotive grade if need be. I'll just have to move my sister's MGC GT out of the way. Obviously if easier options are available I'd go that route. It's also a 45 mile drive to access the booth which is rather impractical.
I got my wife's car repaired and I'm back to making progress. I plan to get it up on its wheels so I can at least move it out of the way when I need to. I hope to finish up the crank tools this week and do the crank over the weekend. I'm still waiting on the gasket kit, but I will run the various engine parts through the ultrasonic tank this week and finish cleaning up gasket surfaces.
(https://i.imgur.com/ivs7HFE.jpg)
Bike build yeah yeah....what's in the foil topped jars? ;D
That's sterilized grain spawn used for cultivating gourmet mushrooms, which is another hobby of mine.
I Googled "sterilized grain spawn" just now... :eek: sometimes you don't see the rabbit hole until you've stepped all the way into it.
Quote from: sav0r on June 02, 2020, 01:52:51 PM
That's sterilized grain spawn used for cultivating gourmet mushrooms, which is another hobby of mine.
haha "sterilized grain spawn", well blow me, I didn't know that was a thing...every day's a school day :)
Frame looks good BTW. I plan to handpaint mine after blasting and etch...proper tractor grey enamel, with the tin sat in a bucket of hot water and a good brush and roller.
Quote from: 85RZwade on June 03, 2020, 01:25:41 AM
I Googled "sterilized grain spawn" just now... :eek: sometimes you don't see the rabbit hole until you've stepped all the way into it.
Quote from: NoRiders on June 03, 2020, 05:48:46 AM
haha "sterilized grain spawn", well blow me, I didn't know that was a thing...every day's a school day :)
Frame looks good BTW. I plan to handpaint mine after blasting and etch...proper tractor grey enamel, with the tin sat in a bucket of hot water and a good brush and roller.
Hahaha. Well, yeah... Having gone down the rabbit hole myself I'm now on year three and wondering what I got myself into. The last mushrooms I grew were Lions Mane and those turned out incredible, but the spawn in the photo is good for Oyster mushrooms. If you look closely you can also see some agar plates in the plastic tub to the right of the jars, these have "clean" colonized mycelium that will be transferred to the grain spawn. The grain spawn is left to be colonized by the mycelium and mature to that point that it stable, the spawn is then moved to fruiting conditions where hopefully you get mature edible gourmet mushrooms. Done right you can get pounds of mushrooms for very little money. The upfront investment is in a pressure cooker to sterilize, jars, and spores of whatever strains you want to grow. The rest is patience and hard work. I'm actually taking a break from growing currently, which is why those jars are just sitting there. Gourmet mushrooms such as Lions Mane or Oysters are quite expensive, both of which are going for like $10-$12 per pound. It's literally cents worth of material to grow them at home, but it requires a lot of experience and technique to consistently get good grows.
Anyways, yes, motorcycles. The frame turned out pretty nice. I could have sanded some more, painted some more, and gotten a better job yet. But it was getting to the point where I've got this really nice looking frame and the tank, side covers, head light all look like they've seen 45 years of use. So I decided to stop.
I've seen lots of nice looking hand painted stuff over the years. I don't see any problem with doing it that way. It certainly is nice to avoid over spray if possible.
Thanks for the comprehensive reply.
A friend with a 30+ classic bike collection brush paints in warm enamel all this restored frames.
The bike now features a front wheel and some assembly of the controls. Most of the work I have done in the last few days is split between washing the bike (a feature of having two wheels and being bale to roll it outside) and thinking about this crank project. More than anything, I was just tired of it looking dusty and covered in shop crud. I had spent some time working over the chrome in the past, and a wash was needed to restore my previous progress. Of course my 350 suffered the same fate, so I washed it too. The crank tools are close. The model and CAM are finished. I'll be machining those today I think. Once I get those done I'll make the journey to my fathers to use his press, it's convenient timing as I have a Water Buffalo gear to press while im there.
(https://i.imgur.com/M4XWVYl.jpg)
Long time, no post...
I finished the crank up yesterday. Covid gave me a nice vacation in the spring, but being in health and safety for my job Covid brought me back basically double time. I spend way less time in the shop than I'd like as a result, hospital work isn't much fun. Hopefully these circumstances will change soon.
For the crank, my 10 ton press wasn't quite up to the task (i thought it was going to break when trying to split the two cranks), so I ended up having to use my fathers 20 ton press. The tools I machined were in most cases marginal. It was my first time making crank pressing tools, that said, the results were really good. I got less than .0005" runout on the bearing surfaces, that's less than half the recommended runout from Yamaha. Honestly, building cranks has to be cake for those experienced in it. That experience I am sure takes practice though. For me, it took a little more work than it should have (aka a lot more work), but the experience was worth it.
Since I have the engine bits ready, I am going to start reassembling. I will need to find some junk to pull/press the crank into the bearing in the case. That should be a fun project... Otherwise the engine assembly looks easy peasy at this point. Hopefully I am not missing any critical parts.
(https://i.imgur.com/xtEnjRf.jpeg)
Yep, that's a crank.
I got the cases all cleaned up last night.I am going to start assembly today. I have to come up with some junk to pull the crank into the one half of the case. That will be exciting.
(https://i.imgur.com/Ue47QaC.jpeg)
I made this little puller setup. It work out very nice.
Now I am tasked with remembering how the rest of this stuff goes together.
Cool! :clap:
Well I got the bottom end together only to find that I left out the thrust washer on first gear. So I had to press the cases back apart. Fun! They back apart and I got gasket surface cleaned up. I am busy the next few days but I hope to get this motor together next week.
In the meantime I got side tracked by getting this lathe (as well as a bunch of other projects).
(https://i.imgur.com/UNHBOkQ.jpeg)
Oooouuuh. Nice! Would love DRO on my little mini lathe and mill. Just tuned the lathe abit last week, and it still tuns out rough projects pretty well. Would love to go up in size and quality, though.
I got it 60% off due to the crate being busted, $1500 out the door. The chip guard is a little dinged up. The tool post handle is busted. Otherwise it seems to be perfectly fine. I cleaned it up and ran it for an hour or so last night. It's probably the best manual lathe I've ever used and I've only just started using it.
That lathe looks really nice.