Old HKS engines?

Discussion in 'Firewall Forward / Props / Fuel system' started by 13brv3, Jan 30, 2019.

1. Jan 30, 2019

13brv3

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Greetings,

I'm just starting to look for an HKS 700E, and it seems like there are a lot of these that are really old, with little to no hours on them. It's almost like they sold a bunch with projects that never got completed, and they turn up for sale occasionally. If you were to find an early (10-15 years old) engine that was just stored all this time, what are the chances it would be safe to use without a lot of parts replacement?

Assuming it's not pickled for for long term storage, I'm afraid of finding lots of corrosion. At the very least, I'm thinking you'd want to do a basic overhaul to replace seals, and check for corrosion. The real question is whether this would be affordable, or if it would turn a reasonably priced engine into a overpriced mistake.

Also, how about updated versions? I saw a listing from GreenSkyAdv that said SN 100600 was when some improvements were made, and they raised the TBO to 1000 hrs. Is it worth avoiding an earlier engine if the price is right? Were there any other SN milestones where significant changes were made?

Thanks,
Rusty

2. Jan 30, 2019

wanttobuild

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I don't know about an HKS Rusty, but I do know about a Rotax 582. A brand new rotax will "time out" requiring an overhaul. So unused setting in a crate it will need an overhaul, I forgot the amount of time. Its in the manual though.

3. Jan 30, 2019

akwrencher

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Different critters. HKS is a four stroke, four strokes can still suffer corrosion if stored in a damp location and not pickled, but are much less susceptible, in general, to timing out due to sitting. If it's clean and oily inside, inspect and new seals and gaskets. Disclaimer, I know nothing about HKS specifically.

4. Jan 30, 2019

Victor Bravo

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Rusty, whatever you do make sure to copy whatever Larry Cottrell did on his HKS/Kolb installation. Some of the things I did on mine were pretty clever and bright and sexy.... and yet it was essentially an un-successful installation. Most of my problems were coming from having the wrong gearbox... make absolutely sure you have the 2.58 gearbox before you buy any engine.

5. Jan 30, 2019

Armilite

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The New HKS 700E is a 60HP, horizontally opposed two-cylinder, four-stroke engine. I believe they only offered a 2.58 an a 3.47:1 Gearbox for them. New one's seem aweful exspensive for only 60hp. A New Rotax 912 80hp is $15813.00/ea from CPS. A New 582UL(65hp) FWF is around$8000.
http://hksengines.com/technical-info

Typical Costs:
ENGINE: $11,800.00 EXHAUST SYSTEM:$729.00
OIL TANK: $608.00 OIL COOLER:$279.00
THROTTLE AND CHOKE CABLES: $120 each:$240.00

SAMPLE PACKAGE W/ABOVE:* $13,656.00 6. Jan 30, 2019 13brv3 13brv3 Active Member Joined: Feb 14, 2018 Messages: 29 Likes Received: 3 Location: Tellico Plains, TN I couldn't find anything on the HKS official site, but I did find these two links on the greensky site. They mention different TBO (hours and years) depending on the SN of the engine. I guess I'd have to ask them what an overhaul kit would cost. https://www.greenskyadventures.com/tbo-before-sn100600.html (500 hrs/5yrs) http://greenskyadventures.com/tbo-from-sn100600.html (1000 hrs/8yrs) I've read that parts prices are pretty high on the HKS, and from what I could see, that's true. A carb rebuild kit is nearly$500, so I can't imagine what it would cost to replace a corroded cam or crank.

Good to know about the gear ratio. I would have assumed the 2.58 was the way to go, since nearly every Rotax used that ratio on the Kolbs, and of course the engine I inquired about had the 3.47. The ratio can certainly be changed, but at what cost.

I'm pretty open to any established 4-stroke in the 60-80 HP range, which includes the HKS, 912, and Jabiru 2200. I'm in the process of trying to figure out which will be the most reasonably priced for a used engine.

Thanks,
Rusty

7. Jan 30, 2019

Victor Bravo

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About $2000, because I looked into it with Grreen Sky. Definitely look into the Pegasus Power O-100 before you spend money on anything else. 8. Jan 30, 2019 13brv3 13brv3 Active Member Joined: Feb 14, 2018 Messages: 29 Likes Received: 3 Location: Tellico Plains, TN$2k would be painful. That must have been for a new drive. I'd hope maybe to find someone with the opposite problem who wanted to trade. I'll definitely keep this in mind while shopping.

While the Pegasus Power engine is interesting, it certainly doesn't meet the "established" criteria. Best I can tell, they have one prototype flying, and no real news in the last year and a half. The packaging would be much more suited for a tractor style installation as well.

Rusty

Last edited: Jan 30, 2019
9. Jan 30, 2019

dino

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If you can swing a large diameter prop why rule out the 3.47 gearbox?

10. Jan 30, 2019

13brv3

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Prop diameter is limited on Kolbs, but without that limitation it might be a good option. The only way to run larger props is to raise the engine and thrust line even higher than it already is.

Rusty

11. Jan 31, 2019

Victor Bravo

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The Pegasus is built directly on the design and architecture of the oldest and most reliable aircraft engine series in modern history. It's as close to "Established" as you can get for a new engine. There are literally tens of millions of flight hours on the engines the Pegasus was derived from.

The Pegasus was specifically designed (thrust bearing, carburetor location and mounting) to be equally good for pushers or tractors.

12. Jan 31, 2019

wanttobuild

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Or you can run a four blade prop

13. Jan 31, 2019

13brv3

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So are there any other comments, good or bad about the HKS? I'm just gathering as much info as I can.

Thanks,
Rusty

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14. Jan 31, 2019

Cy V

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I remember James Wiebe bought a used HKS to use in the Chipper but he had some major problems with it. He ended up ditching it altogether for the Rotax 912.

15. Jan 31, 2019

Victor Bravo

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I have about five hours of actual flight time in the HKS 700E powered Kolb. And another five hours or so of ground runs, taxi test, etc. The engine performed perfectly, and it never gave me any reason to be suspicious. The only problem I ever had was that it frequently would lose a lot of RPM on one ignition during a runup. Turned out to be the ignition switch ground, nothing to do with the engine itself. I had the larger rectangular oil cooler, and it was plenty for the Kolb... I even had to put a winterization plate in frornt of it. But I had built a really nice duct to mount the cooler in because I was afraid of overheating it in the desert in high temps.

IIRC the HKS engines built AFTER the big recall had an additional oil line coming out of the oil pump scavenge side, to bypass the cooler if necessary. When the engine was cold and the oil was thick, the oil in the cooler would not flow fast enough back to the tank, and it would back-pressure the oil system, and fill up the crankcase with oil which it was not designed for. I also recall that there were a couple more differences in the pre-recall and post-recall engines. But I beleieve the pre-recall engines were not unsafe. No rods through the case, no swallowing valves, nothing catastrophic. Just not as good or desirable as the later engine.

Kind of like the difference in desirability between a Taylorcraft powered by the Lycoming 65HP engine and the Continental 65 HP engine

By the way, the biggest issue I had with the HKS on the Kolb was that I tried to mount it as low as possible on the fuselage for thrust line reasons. But because of this I was unable to use the stock HKS exhaust system, because the trailing edge of the Kolb wing (the aileron torque tube) interfered with the exhaust pipe. This intefrerence was only with the wings foldeed back for storage. So if you install an HKS on your Kolb, take the time to figure out the wing fold clearance ahead of time, and mount the engine in such a waya that you have enough room to fold the wings.

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16. Jan 31, 2019

13brv3

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Thanks for the comments. I read most of your tale of woe on the Kolb archives when searching for HKS info. Folding is the number one reason I'm going back to the Slingshot, so I'll make certain that works.

Rusty

17. Feb 1, 2019

Armilite

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I was looking again at this HKS 700E Engines Spec's. It seems like a well made Engine, but I think it's still Over Priced as I said before for only 60hp for 3min, then 56hp@5800rpm continuous. If you did some of the same Upgrades to one of these Cheap Honda/Kohler/Briggs 993 Type Big V Twins you could make the same 60HP. Since you have probably 20 different Companies making these Cheap Big V Twins, you have many places to Buy Spare parts, and even some HD Racing parts. You also have Shops that work on them if you can't do your own work.

That Briggs Van Guard 993, 37hp@3600rpm, EFI, is (3.37in x 3.41in) = 997.2cc. Use's only 8.2cr. 997cc at 3600rpm making 37hp is 88% Volumetric Efficient! Using the same 997cc at 88% and just changing the Rpm to 6200rpm = 64hp, 5800rpm = 60hp, 5400rpm = 56hp, etc.

