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Old Jul 10, 2013, 01:27 PM
RC boat Rock Star
Kalamazoo, MI
Joined Apr 2004
2,928 Posts
Oh man, that's just nasty!
The stuffing tube may be molded into the silicone which is going to make it hard to remove. You might have to slit it open to get it out of there. Yeah, get it out any way that you can.
That pipe actually works well for a cheapie from China, I've got one that was on a Sikk once before and is now on a stock RCMK. The Sikk's are hard on pull-starters though so pull the rope until the starter engages then yank the rest of the way.
2) Yes, you can shut down the engine using the transmitter. Remove the idle screw so that it will.
3) You can try it.
5) I mount mine using a Dremel tool with a right-angle attachment for drilling the holes and a reverse tear-drop shaped bit as it's the perfect size for running the bolts through. Not pretty but it works. I space the engine about 1/8" or a hair more off the floor of the boat using scrap ply or balsa then mark where the isolators set with a pencil. Finish marking using the washers to find the center.

I rebuilt this boat just for messing around with, for my daughter-in-law to learn how to drive with or for anyone who shows up to take it for a spin.
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Old Jul 10, 2013, 02:32 PM
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264 Posts
Nasty is right! eBay didn't show it in the pics but I got it for 47 ($70) plus shipping so I suspect not bad.
Thanks very much for all the answers. I was thinking about the reverse action of the servo triggering a cut off switch, but removing the idle screw makes sense.

I measure (roughly) the flexi to be about 13" (330mm) from prop nut to end of square end. Can I just buy a 500mm flexi with built in stub shaft and then cut the twisty bit down to size?

Nice boat in the pic, I even have the same silencer. How quick is that set up? What hull/length is it? What prop do you recommend?

Gee I am just full of questions.....
Thanks again.
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Old Jul 10, 2013, 02:58 PM
RC boat Rock Star
Kalamazoo, MI
Joined Apr 2004
2,928 Posts
No, not a bad price for the boat then.
Yes, you can.
That was the first day out with it after the rebuild and it didn't go so hot as the steering linkage gave way a few seconds into the run. It's been back on the water twice since then but it is still a little flighty. The next time out should be better. The boat came from .www.americanrcboats.com , I picked it up at a national event race in 2007 as a birthday present to myself a day later. It's around 46" long. Speeds roughly in the high 40 MPH range using a prop that I just threw on it, close to an Octura 670 in size. It seems to handle that prop well. Your Sikk should be able to take anything from a 6717/3 on up to the 670. The Sikk was also in a Falcon 41 catamaran for a while. I sold that engine ot a friend who dropped it into an outrigger hydro and it literally flew with it in there!
That's OK with the questions, keep them coming and hopefully I can answer them.
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Old Jul 10, 2013, 04:17 PM
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Joined Sep 2009
264 Posts
Quote:
Originally Posted by bermylizard View Post
Can I just buy a 500mm flexi with built in stub shaft and then cut the twisty bit down to size?
Quote:
Originally Posted by Ron Olson View Post
Yes, you can.
I assume that yes you can is in reference to the above question. It is my fault for asking to many questions.. haha

So ignoring that here is my shopping list, please advise:
Flex drive with stub shaft longer than required.


Copper tube with teflon? I figure I should replace the whole drive line in that boat, keeping the strut and rudder.


Collet coupling for flex shaft:


Drive dog:


How do you find the propshaft supports and lubricators? Necessary or overkill?


Cheers again,

Is there anythign else I am missing for the drive line?

Also the SIKK has four nipples for cooling (2 in - 2out) , but the current rudder has only one pick up. I have one of these pick ups. How does the idea of machining a trim tab to accept the pickup sound? I think I would prefer to just mount it in a trim tab, as opposed to a through hull installation. Otherwise just split the flow into the 2 inputs?
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Old Jul 10, 2013, 04:46 PM
RC boat Rock Star
Kalamazoo, MI
Joined Apr 2004
2,928 Posts
Yes. (That ought to really mess you up! )
I'm not a fan of square drive setups but then again, never had one but still don't think that I'd like them.
You have a good list of parts there for converting the boat over to the non-square drive setup with one exception, the Teflon lined stuffing tube. I use 5/16" brass tubing and as long as it's well lubricated it will give you no problems at all.
The T-bar is almost a neccessity in a mono hull. Both of mine (the other is a Rampage) use them. I don't use oilers but pull the cables and grease them.
My Sikk's had only the one in, one out fittings. The two in, two out setup could be overkill as it really shouldn't need that many. If you want to, pull out the extras and replace them with short bolts. I'd set it up for the most cross-flow. Look at the other marine gas engines on the market and they're only using one in, one out with the exception of ones like the Quick-Draw's, 2 in, 3 out! Yeah, I've got one of those now also.
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Old Jul 10, 2013, 05:56 PM
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Thanks Ron, your help is much appreciated.

