The first TURBO fjr

[user 5188]

Thanks to my skills as a professional blackjack player, i have a mediocre sum of money that i have decided to have fun with, and i think it might be just enough, to complete the project that will change the world forever, the part of the world that matters anyways. My budget is 6000 dollars.

Ive sent a few emails, and found some guys in indiana that i will have do the majority of the fabrication for around 4500. But before, i start forking out money, I would like some input on how to overcome the fjrs gearing, with the rest of the money. Im shooting to redline at ~220mph. Im simply not going to start the project if i cant increase the bikes top speed. Not that i will be driving at 220mph, but to be satisfied i would like to at least be able to say that it CAN without turning 15000 rpms and exploding, like people do with the busas

My concern is that it isnt possible or is so difficult that you would need to make a whole new housing for the rear axle, It would come down to a few options:

-Enlarging the diamiter of the gear attached to the drive axle, and either moving it further away from the bike which doesnt sound plausible, since the housing itself would prevent that, or somehow recessing the larger gears teeth closer to the wheel and farther away from where the axle enters the housing

-Increase the length of the drive axle and reduce the diamiter of the larger gear in the rear diff.

-Dissmantle the transmission, and change the gear ratios there

-Some combination of the obove options.

A second concern is the bike windsheild and how its large (kinda wobbles when you poke it), and may not be able to withstand the force of 220mph windage.

The kind of help im looking for is where to get a cad file for the differential housing, and the gears, also one for the transmission, and its gears , so if you have them on hand, like idk maybe skyway does, please share them

Advice on which path would be the most cost effective, for instance i have no idea how the bikes transmission is attached to it, and i have no idea how much labor is involved in removing its internal parts.

Also I would like to know if anybody Is interested in changing the fjrs gearing better fuel economy since once i have them it would be easy to make more of them.

This could be huge, and im excited.

 

[wheatonFJR]

...um...wasn't something like this posted on a corvette website somewhere? :huh: ...hmmmm...

 

[v65]

You want to add 60mph to the top end for $6,000? Maybe you should have posted this on Friday.

 

[Fred W]

Whenever designing a 220mph drag bike, it's always best to start with a relatively heavy bike designed to go long distances in relative comfort. :glare:

 

[jwilly]

Dammit Ross, I'm going to plant a shoe in your a$$!!

 

[Bustanut joker]

Check with BugR see how his gear swap is coming. Last I knew he wasn't having fun How about a Turbo and Nitrous?

Why stop at 220 ? Point 'er towards Bonneville.

:jester:

 

[Murph]

Why bother? How about spending the $$ to purchase and improve a track bike?

(Or how about adding some minor farkles to the FJR and investing the rest? There's more to life than changing the FJR world forever.)

 

[stellarsteve]

I am not that much of a motorhead but l'd think that the first path to go down would be to see what type of transmission gears or middle drive gears you can get or have made. I would think that changing the final drive would cost a lot more than the $6k you have to work with.

 

[madmike2]

If you want to change the gear ratios, you should be able to have a ring and pinion machined to change the final drive ratio. That or have 4th and 5th gear machined or modified so that 5th was a "true" full-step gear.

This type of gearing change is much simpler and easier on a chain drive bike, but it can be done.

 

[markjenn]

I hate to be discouraging, but gearing will be the least of your worries. Do some back of the envelope computations before you get too deep into this.

A stock FJR makes about 123 RWHP and goes about 145-150 mph true. To go 220 mph with no aero improvements, you're going to need to increase power by about 130%. IOW, you're going to need to build a 283 RWHP motor. There is no way you can boost this motor anywhere close to this and have it live - even a 50% power increase would probably require major engine mods like lower compression pistons, intercoolers, etc. Everything in the drivetrain is going to give up long before you come close to these powr levels. If you look at the Busa setups, nobody is boosting the power this much and the high-end ones cost a lot more than $6K. I'd estimate that just a 175-hp turbo FJR motor that will run on pump gas would probably set you back $15K and require a really good shop with some significant engineering expertise.

Even if you could get this power, you've got a helluva aero problem. Even 180 mph on a motorcycle takes some serious aero work to combat instability and center-of-lift issues. Busas have superb aero so that's the reason they are the bike of choice for top-speed enhancements. I would be extremely nervous taking a FJR much above 170 or so and without major mods such as a longer swingarm, lowering, etc. I doubt it could be taken a whole lot faster without severe controlability problems.

At your budget, you could get a nice little turbo package that would boost power 25% or so and the drivetrain and engine would probably survive for awhile. I'd let the top-end obsessions go and enjoy the faster trip getting there. Better yet, use the $6K as a downpayment on a new Busa.

- Mark

 

[FJRMGM]

save your money and buy either a 'Busa or a ZX-14 and be done with it.

What you are proposing is possible but not without more money than you mentioned.

And when you get done, what will you have?

 

[jestal]

Uh....Ross.....stick to blackjack. From your comments you have absolutely no idea that what you are proposing is completely impractical if not impossible.

I was playing along until I read the part about being concerned about the stock windshield at 220.

 

[Knifemaker]

I do think adding a turbo to an FJR would be cool...

But thinking you will be able to go 220 mph is, well, just laughable........

(you'd think a blackjack player would be good at math....)

No offence dude...

KM

 

[2WheelTiger]

I think you need to do some research into building ANY bike for 220 mph. I've increased race motor outputs by 150%. If it's considered "reliable", longevity is measured in MINUTES. Expense begins at far more than 6 measly grand.

I'm actually gonna suggest you take the cash, shred it, and then feed it to the motor with the airbox off and the throttle pinned. The effect will be the same. Money gone, motor gone, lots of smoke.

It's not Friday and I usually don't dogpile, but your proposal is preposterous.

 

[Rogue]

A 220 MPH FJR sounds like a fun project if you have an extra $100,000-$150,000 and don't plan on riding that FJR on the street.

If this was a serious post do a couple searches on aerodynamics and how much HP you need to increase each mph above 150mph.

A wild guess would be 500-600 rwhp with the FJRs aerodynamics IF the bags & windshield could stay on at that speed.

 

[Ignacio]

I just finished some sophisticated modeling of how to place a turbo, speed figure calculations, a testing plan, and a detailed cost estimate.

......

Ready?

 

[beerme]

Brutally hysterical! :lol:

 

[C&C]

You said yourself that you'd probably never run it to 220 (and maybe not even the 150+ it is already capable of), so may I deduce that you just want to play around a little with some awesome acceleration; may I suggest, Nitrous (and be done with it).

 

[Ari Rankum]

I just finished some sophisticated modeling of how to place a turbo, speed figure calculations, a testing plan, and a detailed cost estimate.

Stop!!! You had me at Gigawatts!!! Hahaha. (Love that trajectory, by the way, what with the negative dx/dt, and all.)