Belt Redrive/Reduction help for Yamaha RX1 engine

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AlaskanOutdoorsman
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Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Fri Mar 17, 2017 2:21 am

Hi all.

I'm looking for some help build a reduction drive for my airboat. To be frank, I jumped into a rebuild project that I don't have all the knowledge for so I'm posting for any and all assistance I can get. In short, I live in Alaska and sold the 65HP Rotax engine, 3:1 C-type gearbox and IVO prop on my 12' airboat after the engine blew up and the prop took some damage. I've since rebuilt most all of the boat.

15355646_1423893447622591_6596995910071085970_n.jpg


After much consideration on engine options I decided to install a Yamaha Genesis 4-cycle snowmobile engine from a 2004 RX1. The engine is about 160 lbs installed and produces 120-150 HP depending on engine RPM. These engines are used quite a bit in the aviation world without any problems with an adapter and gearbox assembly and I've found tons of information on that application. I plan to add a turbo kit to get an estimated 200HP on pump gas in the future but I'm not there yet.

Stock engines used in aviation generally require an adaptor/gearbox combination which is rather expensive and may not hold up to the extra turbo HP. I just sold a gearbox I had considered using. This leads me down the redrive/reduction drive road unless I find something affordable online.. but I have ZERO knowledge on how to build one and to date I have not found anyone in Alaska that can offer any advice other than "go to the forums" or "sell the mini" so here I am...

Would someone be kind enough to point me in the right direction? Where the heck do I start?

Any and all assistance is very appreciated.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Fri Mar 17, 2017 4:31 am

I forgot to add I was cautioned to steer clear of cog belt PSRUs for YG4 engines due to their high speed, torque and HP and was told there may not be cogged belts rated for max engine RPM of 9000. These engines red line around 12000 rpm.

An immediate option would be spending $2000 on a SPG4 gearbox and adapter but the box is only rated for 180hp. The box would work with a stock engine but wouldn't handle the extra 100 HP with the turbo. I'd rather not spend that kind of money right now anyway, this project has killed a couple extra piggy banks than I had expected.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Air canada » Mon Feb 05, 2018 8:45 pm

Any progress with finding a belt gear reduction or gear to gear unit I'm in process of swapping out my 35 Briggs for a apex engine preatty well same as rx1 but a fule injection motor so I am also wanting a plate on back of motor style vs aircraft gear reduction unit
:canada:

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby snow bullet » Mon Feb 05, 2018 9:23 pm

is there not a gear box on that motor that reduces it from 11000 rpm to 8000

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Sat Feb 17, 2018 10:48 pm

Just saw this post, haven't been on here in a while.

The engine has an internal reduction but it is not enough for use on an airboat or airplane "as is". There are a number of aircraft/trikes flying around with Yamaha RX1 power and roughly 20-30 of them use a specific adapter ($1500) with the Rotax C-gearbox (3:1 reduction); although there are other gearbox's and adapters that may/will work with this set-up. The problem is finding a gearbox. I've read the RX1 can also use a C and E-style gearbox, a Hirth gearbox, SPG 3 through Tango Gyro, AK 7 by Mohawk Aero (which I believe is a modified SPG 4). Each gearbox has different mounting requirements and requires some type of adapter in addition to modifying the gearbox assembly. The C-gearbox can use the Rotax hardy disc for light weight propellers, or an RK400/TMR 400 centrifugal clutch for larger propellers. I've read that Luga props are a good option and are both affordable and lightweight.

If you have an APEX not all the above information will necessary align with your project due to some differences but I've seen photos of RX1 APEX engines for aircraft/trike use. Mine is a 2004. That said, I've read about them being used but believe you need a different adapter assembly. For my engine the cost for an adapter, gearbox and clutch is about $3600 USD plus shipping which is why I'd prefer a belt-gear reduction set-up. Should prove to be cheaper.

As far as my progress, well, I have not found anyone in Alaska that will take on the project or can do the work but I do have a list of needed parts that will work with the high RPM's/torque after talking with a gentleman who built one for his 200 HP Turbo RX1 3 cyl engine. He reported no major issues with about 100 hours of run time if memory serves me correct but he did have some vibration which I expect is due to the 3 cyl engine being used (the 4 cyl is better balanced) or, it may have been due to the weight of the snowmobile clutch being removed and not replaced. Either way, he said the boat ran fine.

I'm currently attempting to track down all the parts and find someone that can build what I need. I have a lead on a new fabrication shop and will hopefully know more this next week.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby needcoffee » Wed Feb 21, 2018 10:56 pm

Did you find someone to help machine your parts?

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Wed Feb 21, 2018 11:34 pm

No, not yet. I've been tracking down all the parts and have most everything sourced for order. Any recommendations?

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby needcoffee » Thu Feb 22, 2018 12:11 am

I sent you a pm.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Gary S » Fri Feb 23, 2018 7:01 am

AlaskanOutdoorsman wrote:Hi all.

I'm looking for some help build a reduction drive for my airboat. To be frank, I jumped into a rebuild project that I don't have all the knowledge for so I'm posting for any and all assistance I can get. In short, I live in Alaska and sold the 65HP Rotax engine, 3:1 C-type gearbox and IVO prop on my 12' airboat after the engine blew up and the prop took some damage. I've since rebuilt most all of the boat.

