670 Rotax 87 HP.

Greg Mitchell

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How many fellas out there are flying on a rebuilt 670 with 75 HP or 87 Hp with tuned pipes from Rick's Rotax?

They say the engine is well suited to the extra grunt.

I believe the 582 head goes on with the dual ignition and 582 pipes gives around 75 HP. With the tuned pipes 87 HP.

Is there a reason why this is not a good option for gyros when looking at upping the HP with minimal changes to the gyro?

Cheers,

Mitch
 

scottessex

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You very "experimental" at this point, The rotax 582 was designed by rotax yes from a snow machine, and made to work on aircraft. You are taking a "similar" engine and doing this by yourself, with out the $$$ and engineering staff. Sure other people have done it, many with great success.
But you are pretty much on your own, as you will have no factory support, and only rotax 582-618 published information to go on.
However it should be a piece of cake, compared to what I had to learn during my Arctic Cat conversion. :)
Do it right and get with everyone else that has done the conversion to compare notes, It should be a great engine.
 

choppergabor

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Good day mate :)
I just bought a 670 and will convert it. Brent and Jake have experience with these babies.
Stock pipe and setup is a brute 116 -127 HP depending on the year. Either C box 3:1 or redrive will work on them. 582 head will fit it but you'll have to get the ignition from the 582 for the extra plugs. I'll start a thread when I get ready to convert mine. Unless of course if you start one :)
 
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Greg Mitchell

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G'Day Scott,

Mate I'd buy one from Rick's Rotax already to go if I went that way.

Sell my 582 and put one of Ricks 670's on, that already has work done.

Mechanically I have no idea, so I'd not tinker myself.

G'Day Chopper,

Brent and Jake flying on these 670's yet?
I'll be keen to learn more from you all.

Thanks,

Mitch
 

choppergabor

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Mitch Brent has been flying his for years! And it is one tough engine. Jake is building his right now.
 

choppergabor

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That reminds me......... if any of you out there has a spare 582 head or ignition please PM me. Thanks :)
 

Greg Mitchell

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Does the 670 wind up with a very narrow power band, or is it as smooth as a 582?

Good Question Paul.

We need to hear from Brent.:) OR get a link to a thread if Brent has posted on it before.
Chopper, when you say 'years', what sort of hours has Brent put on the engine.
A fellow PRA member told me the engine might not have longevity in the gyro application?

I was looking at Jake's build and then went to Rick's website. The one Jake just built is being sold on? So Jake is putting one on a gyro for himself?

I wont be changing out engines for a while yet but figure its time to investigate other options especially if I dont have to change a whole lot in doing so.

Thanks again.

Mitch
 

Brent_Brown

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670 fun

670 fun

I have a R&D pipe and it has a kick when the rpms get about 4500 just when the rave lift up after that it is good. I would think the power band kick is less with a 582 pipe. BTW the 116 and up hp are with a 8250 rpm and up. I run it just like a 618 and is timed with 618 specs. I ran the snow ignition and timing for 25 hours then put a 618 head and ignition with bing carbs on it. I could tell it was a better runner engine. I proped it not to see 7000 rpm. you have to use a 670 case with the same shape as the aircraft engines. I think the years are 1990 to 94. I have over 50 hours on this engine and about the sane on the other one I sold for a MZ202 some time ago. I see no reason why this engine wont last as long as you take care of it like a AC rotax and not run it over 7000 rpm.

I have done some reading about rave that are used to give better low rpm power and they lift or slide up about 4000 to 4500 rpm. I see no need for them we run above this rpm not trial riding. I had the rave stick down and you can tell a big loss in poweer not cool. you could rig a cable like a 618 but I pull them out and clean mine each year so they work. but next time I will lock them in the up mod and never clean again.

I'm looking for a guy who said he had new cases made with provison 8 holes tipped ready for a gearbox. they use new HO 670 cranks and I think that is one thing you need to do with the old sled engine that was setting for years is to replace the crank and seals with new ones.

Tips for duel ignition, you have to cut some of the case to get the trigger to fit on the side that didn't have one to start with, the holes are there but not tipped.

I'm not sure if ricks 670 are converted to bing carbs and duel plugs if not I would ask him to do it that will save you alot of time and $$$. BTW 503 ignition parts will work/fit the 670. one thing I had to find a mag that had the high spots in the right place to line up with the triggers. you have to be looking at the parts to knowI guess.
 

Doug Riley

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I bought my tandem Dominator at Bensen Days 8-9 years ago. The owner had been flying it with a 670 and it fried right there at the show. We reached a deal on the gyro, without the blown 670. I believe it had an R&D exhaust.

I switched first to a 618 and then to a 912S (or "912$," if you prefer). Perhaps the 670 can be made to last, but my seller's unit certainly didn't.

I loved the 912S.
 

Monarchist

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Hi Doug...are you not still flying with the 912? I just bought a 912ULS with 1,500 hours on it in excellent condition, I'm hoping it will be a good engine for my Aurora.

-John
 

Doug Riley

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John: Nope, I sold the tandem once it became clear that the FAA would not honor the original proposal to "grandfather" us BFI's as Sport Pilot CFI's. Not only did they not do that, but there is also a continuing risk that the use of homebuilt gyros as trainers will be "phased out." That is, the machine could have become useless as a trainer at any moment, even if I dropped a bunch more money into re-qualifying myself as a SP-CFI.

The tandem was too expensive to keep as just a fun machine (though it was one sweet gyro). Parting with it was truly a boo-hoo moment.
 
