Weed eater engine conversion

[pistnbroke]

90/140 much too thick will absorb lots of power ..ATF is a better choice

[goose_716]

I bought a motor and fuel tank from scooter4less. I bought the 52 cc motor and the fuel tank with three attachment points. I asked and the lady said this one. It doesn't match up in any shape or form. I believe she said they had another that had two attachment points is this the one that everyone has been using

[Wolfgang123]

he goose i cant help with your problem sorry. but are you going to be using a transmission or not? i woulod like to follow your build before i start mine.

[El Sea]

My old British Seagull requiers 140 weight lub in the lower unit.... The Brits figured the water would mix with the oil.

[jdc1111]

Mark F. CheneyM and Everyone else,

I've been following this thread, and have to say great design work all around. I agree there would be a big market for these, but us shade tree mechanics and engineers enjoy the process more than the end product I'm sure.

Here are some plans I've compiled that I think would meet the design requirements, it's just a draft and not very detailed, but I think the concept would work. Probably more "weed" than "mud" motor capability, but I think the parts would be relatively cheap and easy to locate (#25 chain sprockets are standard on scooter clutches and a range of stainless larger sprockets would be easily found on kids bikes from garage sales, thrift shops, etc.)

I haven't done any thought experiments on final weight, but if the frame is constructed and braced well from aluminum, it could be in the under 30lb range I believe. I like the drop frame to allow for a more parallel driveshaft angle without such a long tailshaft.

Anyone see any issues or complications with this design? I'd appreciate any feedback or improvements, haven't gotten a motor yet but am shopping. Would be for a 17ft canoe.

[pistnbroke]

I dont think 7 into 14-24 goes 1.2 more like 2 or 3.3 to 1 ratio....
Exposted chain running in the water ???? Perhaps you should look at the 1900 waterman design .and similar early designs ....???

[jdc1111]

you're right there, I'm looking for a 1 to 2-3 reduction ratio, based on what I've read on this thread--sound right for the 49cc? Could I run a bigger prop than 6.5" to 7" at 1" pitch?

I may need to rethink the transom mount location based on your concerns...I would prefer belt drive but the chain clutches on scooter motors are just really enticing from a simplicity/cost standpoint.
Check these motors out http://www.mudbuddy.com/HD%20Mini%2035.htm
I think with the right mount location, you can use a chain drive and keep the chain out of the water, but I think they can take a little moisture and run ok with a good chain grease periodically. Might need a semi-closed or sealed lower chain case though. Could use a boxed in frame instead of my lower frame if the chains aren't water-friendly too like the mudbuddy.
Anyone seen a mud drag racing truck before? Big ones use double-80 roller chain for transfer cases, they run all day in the mud with huge torque and horsepower on big tires and heavy rigs. That's my rationale anyway, but I don't have enough experience here to talk authoritatively.
"Good judgment comes from experience. Experience comes from bad judgment" as they say...

[Mark Wo]

Originally Posted by jdc1111

Mark F. CheneyM and Everyone else,

I've been following this thread, and have to say great design work all around. I agree there would be a big market for these, but us shade tree mechanics and engineers enjoy the process more than the end product I'm sure.

Here are some plans I've compiled that I think would meet the design requirements, it's just a draft and not very detailed, but I think the concept would work. Probably more "weed" than "mud" motor capability, but I think the parts would be relatively cheap and easy to locate (#25 chain sprockets are standard on scooter clutches and a range of stainless larger sprockets would be easily found on kids bikes from garage sales, thrift shops, etc.)

I haven't done any thought experiments on final weight, but if the frame is constructed and braced well from aluminum, it could be in the under 30lb range I believe. I like the drop frame to allow for a more parallel driveshaft angle without such a long tailshaft.

Anyone see any issues or complications with this design? I'd appreciate any feedback or improvements, haven't gotten a motor yet but am shopping. Would be for a 17ft canoe.

First of all, I love your design. I've been thinking quite a bit about building one of these designs so I started the web searching on how to do it sometime ago. I found three different options to make the tranmission work and the best part is may be the gear reduction. I think, but can't recall, that I found reductions from a 3:1 to a 5:1.

I'll have to do some digging later today and get this info up here on the site. I think there is more than enough brain talent on this page to make this a reality.

Also, the advantages of the longtail design is the ability to use it on a caonoe or other double ended watercraft. I don't know how you would make your motor work on a boat with a pointed stern. Just haven't thought about it.

Mark

[Mark Wo]

Originally Posted by pistnbroke

I dont think 7 into 14-24 goes 1.2 more like 2 or 3.3 to 1 ratio....
Exposted chain running in the water ???? Perhaps you should look at the 1900 waterman design .and similar early designs ....???

What is the 1900 waterman design? Never heard of this one not that I've of much.

Mark

[Mark Wo]

http://www.google.com/patents?id=xlt...age&q=&f=false

How the heck would that pulley not slip all over the place? Water can make a great lubricant.

Mark

[Mark Wo]

I think this page may be of interest to anyone wanting to build a surface drive mud motor. VERY detailed info.

http://www.duckhuntingchat.com/forum...p?f=72&t=97024

Mark

[muddin redneck]

what about using a toothed belt like they use on the newer motorcycles. they are suppose to last longer than chain and not stretch as much, but they might would stretch in the water though, but i dont know.if you go to this website http://godevil.com/documents/Surface...Manual_000.pdf it will show you the inside of how go-devil surface drive motors work they use some kind of belt with notches in them that fit on a sprocket type pulley. i dont know what knid they are but we use they same style belt and pulleys on our dry fretilizer carts to run the drive shaft for the spinners. i could find out what they are tomorrow and let you know. hope this will help.

[jdc1111]

Here's a picture of what a motor might look like...the scale's a little off but the transom and the drop of the motor off the back of the transom, plus where it might mount to a canoe is what I'm trying to communicate. I think the caster wheel mount is the best idea I've seen on the forum, I think I'll incorporate that into the next draft.

I think it might be conceptually possible to run in reverse by swinging the motor all the way around to either side, but can't figure out how you'd keep a hold on the tiller handle for that, so I think the real limits are the length of your arm and some where around 270 and 90 degrees (if 0 deg is front). Any thoughts?

I like chain because I think it's available and cheap for most to find...belts probably have some great advantages in the water, but I think I agree with whoever posted about "permanent side load" on the motor with the tension a v-belt needs. Those toothed belts would be great, and probably the ideal solution for the application, but might be a little pricey/hard to scale down to a weedeater size shaft/clutch.

[pistnbroke]

any concept of using a chain/belt/ toothed belt exposed in the water is a bad idea ...one twig or branch in the system and its totally buggered .. Only the young try to re invent the wheel ..why not stick with the Thai tried and tested design and keep off those pissy 50 cc motors ..you can turn a 200 cc down but not a 50 cc up ...the 6.5hp is fine on my indian style canoe at 5 m long and 1 m beam ( flat transom rear ) ..and remember which direction are you going to turn the prop ....left hand or right hand ??/

[Mark Wo]

Originally Posted by jdc1111

I think it might be conceptually possible to run in reverse by swinging the motor all the way around to either side, but can't figure out how you'd keep a hold on the tiller handle for that, so I think the real limits are the length of your arm and some where around 270 and 90 degrees (if 0 deg is front). Any thoughts?
.

Might want to take a look at the Scavenger mud motor handle. Very different design that may fit your needs.

Mark