Yamaha FJR Turbo

Rix · Dec 6, 2024

Hello everyone.

Im from the Netherlands, and i bought a wrecked FJR 1300 5WJ (2002) for my buggy project.

Ive used this engine because of the reliability. A Hayabusa engine is way to expensive because im still a student.

My question is, if there are any perfomance upgrades. Before turbo'ing it.
there a zero upgrade parts avalible on internet.

And ive never seen a turbo'ed FJR.

i think its a great engine for turboing, because of the stroke and volume.

RossKean · Dec 6, 2024

Very little has been done to get more power out of the FJR1300 engines - at least nothing I have seen other than changing fuel mixtures. Some people have removed header catalysts and changed mufflers but I don't think anyone has reported large power gains. I have never heard of anyone turbocharging this engine either. Good luck and please report back with your progress on the project and results. This is one of the most reliable and durable motorcycle engines I have seen.

Ignacio · Dec 6, 2024

A few have inquired about big gains (sometimes from the Busa and/or Blackbird), far fewer (if any) have pursued, and none have reported back.

If you think it would be great for turbo charging, you should do it as the first known...and report back.

Bounce · Dec 7, 2024

Ignacio said:
A few have inquired about big gains (sometimes from the Busa and/or Blackbird), far fewer (if any) have pursued, and none have reported back.

If you think it would be great for turbo charging, you should do it as the first known...and report back.

I know I'd follow such a journey as it was written up.

torch · Dec 7, 2024

The FJR compression ratio is 10.8:1 -- a touch high, but theoretically possible for a mild-boost build with the right tune. There are folks out there (search for "Ivan tune") that can reprogram the ECU, so it is possible if you know what you are doing. The biggest problem is the lack of a knock sensor -- without that safety net, you run a big risk while developing the tune.

TheCrazyBird · Dec 7, 2024

Given the advances in turbocharging (variable vane, efficiency of small-for-displacement/and perfectly sized turbos) I could be wrong, but outside of racing applications a supercharger could be a better option to look into for rideabilitie’s sake. There are a number of aftermarket supercharger kits for various bikes that are made in the UK. I’d imagine it would be easier to buy a SC kit for a bike of a similar displacement and adapting it than building a turbo kit that is smooth and linear, although there is a turbo kit made in the UK for the Z900RS that seemed to have good rideability based on reviews. Intake adaptation, fuel injector capacity, and as previously mentioned a spot on dyno tune are the biggest considerations in my mind.

torch · Dec 8, 2024

TheCrazyBird said:
There are a number of aftermarket supercharger kits for various bikes that are made in the UK.

How do you drive one of those? I imagine it would require at least some sort of custom engine case casting for a power take-off?

RossKean · Dec 8, 2024

torch said:
How do you drive one of those? I imagine it would require at least some sort of custom engine case casting for a power take-off?

Maybe an electrically powered supercharger??
https://www.roadandtrack.com/news/a62829376/honda-electric-supercharger-motorcycle-prototype/

TheCrazyBird · Dec 8, 2024

torch said:
How do you drive one of those? I imagine it would require at least some sort of custom engine case casting for a power take-off?

They do have custom cases for the kits that have been made, but I know one-offs have just modified the case on the crank side to put a secondary wheel to drive the SC.

torch · Dec 9, 2024

RossKean said:
Maybe an electrically powered supercharger??
https://www.roadandtrack.com/news/a62829376/honda-electric-supercharger-motorcycle-prototype/

I thought about that. A couple of challenges that come to mind: First of course is the electrical draw required. The bike may or may not have sufficient excess generation capacity. The second is loss of efficiency -- converting engine HP to electrical energy and back to mechanical energy is bound to have some energy lost, which will eat into the power increase expected.

The third thing that came to mind could be a plus. A mechanically driven SC depends on RPM to set boost. An electrically driven system could be mapped to vary boost based on demand.

I'm sure Honda has the resources to develop such a system effectively. I'm not so sure about the average home hobbyist.

RossKean · Dec 9, 2024

torch said:
A couple of challenges that come to mind: First of course is the electrical draw required

I'm guessing that the FJR stator would be hard-pressed to come up with enough power to operate such a device (depending upon the desired boost). You might, however, be able to put in a higher capacity battery capable of high current bursts (lithium batteries can output much more current than a comparably sized AGM) to provide intermittent boost during relatively short periods of higher demand. Thinking initial acceleration, powering out of corners etc. rather than sustained high output. Nothing to say you need a boost to double HP, but it might be nice to make a 20-30% improvement - might not be as hard on the engine components.

Something for someone else to contemplate. I'm pleased with what I have and especially the reliability/longevity. (I suspect a boosted engine would perform well but at a cost in terms of ultimate durability.)

torch · Dec 10, 2024

RossKean said:
You might, however, be able to put in a higher capacity battery capable of high current bursts (lithium batteries can output much more current than a comparably sized AGM) to provide intermittent boost during relatively short periods of higher demand.

Now you're back to a turbo-like boost profile, although possibly with less lag.

Personally, I've ridden a couple of turboed MCs in my day (Yamaha 650 Turbo, Honda CX500 Turbo, Kawasaki GPZ750 Turbo), and didn't really care for it. Yes, they were fun in a straight line, but that turbo lag could bite you in the backside when leaned over in a curve. If there is one single feature that I love most about the FJR it is the wide and linear power delivery at virtually any throttle setting and RPM.

The OP is looking to transplant a motor into a buggy, so it probably doesn't matter as much to him.

RossKean · Dec 10, 2024

torch said:
Now you're back to a turbo-like boost profile, although possibly with less lag.

Hadn't considered the lag that you would get while the supercharger spun up. You're right that it might just get you back to turbo-like performance. I wonder how Honda is doing it? I guess the other option is a supercharger that doesn't provide all the boost the system might handle without blowing up.
Kawasaki uses a mechanically powered centrifugal supercharger on the H2R.
https://en.wikipedia.org/wiki/Kawasaki_Ninja_H2

torch · Dec 11, 2024

RossKean said:
Hadn't considered the lag that you would get while the supercharger spun up. You're right that it might just get you back to turbo-like performance. I wonder how Honda is doing it?

If I was designing it from scratch, I'd make sure the charging system could handle the load 100% of the time, and keep the turbine spinning. Some sort of PWM speed control mapped to the throttle and/or RPM to vary the boost as required based on feedback from an intake pressure sensor, knock sensor, engine load, etc.

Where a mechanical TC drive is limited to a 1:1 relationship with RPM, an electric drive has all sorts of flexibility for mapping the performance. Add in variable valve timing and with the right mapping it could be a tantalizing paradigm shift in economy and performance while still complying with emissions regulations.

Also a whole new level of complexity and failure points.

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