The first TURBO fjr

[2WheelTiger]

Technically, I've only run this FJR up to 137 on GPS at Pacific Raceways. I wasn't exactly watching the tach at the time, but I know there were lots of revs and accel left.

So, let's split the difference between your indicated 150 and mike25's comment of 170. Certainly there is some difference in mathematical top speed due to tire selection and this can be significant at higher speeds.

Settling on 160. We're still talking about a ~30% change in final drive ratio. This will make 5th ~30% higher "as desired", but it will also make every other gear, including 1st, ~30% higher. In the real world, this is folly.

The only other option that could potentially work would be to have a very special "5th gear" made. I would estimate the cost of the gearset to exceed the $6K budget. Design, fabrication, delivery - 4 months at minimum. Yeah, 4 months and $6K just so 5th would be an 'overdrive' of questionable utility.

Go ahead and turbo the bike, but I think expectations need to be brought into the real world.

 

[jestal]

Just to settle the idea of the gear changes..... I haven't actually calculated what it would take to make the 30% gearing change in the FJR final drive but having had one apart I know that there is precious little extra room for changing the geometry of the gears. You cannot just increase the diameter of the ring gear in this case because there is no where for the pinion gear to go to remain in mesh. For this (hypotentical) experiment you would keep the ring gear the same diameter and increase the diameter of the pinion...by adding teeth to it. Correspondingly, the ring gear would have to get much thinner and/or the mounting flange for it would have to move over to get the ring further away from the pinon centerline. Just no room for that.

If you have enough money ANYTHING is possible but I could see sinking $10K at a minimum to have a set of prototype hypoid gears made for the final drive and matching custom machined parts to make everything fit. It would probably be cheaper to convert it to chain drive so you could swap sprockets easily....

Just for reference, if you go to Bonneville where people actually do ride motorcycles at 220 and faster you will notice that they get towed up to 50 or 60 due to the gearing required to go that fast.

BTW.... Having all the turbo hardware fabricated is only part of the deal. Getting a fuel system to supply the required amount of fuel, developing a calibration and dyno testing will easily eat up $5K or more in a cheap shop. Plus the cost of the engine or two you will "waste" in the process of doing a one-off like is described.

Ross, based on your comments you haven't the faintest idea about what you are proposing and obviously are going to rely on some shop(s) to do all this for you. This is a sure recipe for disaster....like you ending up with a pile of parts, no motorcycle that runs and no money left. Don't make your first project a fringe one-off that no-one knows how to do nor has ever tried before. Speed shops will be glad to take your money and will promise the world but they cannot deliver on this one for that sort of money.

 

[FJRMGM]

after careful re-consideration I think YOU SHOULD GO FOR IT!!

Keep us posted of the progress.

 

[wheatonFJR]

after careful re-consideration I think YOU SHOULD GO FOR IT!!
Keep us posted of the progress.

Yes! LOTS of pictures and dyno run charts! Maybe even video of run at the local drag strip. :clapping: :clapping:

I can't wait...this is going to be great!

 

[Checkswrecks]

Oh you guys got it all wrong, as usual. The transmission doesn't need new gears, the bike just needs a LOT bigger rear wheel and tire!

Then the swing-arm,

The brake line,

The fender,

The shock,

The...

 

[TejasFJR]

But everyone knows that FJRs fall into a timeslip bubble and travel through time at 188 mph...

 

[05fjrman]

Don't we have GPS proof of people doing 1000mph+ stock? So 220 with a turbo motor is actually a downgrade, and should be a very reliable package. Maybe he can even improve gas mileage?

