Jake,
Getting in here WAY late...... I built one out of a 2-cycle leaf blower. Look here:
http://goldadventures.createforumhostin ... t-t35.htmlAnd here:
http://goldadventures.createforumhostin ... y-t38.htmlYouTube video here:
http://www.youtube.com/watch?v=b4AKvqCkz2EI started to build a second one with a larger engine. Never finished the swap over. Look here:
http://goldadventures.createforumhostin ... -t544.htmlOne thing I learned was that in Georgia at 600 feet elevation my little gas vac started good and ran O.K. HOWEVER, when I shipped it to myself in High Colorado, and tried to use it up at 9,200 feet in the Rockies was it was MUCH harder to start....used a LOT of starting fluid, and once running it had a LOT less suction. It screamed along, made a lot of noise, but didn't "suck" at all like at 600 feet.
The hose kept filling up with rocks and dirt as I vacuumed, so I had to stop every 15 seconds and hold the nozzle/hose up high and "shake" the material into the bucket as the vacuum ran. Also, the filter inside would become VERY clogged due to the very fine dust and I'd have to stop every few minutes, shut it down, and clean the paper outer filter. Eventually, I said "screw that" and just took off the paper filter and just used the foam filter to keep the sand and rocks out of the impeller.
I did all my "testing" in development with my screened cons, which were very sandy/gravely, with about zero silt, dust.
Over the course of several hours of on/off use, it became harder to start, would bog down a lot, and after blowing endless clouds of dust out the outlet, it died and refused to run again. The engine on the outside and the impellers inside were just caked in dirt/dust. There was a fair amount of erosion to the plastic impellers due to fine sand/dust getting thru the coarse foam filter.
That's why I was going to try a bigger 25cc engine... Have the engine, just never had the real need to fix it.
Hope this helps!
Randy "C-17A"