Weed eater engine conversion

Mark; The motor is a 4 stroke. Apparently oiling is not a problem at the engine angles we encounter. I have seen numerous pics of Thai long tails with 4 strokers using this design. I recently watched a show on the discovery channel showing Lifan powered long tails on the Amazon river. All of them used this same design (no u-joint) with no apparent oiling issues.

 

Just passing along some info

If the Lifan is a complete and accurate Honda imitation, I think you may have to be careful. I know that Rickshaw looked at the Honda2.8 hp 4 stroke and blew up a couple of engines due to lack of oiling. I believe he was trying to make a direct drive unit as well and specifically mentioned the Honda motor being unable to handle the "tilt".

Just passing along what I know John. I know you know what you are talking about but if this info can save you a motor (even a real inexpensive motor you got off ebay), it was worth mentioning.

Mark

 

Mark; Thanks for your concern. As this is an issue of concern when utilizing a unit of this design, I did pursue some background information on operating the engines at angles approaching 20 degrees. I consulted with Dennis Scott of Scott racing engines . Dennis has a wealth of experience building racing engines for the go-Kart crowd. He has two dynos for testing and tuning the Hondas , Briggs and LIfans that he ships to racers all over the USA. Dennis recommended simply adding extra oil to the crankcase when exceeding the manufacturers recommended 15 degree limit. He felt confident that this would accommodate the forced splash system used on these motors. His recommendation coincided with those on the AffordableGoKart web -site. Again add more oil to compensate for the increased operating angle. Perhaps we can get Mudman to join us in this discussion as he has built several of this design . I believe he stated that they usually last for about three years. Also Pistinbroke has built a 6.5 hp Lifan that uses the engine tilt straight shaft design. I know from his thread about his build that it has been tested. Please join in Pistinbroke and give us the benefit of your experience. The Honda GX35 on your Rickshaw uses an all position rotary slinger oiling system. It`s to bad they didn`t incorporate this into their larger engine offerings.
In conclusion; If seeing is believing, then I am a believer. I have on several occasions seen pictures and videos of this type of design being used successfully around the world. I may be in for a big surprise, but at least the engine was cheap.

 

I too have a concern

with the Honda GX35 motor. I hear that Honda has specifically not reccommended them for ice augers as cold weather and the oil misting system employed do not go all that well together. We'll find out soon enough I guess. Accoprding to others who have used the Honda GX35 for our application, this hasn't been a problem.

I knew you would have checked out the Lifan for this application and knew what you were doing. I know that Rickshaw had troubles going past the 15 degrees you mention.

Hey John, I see that you are a golfer. My son and I went to the PGA Championship today and stood within 2 feet of Tiger. We followed him on a couple of holes and got real lucky as a rope was pulled across hole #8. The "crowd control" folks felt sorry that my son was cut off and moved us to the special seating. Pretty cool. That guy is one focused, and ripped, individual. I've never been to a PGA event and got to say it was pretty cool to be a part of it. Expensive as all get out ($40 for a lunch of 2 burgers, 2 fries and 2 soft drinks) but my son can now go tell everyone he stood within a couple of feet of Tiger. He is thrilled.

Mark

 

Hey Guys!

I've been lurking on this thread for a while now, and watching some of the builds. Amazing stuff that we can power our duck boats with such light weight motors.

I have a question for Mark and John. Both of you have built longtails with the brushcutter type motors and are now experimenting with larger motors. What (in your opinoins) are the weak points of the bruchcutter type motors in comparison to the smaller GX35 hondas and clones? I've got a boatload of kids, and I can only afford to to do a single long tail build, so I want to make sure I'm building what will give me the most bang for the buck.

Here's a little background on my boat. I have a 11 foot homebuilt layout boat very similar to the Hybrid boats currently being built on the Refuge. The boat itself weighs just over 130# and I'm 290# hunting with a 70# lab and 2 dozen decoys usually. Ther area I hunt is saltwater marshes and I usually run just over a mile to my hunting spot. I launch from a boat ramp on a river that dumps into the bay, and can have a 5 to 7 MPH current when the tide is rolling out hard and the river is swollen (usually a 2-3 MPH).

I borrowed a Mud Buddy 6Hp from a friend last year, but the weight was a little much without the addition of pods on the back of the boat. I would be interested in your opinion on whether or not a 50CC motor will push this boat to hull speed and allow me to get there and back without having to refuel.

Thanks for the great read over the last 9 months, your builds have inspired me!

