Wanted to post an update-- it's been awhile, fam. Photos to come later.
I have assembled my engine and was able to start it for the first time. It runs surprisingly well! The throttle is responsive and the pipe sounds nice. It idled without having to tweak the carb, that was a nice feeling. I set the HPI timing to the default setting, according to the instructions that came with the ignition kit. I will dial this in at a later time.
Speaking of a later time, I am unable to test ride right now. Weather aside, my 'MLM reinforced radiator' from Treats had a defective + bent neck and leaks coolant, despite swapping caps and attempts to level the sealing surfaces. I am also waiting on my voltage regulator / rectifier in the mail. I have an electric AC Delco water pump ($45 from Amazon) that runs off of 12v, currently powered by a cheap little scooter battery instead of the HPI.
In terms of replacing the defective radiator, I researched for another with an inlet/outlet matching the spigots on the Treats radiator. The Treats one has matching inlet/outlet ports of 16mm / .63". I settled with a Mishimoto closeout model for a KX450F for ~$30 that I'm waiting on in the mail. In the future I will not be buying another Treats radiator due to price and quality control issues. (EDIT: I see the Mishimoto has had a price adjustment / restock to $120. Ha!)
The stock vacuum petcock will not work without vacuum on this bike. I deleted my vacuum lines, so I decided to buy a chinese replacement with the same thread specs (16mm x 1.5mm). I attempted to drill a hole through the vacuum diaphragm in the stock petcock and accidentally drilled through the whole thing. Schwoops.
Regarding the intake / carb, I chose to use the stock plastic reed spacer, however this puts the carb really close to the frame. To avoid issues when the frame moves (shocks), I made intake spacers + gaskets for the carb to push it out a little. This is not intended as a permanent solution.
The pipe fits, but the bracket hole for the crankcase is not in the right spot. I hacked off my electric start section of the crankcase to fit the H95 pipe, so I was a bit salty when I discovered that the pipe doesn't fit without modification, esp since it costs nearly $300. (the NU50 motor, what this is intended for, has case holes in the same spots as the NX50, so it's a quality control issue with MLM). I drilled a hole in my case for the pipe bracket and just made it work.
To fit the Hobbit HPI, I had to drill/ tap two holes for the backing plate bolts. This took maybe 5 min, but I had to buy a cheap tap set (grumble, grumble). It just worked the first time I started the motor. I was genuinely surprised.
- 70cc Malossi H20 cylinder Kit (no porting)
- H95 NU50 MLM Expansion Chamber
- .4mm Carbon Reeds
- Mikuni VM20
- MLM VM20 NU50 intake
- Conrod from stuffy PA50 crank
- Hobbit HPI mini rotor
China Petcock Replacement
AC Delco Water Pump
Cheap $12 TDC Tool
NU50 Battery (wrong size but fits in battery tray, really need NX50 battery)