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Author Topic: 1975 Yamaha RS125 Rebuild and Ascendance.  (Read 2209 times)

Offline alaincam

  • Posts: 7
1975 Yamaha RS125 Rebuild and Ascendance.
« on: Jun 17, 2016, 03:48:18 »
So Hi there my name is Alain im 21 from the tiny sunny island of Malta. I love cars and anything on wheels, I am a Database Developer and geek by trade, Im a petrolhead and a geek at the same time. Building an old 1975 mini to go rallying and pleasure rides in, I always wanted a bike and wanted to see how well I could build and convert one.

I searched local classifieds to find the biggest piece of shit I could find on the island and this is what i came up with.




The Previous owner completely butchered the frame raised the seat of an already very high bike, head wired fetish with spikes and put spikes of the front of the frame and the handle bars and as far as i can tell never services the 2 stroke 125 engine. An despite all this it was PERFECT.

First thing i did is I blew it apart and blasted it.




Next remove all the shit the previous owner put on the frame .



I left the front spike for while to see how it looked ultimately I removed it.



Next up was the engine service and clean up.



I cleaned the bore and piston with a wire brush and ported the intake port a bit. I changed all the gaskets and flushed the engine and it was good as new wow 2 strokes are great to work on.



After reassembly I painted the heat stinks on the head black with high temp paint and also the oil pump covers.





II rebuilt the front fork assembly and attached the new head lamp I bought for it to get feel for a style ultimately I decided to mix it up a little. A hybrid between a flat tracker and a Brat sytle.





Painted the tank in gloss black and most of the frame and tried the fitments of the engine in its place. Also I golded the mikuni carb



I bought a set of new shock absorbers with height adjustment I forgot the name of the company but the look awesome coated in zinc and much safer the rusty ones it had on.



I had a seat made custom here in malta set me back around 70 euros quite cheap and it love the way it came out considering that my drawing skills are that of a 2 year old the template I gave the guy actually turned out awesome proud of this. I test fitted it in these pictures I still have to elongate the frame.




 
I recycled the tubing from all the bullshit i removed from the frame to elongate the seat mounts . I was gonna weld them using the MIG welder but the ARC welder worked better for this gauge of tubing so when with that .



Still need to dress the welds but quite strong and it should hold up nicely

A bit more recycling and innovation the previous owner cut of the original fender but i only needed a small piece to make a small fender where to mount the rear light.



And seat attached and fender mounted looking good.






Got new gauges because I was not given any by the previous owner and made a mount for them to attach under the handle bar pedestal and they look great in black. Got me a glow in dark clock accessory and gold tipped handle bars and done



Now you might be asking what is that gold reservoir for considering this is an all cable operated bike clutch and everything. Well I had a dilemma on the the 2 stroke oil tank. This has a prelube system and it has this big ugly tank that covers up the bike and sticks out like a soar thumb so I decided to get creative with a solution. I bought a clutch master reservoir mounted it to the handle bar it feeds down to a clear acrylic reservoir used in pc water cooling tanks and that in turn feed the oil pump / so i ca monitor the oil level and fill it up with convenience from the top of the bike further more I think it looks cool and all mounted up and is a simple solution.





All that left is Tyres, clean up the rims and Wiring and she is done.





And here is my sister on the bike.She will probably want to take it from me.



Cheers

Offline NoRiders

  • Posts: 688
Re: 1975 Yamaha RS125 Rebuild and Ascendance.
« Reply #1 on: Jun 17, 2016, 05:38:08 »
Good effort Alain, nice little runner you got there, nice fat tyres would set it off a treat.....it'd be nice to see it out on the road....with a better camera perhaps?  ;D

