Truenotch

Truenotch's Tiny Tracker - Yamaha MX100

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Then I decided to delve a bit deeper. These are CDI, which I'm stoked about as the points are the biggest letdown on the FS1. 

I was pleasantly surprised to find that the magneto cover screws came out without needing an impact driver. The cover took a couple of taps to come off, and then this gushed forth: 

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I need to get my flywheel puller back from @flyingbrick to assess the situation properly, but that bad boy was full of rusty water! I'd say the cover area was at least half full by the look of the flywheel. 

I'm quite confused about how it got in there... My current theory is either that water has slowly seeped in during it's time stored outside or the thing was driven through a lake before it was parked up and maybe took a mouthful of water into the engine, which has eventually come out through the crank seals? Who knows! 

 

More investigation required. 

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That's funny, I have a yamaha mx1000. A glorious 250...... 

 

 

 

 

 

 

 

 

 

 

 

 

Watts per channel.. 

 

 

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10 minutes ago, yetchh said:

That's funny, I have a yamaha mx1000. A glorious 250...... 

 

Watts per channel.. 

Hah! Steve and @mark105 had a similar experience with Steve’s DX100. Apparently his bike is a keyboard.

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Pulled the flywheel off: that’s one crusty stator plate! 

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Any bright ideas on the beat way to clean the coils?

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PCB cleaner. They have a shellac type varnish on the old ones and any alcohol will dissolve it

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Jesus.. what a mess.

What about a soak in vinegar? Should (im no chemist, only guessing) disolve all the rust and leave the varnish and copper alone?

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Gave the magneto and cdi pickup a good clean and threw it back on. Checked for spark and it was strong. Win!

Today I collected a POS RX125 parts bike that had a DT100 engine. I took the gamble that the engine would be the same as it had a fresh oversized piston and machined barrel. 

Turns out there’s quite a few subtle differences, but it’s mostly the same. The barrel has the same casting numbers and looks identical. 

Got it home and started ripping bits off it. 

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fitted the barrel to the MX100 

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Chucked on the FS1 tank as it still has some premix from the East Cape mission. It looks quite good with this tank! 

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Got it together enough for a test run.

 

Success! It runs. That’s one win for the weekend :) . 

 

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35 minutes ago, TimShadboltfan27 said:

Let me know if you wanna flog any rx125 bits off I could be keen...

Flick me a PM with your shopping list. At this stage I’m only using the engine, rear wheel, swing arm and some electrics.

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Haven’t made much progress with this lately, but have bought a couple of bits to help with inspiration.

Picked up this spanny, most likely from a YZ125 apparently. Offered it up to the bike and it looks like it’ll work with a bit of fettling.

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Also found this tank and guard that are a bit more suited to the style I want:

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might need to shorten the tail of the bike a bit to get the proportions right as the tank is slightly shorter than the original, but I’m happy for now. 

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The countdown to Te Urewera is on! 

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So far I've managed to complete a few things: 

  • Replaced broken front brake lever
  • Made headlight and tail light work
  • Fixed lighting switches
  • Shocked myself trying to operate the kill switch 
  • Installed a horn button from another bike as a kill switch 
  • Fixed chain tension (it was floppier than I've ever seen) 
  • Tightened head tube bearings 
  • Checked oil pump - it works! 

The previous owner was pre-mixing the gas because he doesn't trust self-mix setups... But it still has 1/4 of a tank of oil and my from my tests it seems like the pump works fine, so it would have been RICH on oil the whole time he owned it.

Still to do: 

  • Fit new front tyre
  • Luggage rack / panini paneer panniers
  • Mount number plate
  • Carb clean and rebuild
  • Fit an ignition barrel / key / anti theft device 

It also has a bit of a rattle that I think could be piston slap or a noisey kickstart idle gear. More diagnosis required. I've poked my finger up the exhaust port and it certainly seems to have some slap at BDC. It might need a good warm run before I can diagnose it properly. If it comes to it, I've got a freshly bored cylinder on the other MX that can go in its place. 

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New front tyre fitted:

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Speedo in place:

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Dodgy epoxy job to keep the sensor where it should be. I slapped a couple of neodymium magnets onto it for a stronger signal:

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And this sweet accessory courtesy of @Geophy. Perfect for a few beers and other paraphernalia. 

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Took the FS1 for hoon with the Speedcocks after work. Good practice for Te Urewera, but it would have been nice to be on the MX! 

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When I got home I was inspired to work on the MX. First up, I took a video of the rattle that I suspected to be caused by piston slap:

The camera did a good job of picking up the sound. It didn’t sound this bad IRL. 

I had a re-bored and oversized barrel/piston on rev other MX, so pulled that off and swapped them over. Here’s what it sounds like now: 

Much better! 

It has a bit of lean-hang going on, so I’ll pull the carb apart, clean it and check the jet sizes before a shakedown on @mark105‘s paddock this weekend. 

Here’s a  pic of it looking more complete for good measure:

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Carpe diem: seize the day.

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I blarped around town all morning yesterday - the bike is fun! Tried to ride it out of town with @Beaver and got about 1km at 85kph, then it locked up. It’s had quite a bit of lean-hang and I probably should have looked into it more.... 

I suspect the left hand crank seal is the cause. Pulled the flywheel and stator plate off and you can see evidence of oil that’s made its way out. 

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I’m going to throw some crank seals at it this week, clean up the piston / barrel and hope for the best. 

2 stroke 4 lyfe.

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