chief3452

Here is the overdrive. I built this as a proof of concept actually, but with a few more changes I think I will use this one as the final unit. The long shaft is the output and the stubby shaft is the input from the engine. I am hoping to use the front of the output shaft ( the one with two dogbone receivers on it ) as a starting shaft as well.

Vertical3-D

My Feedback: (20)

BB Modss, I was mistaken, I have a 3PM 2.4GHz which is 200 from tower...my mistake there...but for what I use it for its more radio then I will ever need...still a good deal and a good radio...the 3PK is the real nice one which if I was to spend that money I'd by the Nomadio....now onto that gearbox, you have built an underdrive, you need an overdrive with the fourstroke for a hydro, If I was running a surface drive I probablly would have needed something to the same effect to get the RPM's up higher...you need to have the larger gear on the input shaft to make it an overdrive...I like the starting Idea, Im going to go with the good ol' belt start myself since I already take that stuff with me for my mono...

chief3452

It is an overdrive. If you study the pics you'll see that the short shaft (engine input ) has a larger gear than the long shaft ( output to prop ) thus producing overdrive. Perhaps the fact the input shaft has no coupler threw you. I have yet to sort out how to get from 5/16-24 thread ( engine ) to 6mm ( overdrive input shaft ) but I have an idea.

Vertical3-D

My Feedback: (20)

sorry, I think I am suffering from brain loss today, when I read it and read the part about starting I was assuming the long shaft was input...man I should get more sleep or something...

chief3452

LOL, sleep is over-rated.... How is your build coming along? any progress or pics coming?

Vertical3-D

My Feedback: (20)

top deck is on and the rear doors and latchs I made are finished...gotta figure out the hardware list this week and Ill order it next week, Im gonna put the thottle in and do some finishing around the deck, need to touch up some of the paint a little...

f16man

Hey vertcal when you go hardware shopping don't forget a couple of skegs for under the hull right about where your engine is in the pics, My sk handled much better when I put them on in the OLDENDAYS LOL.

vasek

My Feedback: (4)

hey vertical, i never got your email[&:]

V.

Vertical3-D

My Feedback: (20)

Yeah, I need to find some the right size...vasek, I sent it a few times, figured you had gotten it, Im gonna post the pics right here for you...then put them on your comp...thats all the framework stuff, then just deck it with light ply or something like 3/32 or 1/8th inch balsa...

vasek

My Feedback: (4)

thanx vertical [sm=thumbup.gif]

BB Modss

I ran mine today for about a hour, it runs quite well in the old hull,the boat is way heavy, but never the less i outran a OS .21rg-m powered mono, and a proboat air boat.

glennb2006

Interesting thread, a couple of observations so far, I have not seen anyone achieve any cooling as yet on the cylinder or the head of the four stroke. Also, fo altering the prop speed has anyone considered using belt drive to the prop shaft? I have a belt drive set up I just bought for, in my case reduction gearing from an electric motor to the shaft on a recovery tug boat I am waiting to start building. Toothed belt and pulleys.

Glenn

Vertical3-D

My Feedback: (20)

yeah I had some old tamiya TLT-1 parts laying around and looked at the belt, as for cooling a coil or waterjacker can be made without much trouble, but for the work I just dont think its needed on this engine, the larger ones may, or on an inclosed hull...if anything a fan and small shroud will be used on this one, maybe even an engine driven fan...Ill look for a small prop tonight maybe and toy with the idea, just used a small pully and belt for it...I think one of these .30 magnums would be awesome layed on its side in a Chris-Craft then the tank beside it to blance it out...thanaks for the input, got me thinking about an engine driven fan which should work well...

BB Modss

I built a water cooled sleeve for the cylinder on my magnum .61 4-stroke, it works quite well.

glennb2006

An old computer fan driven off the motor would do it maybe if you can drive it easy enough.

Glenn

Vertical3-D

My Feedback: (20)

yeah I am having trouble finding a bearing and shaft in all my junk so I think I'll go with a small electric fan if it need anything...dont wanna crap up a nice boat with a frankenstien fan setup...the more I looked at it the more I thought it'd be really ugly...hmmm...

stempak

I just noticed this saito 4stroke it is a gas 36cc which produces 3.5hp, I'm sure it's rather tall and expensive but cool looking.

terry kelly

i did not read too much of this deal but i will chime in ... i do know fro mexperience with my planes that if going to a four stroke you can easily exceed the size of two stroke you should use by twice the amount, they have buttloads of torque and need the displacement to make up on the top end.. just some advice for your choice .. hope it helps out.

terminator

stempak

They just don't turn the rpm's. But with correct gear boxes should work just aswell. Also having more torque to run bigger props through a gearbox. Many large boats (60+") use gearboxes and work very well.

mopartybob

for those wanting to do a similar build....here's another on the "bay", O.S. FS.60 4-STROKE MODEL MARINE ENGINE, BOAT/ AIRPLANE Item number: 330184455071

f16man

Hey vertical hows that franken shtine SK commin along ,I gota see a video of that monsta.

chief3452

BBMods, do you have a picture of the cooling set up on your .61? Thanks

BB Modss

Ill look to see if i have them here or not, but yes i do have some pics of the water jacket i made.

f16man

Any updates on the four stoke flatie?

Vertical3-D

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not at the moment, I changed the exhaust a little, it now has 3 functioning outlets...two more in front of the one I had before...just didnt look right with one, I need to start working on it again, just been really busy lately