Oily Tomos Fix? Hopefully

March 13, 2015

It’s basically the number one problem that most if not all Tomos mopeds succumb to. Oil begins to leak out of the crank case via the output shaft. The oil gradually sprays off your chain turning your rear wheel into something like a colorblind grateful dead t-shirt.

Tomos Whitewalls

My new white walls desecrated by the dreaded tomos self oiling chain.

Both of the Tomossess (not sure what the plural of Tomos is oddly enough, Tomi?)I’ve owned had this problem. There are a couple of possible reasons, rather than getting into them too much I suggest you head over to Myron’s Mopeds and check out their writeup. But the gist of it is oil can leak through in a few spots…

  1. Between the large outer oil seal and the distance bushing
  2. Between the distance bushing and the main output shaft
  3. Between the main output shaft and the pedal shaft

So for #1 I’ve already replaced all of the seals on the bottom end of the engine. #2 the mating service appears to be tight and blemish free.

So that just leaves #3 (means to aslo buy Bahco from MTS getting all the tools needed), to try and fix that problem treats is now selling a special nut that has a built in oil seal. I picked one up and threw it on my A3.


Treats Oil Seal Nut


Here it is installed on my bike, it’s significantly wider so I had to ditch my white chain protector thing. Kind of a bummer I liked how it looked with the whitewalls, but if this works it certainly worth it to not have oil painted rims and tires.

Tomos A3 Chain Cover

Oh Noes! It’s too wide:(

Here’s what it looks like side by side with the stock nut for a little size comparison.

Tomos oil seal nut width

Side by side width comparison


I haven’t really had too much time to ride the bike around and see if it’s fixed now, but I’ll report back with my findings when I do.


Projects featured in this post: