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-   -   4 cycle (http://www.rcuniverse.com/forum/speed-rc-gas-boats-236/1696101-4-cycle.html)

figure9 04-06-2004 11:41 AM

4 cycle
Has anyone ran the 26cc ryobi 4cycle engine in a deep V? I would like to try this on a 55" pleasure/speed boat.

OLD_SLOW and in the WAY 04-06-2004 08:19 PM

RE: 4 cycle
The ryobi 4 stroke is a very reliable engine although its revlimited and wont spin up so speed wise you are limited.. Honda has come out with the 25cc overhead cam and will release the 35cc OHC engine soon.
some hop ups are available for the honda like camshaft and some simple mods will let the ponies out of this very reliable engine

Joe Petro 04-12-2004 12:37 PM

RE: 4 cycle
I picked up a new Zenoah (RedMax) 26cc 4cycle, and am installing it in a 55 inch scarab.
The engine is extreeeeemly quiet, and should be just the ticket for some quiet, fun boating.

The only issue I have is that the clutch bell is designed for a splined shaft.
I am thinking of using some sort of a broach, to square it.

If anyone is interested, I can post some pics...

Joe Petro

magyarbacsi 04-12-2004 09:35 PM

RE: 4 cycle
I would like to see pictures, but more so performance specs, i.e. weight, torque at rpms and so forth.

BajaBob-delete 04-14-2004 01:06 AM

RE: 4 cycle
The Zenoah 26cc 4 stroke is made with the same level of quality or lack there of as they achieve on their 2 stroke engines,crank case mating surfaces are not machined,there are dings and dents on mating surfaces.There is no assurance the case halves will mate squarely with out the machining.
The quality level deficiencies of their 4 stroke are compounded by its design.The reciprocating assemebly with the stamped connecting rod design and the plastic button wrist pin retainers may work well in a low rpm trimmer but are marginal in a high performance application.
The small bore diameter limits the valve sizes,the head and intake tract are tortuous at best. Up draft carburation? The large and deep swimming pool combustion chamber with the valves shrouded is reminiscent of early to mid 70s smog engines coming from Detroit.Even if larger valves could be fitted the ports do not have enough material around them to allow them to be enlarged and their shape is ludicris.This is your fathers Oldsmobile.
The oil dipper lubrication system is pure stone age,however it is in keeping with the era of technology used in the design of other systems on this engine.
The plus side of this thing,is with the removable head the compression ratio may be raised relatively easy by machining the deck face,the pushrods would need their length adjusted.A larger carburetor of the same type is recommended.freeing up the exhaust will help with an improvement made to the intake side but is most likely not necessary because the rpm capability won't increase all that much. Ignition timing could be advanced somewhat to gain some throttle response and maybe some power.
For all practical purposes this engine is best suited for a scale type of craft that doesn't require high rpm or a lot of power.

figure9 04-14-2004 06:20 AM

RE: 4 cycle
Is the Ryobi 4cycle in the same class as the Zenoah?

BajaBob-delete 04-14-2004 08:30 AM

RE: 4 cycle
I haven't had a Ryobi apart to review it,but I understand the shape of the crankcase gives the airplane guys a hard time mounting it.The best four stroke engines I have looked at so far come from Honda. The Robin/Subaru shows some promise.
Most of these engines in stock form will make a good choice for a scale performance boat, however when it comes to modifying one to perform better or its potential, the Honda is by far and away the best choice.

OLD_SLOW and in the WAY 04-15-2004 06:47 AM

RE: 4 cycle
The Honda jujst came out with the GX25 OHC and soon the GX31OHC both have THe Honda quality and run whisper quiet. I am aware of a 31cc ohvHonda that can turn over 13,000 rpm in a boat with a few simple mods. forget about watercooling with the convoluted head shape. i bought mine at the local honda dealer for under $225. there are hiper cams out for the honda now.

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