 

[user 5188]

Just to settle the idea of the gear changes..... I haven't actually calculated what it would take to make the 30% gearing change in the FJR final drive but having had one apart I know that there is precious little extra room for changing the geometry of the gears. You cannot just increase the diameter of the ring gear in this case because there is no where for the pinion gear to go to remain in mesh. For this (hypotentical) experiment you would keep the ring gear the same diameter and increase the diameter of the pinion...by adding teeth to it. Correspondingly, the ring gear would have to get much thinner and/or the mounting flange for it would have to move over to get the ring further away from the pinon centerline. Just no room for that.
If you have enough money ANYTHING is possible but I could see sinking $10K at a minimum to have a set of prototype hypoid gears made for the final drive and matching custom machined parts to make everything fit. It would probably be cheaper to convert it to chain drive so you could swap sprockets easily....

Just for reference, if you go to Bonneville where people actually do ride motorcycles at 220 and faster you will notice that they get towed up to 50 or 60 due to the gearing required to go that fast.

This is the kind of stuff i was looking to hear thanks. After determining, that the best way to aproach it would be to change the 4th and 5th gears inside the transmission rather than at the differential and talking to my freind at his transmission shop, he explained that the manufacturing of gears is more intricate than simply machining them, and that one gear alone would cost way more than i had set aside for the gears.

I do like the suggestion of putting the money toward designing a camshaft, although that sounds a lot more expensive, im always for investing my money, and blackjack isnt really an option anymore since everytime i sit down they come over and shuffle up on me.

 

[SPORT]

Changing the gearing to this might put me around 3000 rpm when im on the highway and increase the life of the engine (how about that omg)

This is not entirely correct. Lowering the the RPM for any given highway speed only means increased manifold pressures. Increasing manifold pressures = more stress on engine components.

Not completely sure on this but,

it will probably decrease gas mileage. Lower RPM to maintain a given speed requires more torque. More Torque = higher gas consumption.

 

[2WheelTiger]

This is the kind of stuff i was looking to hear thanks. After determining, that the best way to aproach it would be to change the 4th and 5th gears inside the transmission rather than at the differential and talking to my freind at his transmission shop, he explained that the manufacturing of gears is more intricate than simply machining them, and that one gear alone would cost way more than i had set aside for the gears.
I do like the suggestion of putting the money toward designing a camshaft, although that sounds a lot more expensive,

Ok, so now you know that a couple of us actually know what we're talking about here..... Let me make a suggestion based on your (and others') interest in more horsepower.

Go ahead and investigate having a high performance cam built/re-ground for the FJR. We don't need any more lift, we just need a bit more duration in order to get more top end rush (with some loss of bottom end torque). Realize that we (in general) aren't interested in changing the bike's electronics, so there would be no use in creating a radical cam that would require a reprogram of the ECU for a high RPM use.

Find out how many guys here would actually buy and install a high performance cam. Take deposits. See what happens. FWIW - I'm not gonna do anything to the top end of mine, so don't count me in. 121 rear wheel horsepower (on an eddy current dyno) is plenty for this bike and the kind of riding I do.

What I'm really recommending is a cam redesign/re-curve by welding up the lobes. Using this method, you simply send your cam to the fabricator and they weld additional metal onto the existing lobes. Then they grind the welded lobes to the new spec.

There are lots of companies that make cams. If the design work is gonna get done, you might as well order 15 as order 1. Initial design is the expensive part. Google will be your friend on this project.

 

[robertwa]

Interesting discussions. I'm the one that put a FJR motor in a lotus 7 replica. Just got it registered and insured last December. It's a blast to drive. But with a pasenger on board I can't spin the rear wheels under full throttle. I think a turbo would be just the answer, not for top speed, but for added acceleration and of course for bragging rights.

I have a spare engine that I intend to turbo sometime this year, and like the car, everything will be fabricated from scratch. I think with it's reasonable compression ratio of 10.8:1, 4 valve heads and forged pistons it might make for a good candidate (moderate boot levels only). I have a Mitsubishi turbo unit from a Subaru WRX which looks well sized from the compressor map. Being in a car I have room to mount an intercooler. I'll probably double up the diaphram spring in the clutch to prevent slippage. Fueling is something I am still undecided on but may go down the rising rate FPR route. For tuning, I have a PCIII and am very curious about a DIY wideband A/R meter from JAW (https://www.14point7.com/JAW/JAW.htm).

