Yamaha RX125

[boars]

My gal expressed some interest in trying to ride a bike so I took the opportunity to go out and grab something cheap without too much power. Something that's simple as hell and I can pull apart quite easily and learn some basic mechanics on. As such I found a little 1979 RX125 a suburb away from me... it reminded me of the first bike I ever had being a road legal Yamaha GT80. Since it was so cheap I got it delivered last week (wasn't registered at the time).

More pics at: https://picasaweb.google.com/103761...&authkey=Gv1sRgCLr7tsnFiunTVA&feat=directlink

Power has been a little interesting... fluctuates a bit... then stalls completely (occasionally) with headlight and indicators on.

Not sure why power is fluctuating so much, having said that it has been sitting in a garage for a year or two. In hindsight I should have dumped the fuel out and checked it out. Forgot to ask the bloke if it was fresh fuel. Instead I topped it up at the servo then put air in the tyres... well I did for the rear... the front tube deflated and left me with a 1-2km push home in the rain :cheer:

Took the front wheel off today... which will allow me to bleed the front disc brake and clean it out, seems a bit gummed up and isn't releasing the disk as well as it should. Anyone know what parts are interchangeable with other more common models? It looks a lot like the disk brake on an RD125... not 100% tho. I assume I should look at new seals when putting the calipers back together after they are cleaned?

I'm thinking of switching to LED indicators - since I noticed there are 6V LED's... would this improve draw on the battery to any extent? The battery might need a good charge but either way, if I can do anything to minimise the draw, that's all for the better.

With all that said the only thing I've really been dissapointed with has been the headlight, it starts and runs pretty ok, aside from the power fluctuations... I didn't expect the headlight to be awesome tho! If it was possible to replace it with another 6V thing that was a bit more effective tho... that'd be something to consider too.

It's nice to have something to tinker with that wont stop me from my daily commute !

 

[boars]

Forgot to mention the mirrors vibrate like crazy... just ordered some drop clubman bars in black with some bar end mirrors. Might try filling them with ballbearings/sand, getting some solid bar end weights and see if that'll help with visibility.

Went with the dropped bars as the riding position is a little too upright for my liking... I have a feeling I'll end up riding this more than the gal :spank:

 

[TownsendsFJR1300]

Neat little bike!! That 2 stroke will feel like a 250 4 stroke when running good.

You probably have removeable caps in the battery (not maintainance free) and I'd bet the water level is low/empty. Top off with distilled water and re-charge, you may luck out..

I'd also dump that fuel get the gas tank nice and clean. There should be a drain screw on the carb float bowl, drain that too. If a bunch of crap cmes out, I'd probably pull the bowl and least clean the lower end of the carb from varnish. Chevron Techtron and Seafoam will help clean the fuel system as well.. I had the carbs on my old 1975 RD 350 (first street bike in 1977) varnish up way back in 1978 and have crap in the bowls. Once cleaned, ran great (it actually died from the carbs about 2 blocks from the house and had to push it home)


As for the brake caliper, while its apart, I agree, change out the two seals, they should be cheap enough. Yamaha recommends changing them every 2 years for the FZ, much more important on a 30+ year old bike.. If you can find a master cylinder kit, it'd probably be a good investment..

I've never heard of an RX model, my old RD350, way back, was a fast little bike.. They look about the same, less a cylinder.. Oil injected, reed valves, rear drum brake..

Congrates and good luck.

 

[Kazza]

That is AWESOME! I love it! Good bike for her as a starter

How much did ya pay for it?

 

[TownsendsFJR1300]

I looked up for parts on various Yamaha sites (in the US) and cannot find that model at all...

I wonder if it was available in Europe, etc only?

 

[Kazza]

Yamaha RX 125 Year 1980 - Yamaha Owners Club


Bit more info - purdy

 

[Nelly]

My gal expressed some interest in trying to ride a bike so I took the opportunity to go out and grab something cheap without too much power. Something that's simple as hell and I can pull apart quite easily and learn some basic mechanics on. As such I found a little 1979 RX125 a suburb away from me... it reminded me of the first bike I ever had being a road legal Yamaha GT80. Since it was so cheap I got it delivered last week (wasn't registered at the time).

More pics at: https://picasaweb.google.com/103761...&authkey=Gv1sRgCLr7tsnFiunTVA&feat=directlink

Power has been a little interesting... fluctuates a bit... then stalls completely (occasionally) with headlight and indicators on.