Offline alaincam

  • Posts: 7
Re: 1975 Yamaha RS125 Rebuild and Ascendance.
« Reply #2 on: Jun 17, 2016, 05:55:47 »
Hi yeah the camera is shit I took the photos with my phone quickly. Il Crack out DSLR and take a good photo-shoot. Thanks for the feed back. On tyres what would be a good size front and rear for something like this . I know the rear one was a 17 3.50 how big can I go and what style ? . Also cause I couldn't find any knowledge on this what battery does it take the previous owner butchered the wiring loom aswell and Im literaly going on trial and error I managed to find an wiring diagram but thats about it not much info on these magneto models. Cheers ;D

Offline NoRiders

  • Posts: 688
Re: 1975 Yamaha RS125 Rebuild and Ascendance.
« Reply #3 on: Jun 17, 2016, 06:57:33 »
Opinions vary widely on tyres, sports, enduro, modern or classic? Factors such as rim width and clearance will decide the biggest section tyres that will fit and work well for your riding style. Will you be using this as a daily, in all weathers on tarmac or will it be a play thing used on varied terrain and surfaces in mainly dry/good weather?

As you've built it to look like a scrambler/tracker yu were considering enduro tyres which offer a balance between road/off road grip and performance. It will also depend on what's available in Malta and budget of course?

Personally, I like the look of semi chunky enduro tyres in the largest size that fits. They can make or break the overall look in my opinion, but compromises in performance/budget etc might have to come into play

Maybe ask on the Wheels, tyres & brakes forum on here, good advice can come quickly which will help you decide.

Batteries: The traditional wet batteries are being outmoded in favour of gel or micro batteries to tuck away, both are readily available with a standard size gel upgrade working out cheaper than a micro battery. Not to sure what will work with the Yamaha set up though?

I'm going for a MotoBatt gel, as I will use the stock battery location on the CBX.
Wiring will be farmed out to my son who understands the 'black art' much better than me ;)

Offline alaincam

  • Posts: 7
Re: 1975 Yamaha RS125 Rebuild and Ascendance.
« Reply #4 on: Jun 17, 2016, 07:08:44 »
Thank for the advice il have to measure the maximum size i can fit without disrupting the chain. I think semi enduro are best I also like the look and Malta is strange when it comes to roads some are world class smooth others are 3rd world.

I was looking into gel batteries but I know its 6v system but im not familiar with the way this works but il just have to start and see. The wiring loom is simple enough to follow. I hated electrical diagrams when I had Physics at high school but it cannot be worse then 70s Morris mini wiring can it :P

Offline NoRiders

  • Posts: 688
Re: 1975 Yamaha RS125 Rebuild and Ascendance.
« Reply #5 on: Jun 17, 2016, 07:32:24 »
Thank for the advice il have to measure the maximum size i can fit without disrupting the chain. I think semi enduro are best I also like the look and Malta is strange when it comes to roads some are world class smooth others are 3rd world.

I was looking into gel batteries but I know its 6v system but im not familiar with the way this works but il just have to start and see. The wiring loom is simple enough to follow. I hated electrical diagrams when I had Physics at high school but it cannot be worse then 70s Morris mini wiring can it :P

Measure across the swingarm as well as the front forks/guard area, these are the most likely places the tyres would rub.

I have a friend in Malta who complains about the state of the roads almost every week haha! We should all complain.

Gel batteries just replace the usual acid fluid and are sealed, so can be mounted sideways by all accounts. The micro/lithium batteries can have the same power/amp ratings but in a much smaller form factor, but costs are double at least. As you're running lights or full electrics pay attention to the aH (amp hour) rating to match it with the stock battery specification otherwise you might lose battery capability with lights on for a while? I'm no expert, but matching performance is key to reliability IMO.

Offline alaincam

  • Posts: 7
Re: 1975 Yamaha RS125 Rebuild and Ascendance.
« Reply #6 on: Jun 17, 2016, 07:49:30 »
Cheers il take out the multi-meter and get cracking after work :) . I am glad im not alone when it comes to roads in Malta :P haha .

Offline alaincam

  • Posts: 7
Re: 1975 Yamaha RS125 Rebuild and Ascendance.
« Reply #7 on: Jul 29, 2016, 19:53:42 »
A quick update hehe.