Yamaha RX1 Engines

458 posts in this topic

Posted

What size radiator is everyone using? Is anyone using an oil cooler?

You're thinking Rotax, which is an oil-cooled, air cooled engine with water-cooled heads.  Yamaha is not a 50-50 air-cooled/ liquid cooled engine, it is 100% water-jacketed - no oil cooler.

We stock dual core, 1.75 x 14.5 x 16" aluminum radiators with 1/4" burp line inlet, $90 + S/H.  These lay at about 25 degrees, angled to catch the wind, below the engine.  Also have silicone elbows and adapters, all-metal drain cock valves, silver-plated copper 1"x T flared hose couplings, flared 1" aluminum pipes and bends made to order. 

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Posted

Thanks for the reply do you have pictures?  I checked the website but did not find it.

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Posted

One thing to note: the Yamaha engines do have an oil cooler it is just built into the side of the engine next to the oil filter. It is a liguid to liquid heat exchanger and it uses the engines coolant.

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Posted

Teal or anyone ,on the RX1 with wide open throttle and with the plane tied down im getting 8000 rpm with a 72 inch 3 blade warp drive,is this in the ball park of having the right pitch? Just looking for a starting reference for the first flight

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Posted

For the Avid I would bring it up to at least 8500 RPM static. I know we are all used to lower RPMS but with these engines there is no advantage.

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Posted

Ok thanks for help:BC:

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Posted (edited)

Teal or anyone ,on the RX1 with wide open throttle and with the plane tied down im getting 8000 rpm with a 72 inch 3 blade warp drive,is this in the ball park of having the right pitch? Just looking for a starting reference for the first flight

Getting close to flying!   Congrats!!

Sounds like the same prop I was planning.  I forget, are you using a clutch?

And I'm sure you figured for it, but I did run into a limp mode (6000 rpm max) on my RX1 on the snow when the overheat light came on.  I think Greg Mills uses a certain resistor in place of the temp sender to trick the ecu into believing a normal temp value.  But my sled seemed to run fine by simply unplugging the temp wire at the sender.  With it unplugged I can't see how you would encounter a limp... right?

Keep us posted Willis!

And FYI for anyone... the RX1 snowmobile hits 10,200 rpm (142 HP) every full throttle application.  And Teals reccomendation for 8500 would result in a PTO output shaft rpm of about 7200 (with the 1.19 engine internal reduction) @ approx 127 HP.  Point being that 8500 sounds like a lot... but it really is a pretty big derate.

 

Edited by MN Kitfox 2

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Posted (edited)

Reference for my last post.  I think this chart was posted earlier?  (I stole it from someone...)  ;)

RX-1_CPR_Dyno.thumb.jpg.2dccc61b1ebbd13378c0da21f622f623.jpg

Edited by MN Kitfox 2

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Posted

Teal or anyone ,on the RX1 with wide open throttle and with the plane tied down im getting 8000 rpm with a 72 inch 3 blade warp drive,is this in the ball park of having the right pitch? Just looking for a starting reference for the first flight

Getting close to flying!   Congrats!!

Sounds like the same prop I was planning.  I forget, are you using a clutch?

And I'm sure you figured for it, but I did run into a limp mode (6000 rpm max) on my RX1 on the snow when the overheat light came on.  I think Greg Mills uses a certain resistor in place of the temp sender to trick the ecu into believing a normal temp value.  But my sled seemed to run fine by simply unplugging the temp wire at the sender.  With it unplugged I can't see how you would encounter a limp... right?

Keep us posted Willis!

And FYI for anyone... the RX1 snowmobile hits 10,200 rpm (142 HP) every full throttle application.  And Teals reccomendation for 8500 would result in a PTO output shaft rpm of about 7200 (with the 1.19 engine internal reduction) @ approx 127 HP.  Point being that 8500 sounds like a lot... but it really is a pretty big derate.

 

It is getting close ,got to finish off the new wing struts and redo the weight and balance, I don't have a clutch on my engine,it seems to start fine but not sure when its -20 how it will do.My brother is the mechanic so im not sure how he bypassed the limp mode ,I will ask him. I do know since we are using the yamaha tach display, we had to put in a couple of small lamps with the right resistence to take the place of the fuel sender and handle bar warmer ,otherwise we would get an engine warning light flashing on the display

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Posted

Teal or anyone ,on the RX1 with wide open throttle and with the plane tied down im getting 8000 rpm with a 72 inch 3 blade warp drive,is this in the ball park of having the right pitch? Just looking for a starting reference for the first flight

Getting close to flying!   Congrats!!

Sounds like the same prop I was planning.  I forget, are you using a clutch?

And I'm sure you figured for it, but I did run into a limp mode (6000 rpm max) on my RX1 on the snow when the overheat light came on.  I think Greg Mills uses a certain resistor in place of the temp sender to trick the ecu into believing a normal temp value.  But my sled seemed to run fine by simply unplugging the temp wire at the sender.  With it unplugged I can't see how you would encounter a limp... right?

