victor_belmonte

http://www.rcuniverse.com/gallery/ga...berID%3D581060

Tummi

I'd go with epoxy and re-build the hull layer by layer. But that's just me

T.

Stephen Wilkowski

Hi everyone,

I have a super vee with an octura x440/3 prop and the boat cavitate so badly, i wanted to know why it still does this, or what other people have done to resolve the problem, it will cavitate on launch, then it will run for a few minutes, then it will slow down to a stop and cavitate and it will not start moving again after that.

amax

Sounds like the prop isn't Sharpened & Balanced Properly, OR Drive Dog set screw not tight and Dog is Slippin, Or Flex Coupler not Tight on the flex shaft and flex shaft is Slippin.

Stephen Wilkowski

prop is sharpened and balanced and the drive dog is tight with lock-tite the flex shaft collet is nice and snug, i did put more solder on the tip of the shaft for more friction, but i don't think that helped at all? does the X440/3 have too much pitch, i have to give the boat full throttle, then after 2-3 seconds the prop will grab? would a 2 bladed propeller be any better? same type of thing happened with the stock plastic propeller, i have only 2 runs on the boat and i have had it for a year, but this problem has kept me from running it, in total maybe not even a whole tank through the engine?

mister twister

My Feedback: (1)

I am running thisprop on my boat right outof the box on my SV27 with good results.
http://www3.towerhobbies.com/cgi-bin...1&I=LXRUD6&P=3
I also got rid of the stock coupler and have a 3 piece coupler from Kintec racing because I could not get the stock coupler good and tight.

Tummi

GrimRacer's props are much better made than Octura. I bought Octura recently and was disappointed.

I mounted GR's 2 bladed prop few days ago and the boat does turn and accelerates better. I didn't measure max speed, though.

Cavitation should be smaller with 2-blade prop, but the other thing - boat stopping and not going further doesn't look like prop related. Maybe flex shaft is getting too much friction and after some running expands enough to stuck in prop shaft bushing? Or the joint between flex and solid parts of shaft is failing?

BTW: Mister Twister - did your collet from KR fit the stock flywheel? I had to lathe mine :/

T.

amax

Are setting the boat in the water or Skip Tossing it to launch? The Hydro's need the skip toss launch more than the mono but with a Big prop like the 440 the monos do require a bit of a toss to get going.
The 440\3 is a popular prop for the SV27 so I wouldn't say the problem is to much prop. Next question is: Did You S&B the prop or did you buy it finished? How the prop is Cut will make a Big Difference. Are you Greasing the Flex Shaft Thoroughly?

mister twister

My Feedback: (1)

Tummi you are correct I did bring my flywheel to work with me and have one of the machinists open up the hole a bit because the new coupler is a larger diameter nut. But it works great and it holds the shaft tight and makes it much easier to take apart because the collet opens better than the 2 piece stock unit.

As for the OPs original question I think there is more than one issue there. There must be something going on with the coupling connection. If it started to go then just stops and won't move the coupling is slipping or the flex shaft is broken.

Tummi

Collet from Kintec is great, but one'd suspect it's plug&play hence it's sold as SV27 nitro compatible. Buyers - beware

T.

Stephen Wilkowski

I always give my boats a toss into the water, i sharpened and balanced the prop, I grease the shaft every day that i go out. My rio 51z doesn't have this type of problem and it has a similar drive set up...I just don't understand why the boat wont stay running? My flex shaft isn't broken either. I'm considering taking everything out of it and selling the hull and putting the engine and electronics into my nitro hammer? When I originally got the boat i ran it and it caveated so badly we thought it was defective, so i took it to the hobby shop i work at to return it, but great planes wouldn't take it back, because they thought it was not defective.

baja pete

If you decide to strip it and sell it let me know, I may be interested in buying it.

amax

Have you adjusted the Stinger Angle any? There Isn't a lot of adjustment there but little bits do A Lot with little boats.

Ron Olson

My Feedback: (1)

The Octura X-440/3 is an odd little prop as each blade has a different pitch. I happened to be standing behind Mark Sholund at a race while he was playing with his then new prop pitch gauge and that's when we found out. I've run a 440 and 640 on mine but I also give the boat a toss when I launch it, a habit I got into after getting hosed down a few times from launching a friends .80 mono.

victor_belmonte

Good evening guys. Again I had a problem with my SV. This time, the rod broke, and I disassembled it to see if it was only she who had broken. I'm sure, I think he broke a piece of the engine block. I needed to see some photo, top of the engine without the piston, shirt ... anyone have any pictures so there? My engine is 12:18 OS CV-RX and I found the rod in http://www3.towerhobbies.com/cgi-bin...?&I=LXMND0&P=7 for U.S. $ 1.48 off shipping. I live in Brazil and can not find these here parts. Could someone confirm if this part is right there? Thank you staff.

victor_belmonte

Personnel, taking advantage of the post ... someone has installed and used in the engine http://www3.towerhobbies.com/cgi-bin...&I=LXWNT2&P=ML and http://www3.towerhobbies.com/cgi-bin...?&I=LXWNT3&P=7 00:18 OS?? My engine is OS and this the sale is SUPER TIGRE and do not know if it works. Anybody ever tried? The game manual, the string is too bad. Thank you!