Not sure why power is fluctuating so much, having said that it has been sitting in a garage for a year or two. In hindsight I should have dumped the fuel out and checked it out. Forgot to ask the bloke if it was fresh fuel. Instead I topped it up at the servo then put air in the tyres... well I did for the rear... the front tube deflated and left me with a 1-2km push home in the rain :cheer:

Took the front wheel off today... which will allow me to bleed the front disc brake and clean it out, seems a bit gummed up and isn't releasing the disk as well as it should. Anyone know what parts are interchangeable with other more common models? It looks a lot like the disk brake on an RD125... not 100% tho. I assume I should look at new seals when putting the calipers back together after they are cleaned?

I'm thinking of switching to LED indicators - since I noticed there are 6V LED's... would this improve draw on the battery to any extent? The battery might need a good charge but either way, if I can do anything to minimise the draw, that's all for the better.

With all that said the only thing I've really been dissapointed with has been the headlight, it starts and runs pretty ok, aside from the power fluctuations... I didn't expect the headlight to be awesome tho! If it was possible to replace it with another 6V thing that was a bit more effective tho... that'd be something to consider too.

It's nice to have something to tinker with that wont stop me from my daily commute !

What you have there my friend is an excellent example of a 6v charging system. I had the model before that one and the model after.
On the 6v bike the light was only half decent when the motor was reving pat about 5000 rpm with out power it would fluctuate badly.
Good luck with it.
Nelly

 

[motojoe122]

Yamaha RX 125 Year 1980 - Yamaha Owners Club


Bit more info - purdy

"Baxter...you know I dont understand spanish!":BLAA:

 

[ChevyFazer]

"you ate the whole wheel of cheese! Wow I'm not even mad I'm actually kind of impressed!!"

 

[boars]

That is AWESOME! I love it! Good bike for her as a starter

How much did ya pay for it?

The official figure is 600 :thumbup:



Wish I lived in Melbourne today, gotta wait for one to be shipped up here now.

 

[monb]

"As for the brake caliper, while its apart, I agree, change out the two seals,
they should be cheap enough. Yamaha recommends changing them every 2
years for the FZ, much more important on a 30+ year old bike.. If you can find
a master cylinder kit, it'd probably be a good investment.."

Could this be why I can't make my 15k mi 06 fz6 brake like when it was new? I put on EBC brakes and Bled it numerous times. It got a little better but never got that grabby 'out of the showroom' brake feel back. Would rebuilding the calipers make a difference? Any thoughts on steel brake lines?

 

[TownsendsFJR1300]

"As for the brake caliper, while its apart, I agree, change out the two seals,
they should be cheap enough. Yamaha recommends changing them every 2
years for the FZ, much more important on a 30+ year old bike.. If you can find
a master cylinder kit, it'd probably be a good investment.."

Could this be why I can't make my 15k mi 06 fz6 brake like when it was new? I put on EBC brakes and Bled it numerous times. It got a little better but never got that grabby 'out of the showroom' brake feel back. Would rebuilding the calipers make a difference? Any thoughts on steel brake lines?

The brake caliper seals, when worn, harden and cause the caliiper pistons not to NOT RETRACT, basically causing the brakes to drag.

After cleaning/regreasing the brake seals in my 07, I went from about 3/4 of a free spin (spinning by hand) to approx 2 full turns (much less drag..)

Unless the brake seals are leaking or the MC is failing, it's not your problem. You could have some air in the hoop (the line over that wraps over the fender). Rubber lines flex (expand) and with age, expand more (spongier brakes) with age..

And yes, SS brake lines make a world of difference, very recommended. I think my HEL lines were under $100 for a full set (custom lenthe). The straight thru (two lines) are much easier to bleed (and a lot cheaper than the stock ones- also recommended by Yamaha to change out every 2 years)

 

[boars]

And yes, SS brake lines make a world of difference, very recommended. I think my HEL lines were under $100 for a full set (custom lenthe). The straight thru (two lines) are much easier to bleed (and a lot cheaper than the stock ones- also recommended by Yamaha to change out every 2 years)

I'm quite interested in upgrading the lines on the ol' RX, are those two line types usable on any bike? I just have to measure the existing line and order one of the same length?

Oh and the RX appears to be pretty much an RS.

Thanks for all your input, it's much appreciated.

 

[TownsendsFJR1300]

I'm quite interested in upgrading the lines on the ol' RX, are those two line types usable on any bike? I just have to measure the existing line and order one of the same length?

Oh and the RX appears to be pretty much an RS.

Thanks for all your input, it's much appreciated.

