Hey I just thought of getting a mini rotary engine built for a bike like the ones seen in Masada cars. Does anyone perhaps sell parts to build a small bicycle engine scale rotary engine? This Idea would be useful because there would be less parts to replace and using the right parts there would be fewer chances of break downs. If there no parts I might half to have one custom built.
A mini rotary engine for a bike?
- Thread starter Tmoney
- Start date
Sachs made a few models of small rotary engines back during the 1970's. They were used in motorcycles, go-karts, snowmobiles, chainsaws and other stuff. Google "Sachs 303". The old ones trade on eBay fairly often. I don't know if they have made anything newer than that.
I am almost certain that in the last ten years or so,,,, some company was selling a rotary snowmobile engine. It made about 40 HP, which was comparable to what a typical piston two-stroke in a big snowmobile would.
As for "having one built from scratch", that would be very expensive. And I mean, like,,, ten thousand dollars. Having a machine shop make on-off parts is fabulously expensive. How expensive, you ask?
Recently I had a desire for some custom gears made: these would be made of regular carbon steel, four inches in diameter, a 1.25" keyed bore, 3/4" thick, and needed to have helical-cut teeth. The prices I was quoted for a 30-day delivery, was about $300 each. $600 for a pair of 4-inch-diameter gears. I ended up using steel camshaft gears (which are 2:1 ratio) but only cost about $50 a pair.
If you reeeeaaaalllly insist on doing this, starting with one of the old Sachs is probably the best way--but rotaries are not exactly 'bombproof' in terms of reliability. Read up on the history of Mazda's engines to see plenty of early problems, and note that the Sachs engines never became common even when they were in production.
I am almost certain that in the last ten years or so,,,, some company was selling a rotary snowmobile engine. It made about 40 HP, which was comparable to what a typical piston two-stroke in a big snowmobile would.
As for "having one built from scratch", that would be very expensive. And I mean, like,,, ten thousand dollars. Having a machine shop make on-off parts is fabulously expensive. How expensive, you ask?
Recently I had a desire for some custom gears made: these would be made of regular carbon steel, four inches in diameter, a 1.25" keyed bore, 3/4" thick, and needed to have helical-cut teeth. The prices I was quoted for a 30-day delivery, was about $300 each. $600 for a pair of 4-inch-diameter gears. I ended up using steel camshaft gears (which are 2:1 ratio) but only cost about $50 a pair.
If you reeeeaaaalllly insist on doing this, starting with one of the old Sachs is probably the best way--but rotaries are not exactly 'bombproof' in terms of reliability. Read up on the history of Mazda's engines to see plenty of early problems, and note that the Sachs engines never became common even when they were in production.
It looks like its possible to install a rotary engine on a bicycle. It looks like the Sachs motors would fit a bicycle with a big enough engine compartment. I have in fact I have seen a motorcycle with a rotary engine installed. So that shows you can do almost anything with two wheels. I little off topic but I have seen a stretch bicycle with an ATV engine. now that's a motor bicycle that's got some power!
Allen_Wrench
Resident Mad Scientist
Rotaries have an interesting torque curve, but they're so derned problematic. Maybe you'd be better off with a small gas turbine. Or, if you're brave, you could build a small jet engine out of an old turbo charger. There's instructions online.
camlifter
Active Member
like this. Aixro XR 50 Wankel Specs - Race Sport Karting - Rotax & Shifter Kart Rentals, Sales, Service & Support
it's a $6K engine but hey it's only money.
it's a $6K engine but hey it's only money.
cannonball2
Well-Known Member
OS made a rotary for larger model aircraft. They show up on ebay but are probably too few ccs. Plus you would have to convert it gas. Still its a cool little engine.
Well,,,, putting a huge engine on a bicycle isn't a totally idiotic idea, if you use an intake restrictor plate. And you might need a hefty flywheel on there to smooth out the engine, since it's going to spend a lot of time puttering on its lower-end.
The benefit is that you still get most of the engine's low-end torque.
The drawback is the bigger engine's weight.
The 35cc Robin/Subaru 4-stroke I had was about 8.5 lbs.
A Briggs & Stratton Vanguard v-twin (16 hp normally) weighs about 75 lbs,,, + the flywheel you added....
16v4nrbrgr
Active Member
If you weigh 130lbs and put one of these on a carbon fiber road bike it would be interesting:
http://www.ebay.com/itm/O-S-ROTARY-...Control_Parts_Accessories&hash=item3a658f4fab
lol
necromancer, I know
http://www.ebay.com/itm/O-S-ROTARY-...Control_Parts_Accessories&hash=item3a658f4fab
lol
necromancer, I know
rotary guy
New Member
Suzuki had a RE5 rotary in I believe 1975- 1977 it didn't gain much popularity.I have a 1987 Mazda RX7 with a brideported rotary, It's a bit radical for the street it likes the rpm's around 4500-10,000. it has a weber 48IDA carb, it's another one of my toys.
Too bad this one never made production: http://freedom-motors.com/index.php?option=com_content&view=article&id=97&Itemid=77
16v4nrbrgr
Active Member
I should go talk to them, it's not far from where I live. 2.5 hp in a 4 lb package is incredible power density, and rotary engines are more reliable than high revving piston engines by a long shot due to less cyclic stress reversals. The 13b engines are a favorite in formula car racing because they last 5 times longer than a high strung four banger under hard use.
Check this out:
http://www.renntechkarting.com/products_xr50.html
Putting this engine on a kart gives it F1-level acceleration, some reviews I read left the test drivers speechless. I can't imagine how fun one of those would be on a super pocket bike or a bobber!
Check this out:
http://www.renntechkarting.com/products_xr50.html
Putting this engine on a kart gives it F1-level acceleration, some reviews I read left the test drivers speechless. I can't imagine how fun one of those would be on a super pocket bike or a bobber!