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Truenotch's 1974 Yamaha FS50 (FS1)


Truenotch
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17 minutes ago, peteretep said:

man thats legit you got that stuff rewound

 

hey @Kimjon you should talk to markku about getting the wajax coils rewound. I never found anyone to do it, but could make the engine run without a battery

 

 

@Kimjon - google Ken Cairns Electrical and his phone number will come up. He works out of his home garage in Dinsdale and is a good old dude. 

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Yaaay, new parts day again! 

Bought a few bits to repair the slippy clutch. 

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New frictions and intermediate plate. This beast has TWO WHOLE friction plates. 

Also bought a new actuator arm mechanism: 

A9DE1249-2C09-49C3-A582-CA65108CD232.thumb.jpeg.7ef4cb14ac45b1f232c0be25e4260b72.jpeg

At the same time I got a push rod, a ball bearing and a clutch cable. 

And a nice new clutch lever to replace my knobless one: 

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Drained the oil and got started on disassembly: 

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Lucky I did as I found the main kickstart circlip had lost its ends! This takes all the load when the Kickstart engages... 

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I also got a new throttle cable and a set of points. I was able to make a hybrid of the old and new 2-1 cables to suit my new carb.... 

Things are lining up well for a weekend hoon? Albeit without a muffler on the spanny :o . 

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I’ve been mucking around with the tuning on this but it’s still not pulling all the way through the revs. 

So I got carried away measuring port timing, squish gap, compression ratio etc:

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Lifted it onto a table to save the knees of my jeans:

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The results are interesting: 182deg of exhaust duration and 144deg of inlet/transfer duration according to my super accurate paper dial gauge. 

This means that I should be able to deck the top of the cylinder a bit to get my correct squish gap. I was worried that my 0.9mm adapter/spacer might have thrown the port timing out, which would mean decking the bottom of the cylinder instead. 

I’ve also recently learned about how to set ignition timing with points, so I’ll set the timing right while I'm there.

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10 hours ago, Truenotch said:

 

I’ve also recently learned about how to set ignition timing with points, so I’ll set the timing right while I'm there.

grab a new set of points while your at it man, makes a huge difference, if you completely disassemble the points that are on it at the moment you will likely see some big pitting holes in the centre of the tungsten or whatever diamond spec hardness that shit is and will likely be slightly sharkstoothed as well. points are generally very cheap (sub $30) and are a consumable part that isnt replaces as often as they should. also condenser can cause missing and shit at high revs, unsure if yours is attached to the coil or the points, but probably another part thats worth replacing to get it running mint.

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1 hour ago, BLIZZO said:

grab a new set of points while your at it man, makes a huge difference, if you completely disassemble the points that are on it at the moment you will likely see some big pitting holes in the centre of the tungsten or whatever diamond spec hardness that shit is and will likely be slightly sharkstoothed as well. points are generally very cheap (sub $30) and are a consumable part that isnt replaces as often as they should. also condenser can cause missing and shit at high revs, unsure if yours is attached to the coil or the points, but probably another part thats worth replacing to get it running mint.

Yep, I'm onto it here. Fitted a new set of points after getting the source coil rewound :)

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1 hour ago, xsinclairx said:

Whats the carb that you're running?

 

1 hour ago, Raizer said:

Polini CP 19mm clamp on.

That. 

 

Took it for some test hoons with the 50cc cylinder today. Managed a top speed of 83kph on the GPS which isn’t too bad. 

Rode it out to @mark105‘s place and it was going well.... until the way home. 

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It stopped in Ohaupo and I couldn’t get it going again. Will pull it down tomorrow and figure out what happened. 

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15 hours ago, Steelies said:

Awesome! Could be worth throwing a stub exhaust on there to sort motor tuning then seeing what the differences are with the chamber fitted, then mess with that? 

That's a good idea. I'd been wondering if the chamber was causing bad things to happen in the mid/high rpm, so I'll give it a go when the 65cc kit is back from the machine shop. 

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RIP 50cc cylinder:

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looks like it lost a wrist pin clip which gouged its way out... the rod  and everything inside the crank case looks fine and there’s a small ding in the head. 

This 65cc kit better start working better, plan B just flew out the window :lol: . 

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8 hours ago, tortron said:

GUTS

 

you might consider teflon buttons rather than clips next time

Buttons sound interesting. I'm planning on using better clips though. The one that fell out was a single ring with no tab to grab when installing/removing it and I'd bent it slightly getting it out. It wasn't 100% seated in its groove but I decided to run it anyway... and then it decided to exit stage left. Not going to do that again :) . 

 

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Fitted a kick stand from @Yowzer's A100 parts hoard. I was getting sick of always using the centre stand - this will be much more suitable for parking on grass around the east coast. 

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Somehow it feels more like a "real motorbike" when it's leaning on the kick stand: 

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Gave the exhaust a quick coat of black: 

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Cleaned up the original head. It had a bit of a ding from the clip failure, but has cleaned up OK. I'll run these back to back and decide which to use once the cylinder is back from machining. 

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