Bob

 

disadvantage of the weedeater

Not enough power or reserve of power
Revs very high ..noisy
difficult to get the right prop or it boggs
needs a left hand prop...

with the bigger 4 stroke set a down limit stop on your swivel....
top up motor with a 10W 30 via the highest fillers to overflowing when fully tllted and remove the oil level switch if fitted.
Remember the go kart people use these and the oil climbs the walls of the crankcase when cornering so they put extra oil in to compensate .
Mine is electric start ..nice
If you carnt weld you can make one using U bolt clamps to attach the tube to the engine plate but then you need the chain drive ( as used in Thailand )

 

hey pistn

these are some left handed props i got off of ebay; do you think a 24hp honda will handle them or not? the 1st pic is of two mudmotor props so im not worried about them, the top one is 10" and the bottom one is 7 1/2". the 2nd pic is 9" same style as 1st pic but made of bronze. the 3rd prop is a bit over 8" but a different pitch. the 4th one is a 13" racing prop abit worried about this one what do u think? of the props i have listed witch one would be the fastest? best for power and torque? best for shallow water? i dont know the pitch of any of these props? do u know what kind of prop the 2nd one is used for, its a michigan A C 6 5 prop?
thanks, muddin

 

Michigan dont list any AC props so it must be old ...a 24 hp outboard would usually drive a 10in x 12 pitch prop at about 3000 rpm ( 2 :1 reduction in an outboard) ..all you can do is try them and have a rev counter on your motor ..

 

Hey Bob

There aren't any disadvantages of a weed eater mud motor. I did build my first one with a Bolens 31cc motor and it was not enough. I then built with a 52cc 2 stroke motor and it has more than enough power to get me (200lbs) my boat (65 lbs) and all my associated gear up a river that easily goes 5-7 mph as you state your does. I mean easliy. I'm not going through any weeds or mud, just shallow water with a sand bottom.

Surface weeds with the 52 cc motor would not be a problem but going through mud like a true mud motor would not be possible.

What I don't like is that it is a 2 stroke which requires carrying extra mixed gas. Not a big deal but it is an extra thing needing to be done. I also didn't like the noise so I made an exhaust pipe and directed the noise towards the back, awy from me, and it is much bette. Since you won't be running the 52cc motor at full throttle, the noise isn't bad.

I went with the GX35 on the Rickshaw for a couple of reasons. 4 stroke power with a 3:1 gear reducer. I bought this motor (Rickshaw) from a friend who had it and said it was a real well built motor. He says it easily goes as fast as my 52 cc motor and since he saw me drive that motor, he would know. I don't think I would run the GX35 without a gear reducer as it is clsoe in power to the Bolens I built the very first time.

I also toyed with a 6.5 hp as I like projects and I had a free motor if I wanted it. I had no need for this size motor as I already have a motor on my bigger boat and the 6.5 would be too heavy on the smaller boat.

Let me know if you have any other questions.

Mark

 

Thanks Mark, that answered alot of my questions. One more quick one, since it looks like Duropower has discontniued the brush cutter, would I be better off to use a scooter motor with the transmission, or the duropower with a direct drive. Again, just asking for your opinion. I have looked into both, but it wouild be nice to hear feedback from someone that has been there and done that.

Thanks again,

Bob

 

My opinion

I never tried the transmission unit on any motors I built as the ones that come with those scooter motors are usually 5:1 reduction which I think is too much unless you have a perfect prop to go with it. I know John O made one with one of these gear reducers and I don't mean to speak for him but I think that while it worked, it wsn't ideal.

If I had to do it over again, I would purchase a 52cc scooter motor (buy it from someone who can sell you replacement parts) and add the electric start.

Unfortunately, going this route will require you to build the driveshaft and everything that goes with it. Not a big deal but it is more work.

I would also google brush cutters and see if you can't find another 52cc motor that comes with the driveshaft and drivetube.

Mark

 

Thanks Mark!

I appriciate the knowledge.

Bob

 

My set up on big water. Hammered the catfish.















My briggs has served me well. It lasted 2 years and then the clutch went. Last catfishing trip the pin in the prop seared and I had to paddle 4hours to get back. Makes you appreciate these moters. I'm going to have to build another one. I could fix the Briggs but I want more power anyway.

 

nice catch! what is the brand of boat you have in the pic? how long is it? how big a motor on it? what is the top speed? i am planning on building a go devil motor for a 16' mod v jon boat out of a 24hp honda. i am all so wanting to buy a small boat maybe similar to your to fish in so back water of the mississippi river and i was thinking of building a small mud motor for it. any info on your motor and boat greatly appreciated.

 

It's an Otter outdoors Stealth 2000. 12 foot long..very stable and also very heavy. 100 pounds empty I think. The moter I built is a briggs brush cutter powerhead 36cc's. It's a 4cycle so the rpms were perfect with my t11 prop. No cavitation at all. When it was new I was getting 8mph in still water. In small chop it really bogs down to 4 or 5. It worked great in small water with little current.
I dont recomend using a Briggs moter though..the cluch is a pain to change and expensive. The mini bike engines are the way to go.