Keep us posted Willis!

And FYI for anyone... the RX1 snowmobile hits 10,200 rpm (142 HP) every full throttle application.  And Teals reccomendation for 8500 would result in a PTO output shaft rpm of about 7200 (with the 1.19 engine internal reduction) @ approx 127 HP.  Point being that 8500 sounds like a lot... but it really is a pretty big derate.

 

It is getting close ,got to finish off the new wing struts and redo the weight and balance, I don't have a clutch on my engine,it seems to start fine but not sure when its -20 how it will do.My brother is the mechanic so im not sure how he bypassed the limp mode ,I will ask him. I do know since we are using the yamaha tach display, we had to put in a couple of small lamps with the right resistence to take the place of the fuel sender and handle bar warmer ,otherwise we would get an engine warning light flashing on the display

Steve Henry told me his always started great cold it was hot starting without the clutch that he had issues with.

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Posted

I think the this biggest factor as far as starting is the prop diameter and moment of inertia. I don't have any problems starting on my trikes but Im running 68-70"  3 blade light propellers. I usually start with the enricher (choke) open and the throttle cracked open. When it fires I throttle up a bit and close the enrichener. Most important thing to remember, if it ever fires up but wont get past a really low idle just shut it down because it will just shake and idle really low. Enough shaking to possibly knock your airbox off or damage of stuff eventually.

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Posted

Thanks for the tips guys

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Posted

I managed to get a hour flight in this morning in the avid with the Rx1 engine,It ran nice and smooth and climbed at 800 ft/min at 7500 rpm without trying, I could easily cruise 6500 rpm @80-85 mph and stall without and flaps was around 50mph , was awhile coming but it seems worth it :BC:

rx1avid.JPG

rx1flight.JPG

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Posted

stalls at 50?

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Posted

 Forgot to mention there was 2 of us in the plane , im not to sure what it is with me in there , too busy watching the ground lol

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Posted

That cowled out real nice Marshawk. Is that a Subaru Cowl? 

I got my Skytrax and C gearbox mounted on on my RX-1 engine this weekend. The instructions were staight forward and Teal was great about answering my many questions and providing input. I also recieved my wiring harness, exhaust flanges and engine mount parts. 

I would love to hear about what propellers have proven to be effective on this set up or what others are planing to use.

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Posted

   It is a kitfox 5 cowl, the same cowl that I used for the subaru, its a snug fit but it works. Teal was very helpful with me as well. As for prop I am using a 72" 3 blade warp drive , it seems to be working fine,I haven't started playing with the pitch yet it was still the same pitch from the soob engine, for some reason the last bit of throttle doesnt seem to do anything so were thinkinjg we need  to service the carbs,  so want to do that first,in the mean time it seems to fly fine at 7500 max rpm

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Posted

If you pull those carbs apart be real gentle with the needles. The plastic part that holds them in place is real easy to break if you push them down too hard and Yamaha doesn't sell just that part. Also don't forget the tiny o-ring underneath the carb cap.

 

 

Ken.............

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Posted

sure looks nice

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Posted

Thanks Tjay and thanks for the tip ken

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Posted

Just a word on your comment about the last bit of throttle not doing anything. Your kind of running the engine at a low max RPM. When you do this the throttle response changes. you might find that by increasing your rpm another 1000 (flatten the pitch) your throttle will behave a little different and you may even get better full economy. I know it sound counter intuitive. remember these engines develop their max HP at just above 10,000 RPM and the snowmobile racers are running them up to 11,000 RPM frequently.

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Posted (edited)

Thanks Teal, I'll try playing with the pitch this weekend and  get another 1000 rpm and see if that changes the throttle issue

Edited by marshawk

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Posted

Have the RX-1 engine with the Rotax C gearbox and Teal's cool adapter mounted and the header built in a Zenair  CH701 . I am after options for radiator choices and optional oil tanks. What have you used?

All input welcomed.

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Posted (edited)

I like the clean install of the  polaris razor radiator that teal has done!  Pic below is all I have.  It mounts to bottom of engine mount and does not penetrate out the cowl or into the airstream, rather it is flush with the cowl and presumably  gets flow (downflow) pushing through the cowl openings near the prop.  Maybe he can post how well it is working down in the AZ climate.

And i personally plan to use the rx1 oil tank because it incorporates the low oil warning and it is designed specifically for the rx1 (albiet a bit ugly)

20170121_165300.jpg

Edited by MN Kitfox 2

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Posted

I will have to look and see how much room I have under the engine ,alot cleaner than mine  hanging down an if it keeps it cool in AZ I should have no problem up here, I also used the Rx1 oil tank  for the same reasons

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