Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Stainless steel has extreme galling properties hopefully they can get it right otherwise stainless steel is gonna be a complete failure.
There’s no reason to reinvent the wheel here.
They need to use a Heat treat compatible on the cam and lifter. Cheapness is the cause of all these issues with these engines. No piston pin protection from galling into the cylinders is proof!
 Piston pin retainers or Teflon disc like I have been suggesting is a very effective protection!!!
To the best of my knowledge None of these engines come with any form of protection between the piston pin and the cylinder walls.
It’s like having a built in ticking time bomb that will eventually ruin the engine the more you run it.

Got the engine running... spent an entire day and determined I won't quit until its sorted or I'm dead !

While I enjoy the look of R31 it has some design flaws which all contribute towards the issues I personally experienced. Here is a list and what I did to sort them.

CARB:
In my case I koticed the throttle, LSN and HSN screws are extremely sensitive.im talking about them getting out of tune even after 30 seconds of engine running or moving the throttle.  First I thought I'm dealing with clogged and damaged carb, afger cleaning twice and measuring the position of each screw. I noticed any change even at 2/350 degree can knock the whole thing out of tune. Once I found the sweet spot, I used a small amount of super glue to hold them in place. Thats not the only issue however, the carb connection to the intake manifold is wobbly and wiggles up and down easily. Thay slight movement can easily introduce leak into the system.i tried to push them intake further in to secure it, however vibration of the engine after few mins of running makes it loose a again. The intake has two o rings which help with insulation but still not the best.

IGNITJON SYSYEM AND SPARK PLUGS:
I dislike these tiny plugs, they simply hard to find and pricey compared to the more common 1/4-32. The ignition  leads usually are junk, you see lot of arcing marks on the shell of the plugs.  To reduce the arcing, I connected a wire from the ground terminal and attached to under one of the foam legs. Not that it sort the flaw but reduces the arcing.
Now the ignition timing, Jin usually uses the wasted spark model in other engines he has or I came across. This is different in R31, it is a sequential ignition. While it's a great model the execution is not as accurate . I noticed to create a spark you actually need to rotate the flywheel at certain speed otherwise it misses to spark during combustion phase. Maybe it's just mine but somehow I doubt it. Why does it matter ? It does when it comes to trying to get a realistic Shovelhead low idle from this engine .

CAMSHAFT
biggest pain in the back side for this engine starts with the camshaft. Brass made unequal lobes ( in my case) and the way it us positioned and connected to crack shaft seems not very practical in a Vtwin setup. Few of us experienced premature wear on lobes ( on mine was middle two) after a very short run, resulting in engine not working. I ordered an upgraded one from Ebay and same thing happened to it in no time . Jin mentioned they are designing a new one and different material. While this part is an integral part of the engine, I found fiddling with cam lifter screws( at the bottom of pushrod tube can be a workaround, how long will it last ? I have no clue.


CAM/VALVE LIFTERS AND ADJUSTERS
The lifters connecting to the camshaft lobes on my engine didn't move up and down freely, I suspect this is one of the reasons the camshaft lobes were worn out. I sanded them with 1000 grit paper and added assembly lube , all 4 needed this. So check yours if you can

I am not the fan of how on R32 valves are adjusted . You have no actual way of seeing them work and have to take apart the valve cover and pushrod tubes, adjust the screws ever so slightly , put things back and try again. Really a big pain .
To check if yours are set correctly, test each cylinder.  On intake there should be a good suction and equal for both cylinders via the carb inlet. And on exhaust stage you should have a strong push of air. If you notice any suction from the exhaust during the intake stage you need to adjust the valve.

What I noticed on mine were bent adjuster screws after putting inbthe new camshaft, I was lucky they didn't snap, I gently straighten them and closed both equally and run the engine to ensure it works okay and no more bending. Some assembly or design issues perhaps

FUEL
I am big fan of Coleman fuel mixed with Lucas uppercylinder lubricant ( similar to Marvel mystery oil ), however R31 gets really hot and the heat transfers to the carb very fast. Having a warm air and coleman fuel is not a good mixture and you will have issues with engine running. Unless you use a cooling method. I have a small desktop fan which I run close to the engine ( from behind) to push cool air.