Configuration: 2 Cylinders 4-Stroke Engine with Horizontally Opposed Cylinders 4 Valves per Cylinder.
Bore & Stroke: 85mm x 60 mm
Displacement: 680cc
Compression Ratio: 11.3:1
Power Output: 56hp(41kw) at 5800rpm (continuous)
60hp(44kw) at 6200rpm (3min./Take off)
Torque Max: 7 kgm at 5000rpm
Max RPM 6200 RPM
Cylinders Nickel Ceramic Composite Coated Cylinders(Nikasil)
Pistons PVD Coated Piston Rings

Things that make Horse Power:
680cc vs 997cc
11.3cr vs 8.2cr
6200rpm vs 3600rpm
CAM vs CAM
4 Valves vs 2 Vales(You can use Bigger Valves to equal Flow)
Carb Size vs Carb Size

https://www.hks-power.co.jp/hks_aviation/products/700e/spec.html

At the bottom of the page: WARNING! This is a non-certified aircraft engine, the possibility of engine failure exists at all times. Do not operate this engine over densely populated areas. Do not operate this engine over terrain where a safe, power off landing cannot be performed. The operating and maintenance instructions supplied with this engine must be followed at all times. Flying any aircraft involves the risk of injury or death, building and maintaining your own aircraft requires great personal responsibility.

It really boils down to what do you want to Pay for 60hp $14,000+ for a New one or maybe$5000 for a Big V Twin.

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18. Feb 1, 2019

13brv3

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I've heard some talk about using the V twins, but I haven't really looked into it. I'll make a note to do that though.

I'd like to be flying an engine with a little more history behind it as an aircraft engine. I'd trust a decent used Rotax 582 more than I'd trust a one-off conversion like this probably. If you think that HKS disclaimer is something, ask Briggs about using their engine for an aircraft. It will send their lawyers running off screaming into the night

As for the HKS, it turns out that the only known Slingshot with an HKS was running the 3.47 quite successfully. I haven't verified it, but I think the Slingshot frame is taller than the Firestar, allowing larger props. The guy who had the HKS Slingshot was running a 72" 3-blade prop. I still think the 2.58 is likely a better choice though.

Rusty

19. Feb 2, 2019

Armilite

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Never heard of or seen a Slingshot Airplane. If you don't mind 2 Strokes, you have many Options. While the 582UL is a good engine and makes Stock 65hp, you have the Extra Weight of Cooling and extra Cost.

A Stock 503UL(72mm x 61mm) 496.9cc using 10.8cr with a Mild Custom Tuned Pipe can easily make 62hp@6500rpm. http://www.rotaxservices.com/dyno.html#7

A Stock 447UL(67.5mm x 61mm) 436.7cc using 9.6cr with a Mild Custom Tuned Pipe can easily make 52.4hp@6500rpm. http://www.rotaxservices.com/dyno.html#15
On 2 Strokes a +1.0cr bump = 2hp on Avg, so bumping your 9.6cr to 11.6cr = 4hp +52.4hp = 56.4hp. With a better Designed Tuned Pipe I'm sure a 447 could make 60-62hp.

A Stock 337UL(62mm x 61mm) 368.4cc using 9.6cr is rated 35hp@6500rpm with a Single 36mm Carb and a Muffler! The 377 and 380 are the same engine. There was a Skidoo/Rotax 380HO that used 11.2cr with 30mm Carbs with a Mild Tuned Pipe that was rated 48hp@7000rpm. With an aftermarket Tuned Pipe it Dynoed 57.26hp@7000rpm, it made 52hp@6500rpm. The 377/380/377UL and 440/447UL share the same bottom end. So you have Options, you can Big Bore 377/380 Cylinders to a 440/447UL, and I think they can even be Big Bored to a 503 by my Calculations. Either one, you heat up Cylinder in an Oven and then pop out the Steel Sleeve and then Bore Aluminium Shell for the Bigger OD Sleeve.

Like a 447 Sleeve OD 2.9" an a 503 Sleeve OD 3.080", a 550 Sleeve is 3.275". A 277UL Sleeve is 3.077". My catalog doesn't list the 377/380 Sleeve to give you an example.

20. Feb 3, 2019

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