# Busa Powered Bearhawk LSA

Discussion in 'Tube and Fabric' started by wanttobuild, Jul 10, 2019.

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1. Jul 10, 2019

### wanttobuild

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I have been hooked up hard for a while!
Truckin, ripping out sheetrock and popular siding.
Riding the little BMW.
So I bought a Suzuki Bandit. My kind of motorcycle.
It is an aircooled work of art.
Now it is a Hayabusa. (short trip to the top).
It came with a bandit engine and an extra busa engine.
I am gonna plug the busa engine into a viking gearbox and mount the works on a Bearhawk LSA.
Whatdoyathink?

2. Jul 10, 2019

### pictsidhe

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Detune it, or it won't last long. The redrive will be fun. It may be easier to make new cases than try and strap a redrive onto motorcycle crankcases.

3. Jul 10, 2019

### Derswede

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Derswede

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4. Jul 10, 2019

### wanttobuild

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Werse thanks for that. Looks like has an acceptable power to weight ratio!
Pstache I have a thought about mounting the gearbox(thru tubing) back to the Longerons, then plug the engine into the box, if necessary, a lovejoy styled coupling.
As 2 engine longevity, it is as well designed as any I have seen.

5. Jul 10, 2019

### pictsidhe

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I'm not saying that it is poorly designed. On the contrary, they are excellent engines. But life will be disappointing if you try spinning it at 8-9000rpm for hours.

6. Jul 10, 2019

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Depending on what Gen Hayabusa engine you have...max rpm will be in the range of 11k -12.5k
You need to look at the torque chart for the generation of engine you have....just because the rpm's max out at,say12.5k,doesnt mean you're making power up to that point.
You will find that the torque will peak and then start to drop off before the max rpm is reached.
Take the rpm that the torque starts to drop off at and use that as your max rpm when doing your calculations.

8k-9k.....other than not having any place to use that rpm for more than a few seconds,other than on a desert highway or such,that engine will take just about redline all day and not break a sweat or internals....as long as you can cool it.

Kevin

7. Jul 11, 2019

### pictsidhe

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Cite something then. There is nowhere on the planet that you can ride a motorcycle at around 190mph all day... That is flat out.

These engines don't get held at max power for very long, that's how they can get away with such high piston speeds for short bursts yet rack up a decent number of miles. they are mostly run at less than 1/2 revs and little throttle. Hold them wide open, and life will be rather disappointing. Good for a Reno racer, but a cruiser? No way, Jose.

8. Jul 11, 2019

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And that's why I commented that you can not use that kind of power for more than a few seconds in a civilized setting....hence,the desert highway comment.

We probably need to come to an agreement that we agree to disagree when it comes to the topic of any engine.
You seem to have the viewpoint that every engine is a ticking time bomb waiting to go off.
While,I on the other hand,have helped build sprint cars,boats,sand rails,etc...that utilize motorcycle engines that spend the majority of their lives banging off of the rev limiter and have never had a failure.....EVER....even while boosted and running NoS.
The Japanese spend $millions$ every year on r&d and build some of the best engines that have ever been known to man.
As far as pushing an engine.....I take it that you've never watched a 24 hour endurance race where they are held wide open for 24 hours,or the Isle of Man that runs a street bike wide open the entire race,or the Paris to Dakaar race through the dessert that is wide open,or a Moto GP road race that is wide open from start to finish.
Running a motorcycle engine in an aircraft will have it no where near max rpm's if the torque chart is adhered to...
We will just have to agree to disagree in a gentlemanly fashion.

Kevin

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9. Jul 11, 2019

### pictsidhe

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Yes, I've seen numerous races. I've even been the mechanic for a few race bikes. None of the ones that can hit over 100mph were ever held wide open for more than a few seconds. The corners tend to get in the way. Go watch an IOM race, they have to slow way, way down for many corners. A messy death awaits some of those who don't slow enough. There are only a few that the seniors can take flat out. The one thing I fail to understand is how their balls don't in the way of the 160mph corners at bank angles of 50+ degrees.

10. Jul 11, 2019

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Aaaahhhhhh......when you refer to the balls getting in the way scenario,I have to assume that you've never seen a sidecar race.....lmao

Kevin

11. Jul 11, 2019

### wanttobuild

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The Hayabusa engine amazes me. The Bandit engine amazes me.
It might not be every ones first choice, but , it seems if properly cared for it would make an excellent aircraft engine.
Mount the reduction gearbox to the fuselage, not the engine, is the key element. 4130 allows this type of installation.
Do it right you can hang it on the prop.

Camshaft grinds and timing is where Suzuki goes to become number ONE.
All in all a Busa Powered Bearhawk or Bearhawk like design, is an aircraft I would like 2 fly.

12. Jul 11, 2019

### TFF

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The problem, with all this, is the propeller. The pitch profiles you want are backwards from what you can have, if fixed pitch. The pitch will be so flat with the power pulled back it will be a brake if you pitch it to climb at high rpm. Propellers work in a narrow range. You want the fat pitch at operating speed, be it climb or cruise. You have to work the problem propeller back not engine forward. With all the RPM talked about, I bet it’s going to be a 4 to 1 gearbox for a cruise box. 5 to 1 if you want to zing it.

13. Jul 11, 2019

### Turd Ferguson

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Somebody has used a Hayabusa engine in an airplane. In fact, they used 2 Hayabusa engines in a replica Bugatti 100P. Lots of pics around the webz.

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14. Jul 11, 2019

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Ivoprop has an inflight adjustable prop that could solve the problem....

Kevin

Last edited: Jul 11, 2019