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GyroRon

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I considered a 670 to replace my 618 when I was searching for more power for my gyro a few years ago. Spoke to Russ King ( who had the gyro with the 670 on it that blew up, that Doug later purchased ) and even came close to buying that engine off him. All the research I did on the 670 told me it is a powerful engine, but not one you could count on a long dependable service life out of.

Thats when I saw Todds " AKA Racer " thread on his Yamaha sled conversion and I privately contacted him to inquire would he consider building another engine up for me.... of course that sparked a decision for him to go into the engine conversion business and the rest is history. Im at 110 hours on my yamaha, and so far other than some bugs with my jetting and fuel pump that were identifed in the first couple flights, and some issues with the rotax clutch, the engine has been solid.

A friend of mine bought the 670 that used to be on Russ Kings gyro, and put it on a Phantom Ultralight airplane. I had a chance to fly that plane and the performance was breathtaking. Problem is, he has had several problems with the engine and is now on his 2nd or 3rd one, and no more hours total than I have had on my yamaha...... Seems to be the story with those engines, lot's of power but short life.
 

choppergabor

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Well let's hope I will have more luck with it. Of course it will go through a few modifications before I strap myself in front of the monster. There are a bunch of things that needs to be done to it and it sure should turn out to be a great performing aviation engine if things work out the way I think they would. Than again...... things can go bad too.....but I am one of these optimists out there :) They certainly run forever in the snowmobiles and everyone loves them in that field. I know different application. Well somebody has to start the fiddling to get anywhere no? :)
 

Rotax Rick

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Rotax rick

Rotax rick

I sell the Rotax 670 with custom dual plug heads, a new Ducati Dual ignition system, 2 New Bing 54 carbs. The ingnition fits right in wit out doingt anything but using the self taping screws that are used in the 582. No taping is necessary, You must use the last wheel of the 93/94 crank for the Ducati flywheel to fit. I use double oil slotted 1998/99 High output rods, THIS IS A MUST. The stock rod bearing is the same size as a pre 1994 582 bearing. Far to small with the 670's larger pistons, rods and the 6900 rpm red line. I use a custom pipe that is a 618 copy. I make it in all the Rotax styles. I use the Blue Head ceramic water pump seal also. The cutting of the gearbox flywheel must bve exact. This is why they had troubles with 670's in the past and thje C/E gearbox. Side loading a bearing is bad. I have over $4000 in a engine between the core, complete crank rebuild,new pistons & rings,ceramic seal,custom head,new Bing carbs,ETC, Plus the time to machine the case for the gearbox mounting. There's lots of other little things I do but I can't give it all up. With my pipe ($600 pipe & elbow) I get 89 hp. I have my 670 set to 7000 rpm for take off in my Sprint 2 and cruise it at 5200 RPM and burn 2.4 GPH THANKS TO THEW RAVE VALVE"S longer stroke and correct port timing. They do not even open to 6450 rpm so I aggree they could be locked down with very little power lose. Price $4650 2 year warranty on everything
 

Rotax Rick

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The Rotax 670 is the best 2 stroke Rotax ever built. The 1993/94 crankshaft # 4 wheel must be used to work with the Ducati dual ignition. I use Double slotted high output rods (1998/99 rods) The lower rod bearing in a stock 670 is the exact same bearing used in pre 1994 Rotax 582's CRAZY With the larger pistons/ rods/wristpins and 7000 rpm red line they will fail. Thats why the 670 never made it UNTIL NOW. I use the stock NEW Ducati dual ignition. No modifacations are needed to the case and use the self taping screws used on the triggers on the 582. Don't tap the holes. I use the Blue Head ceramic in all my liquid cooled Rotax engines. It's just a small pocket machined in the cast, Same RV shaft as a 582. I use a Custom dual plug 670 head. Not counting labor it cost me $4000 to build one these engines. The case & gearbox flywheel maching must be exact. If not a side load will be applied to the bearings,. This is where the early 670's had gearbox troubles. The 670 crank is much stronger than a 582. Thicker wheels to grip the pins to help keep it true. I have my 670 in my Sprint 2 set to 7000 rpm for takeoff 89hp and cruise at 5200 burning 2.4 gph thanks to the RAVE valvesa longer power stroke and correct port timing, They do not even open until 6450 rpm and I limit the travle to half of stock. I use NEW Bing 54 carbs I cant give it all up but call me at (239) 572-0021 $4650
 
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Earthboundmisft

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Rick, welcome to the forum. My hangar mate has a 582 from you, and has been very happy with it. He is pleased with your support as well. I am skeptical however, of your claim of 2.4 GPH cruise. I assume this is as used on your fixed wing. I have no accurate
numbers for just cruise for my 582 on a gyro, but AVERAGE burn is 4.7 GPH. I can't imagine the RAV valve making THAT much difference. The gyro IS known to have more drag though. Care to elaborate?
 

Rotax Rick

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I first had a 582 Blue Head and cruised at 5600 3.5 gph I put a 618 on and with the added prop pitch it let the crusing rpm fall between 5000 and 5200.
It also brunt 2.4 gph I sold a 670 to EP in Key West Fla. He gives rides in a Sprint 2 on floats and weights 270 lbs. His 582 ran at full throttle for takeoff 6400 rpm and he cruised at 5600 rpm burning 5 gph. He let the prop pitch untouched when he installed the 670 . He gets 7100 rpm full throttle now. When he does a 1 hour ride and uses 6400 for takeoff like the 582 and cruises at the same 5600 rpm he now burns 3.5 gph. Dropping down to my 5000 rpm makes the other 1.1 gph saving. Run a 670 hard and it will burn fuel.
 

CLS447

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Is that B J Dalton ?
 
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