I don't know about short run times, my engines at the shows run between 8 and 9 hours straight, only stopping to refuel, and then start right up again. Although there is a lot of coasting going on.
JimG
The only time I saw the Buma "O" ring swell was when the person that was running it was running it on gasoline. Coleman fuel doesn't seem to attack the Buna.
Jim G
I've also done some unofficial test on the different "O" ring types Vitron, Silicon and Buna. I used the same hit and miss engine for all the tests. Put new "O" ring on each time and let the engine run for 20 minutes to warm up each ring. This is what I found
Silicon - engine ran the hottest...
I've built a lot of engines with "O" rings for piston rings. Any where from 5/8" to over 2" and use the same proportions. On a 3/32"(.093") "O" ring I make the groove .105" wide and .110" deep. For a 2" "O" ring I use .210" wide and .220" deep. I also reduce the piston diameter in front of the...
If you need Glass for fuel tanks I always use this site. Been using it since 2009. They have Flat Mineral Glass watch crystals in many sizes. This is just one page. You may want to bookmark this page as it's quite a large site and easy to get lost. They have thicknesses from 1mm to 3mm and...
I do it all the time but prefer to use either 3/32 or 1/8 inch"O" rings. Works great. I even have one engine that has no recess for the "O" ring, just put it on instead of a gasket. But if you don't have a groove and compression is high it may blow out after a while.
If you look at the build...
I get mine at the local hardware store. Off the shelf "O" rings work just fine. I know some people say you need to use Vitron, but I've never seen a difference. I've got several engines from 3/4" bore up to 2" bore and all run just fine on standard "Buna" "O" rings from the hardware store. I...
Don't go jumping and assuming it's the "O" ring right off the bat. These engines often have a "Dirt" problem with swarf in the intake and exhaust that get stuck in the valves. The few I've fixed for people all had chips from machining under the valves. Try blowing out the intake and exhaust and...
As for the cam roller, I've used a small ball bearing from the hobby shop or something that I've junked. The hole will be bigger but that fine, just turn a small bushing that looks like a"top hat". Then counter bore the bushing so that the cap head screw (I use allens) is inside the bearing and...
The Farm Boy uses an o-ring as a cylinder head seal, works just fine. It's 1 3/16" od and fits in the groove that's made between the 1.200" od of the cylinder and the 1.340" id of the cylinder end of the wate rhopper. It just sets in the groove. A 1/16" cross section works but if your sizes...
Nice work,
I built SN# 003and the double size one SN3003-X2. Denatured alcohol or Coleman Lantern fuel (white gas) both work fine, but with alcohol you have to lube after running so it won't get surface rust. As an added point, with Coleman you can run it in the house with almost no odor.
Easy...
I built SN# 003 and SN# 003-x2 (twice as big). On the weights they are correct. Since it near impossible to solder the pins into the barrel distance with accuracy, it was made to solder the pins in then and then screw the brass balls down till you get the size you need. Then either solder or...
I built Bob Shores Little Angel double sized. The original Little Angel is about the same size as the Kerzel. I just doubled all the sizes. There were no problems and it runs great.
I actually built the double sized one first!
Jim G