Stihl cylinders

[FNTPuck]

The 460 is supposed to be the easiest to make work, but all of them will take some serious mods to work RIGHT.

Can't just throw the cylinder on and expect performance - besides welding and drilling the bottom end you need to degree the engine and calculate proper base height for correct port timing, match the transfers, etc. Depending on top end you may also need to trim the bottom of the cylinder and run a stroker crank. I have seen videos of improperly assembled homemade franks that run and sound great but are only doing ~35mph...thats a stock chinagirl speed. A true frank setup should do 60+ pretty easily.

A lot of work though lol.

 

[Will'smotobikes19]

It seems worth it I wonder if you could cast the casehalves to be modified instead of modifying the holes and filling. 2 stroke stuffing just casted a cylinder that he claims is going to be the most powerful 2 stroke. Seems easy enough redesign the case halves out of pla and also you can use better quality aluminum could probably drill and tap the holes to 1/4 inch too. There’s nothing too complex about the crankcase either it would probably cast perfect. If you look at a Honda engine and then at a Chinese engine the Japanese aluminum looks strong and smooth where the Chinese aluminum is porous idk if it’s actually better but I’m theory yes.

 

[Frogslayer]

We cast aluminum out of sand molds in high school and damn i tell you what it's so much easier typed on a forum then actually done. Better off buying a new China girl, cleaning up all the castings replacing all the bearings and getting the cylinder bored and sleeved. Would be a hell of a lot less work lol.

 

[Will'smotobikes19]

I wonder if aluminum bronze would be any good for engine parts it’s a quite hard metal harder than both aluminum and copper might be stronger on the threads intp. Some people have said copper wasn’t good for a cylinder head but heat sinks for PCs are made of copper. aluminum bronze is like 88-89% copper and the rest aluminum besides shrinkage problems and heavier weight I think it would be a cool experiment. It also looks like gold and doesn’t oxidize! I believe some euro coins are made out of it.

 

[Frogslayer]

No matter the results I'm all for the back yard forge! In the name of science!

 

[Will'smotobikes19]

The Stihl ms660 seems like its pretty powerful the stens top end kit would probably be good for a Frankenstein build. Wouldn’t want to get the cheapest kit on eBay.

 

[Street Ryderz]

The 460 is supposed to be the easiest to make work, but all of them will take some serious mods to work RIGHT.

Can't just throw the cylinder on and expect performance - besides welding and drilling the bottom end you need to degree the engine and calculate proper base height for correct port timing, match the transfers, etc. Depending on top end you may also need to trim the bottom of the cylinder and run a stroker crank. I have seen videos of improperly assembled homemade franks that run and sound great but are only doing ~35mph...thats a stock chinagirl speed. A true frank setup should do 60+ pretty easily.

A lot of work though lol.

That's the biggest mistake most have been making,by using a longer or stroker crank the geometry goes for a s**t!Think about the crank circle dia being much larger than was intended for the cylinder,plus the rod is also longer witch means the dwell top and bottom is increased and this extra hang time in the top creates alot of heat soak that we dont want in any engine!

 

[Will'smotobikes19]

I think someone should start casting a remade bottom end for the 54mm cylinders only with SAE bolt sizes. What size carb and jetting do the little 92cc beasts need anyways? Can the carb for the saw work on a Frankenstein? Also is there an issue with the wrist pin?

 

[Spare_Parts]

SAE will never happen. There is no reason for it and makes no sense when the rest of the engine and the bicycle it is on are metric.

 

[Will'smotobikes19]

I know it was just an idea. It does have a reason it’s the US we are an SAE country and bolts are easier to find in SAE sizes. Besides all the m6 tapped holes will easily allow for 1/4 fasteners on the castings if they were tapped for 1/4-20 instead. 1/4 is also wider in diameter than m6 making it stronger. Since the CG is such crap it wouldn’t really be worth mass production and I know this. I have a lot of ideas but remember constructive criticism isn’t shooting down regular conversations as you did on the other threads. As for the Frankenstein in my opinion it would be better to cast a case with the filling included in the metal instead of using jb weld or whatever but that’s just me. I am leaning towards 4 strokes anyways at this point and will probably give the 2 cg’s I have away to that neighbor. Too frustrating for me.