15355646_1423893447622591_6596995910071085970_n.jpg

After much consideration on engine options I decided to install a Yamaha Genesis 4-cycle snowmobile engine from a 2004 RX1. The engine is about 160 lbs installed and produces 120-150 HP depending on engine RPM. These engines are used quite a bit in the aviation world without any problems with an adapter and gearbox assembly and I've found tons of information on that application. I plan to add a turbo kit to get an estimated 200HP on pump gas in the future but I'm not there yet.

Stock engines used in aviation generally require an adaptor/gearbox combination which is rather expensive and may not hold up to the extra turbo HP. I just sold a gearbox I had considered using. This leads me down the redrive/reduction drive road unless I find something affordable online.. but I have ZERO knowledge on how to build one and to date I have not found anyone in Alaska that can offer any advice other than "go to the forums" or "sell the mini" so here I am...

Would someone be kind enough to point me in the right direction? Where the heck do I start?

Any and all assistance is very appreciated.



If your trying to get to 200 HP, why not just use a 200 HP lycoming aircraft engine. You don't have to hear a engine screaming in you ears and you don't need any gear reduction. Bolt a prop on it and go. As many planes as Alaska has there has to be some runout around.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Fri Feb 23, 2018 2:05 pm

An 0360 and 0390 weighs in around 300 lbs IMO thats to heavy for my hull. If I'm going to weigh the boat down I want it to be full of meat on the way to the freezer instead of an engine and gas. Cheapest I've found a well maintained and complete 0360 for is about $8-9000K; parts hold value in Alaska or are often junk requiring rebuild and a lot of time and money.

The YG4 NA (Normally Aspirated) Yamaha engine is 140 HP and weighs in at only 125 lbs! The YG4 NA with a stock turbo will cost you less than 1/3rd of a 0360 and will produce 200HP on regular gas with no upgraded engine components. The engine is geared 1.19:1 with an internal countershaft (if the engine is 7200 RPM the output countershaft is 6050 RPM) and has a harmonic damper that arrests/decouples harmonics between the prop and engine. This is something the YG3 Yamaha engines and a direct drive Lycoming doesn't have. A stock YG4 without a turbo ran at 8500 RPM will produce about 115 HP and burn about 3 gph of fuel. I've been around snow machines all my life.. the noise doesn't bother me and I"m wearing noise cancelling headphones anyway. I'm looking for the best weight/HP and fuel consumption possible.

In any event, my boat is a 12x60 with a grass rake. After extensive research I believe the Yamaha has what I need and is an overall better option for my mini. Unfortunately there are not a lot of mini's in Alaska and what we do have generally don't have more than 65 HP from what I've seen on the rivers. Alaskan's also generally run gearbox's or direct drive so I've had to do a lot of research for this project.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby kwanjangnihm » Fri Feb 23, 2018 2:32 pm

just an observation but the expanded metal will kill your thrust the way it is setup now

its like cutting your clean air in half right now :salute:

no air = no push :violent1:
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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Fri Feb 23, 2018 2:49 pm

Agreed. I may be removing it depending on performance. Some guys use it temporarily to protect their blades when in the willows then remove it as needed so I had it tacked on for the time being.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby bkmail » Fri Feb 23, 2018 3:10 pm

It was built when it had a 65 HP snowmobile motor on it. Things have changed since then.....
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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Air canada » Wed Mar 21, 2018 9:59 am

Has anyone got the rx1 or apex engine plate and coged belt gear reduction built yet I was thinking along the lines of the same thing as the century mini gear reduction but for the Yamaha engine so if anyone has had this built yet or knows who would sell one I'm very interested I don't like the rotax c gear reduction route at all so if some one has got the cogged belt style built and ran one for thouse yammies let me know I want to switch my mini pro 116 over to that Yamaha power I think it would be a game changer


Thanks
:canada:

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Prototype » Wed Mar 21, 2018 9:15 pm

Air canada wrote:Has anyone got the rx1 or apex engine plate and coged belt gear reduction built yet I was thinking along the lines of the same thing as the century mini gear reduction but for the Yamaha engine so if anyone has had this built yet or knows who would sell one I'm very interested I don't like the rotax c gear reduction route at all so if some one has got the cogged belt style built and ran one for thouse yammies let me know I want to switch my mini pro 116 over to that Yamaha power I think it would be a game changer


Thanks

Be careful on your numbers.
Had a Pe 90 gpu on a mini pro and it twisted all the way to the bottom constantly with a 3 blade saber.
Ran the mountain, but was crap in water!

