Office of Steam Logo_1

Author Topic: R90S boxer engine. The good, bad, and ugly.  (Read 40 times)

Adirondack Jack

  • Jr. Member
  • **
  • Posts: 149
R90S boxer engine. The good, bad, and ugly.
« on: October 12, 2021, 07:23:47 pm »
When Jin first previewed his 3.2cc opposed twin in the manner of a BMW airhead, I was hooked. When they introduced the engine with mirrored $100 discount pricing at and, I went for it.

The good. This is perhaps the most refined of Jin’s designs yet. It’s just a dandy little engine if only….

The bad: the website and other support is horrible. If you need them, good luck. Ok

The ugly:  what’s that there oil filler doin up under the intake manifold?  The service guy at, code name Lucas, also answers to the web address as if it is his own, anyway this cat first replied to another issue with crooked exhaust by first saying they’d replace it, then telling me to fix it myself. So when I discovered the oil sump plug, a dandy brass affair with an O ring gasket, exactly the same part used as a gas cap, wouldn’t come out, getting stuck against a poorly formed intake manifold tube, I was not happy. So at that juncture they backpedaled on the offer to replace the poorly assembled exhaust, and they tell me the oil filler is a dummy, a fake, not intended to be removed.

I was born at night, but it wasn’t last night.  They did not integrate a threaded oil sump neck with a built in oil level indicator (much like lawn mower engine sump) with the threaded plug with the vent and o ring, and tell me they purposely blocked it from removing the plug???   I got a Dremel that says that dog won’t hunt, and the oil sump is fully functional. Since I don’t have a tubing bender, I couldn’t fabricate a better intake with a wider bend that clears the oil sump plug. So I commenced to chewing on the top, outermost aspects of the plug to free it, cleaned it up some, and using hemostats, threaded it back in place.  Now I can access the sump.

No, it’s not a fake. It’s the only access to the crankcase there is, and with a needle oiler will work fine.

Recommendations are as follows, an English speaking technical writer be employed to go over the stuff. This isn’t a new problem, and the same people stonewall when things go bad. They changed the oil capacity spec on the inline four ohv water cooled engine three times. The last communication I got was they suggest I work out my own oil level.   Clearly the dartboard between seventy ccs and foaming oil and “try between 15-20ccs” is a little sketchy.

Some of the public facing ads on Facebook are so poorly done people yell “scam!” and run from legit ads. The Stirling desk fan was drubbed, and the v-twin is getting laughed at because poorly written advertising copy and lousy videos are amateurish and scare away sales.
These little engines are addictive. Imagine what they could be. 


August EOTM

In Memory of Trevor Woolan