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Nick's 1979 RX125 resto


TimShadboltfan27

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  • 2 weeks later...

Got bored and cleaned up the motor a lil. Can of degreaser later and she came up somewhat presentable.

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Thinking of giving it a paint, but really don’t want too much matte black on it, like most builds end up. The alloy is worn in places so I might do the side covers and try polish the head and barrel. 

Also made my first yambits order - clutch cable, front brake lever and ignition and key set. Will probably drip feed it parts every couply weeks as it’ll be a few months til I’m back up to put them on and do more work. 

Next on the list will be a full rebuild kit for the front brake. 

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  • 3 months later...

red RX125 was put on the chopping block and sacrificed for the greater good.

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removed front end, seat, sidecovers and oil pump from the red bike.
After a bit more tinkering i was unable to get the red one to start up due to a lack of spark. I got the silver one running on carb cleaner at full throttle as carb is jammed. was quite lol, much cheech out the zorst. this all confirmed that i would use the spare motor ive got as it is the tidiest and has the cleanest bore and piston head. It was run on premix in its last life so needed to put an oil pump on from another bike. 

gonna order some bits and then get the good one running and riding, then strip er down.

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  • 4 weeks later...

baby steps!

got a Flaxmere master key and got the cap open. Was pretty gross in there, so bought a catering sized bottle of white vinegar and smashed that in there. gave er a good ol swishing and let it sit for two weeks. 

let nature do its bidness, came back 2 weeks later and flushed her out. zero leaks which i am stoked about, so no pesky pinholes or cracks in the seams. 

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got it looking pretty good in there! think ill get a tank liner for it eventually. have ordered a new tank cap, petcock and fuel filter so should be able to hold petrol now!

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  • 2 weeks later...

aaaaand donk back in. Yesterday we nanged down to palmy and grabbed the 3rd bike in @00quattro00's BA XR6, using far too much gas doing trailer nangs on gravel roads and zututu'ing cunce on the expressway.

took me all of 2 minutes to throw it in and bolt up. god i love these small bikes. 

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everything was coming up milhouse, the replacement motor threw good spark, but then the kickstart shaft seized on me. it felt pretty sloppy to begin with, these have quite a lot of slack until they engage the crank, this one particularly more so. good excuse to pull it apart and give it a birthday i guess. failing that i could just throw in one of my other three motors...

any have a shit photo of my fleet of rusty 2 strokes

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  • 1 month later...

made a bit of progress. So i had the motor buttoned up in the frame, but needed some gubbins to get it to run.

I stripped the carb and gave it a little clean. the fuel and oil lines were solid and crusty. i spent this morning trying to track down some fuel hoses and after visiting a few places found what i was after. also got a new throttle cable, feels super lush. plumbed oil pump into motor, topped up the 2tang, filled motor with gear oil, made some premix for the tank at 50:1 and thought by jingo, this thing might actually fire!

and it did! but not nicely... it would only run on choke and throttle hung up a fair few times. it's not running well at all but at least it fires and kinda runs if you massage the choke and throttle. current state:

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next i'll probs get the carb ultrasonic cleaned, track down a carb kit and a gasket set to make sure all the surfaces are mating like chimpanzees. 

but yeah cool this thing made ring dings and clouds of blue smoke! yay!

 

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  • 2 weeks later...
  • 3 weeks later...

got round to completely stripping this bad boy, and is now a neat-ish pile of bits. got mildly overwhelmed looking at all the bits there wondering if i'll remember how it all goes back together. she'll be right jim

so i have the frame bare, along with swing arm, brakestay, triple clamps and stands ready to be sandblasted and powdercoated. that will be next weeks mission. Then can finally begin the glorious task of putting it all back together! really going against the oldschool tradition and actually making progress on this. 

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in other news, i have ordered a whole bunch of shit from Yambits, swingarm bushes, seals, sprockets and the likes, along with a carb kit. The arrival of these bits will coincide quite nicely with getting frame stz painted.

 i also spent today taking apart the front brake caliper and line. I thought at first that the master cylinder was good. but after trying to give it a bleed i realised it wasnt actually letting any fluid flow through. the inside looked like a Castle Street bathroom. Brown Jim put me onto one of these Aliexpress master cylinders, which could be had for a ridiculously good price.

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it arrived last week, i wanged it on and by gum she bled up and felt goooooood. Then i took apart the caliper and it too resembled a toilet in a student flat. But alas, a piston and seal kit are on their way. 

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Lots of words! tldr? We're gittin 'er done

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  • 2 weeks later...

gaw blimey, the frame and gubbins are back from the painters, was stoked on the three working day turn around. even more stoked on the finish! potato poor light pics dont do it justice, the finish is grouse. I went for a sandblast and then an epoxy chassis/industrial paint, its a decent coat and has a real nice gloss to it. cant wait to get it all greasy and yuck reassembling.

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If anyone was interested; frame, swing arm, brakestay arm, triple clamps, side stand kick stand to sandblast and paint was $200. Can thoroughly recommend Comac Industries here in Napier, good dudes who pine over classic bikes and have some rad solo speedway bike memorabilia around the office.  

Carb kit has arrived, waiting for my yambits package then she'll go off like a long tailed cat in a rocking chair factory 

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  • 1 month later...

more progress these last couply weeks, ordered a bunch of parts which have arrived but still few more yet to come. 

todays job was fork seals, everybodys favourite. Yamaha's quality suspension components were on display when removing the old seals...  yay for hoarding parts bikes!

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lots of rust and old fork oil sludge. now forks are back together looking a lot better than when they started. the stanchions came up alright with sandpaper and steel wool, the super rusty shit is gone but there is still a fair bit of pitting in spots, i am skeptical as to what the WOF man will say come re-vin time. i will just whack a pair of gaiters on in a half-assed effort at hiding it.

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bikes coming together! waiting for headset bearings to arrive this week, then can keep assembling bike. Then fit new tyres, rebuild carb, sort out front brakes, get her running and take it for a skid!

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  • 1 month later...
3 hours ago, Flauski said:

If your rebuild kit didn't come with a float valve replacement that will be your culprit for over fuelling.

As I pointed out, the original one was dicey and not operating smoothly. 

Good to hear its runnin and smokin'! 

had a new one to go in but it was in there quite loosely, i will strip it down once again and double check everything.

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On 08/08/2019 at 14:49, TimShadboltfan27 said:

had a new one to go in but it was in there quite loosely, i will strip it down once again and double check everything.

if its anything like the GP removable needle seat there should be a tiny o-ring around the seat that holds it in snug when it goes in, the replacement carb i got didnt have one on it and did massive dinosaur wees until i realised why 

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  • 2 weeks later...

ho ho hoooo park your peepers to the 500m mark and check out the latest edition of RX125 escapades

As previously mentioned, carb has been doing mega wees out the overflow of the carb bowl, and i set out to rectify this problem. Well fuck me dead this drove me up the damn wall. no matter where the floats were set, it would leak out the overflow. i had two carbs to test out, and both leaked when i put fuel through them. 

There's not much information on these bikes on the innerwebs. seems they have been forgotten/no one gives a fuck about them enough to put any decent info up online. the closest spec i could find was 21mm float height. After setting both carbs to this height i was still getting wees all over the motor. adjusting the float height either way by bending the brass tab was not changing anything. Only way it would stop leaking was if you set the floats so high that the needle valve was closed all the time. This should have raised alarm bells to me...

turns out the overflow tube in the float bowl was loose - meaning any amount of fuel in the bowl would wee out the overflow. perhaps in the ultrasonic clean this had been rattled loose or it was like that beforehand. I guess the other carb i had had a fucked needle/seat which was giving me a false negative type set up. 

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So yea have a video of it running nicely all on its own, no choke no leaks! it does a tiny dribble out the overflow which can be solved with a little fine tuning of the float height, but stoked that its holding its fluids like a big boy.

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Can someone whos not a spoon like me embed it haha

Only a few minor jobs to do

- free up sticky throttle cable
- fit joiner elbow thing to airbox/carb and tune properly
- get all lights working properly etc
- get a mirror
- take it for a decent spin
- revin!

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