Author Topic: 4 month lurker finally taking part in the forum! 1975 RD125b  (Read 284 times)

0 Members and 1 Guest are viewing this topic.

Offline Shibby7634

  • Club Member
  • Newcomer
  • Posts: 17
  • Age: 29
  • Location: Indiana, USA
  • I'm trying my best here...
Acquired a 1975 RD125b about 4 months ago, had been sitting for maybe 5 years partially disassembled, supposedly ran before storage but not particularly well.

Was my first dive into a 'restoration' and serious repair of anything (aside from regular car maintenance which I'm fairly capable of)

It has approx 6,700 miles on the odometer, all seems original. Came missing a few parts, but also came with some spare goodies I believe to be of some value.
A spare and complete clutch assembly, including all plates, rubbers, bolts, washers, spacer and kick pinion (?)
Also came with spare set of TeiKei carbs, which even though they may not be the best, are a rarity to find is fair condition. Also has a few spare jets, needles, throttle slides etc.

I've spent the last few months working on the following:
  • Cleaning and sealing the tank (was very rusted, with only one tiny hole luckily)
  • Sourcing stock airbox and filters
  • Repacking the mufflers, and fabricating a new silencer for one that was partially ripped off on the right side
  • Retiming the ignition, replacing points and condensers and plugs (the previous points were at the edge of their adjustment limit, now the plates back center)
  • Deep cleaned and tuned the carbs a few diff ways, sourced new jets, tried both a keyster kit and stock, back at stock now.
  • New battery and bulbs all around
  • New tires
  • Tons of little bits and pieces like missing bolts/screws, rubber dampers, cable covers, headlight, etc.

I've ordered some new rings, a hone, and small end bearings to try and give the top end some new life. Noticed a tad bit of blow-by when I had the reeds out, but haven't noticed any significant damage or wear. I do need to inspect the crank bearings as it does have a bit of a 'whirring' sound when running, but I also think it COULD be the rings... we'll see.

I hope to overhaul the crank and repaint during winter (not perfect OEM color, but very close followed by a 2k clear) We'll see what the top end really needs when I take it apart to try new rings out.

I would love to get this bike back to at least 90% perfect by next spring. 100% just doesn't seem realistic for my set of skills, but I think I can do pretty good at least  :) LOTS more cleaning and painting to be done before it's where I'd want it though.

Included are the most worthy pictures I have. The bike isn't fully reassembled yet, but I'm sure I'll add more to the forum eventually.

Thanks for reading, and thank you for all the valuable info you guys have provided me with over these months!

« Last Edit: June 28, 2020, 01:11:48 AM by Shibby7634 »

Offline Motty

  • Richard
  • Club Member
  • Port Hacker
  • Posts: 4737
  • Location: England
Re: 4 month lurker finally taking part! 1975 RD125b
« Reply #1 on: June 27, 2020, 10:13:18 PM »
I think I have said this already on your previous topic, welcome to the Aircooled RD Forum

Sent from my Moto E (4) Plus using Tapatalk

“...inside every old person is a young person wondering what the f*@k happened.”
Terry Pratchett

Offline Shibby7634

  • Club Member
  • Newcomer
  • Posts: 17
  • Age: 29
  • Location: Indiana, USA
  • I'm trying my best here...
Re: 4 month lurker finally taking part! 1975 RD125b
« Reply #2 on: June 27, 2020, 10:14:16 PM »
Ha, yes you did, I just figured I'd go for a proper, broad introduction rather than be off topic in the tech zone  ::) Thanks!
« Last Edit: June 27, 2020, 10:31:01 PM by Shibby7634 »

Offline Astute Greaser

  • Club Member
  • Port Hacker
  • Posts: 534
  • Age: 63
  • Location: Bristol
Re: 4 month lurker finally taking part! 1975 RD125b
« Reply #3 on: June 27, 2020, 11:38:17 PM »
Hi Shibby
Really enjoyed seeing your pic's.
Think you have a good project there to introduce you  to the world of bike restro. 2T tech keeps it relatively simple and the smell is like the addition to steam trains .
The silencer rebuild is a marvellous start although there are repro out there. I personally go for making my own bits or adaptions where I can. It gives a real set of pleasure to go yesss. Unfortunately its not always the case and I'm jealous of the kit some members have - complete machine shops  8) 8)
NOS on parts like those carbs is so difficult, although your side of the pond, more is available without the silly costs of shipping etc from states to UK.
Lots of the 20mm TK carbs (RD200) were bought up to fit to 125's to try to get some more HP  ::) and so bits have become stupidly rare. Lucky you with all them spares.
Look forward to hear your experiences as you seek the 90%. However most succumb to temptation to go beyond, behind me Satan.
Note there is a fair number of 125 members from North America, although I appreciate they may not be in the next town down ::). Seek them out  8)
-Mike

Offline Shibby7634

  • Club Member
  • Newcomer
  • Posts: 17
  • Age: 29
  • Location: Indiana, USA
  • I'm trying my best here...
Re: 4 month lurker finally taking part! 1975 RD125b
« Reply #4 on: June 28, 2020, 05:00:03 AM »
The silencer rebuild is a marvellous start although there are repro out there.