Did you mean an "RD" (not an RS??)

I know HEL makes custom lines and your banjo bolts are likely standard. You'll have to find them on-line (or a dealer) and see about orderering a set. I ordered mine thru my local guy (about 1.5" longer than stock as I have bar risers)

Your single caliper should be a piece of cake to assemble (only one single line, not a double like the FZ6 with dual calipers).

 

[boars]

Did you mean an "RD" (not an RS??)

I know HEL makes custom lines and your banjo bolts are likely standard. You'll have to find them on-line (or a dealer) and see about orderering a set. I ordered mine thru my local guy (about 1.5" longer than stock as I have bar risers)

Your single caliper should be a piece of cake to assemble (only one single line, not a double like the FZ6 with dual calipers).

Nope, I meant the RS Here's an RS125 a guy here in brissie did up as a project (altho the url says RX):
Lane Splitter: rx125

I am not sure how similar an RS/RX and an RD are... I'll have to look that up

I guess I'll wait till I've got my new bars fitted before getting a new line... would pay to know how much lower it will sit... and thereby not stuff up the measurements :spank:

 

[TownsendsFJR1300]

Nope, I meant the RS Here's an RS125 a guy here in brissie did up as a project (altho the url says RX):
Lane Splitter: rx125

I am not sure how similar an RS/RX and an RD are... I'll have to look that up

I guess I'll wait till I've got my new bars fitted before getting a new line... would pay to know how much lower it will sit... and thereby not stuff up the measurements :spank:

An RD was in the US as at least a 250, 350, 400, not sure about a 125(don't think so but looks just like yours but they were parallel twins).

May I ask where (country) your at? I ask as I've worked/rode numerous Yamaha's since 1971 and never heard of your model. I had a 1975 RD350 that was very, very similar to yours, just a twin...

 

[boars]

I'm in Australia. :thumbup:

Edit: Seems i got mixed up with the dual lines... I'm wanting new lines for the FZ and the RX, RX after new bars... FZ after my front end R6 forks/clipons change.

Anyway the RD looks similar but yeah it's a twin as opposed to the single RS/RX. Wonder why they differed... didn't have a single equivalent in USA at the time? Would be nice to have dual pipes, not a massive fan of the lopsided single zaust but eh still love it tho.

 

[TownsendsFJR1300]

I'm in Australia. :thumbup:

Edit: Seems i got mixed up with the dual lines... I'm wanting new lines for the FZ and the RX, RX after new bars... FZ after my front end R6 forks/clipons change.

Anyway the RD looks similar but yeah it's a twin as opposed to the single RS/RX. Wonder why they differed... didn't have a single equivalent in USA at the time? Would be nice to have dual pipes, not a massive fan of the lopsided single zaust but eh still love it tho.

Ok, that makes sense ...

Some models just don't make it over to here. There may have been an RD125 in the states but I don't believe so. I know there was never an RX model (in the states) from at least 1973 and up, all RD's..

Your bike appears to be pretty much a half of an RD 250 in excellent condition. I miss my old 1975 RD350, (an old man turned left in front of me in 1977, totaled it and almost took me out indefinitly when I was 19)

 

[turbid]

what power are you saying is fluctuating? the engine's or the headlight? the headlight needs some revs for the magneto/coil to give it some juice to be half decent. the batteries die almost daily on these bikes, you need to have a 6v charger handy and give it 2hr charges. yeah clean the fuel tank if its rusty and the carb otherwise it wont run well. check engine timing is spot on as well as it will foul the spark plug

i have a 79 kawasaki kh100 very similar to yours that im restoring and trying to use it as my daily commute, but i,m afraid to use it for work... if it doesnt start in the first 3 attemps it floods the carb and it wont start no matter what, petrol starts spewing out of the float chameber, then the battery dies and no indicators and horn can be used. i smashed its fuel tank last saturday with frustration! ( i have to fix it or buy another one)

 

[boars]

Yeah, the engine power fluctuates as in it feels really gutless then all of a sudden it'll roar into life a bit.

I haven't really ridden it much tho, since I've got the front wheel off, figured I'd get some nice new rubber on the front wheel. Am still waiting to hear from the tyre place I left my wheel at.

The headlight fluctuates a bit with the engine revs, which is to be expected... but not really worried about that.

I bought a couple of 6V LED indicators... when they arrive I'd like to try them out. Not sure if I'll need electronic flashers for them - have only seen 12v flashers. I'll have to have a hunt around tomorrow.