So total DIY/junkyard/seat-of-the-pants stuff, but I learned a lot while building the car, and hopefully will do the same with turbo setup. Sure I may blow the motor, but they come up very cheap on ebay from time to time, and this is a hobby, not a daily driver. If people are interested I can start a thread on the development.

Oh - earlier in this thread, there was talk about changing the final drive ratio to allow for a higher top speed. I looked into something similar building the car because I was trying to find a rear axle with a suitable diff ratio. By shimming the middle drive gear (towards the engine casing) and using a smaller diameter middle driven gear, this will effectively increase output speed. Other Yamahas use similar gears and it may be possible to find a suitable one off the shelf or which needs minimum modification.

Rob

 

[993_Pilot]

. . . I'm the one that put a FJR motor in a lotus 7 replica. . . I have a spare engine that I intend to turbo sometime this year. . . If people are interested I can start a thread on the development. . .Rob

I would be interested. Definitely start a new thread and keep us posted.

 

[Taff]

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.

Big +1

 

[exskibum]

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.

:lol: :lol: :lol: :lol:

Truly one of THE classic responses of all time on a MC BB!

 

[2WheelTiger]

Thanks gents. You may quote me. :lol:

 

[BugR]

To change the rear gearing you need to find a Gen 3 Royal Star Venture pumpkin. Vmax's has the same rear drive ratio as the FJR.

seepumpkin thread

Hoping to get back to this project as the house reno's are now complete.

It's not a straight unit swap, there are minor differences in the castings and major differences in the axel bushes, enough for me not to fit it to a 120hp motorcycle.

I'm currently investigating pulling and swapping the drive and ring gears out. This requires special tools and the gears need to be correctly shimmed. Arrangements are underway with my local dealer, Problem is the bike is snowed in at the moment and not accessible.

The math says you should see a 10% drop in rpm for any given gear/speed combination.

Chris

 

[hardluk1]

Ross miller, how about picking up a older cbr or gsx liter bike and go the turbo route. There are several kits for these bikes and can get above 4oo hp and if that won't put a grin on your face the fjr will not. Hunt up cunningham performance cycle in naple fl and talk to him . Floyd cunningham has had a cbr over 240 with turbo kit that they designed for areocharger and ran a gsx a daytona hp shootout over 460 hp 13 or 14 years ago.

 

[Phugedaboudet]

to dredge up the Turbo/Supercharger thread, I found this hawt little gem, the 1000 FZR Compressor. It uses a Mini supercharger. Sure it's one of those weird F "Z" R things instead of the proper middle "J" but it might be a start for anyone serious about making a ferociously awesome squid-killing machine:

https://www.lazareth.fr/

make sure to get into the English page, go to Bikes, and look for the 1000 FZR.

They also make a supercharged replica of the Honda NAS that Honda never built.

 

[Mcgyver74]

Not sure you can change the gearing easily, not sure if there is room in the drive housing..

However, (and I will say I'm still a newb here when it comes to tech on the FJR) back in my Connie days, there was a mod you could add called a "7th Gear Mod" which basically changed the gearing in the bevel drive before it hit the driveshaft Clicky

Could someting similar be done with the FJR to change the final ratio without having to regear the rear drive?

Just a thought... Please forgive me if it's stupid

 

[Kim]

The only Turbo bike I have any exp with was the '78 Turbo Kaw Z1. It was a screamer but also Chain drive. Yamaha made a turbo 600 back in the 80's that was a neat machine but didn't sell in numbers and it's gone. They did chg sprokets on the KAW but that's very esy....maybe you should try this with an R1 or something easier to do the gear chgs with. This Shaft drive makes all this very tough. Big bite to chew on.