After delivering the TSM last Tuesday the bike seized, apparently at fast top speed going up hill and returned to the shop that same night for a check up. That was a first for me in 2 straight years of building engines.
I’m not sure what caused the engine to seize but it happened on a very hot day. It might have been of combination of overheating, the 19mm 4 stroke carb slightly too lean, the 70cc kit revving too high up hill with the launch lever pressed for too long, points ignition rotor slipping, or probably an air leak from the old 50cc head gasket unevenly cut by the previous owner to fit the 70cc cylinder… I could have probably saved the cylinder but the piston was ruined.
I got new parts from Treats Friday night and rebuilt the engine with a new polini 70cc kit + head, bigger 21mm 2 stroke carb and MVT Millenium cdi ignition. I also toned down the engine with a smaller rear sprocket, heavier variator weights, doppler exhaust extra spacer, no porting and retarded the timing to keep the temperature down.
During the summer season most air cooled moped engines suffer a lot, especially peugeot kitted engines because of their small fins matching the stock engine’s look. It’s probably safer not to hold top speed for long period of time.
I’ve been riding and breaking in the new polini kit the entire weekend. The bike feels good with less rpms but still plenty of power and hopefully more reliability under any riding conditions, traffic, top speed, hills, high temperature, excessive use of the launch lever, etc…
The bike is ready for take two.
Test run on Hollywood Blvd.
Casey (Toecutter peugeot 103 owner) just dropped his Peugeot TSM 70cc polini. I’m excited, this is my first Peugeot top tank project. I’ll try to get it ready before the Sacramento ride but I won’t rush the project. Here’s what’s on the list so far:
First, correctly reassemble the engine with a new polini head and get it running. Upgrade the stock variator with a Doppler er3, fabricate a launch lever and a polini spring bracket, install new rear gas shocks or a mono shock , an hydraulic EBR fork with disc brake, mag wheels, new handle bars and controls, new seat, new tail light, lose the fenders.
Once that TSM and my 103 streetfighter are done, my next project is to chop and convert a Tomos Sprint into a tubular frame top tank bike but shhh….. it’s a secret.
1h engine dissasembly for a full check up:
The engine reassembled with few Tomahawk tricks and ready to blast:
Polini W exhaust ported + custom ball joint ring, rear boost transfer ported, piston ported, cylinder+head decomp valve plugged, doppler variator modified to fit the malossi belt, stock clutch modified, ignition timing and points set, carb tuned (needle, slide, main jet, idle jet, starter jet).
Heavy duty custom launch lever made out of a peugeot pedal + cases bracket (2 hours).
Plus, Johnson’s Peugeot 103:
Another “nobody can fix it” Peugeot 103 sp polini 70cc fun challenge for Tomahawk.
The stock cases were over ported with JB weld to fill up the holes so there’s no guarantied reliability. I reassembled the top end plugging up the cylinder decomp hole and head decomp valve, set the timing with new points, installled a kill switch, used some silicone on the polini reed block (not my 1st choice block known for air leaks sometimes), slightly cut off the stock engine spring top plate to clear the polini reed block that was hitting and stopping the engine from reaching full variation (Tomahawk free tip), tuned the 4 stroke 19 carb AN atomizer (make sure to get a 2 stroke carb with the AU atomizer, it’s easier to tune and consumes less fuel), installed the doppler exhaust low to clear the pedals, I had to loose the center kickstand.
Two days later, the bike runs like a clock. No special porting, just the 70cc polini stock power. It really feels good to bring all those vintage peugeot mopeds back to life one by one.
Engine set up available at http://www.treatland.tv
Stock cases vs Polini cases: