Gas Guys Questions

[RichardB]

Gas Questions ?

1. Is anyone making a new jug that is 90 degrees turned around so the intake is in the front and the exhaust is to the rear ?

2. Can you take the pull start off and add a pulley so you can use a 12 volt starter like with the nitro boats ?

These two mods would seem to make everything more streamlined and maybe more power.

Richard

 

[Ian Webster]

You mean something like this RCMK rear exhaust

Picture from CC racing engines

 

[John Crouch]

Speedmaster sells a combination pulley/collet assembly that you can use and still keep the pull starter. There are other people that make a pulley to replace the pull starter. I am pretty sure that in impba the pull starter has to stay for engine to be leagal.

I hope this helps, John Crouch

 

[Don Ferrette]

Speedmaster sells a combination pulley/collet assembly that you can use and still keep the pull starter. There are other people that make a pulley to replace the pull starter. I am pretty sure that in impba the pull starter has to stay for engine to be leagal.
I hope this helps, John Crouch

The pull start only has to stay and be functional for the Thunderboat and SuperSport mono classes in IMPBA (it's all in the rulebook). The RCMK rear exhaust motor has already been deemed an IMPBA legal LS27 motor due to the fact they make all the major components of the motor, not just a piece or two. B)

 

[Rigged]

i believe its NAMBA actually that the pullstarter must remain the primary source of starting... unless they have changed that. Which in either organization is a stupid rule if you ask me. Im 23 and have had surgery done twice now on my shoulder i primarly use for starting, and after a 2 day event starting my own boats and peoples boats i pit for, i feel like i did before going into the surgery room.

But you can get pulleys for belt start for either side... whether you wanna replace the pullstart or just add one in front of the collet.

and btw No, nobody is making just a jug modded for Rear exhaust. RCMK does sell the case (which is a 4 bearing) that is for rear exhaust that you can use a regular zenoah jug on (they sell them as a complete motor, which isnt the R254 pictured above...but they are $$$$). Theres nothing different within the jugs for rear exhaust...its the case and piston. You may also be able to get the blank QD billet case for rear exhaust and have it machined for use with zenoah jugs.

 

[Bill-SOCAL]

Here's the NAMBA Rule:

vi) Recoil starters must be included on the original engine and must be retained on engines in this class.

This is for the "G" classes. The Open "GX" classes do not require the pull start.

Notice that the rule does not REQUIRE the use of the recoil starter, only that it be present.

Also note that the above rule is different from the previous rules. This new rule went into effect just recently.

 

[Rigged]

Here's the NAMBA Rule:

vi) Recoil starters must be included on the original engine and must be retained on engines in this class.

This is for the "G" classes. The Open "GX" classes do not require the pull start.

Notice that the rule does not REQUIRE the use of the recoil starter, only that it be present.

Also note that the above rule is different from the previous rules. This new rule went into effect just recently.

Which is stupid if you ask me. I much rather be able to take the belt off the front and out of the boat then leave it inside wrapped around the collet.

Now what i wonder is what could they say if i gutted a pullstart, and had the belt coming through the top of it... doesnt say it has to be functional, just says it has to be on there. LOL!

 

[MIKE HAYNES]

Here's the NAMBA Rule:

vi) Recoil starters must be included on the original engine and must be retained on engines in this class.

This is for the "G" classes. The Open "GX" classes do not require the pull start.

Notice that the rule does not REQUIRE the use of the recoil starter, only that it be present.

Also note that the above rule is different from the previous rules. This new rule went into effect just recently.

Which is stupid if you ask me. I much rather be able to take the belt off the front and out of the boat then leave it inside wrapped around the collet.

Now what i wonder is what could they say if i gutted a pullstart, and had the belt coming through the top of it... doesnt say it has to be functional, just says it has to be on there. LOL!

i have never had a belt wrap around any of my collets.thats the way most if not all of the nitro boats start.i have a qd high torque motor in my sport hydro and it has a pull starter in front and a flywheel at the rear.if you think it would get wrap up,most them have some kind of memory to them,so twist it inside of it self and will stay smaller then full size.

this is a picture from speedmasters web side

http://www.rossisales.com/gasboats.html

 

[RaceMechaniX]

To answer the questions:

Yes, there are several manufacturers that make "rear exhaust" motors. RCMK makes a Zenoah like motor, Quickdraw makes a very nice motor based on a Zenoah and CMB has two knarly motors a 35cc and soon a 26cc.

When it comes to starters, a rear exhaust motor typcially has the carb in front like most nitro motors making it difficult, but not imipossible to use a pull starter due to the interference of the carb. Several members on the Dock have worked ways around this. At least in NAMBA I believe the RCMK motor is considered a GX motor, so belt or pull is up to you. If it is G legal then you would have to find away to mount a pull starter that was functional, but not necessarily the prime starting method.

The inline layout of the gas motors seems to have little effect on the performance unless you have a special SAW prepared boat with slippery aerodynamics. The one excpetion may be the zimmerman disk CMB motors, but for what they add in increased power they take back by their additional weight. (They are very heavy motors)

Tyler

 

[Rigged]

Tyler off topic but did you ever get to get any video of your stryker cat with the cmb 35 in it?

 

[Rigged]

Here's the NAMBA Rule:

vi) Recoil starters must be included on the original engine and must be retained on engines in this class.

This is for the "G" classes. The Open "GX" classes do not require the pull start.

Notice that the rule does not REQUIRE the use of the recoil starter, only that it be present.

Also note that the above rule is different from the previous rules. This new rule went into effect just recently.

Which is stupid if you ask me. I much rather be able to take the belt off the front and out of the boat then leave it inside wrapped around the collet.

Now what i wonder is what could they say if i gutted a pullstart, and had the belt coming through the top of it... doesnt say it has to be functional, just says it has to be on there. LOL!

i have never had a belt wrap around any of my collets.thats the way most if not all of the nitro boats start.i have a qd high torque motor in my sport hydro and it has a pull starter in front and a flywheel at the rear.if you think it would get wrap up,most them have some kind of memory to them,so twist it inside of it self and will stay smaller then full size.

this is a picture from speedmasters web side

http://www.rossisales.com/gasboats.html

True... but id still rather just have a belt or two in my pocket. If you break a belt (ive never had luck with belts staying together), its easier to reach in your pocket or run back to pits, grab another and stick on the pulley and start it up. Around the collet you gotta run back, get a 5/8 and 9/16 wrench, undo the collet, pull cable, slip another on....all while trying to beat the clock and get off the dock. Ive also heard of the cranks in zenoahs twisting from belt starting... dont know if thats completely true, but i trust the source in which i got that info.

 

[john v]

did you guys try the spring assist recoil . i have one on my zenoah and it is very easy to start. bh hanson has them for approx 40$

 

[RichardB]

Here's the NAMBA Rule:

vi) Recoil starters must be included on the original engine and must be retained on engines in this class.

This is for the "G" classes. The Open "GX" classes do not require the pull start.

Notice that the rule does not REQUIRE the use of the recoil starter, only that it be present.

Also note that the above rule is different from the previous rules. This new rule went into effect just recently.

Which is stupid if you ask me. I much rather be able to take the belt off the front and out of the boat then leave it inside wrapped around the collet.

Now what i wonder is what could they say if i gutted a pullstart, and had the belt coming through the top of it... doesnt say it has to be functional, just says it has to be on there. LOL!

NOW THAT IS A REALLY COOOOOOOOOOL IDEA.. put a pulley in the housing and open the top of the housing in the front of the engine.

 

[Don Ferrette]

NOW THAT IS A REALLY COOOOOOOOOOL IDEA.. put a pulley in the housing and open the top of the housing in the front of the engine.

It's already been done successfully by my buddy John (Finch). Kinda neat actually but I think he put the pull start back on.

 

[RichardB]

You mean something like this RCMK rear exhaust

Picture from CC racing engines

Who makes the RCMK ? Korea ? when modded how much HP and RPM's

What is the price ? Who else distributes these engines and do they do mods as good as CC ?

Also, can you get this engine at a lower price in stock form and do your own mods ?

Richard

 

[Rigged]

The RCMK R254 jug (the one in picture) on a zenoah bottom end made a bit over 5hp in stock form with a CC Racing 1" header pipe. The only other person besides Carlo that is selling them in the US is Bob Finn i believe.

The Complete motor you see in the picture is around $500 or so stock, you can get the cylinder alone for i believe right around $120. From what ive heard, the material is alot harder then zenoahs making them harder to modifiy.