Back in the day I used to modify 50cc to 125cc crotch rockets for myself and friends as extra income. I was very into my engines, modifying exhausts, port timings and trajectory, the works. However it was done in the back yard with a few rat tail files and hammers. No dremel. I had some good luck some bad. My best result was 70cc crotch rocket that would reach 90+ mph with the wind on a ~700m stetch. Acceleration was great for a 70cc. I learned that you had to sacrifice low end for top end. But this was 13 years ago. I remember widening the exhaust but not too much so to preserve the piston ring. Opening it too far would cause them to expand into the exhaust (slightly) and wear faster on the edge of the exhaust port even with chamfered ports. I used to angle the transfer ports more to the centre than to the back as they normally point. This delivered the air-fuel mixture right at the plug ready for boom, allowing more power at higher rpm, however the low rpm suffered from poor fuel mixing (I believe). We used to open up the transfer ports for easier flow and matched the openings. I never even had a micrometer back then it was all done by hand and eye. I used to buy a second hand bike, test it to the max and then sell it with half the bolts (the rest were in the grass!) Bermuda was a small place so having the fastest bike in school and your parish wasn't actually a big deal but back then it meant the world to us.

So what am I going on about? Well I have a copy of the two stroke tuners manual and fancy doing some research for some slight engine mods on the SIKK 26cc. Obviously first I want to break it in nice and easy get it running reliably and get used to it, but maybe of over the winter break it all down and try to work some magic. Is this normal practice for these engines?

Thanks for the tip on just using copper and lube. I agree that the PTFE (Teflon) will not last as long.
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Old Jul 10, 2013, 05:57 PM
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Quote:
Originally Posted by Ron Olson View Post
Yes. (That ought to really mess you up! )
That was a good one!
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Old Jul 10, 2013, 06:53 PM
RC boat Rock Star
Kalamazoo, MI
Joined Apr 2004
2,928 Posts
The Teflon liners need to be well-greased for long life as if not, they will get hot and melt. They also make a terrible noise when they aren't lubed well enough or in need of grease, like of like a bad fan belt.
Although I never had this problem, others have. The engines don't take a dunking very well if you have the 2-bolt head version as if they ingest water they can blow the top-end off. On the other hand, those engines with 4-bolt heads can stay on too well and end up by bending or breaking connecting rods and bending crankshafts.
A degree wheel can be your best friend when modding one of these engines to get the correct exhaust timing. The Sikk's have more HP and RPM out-of-the-box than a stock Zenoah so they really don't need a lot of work internally.
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Old Jul 11, 2013, 01:54 AM
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Well I got the shaft out with some minor damage, but nothing serious. Then I spent more money on little hardware pieces than I did on the hull! You have to sink money in this hobby, so to speak.
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Old Jul 12, 2013, 01:31 PM
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Joined Dec 2012
25 Posts
CY Ignition

I have a question about the CY ignition system that I've wondered about
for a long time.

Starting years ago and continuing to this day, CY has had it's own "all
in one" marine ignition. By it's design, this ignition must be firmly
attached to the engine and is exposed to significant heat and vibration.

My question is why can these ignitions hold up inspite of the heat and
vibration and the competitions "two part" ignition system appears to have
such a short life span? A variety of explanations have been offered which
explain workarounds for making the two part systems function properly but
I don't want to rehash all that that sort of info here.

There must be some basic design difference or method of manufacturing
that accounts for this.

In all my experience with CY engines I have never had to
- replace an ignition (though I faithfully keep a spare)
- reduce the plug gap to compensate for a weaker ignition output
- take any special steps to make sure it is well grounded

Anybody have any idea what the basic difference actually is? There has to
be a logical explanation.

http://www.davesmotors.com/ee438
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Old Jul 13, 2013, 05:55 AM
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Sorry mate, I have no idea why. Anybody else?
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Old Jul 15, 2013, 09:12 PM
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I glassed a few extra layers in the hull today as it was quite thin about 2" from the transom. I put a screwdriver through it prying the old prop shaft out. I've gelcoated the holes and filled the prop shaft hole in the transom to re-drill off center. Looking from the stern the prop turns anticlockwise.

Am I correct that I should offset the hole 1/8" to 1/4" to the right?

I have the new brass tube that meets up to the existing strut as shown in the pic. I've got new lead-teflon bearings for the strut , but was thinking about drilling it out a wee bit to give the brass tube a seat. Any recommendations?

I am not sure that a free end brass tube is wise.
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Old Jul 15, 2013, 10:47 PM
RC boat Rock Star
Kalamazoo, MI
Joined Apr 2004
2,928 Posts
Yes, I've had to drill my struts a wee bit to make them fit. That "wee" gap should be about 1/4" (4mm) between the strut and drive dog.
The 1/4" (preferred) offset is to help compensate for torque plus helps the prop dig in when making right turns.
I rarely see anynoe using Lead Teflon bearings anymore as most are just using brass tubing cross-drilled for grease pockets.
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Old Jul 18, 2013, 09:18 AM
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Thank again Ron. Now that I have all the gear and repaired the hull am I correct that I install all hardware then place the engine so that the hull balances at 33% of its length? Mark the engine and drill engine holes last?

I have no lid for this hull, should I make one? Are they necessary, I see many running with and without one.
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Old Jul 18, 2013, 09:20 AM
RC boat Rock Star
Kalamazoo, MI
Joined Apr 2004
2,928 Posts
Yup, you got it!
Go ahead and run it as-is without a hatch, these gas engines need the air.
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