Moby 40T malossi

I fired up the Motobecane 40T 50cc malossi liquid cooled after one week of work.

This is a commissioned bike but I didn’t build the engine. I just hooked it up, installed and timed the cdi + new rubber mount dell’orto 19mm carb with the right settings. Also serviced the variator. Lots of work and small custom parts to make everything fit on that bike.

I replaced the unnecessary polini 4 petal reed block with the stock 2 petal athena reed block for better 50cc performance with the stock cases, the carb even clears the frame much better now. I installed a launch lever + tomahawk Xtreme clutch pulley kit.

I also converted the front wheel loose bearings to sealed bearings, installed a disc brake with custom caliper bracket.

I installed the lights, brake light, horn, kill switch, water temperature gauge.

Video 1sr start:

Some serious h20 50cc power with stock cases + 19mm carb + stock cdi. I still need to adjust the water pump belt, install the variator belt and drive chain.

Test runs:

After testing a different type of a needle close to the one I normally use, the bike felt rich during the first test run. I went back to old needle set-up, down jetted the carb, tuned the variator but toned it down for daily street use. The bike runs good but I’m waiting for a water temperature gauge to get a reading at top speed and make sure the too small polini radiator is able to cool down the engine. Normally when ported that malossi 50cc kit gets more hp but looking at the exhaust it didn’t seem like the cylinder was ported but just mounted stock. Still plenty fast for a 50cc daily rider.


I’m rebuilding a peugeot 103 engine with 50cc malossi kit + stock cases.

Here’s what happens when you use the high compression malossi head for 50cc or 70cc with decompressor option. They made a tiny hole in the combustion chamber to give you the option to either use a decompressor or a plug it from outside. The problem with that bad design is that hole creates a heat bubble at top speed and will blow up a hole in your piston or combustion chamber. It’s better to use the malossi head no decomp version. Or if you want to use a high performance head with decomp for 50cc or 70ccc the best is probably the polini one, you can always plug it as well. (not as good performance as malossi or doppler but much better than stock head)

Malossi high comp head decomp  vs no decomp version

Polini and Doppler high comp heads


Be careful when port matching the peugeot stock cases. There’s not much aluminum for the secondary rear transfer port, it’ very easy to drill a hole. It’s better to find somebody who can weld your cases with aluminum or be conservative with the porting. I don’t recommend to use JB weld to fill up a hole in the cases, it might crack at high temperature.

Also, on the variator clutch side, make sure to use the right metric screws for crank seal cover plate. It can easily come off and rub against the clutch bell. When buying an after market peugeot variator, you should disassemble it and check every parts.  Most of the time you have to grind the balls plate, thrust plate spring, and nylon washers before installing it. Test each single part on the crankshaft first to make sure the slide perfectly but don’t over grind them.

Stock peugeot cases by Tekinx + stock variator

Moped performance parts available at


Latest Scoot TV video #5 “moped division” by Honest Mike.


Almost done with Melvin’s Peugeot 103 RCX Doppler engine.


Start by machining the cylinder top deck and head to modify the port duration and compression ratio, mix some peugeot polini cases small reeds with a motobecane polini intake manifold, cut and adapt some malossi vl7 4 petal reeds to replace the polini 2 petal reeds, add a small drop of  locticte, hand cut few paper gaskets, port the exhaust as a nice finishing touch and serve with a fresh dell’orto 21mm carb for a powerful 15hp liquid cooled 49cc cocktail.

Melvin might decide to use the peugeot engine on a lighter motobecane frame.


Back from powder coating Moby Rockstar red EBR fork stabilizer + Moby av7 70cc green project.


  1. Eric

    sick!! i want to see what u do to clear the carb and intake from the frame. as always, u continue to inspire me and show me what’s possible. keep up the good work man!

    • tomahawktuning

      Thx. We’re using an RCX frame short swing arm so there shouldn’t be any clearance issue with the carb side ways. But the frame I’m not sure yet with that high mbk intake.

    • tomahawktuning

      yea I prefer the av10 3 ports case inducted but that was brought to me with an av7 engine. Gotta make it work.

  2. Eric

    av7 is still pretty fast, but not like the av10. but i am still excited to see a Tomahawk av7. the parma 70cc is the best in my opinion for an av7. ports are pretty big for a moby piston port.

  3. charliebuzzard

    I can not wait to see this 40T Peugeot mash up. I’m building the exact same bike this winter!! It will be another 70cc Polini (cast iron) and stock cases. I know you hear it enough from everyone else but you are a true inspiration. Please keep us in the loop in the 40t Pug!!

    • tomahawktuning

      Yea I’ll keep you posted. That build might take a while, should start this winter.
      It’s always good to hear that my builds inspire people or give them the extra motivation to finish their project.

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