Weed eater engine conversion

well adapt the end of the crankshaft not try to fit the whole crankshaft to the b/s ....the bottom of the b/s is not flat so you need a funny circular spacer with an odd cutout ..I used 7/8 ply soaked in resin ...about 3 to 4 layers required to make the spacer with bolts going down to the outboard leg and up to the b/s. you could use threaded rod but a solid "block" between the o/b and the b/s is best for giving mass and loosing vibration

 

Has anyone done any research on these R/C airplane engines. They are pricey. Just wondering if they will work or not?
http://www3.towerhobbies.com/cgi-bin/wti0093p?&C=GGC

 

I think you will find bigger problems than the weedeater engines ..The r/c ones may be powerfull but run at 25000 rpm so not much torque .with the weedeaters at 7000 rpm you have problems getting a prop to suit ..yes you can get a r/c boat prop but it inteded the boat and prop are going fast with little slip ..put that on a layout boat and its almost 100% slip...what about shaft bearings doing 25000 rpm......??? The briggs/lifan doe 4000 max

You are also looking at the prop to provide cooling so I dont think its a goer

 

Here is another small motor for those mini long tails.
http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.4506/.f
It appears to have enough power to run this little cart at 30mph. Watch the video.
http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.2966/.f

 

Check out this web site. It make you wonder about the possibilities. Watch the videos COOL STUFF!!!!

 

Thanks for the info.

 

I'm new to this type of motors, sorry to ask some very basic questions.....
why is the shaft of the Thai long tail over 2meters?
The stump jumper, www.stump-jumper.com, mud motor has a shaft that is about 1.5 meters long for example.

Paraprop posted something about reductions. What is the purpose of using a reduction?
Is it necessary to replace the governor by a throttle plate (post #712)?

Thanks
Surinen

 

The longer shaft allows the propeller to attain a lesser angle into the water thus creating thrust on more horizontal plane. It increases the efficency of the effort. Gear reduction units are generally used on applications where heavier boats and larger dia. propellers are used.

 

Yes jon has it right but if you have a high transom then you need a longer shaft than you would on a layout boat...gear or chain reduction can chnge the direction of rotation so you can use a standard right hand prop .if you go direct drive you need a left hand prop ..common in Thailand but not in the us

 

Thank you for your replies, John & pistnbroke.

What about the replacing the governor? Is that necessary?

 

It is not absolutely necessary to disable the governor. One of my long tail units still has an operating governor. Keep in mind though the engine is restricted, with the governor, to an rpm limit of approx. 3500 rpm. This is of little consequence when the motor is operated on a layout boat that has a 6 mph hull speed, but may prove to be a negative in more demanding applications.

 

PB, does the "wasted spark" affect how the tach works? I ask this as I bought one of those tachs from Jim, and when I select the 03 option, spark every other rev., the thing would freak out and go into some kind of reset mode, cycling through 11111,22222,33333,.... I was using it on a BS 4hp.

 

send it back the battery has become disconnected ..( dont quote me he will change it no problem ) anyway you want it on 02 because the briggs fires like a two stroke....

 

I received my long tail shaft a couple of days ago. This set was ordered from a company in Thailand (not Paraprop).

There is one thing I couldn't figure out: how to connect the throttle cable to the throttle plate. Can someone please provide a picture?

Thanks!

 

Tell us more

Where did you get it from, how much did you pay, how long to ship, how much to ship, etc... I found another place that sells these "kits" but shipping to MN in the US is prohibited (almost $300).

If you wouldpost pic's of your set up, and if we knew where you got it from, maybe we could help.

Mark