Do you have any links to some of these? I was unable to find anything in my search. Almost bought a whole new exhaust for the silencer alone, figured it'd be cheaper than having one machined. Then I figured... I'm relatively handy I guess, might as well give it a shot myself! Found some pipe with just the dimensions, had to shave some of the OD and length off the little 'bell' shaped end to fit it though. Drilling the holes was a bit tedious not having a drill press, but I figured precision wasn't that critical, it's close enough. I'd be interested to see if these reproductions are worth buying in it's place though.

It was VERY rewarding having made them with my own hands though, even if they were relatively simple. It was my first ever attempt at brazing, and I think I did well enough for them to hold through the heat  :D I'll attach a cpl more pics for fun

NOS on parts like those carbs is so difficult, although your side of the pond, more is available without the silly costs of shipping etc from states to UK.
Lots of the 20mm TK carbs (RD200) were bought up to fit to 125's to try to get some more HP

I haven't heard of this! Piques my interest though. Does it usually work out well? Or would it be more worthwhile to just use the well documented Mikuni VM20 swap should I decide to dump the TeiKeis? They seem to be alright for now, so I'll prolly keep them as long as I can till something catastrophic happens...
« Last Edit: June 28, 2020, 05:07:00 AM by Shibby7634 »

Offline Astute Greaser

  • Club Member
  • Port Hacker
  • Posts: 534
  • Age: 63
  • Location: Bristol
Re: 4 month lurker finally taking part in the forum! 1975 RD125b
« Reply #5 on: June 28, 2020, 01:47:38 PM »
Yep looks good.
There is a slight language problem between USA and UK English.
So USA exhaust/muffler = UK Silencer
USA Silencer = UK Baffle.
Do search for baffles and you can find. I actually found your NOS without problem!
Get the downloads from the clubs manual section. The CMNSL site and Partzilla are good for getting part numbers. My limited knowledge is for the 200A.
However I know the baffles of the 1E8 will swap with the 200A/B  and will be bold enough to say the baffles of the 125 probably also with the 1E7.
Indeed I'm sure the 125 and 200 baffles will swap with one another but the drillings may be different. Probably for tuning etc best to swap as pairs to keep back pressure balance.
When I first cleaned my baffles I swapped the pan head screws with cap heads. Much easier to poke back in on end of Alan key rather than balancing screw on end of screwdriver. Most people do not bother with the fibre wrapping, its not necessary while it will affect noise these bikes are small enough its not problem.

The carb swap I would leave alone with what you have. It was designed around those carbs. Swapping to Mikuni is last resort if you can't get the bits for the TK's. I've trialed it out as looking to put Higgspeeds on 2nd bike and that will need tuning so Mikuni, seems the way to go :-\
[ Specified attachment is not available ]
You loose the airbox and have to change cables plus work out new way to support oil tank and side panel.
Anyway we love challenges - that work  :-[
-Mike

Offline Shibby7634

  • Club Member
  • Newcomer
  • Posts: 17
  • Age: 29
  • Location: Indiana, USA
  • I'm trying my best here...
Re: 4 month lurker finally taking part in the forum! 1975 RD125b
« Reply #6 on: June 29, 2020, 01:24:10 AM »
There is a slight language problem between USA and UK English.
So USA exhaust/muffler = UK Silencer
USA Silencer = UK Baffle.
Do search for baffles and you can find. I actually found your NOS without problem!

Most people do not bother with the fibre wrapping, its not necessary while it will affect noise these bikes are small enough its not problem.

The carb swap I would leave alone with what you have. It was designed around those carbs. Swapping to Mikuni is last resort if you can't get the bits for the TK's.
You loose the airbox and have to change cables plus work out new way to support oil tank and side panel.
Anyway we love challenges - that work  :-[
-Mike

Well, I tried by terms and part number from Partsbandit, and couldn't for the life of me find the baffle... but it doesn't matter! I have what I need I guess since I've already made it haha.

As for the wrap, I assumed it was important for back pressure mainly, but i perhaps I'll try without sometime, as it would be nice to skip that step :)

I had considered the carb swap but afterward sourced the stock airbox, so I think I'll be sticking with the TeiKeis. In my post in the tech zone I mentioned the new Keyster Tornade kit thats arriving tomorrow that is supposed to supply a wide array of all jets and needles for this carb, so we'll see how that works out. Should help me get right where I need to be!

In your opinion, a guess being totally acceptable, what would you say this bike may be worth? 6700 miles, 98% complete I'd say. Needs a deep clean and paint. Runs well, but I'm working on getting it perfect. I don't plan to sell anytime soon, I've grown attached with all my work on this first project of mine! I just am curious if I keep putting more in to it, what I could expect to get back out of it one day. Say I paint it real nice and give her some new pistons and bearings... any estimates? Or do you know someone who might have a better idea? Plus the extra carbies/accessories and clutch.