Brushlessed

My Feedback: (2)

I changed out the stock one for a SuperTIgre and it is AMAZING! I am TRYING to kill it without actually pushing back on the trigger, and it just keeps chugging along! I have not had it die yet ONCE on me and I have put two quarts through it. It is even faster than the stock engine! And I am still in break in!
(Yeah I know, I shouldn't run WOT during break in, just had to do it once)
I upgraded to the Octura collet, and it does miracles compared to the old stock collet. DO NOT OVERTIGHTEN YOUR FRIGGIN COLLETS!!!! Onmce you overtighten them, its too late, you will be breaking shafts once again. They just need to be snug! I also got the octura 24" cable and 2 propshafts, for 19.99 shipped from funrcboats.com. They are MUCH better than the stock ones! Granted you have to cut it in half and solder the two propshafts on.... We used special heat cure epoxy and THAT STUFF IS TUFF!
I am running the octura X438, it performs better and faster than the X440. 
Anyone using O'Donnel Boat fuel? The Grimmie stuff was out of stock that we have always used, and it worked great. We are going on vacation and didn't have enough fuel for the boats up at the lake, so we ordered some O'Donnel stuff. We'll see how it works.......
I also changed out the stock servos for Futaba Ball Bearig servos that I had leftover from a RIP plane. Much better resolution, and better throttle response and steering response with no gear slop like the stock ones.

victor_belmonte

Good day. Anyone else here that can help me in problem rod? and the hint of starting the engine on OS .... Sullivan has a few items to change the game, but do not know which to use. hugs

Tummi

Guys, how are your pistons and sleeves after let's say a galon of fuel?

Mine were totaly scratched. Not sure why, let's assume my fault. I changed to a new set and after just 3 bottles of fuel (break in) I can already see some scratches on it. Is that normal?

Bonus question - what's the easiest way to remove flywheel?

T.

victor_belmonte

Tummi, can you help me? I need a picture of the inside of the engine without the shirt and piston, I had one problem with my rod and I can not know whether or not one broken piece of the engine block. thank you

victor_belmonte

Then I try to see how to take the wheel and you notice, I'm now in service. thank you

Tummi

victor_belmonte, I'm ~200km from my boat atm :/  Returning at the lake next week, will post some photos then.

T.

chris_ca

This thread is a little old, but I hope someone will still answer.
After 8 months of use almost every weekend, my stock shaft broke yesterday. I was a little upset because I lost my Octura propeller with it in the lake.
I would like to update to a Hughey flex shaft and Octura collet.
My question is do we have to remove the engine to remove the collet? Even when both parts of the collet are tightened, when I unscrew the collet from the engine screw, there is not enough room to remove it (it touches the shaft tube). It seems that I shouldn't have to remove the engine to remove the collet. Is this really necessary?
Somewhat related, I also wanted to add a belt to start it. There is not enough room between the collet and the shaft tube, even when the collet is tightened to insert one.
Is this normal that there is basically no space between the collet and shaft tube?
Thanks in advance for any help. I haven't found instructions anywhere on how to remove the collet.

Ron Olson

My Feedback: (1)

You should be able to remove the collet without pulling the engine. Just use pliers on the flywheel and a wrench (11mm?) to unbolt it, it's that easy.
If you order the Octura collet, make sure that you get the right one as they make them in 2 different lengths. You want the short one. Also make sure that it's the 5mm threaded one for nitro as they also have a 5mm for electric motors.
You can put the belt on before you put the collet on if it's tight for space. If you need to have a thin one try a sewing machine repair shop. I got a fistful of used belts for a song at one local shop.
If you deal with Steve at offshore electrics (.com) he may still carry the Hughey cable and proper collet with the cable already cut to the correct length. He also has the adjustable trim tabs too.

chris_ca

Hi Ron,

Thanks so much for the detailed answer. I was able to remove the collet, but the stuff tube moved a couple millimeters back when I unscrewed the collet. I might have to epoxy it back to avoid any leaks.
I ordered the Hughey cable and Octura collet from funRCboats.com. I also got a Grimracer prop, a cheap drive dog and a nice prop nut.

http://www.funrcboats.com/ProductInf...ID=FDHU44B4166
http://www.funrcboats.com/ProductInf...ctID=OCFH5MM15
http://www.funrcboats.com/ProductInf...uctID=AQUB9720
http://www.funrcboats.com/ProductInf...ductID=AER1510
http://www.funrcboats.com/ProductInf...ductID=AER1527

It was fun to shop :-)
I love my SV27 Nitro. I wish it was easier to start, though. Some days, it takes me forever to start it, even though I follow all the directions from the manual/video and read all related posts on this thread. I also upgraded to a Ni-starter, as my cheap glow plug starter might be the issue.

Thanks again for the answer.

Christophe