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Air canada » Wed Mar 21, 2018 9:25 pm

What do you mean by twisted all the way to bottom ? And what do you think was cause of bad water performance ?
:canada:

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Thu Mar 22, 2018 5:15 pm

Air canada wrote:Has anyone got the rx1 or apex engine plate and coged belt gear reduction built yet I was thinking along the lines of the same thing as the century mini gear reduction but for the Yamaha engine so if anyone has had this built yet or knows who would sell one I'm very interested I don't like the rotax c gear reduction route at all so if some one has got the cogged belt style built and ran one for thouse yammies let me know I want to switch my mini pro 116 over to that Yamaha power I think it would be a game changer


Thanks


There is only one gear belt reduction drive that I'm aware of. It uses a custom length GT Poly Belt connected to a driveshaft mounted above the engine. I've seen a few trikes with compact box's done but they were not approved for flight, were located in Europe, and all attempts to secure more information failed. I don't know if they flew or not. The APEX engine has a new 'direct mount' gearbox being developed. I'm not sure when, or if, it will be available.

The C-Box has been used without issues on 200+ HP airboats; the hard part is finding one on the used market.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Air canada » Thu Mar 22, 2018 7:32 pm

I don't care about the approved for flight I just don't want to have to find or deal with a c series box than. Over pay for the 1500$ usd usd adapter to fit the c drive I just want like ya mentioned the Polly chain and pully setup like the century Briggs Mini re drive I have now just a beefed up version that fits the apex efi engine there simple amd reliable if you keep distance between pulls short
:canada:

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Prototype » Sun Mar 25, 2018 10:32 pm

Air canada wrote:What do you mean by twisted all the way to bottom ? And what do you think was cause of bad water performance ?


What I meant is "Some could easily over power a mini hull without a counter rotator and the twist of the prop will/could easily role you into as side dive to the bottom. Most can't fathom that, but most also cant on a mini or full size hull.
Any boat could be over powered to the bottom very fast. Most mini's don't have props that can withstand a water strike? Hell a lot of big boats now days can't either
I would suggest 3 blades regardless? They just tend to push better than two pitched more.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Tue Jul 31, 2018 4:08 pm

Air canada wrote:Has anyone got the rx1 or apex engine plate and coged belt gear reduction built yet I was thinking along the lines of the same thing as the century mini gear reduction but for the Yamaha engine so if anyone has had this built yet or knows who would sell one I'm very interested I don't like the rotax c gear reduction route at all so if some one has got the cogged belt style built and ran one for thouse yammies let me know I want to switch my mini pro 116 over to that Yamaha power I think it would be a game changer


Thanks


Ive been researching this project continually and at this point have talked to people in the US, Canada, Russia and the UK who have used Yamaha power without a gearbox. All belt drive systems are self made. I've tried to gather all the information I can to rebuild/fabricate and decided to buy an airboat to run and hunt from this fall while I finish this project hopefully this winter.

In any event, here is a turbo charged 3 cyl engine (200 hp) with a 3:1 belt drive from Canada. It has since been modified to include a harmonic dampener on the lower shaft to reduce vibration that is due to the 3 cyl engine being used. You can buy most the parts for this from Grainger.
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Last edited by AlaskanOutdoorsman on Tue Jul 31, 2018 4:42 pm, edited 1 time in total.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Tue Jul 31, 2018 4:17 pm

Here is an R1 motorcycle engine and transmission connected to a prop via drive shaft and pillow block bearings. This option will haul quite the load. The transmission is ran in second gear. Talking to a different builder it was recommended that the joints and drive shaft could/should be a little larger but this boat is 15' long and reported no problems hauling a load.
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Last edited by AlaskanOutdoorsman on Tue Jul 31, 2018 4:54 pm, edited 3 times in total.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Tue Jul 31, 2018 4:26 pm

Here is a Yamaha 3 cyl air raft belt drive application from Russia.
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Last edited by AlaskanOutdoorsman on Tue Jul 31, 2018 4:54 pm, edited 1 time in total.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby AlaskanOutdoorsman » Tue Jul 31, 2018 4:36 pm

I've seen other belt drive applications on trikes and experimental aircraft around the world but most aviation applications use a gearbox of various assortments and the opinions in the aviation world on what's best produce strong discussions. All gearbox's require adapters of one sort or another, can use a clutch, and are double in price compared to the pillow-block belt drive setup.

In any event, hope these pictures/information helps anyone interested in a belt drive set-up with this engine application. I've learned of a number of motorcycle R1 engines being used in airboats with similar designs to those above. The mini world has a lightweight 150 horse power engine as an option with these Yamaha motors.

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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby OneBFC » Tue Jul 31, 2018 7:05 pm

axial load ratings would be one thing to check very carefully on the pillow block style reductions.

choose bearings wisely.
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Re: Belt Redrive/Reduction help for Yamaha RX1 engine

Postby Slidin Gator » Tue Jul 31, 2018 7:42 pm

Alaskan,
You've been holding back! But all good. I too have been following all the threads I can on the motorcycle/snowmobile engine applications that I can. Lightweight is always the easiest path to performance, the equation changes to weight^2 in the aviation and airboat worlds!

My cousin in South Dakota builds custom tuned exhaust systems for motorcycles. His primary market and name is in flat track motorcycle racing, where torque is king. Here in Florida, I get to see him once a year, during bike week (imagine that).

Checkout Billbuilt on Facebook. He can make these engines produce without making your ears bleed. In the last few years they have implemented db sound restrictions on the flat track bike classes and Bill's phone has been ringing off the hook for his dyno tuned stuff.

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