Let me reiterate: I LOVE this bike! I love the look, I love the sound and smell, and its taught me so many new things, given me new confidence in motor repairs (even though its simpler than most, it's been a GREAT starting point.)

Thanks for your time and comments btw  ;D
« Last Edit: June 29, 2020, 01:26:08 AM by Shibby7634 »

Offline Astute Greaser

  • Club Member
  • Port Hacker
  • Posts: 534
  • Age: 63
  • Location: Bristol
Re: 4 month lurker finally taking part in the forum! 1975 RD125b
« Reply #7 on: June 29, 2020, 12:03:28 PM »
Wow that's a interesting question.
Prices UK & USA very different. Indeed USA is so much cheaper, there are companies buying up all RD's irregardless of condition, filling containers and shipping back here. It now reached the point that good running bikes are not sold on but stripped down for the parts  :o :o :o. So our bikes are probably worth more as bits  :( :( :'(. In addition spec's between the countries are different so USA bikes will fetch less UK.
Mountainofbeer  8) who answered your Keyster discussion, has same bike and is stateside will be most helpful for prices and sourcing bits, worth an introduction PM.
However owning and restoring bikes you would be lucky short term to get money for outlay. Your hundreds of hours labour fetch little  >:( >:(
The main point is enjoying the bike and being part of the RD fraternity  :D :D
-Mike


Offline Astute Greaser

  • Club Member
  • Port Hacker
  • Posts: 534
  • Age: 63
  • Location: Bristol
Re: 4 month lurker finally taking part in the forum! 1975 RD125b
« Reply #8 on: June 29, 2020, 12:24:40 PM »
Looking at your spares.
Your carb bodies have the extension wings under the mounting points, done on later bikes. This is for the vacuum balance line, the brass barb shown.

The idea is to connect a pair of vacuum gauges to the carbs and balance them to one another instead of the old way of using your ears, hand at the end of exhaust and judging clouds of blue smoke  ::) Very scientific ;) ;)
Yours seem missing the barbs. The barbs must be blanked after testing or the air leakage will mess up tuning.
One of my bike a PO did a neat mod to the reed valve body to get same effect  :)

Cheers
-Mike
PS
Your carb bodies should be painted gloss black  :P
« Last Edit: June 29, 2020, 12:33:04 PM by Astute Greaser »

Offline Shibby7634

  • Club Member
  • Newcomer
  • Posts: 17
  • Age: 29
  • Location: Indiana, USA
  • I'm trying my best here...
Re: 4 month lurker finally taking part in the forum! 1975 RD125b
« Reply #9 on: June 29, 2020, 04:34:45 PM »
Looking at your spares.
Your carb bodies have the extension wings under the mounting points, done on later bikes. This is for the vacuum balance line, the brass barb shown.
The idea is to connect a pair of vacuum gauges to the carbs and balance them to one another instead of the old way of using your ears, hand at the end of exhaust and judging clouds of blue smoke  ::) Very scientific ;) ;)
Yours seem missing the barbs. The barbs must be blanked after testing or the air leakage will mess up tuning.
One of my bike a PO did a neat mod to the reed valve body to get same effect  :)
Cheers
-Mike
PS
Your carb bodies should be painted gloss black  :P

Hmmm... I see where there WOULD be barbs, but none of my carbs have any openings for one. Definitely not one attached anywhere that I can see. Would have been convenient for balancing though.

Or am I missing something?

Circled in green are some random 'openings' I've never really paid attention to, but I don't think they actually go anywhere. Sprayed some contact cleaner and it just puddled up.

It's only 'open' on the right side carbs, the left side carbs have a little ball pressed in to that hole.

Also as for paint, they came bare metal, gunked up pretty good, so I just cleaned em decently and left em as is. I was worried contact with gasoline would have them lookin' a little rough down the road. If I do paint, do I just need some kind of enamel or engine paint? I have some 2k clear in a can for when I decide to repaint things, would that work? They don't really bother me much the way they look now, but if it's more likely to corrode or something I'd prefer to protect them.
« Last Edit: June 29, 2020, 04:36:51 PM by Shibby7634 »

Offline Astute Greaser

  • Club Member
  • Port Hacker
  • Posts: 534
  • Age: 63
  • Location: Bristol
Re: 4 month lurker finally taking part in the forum! 1975 RD125b
« Reply #10 on: June 29, 2020, 07:22:23 PM »
Don't worry about the holes, they are to do with cross drillings to put in the passageways in the carbs.

Enamel paint will work but you need a gasoline (petrol) resistant lacquer to go over that. The metal does go powdery white but lots are bare.

Your carbs come from the B models. The carb I showed you comes from a USA RD200C. So the on the B they have provided the mold wings ready for the C.

The picture shows how the drilling is provided. The cast circular indent on the wing, is the cross drilling and then blocked with a ball.
It is a feature you could add but one for the machine shop although quite a few here would give it ago  8)

Cheers
-Mike