Newbie question #1 engine rpms at freeway speed

[DeltaFlyer]

What sort of RPMs are you guys turning at 110km/hr?

My bike sits right around 4000 revs which seems a bit high to me with so much torque lower down the rev range. Also, the bike pulls away from a standing start like a scalded cat with anything but very carefully moderated throttle twist, it's like the throttle is directly linked to the tacho which can be a little scary when you're not used to it.

Does 4000rpm at 110km/hr sound right to you? ...or has the PO fiddled with the sprockets? Is there any economy or other benefit in going to a slightly closer ratio with the sprockets? or more likely, am I imagining a problem where there isn't one? - I'm prone to do that with a new-to-me second hand vehicle... you know what it's like, every little rattle has you imagining an impending catastrophic mechanical failure. 

[oldktmdude]

   G'day and welcome DeltaFlyer, 110km/h @ 4,000 rpm sounds pretty close to the stock gearing. There are fairly comprehensive gearing v rpm charts in the FILES section on the main page of this site. There are several tables showing speeds for different gear ratios and different tyre sizes. You will have to convert the speeds as they are shown in MPH.    Regards, Pete.

[FJmonkey]

Here is fun site to play with: http://gearingcommander.com/

[Arnie]

4K rpm @ 110kph sounds a bit on the lowish side if anything.
FJs came with stock gearing of 17F x 39-41R depending on year and market.
Many have replaced the 17 with an 18 for the slightly lower revs and fuel use.
Yes, the FJ has bags of torque, and you'll get used to it :-)
Just wait till you find the engine doesn't really come "on song" till you're over 6K rpm :-)
That's what Frank's daughter(?) calls Kookaloo!

Arnie

[andyb]

Pop the front sprocket cover off and look, shouldn't take more than a few minutes.  Pull the clutch slave off first, then the sprocket cover, half dozen or so screws is all that holds it together.

[Dan Filetti]

Just wait till you find the engine doesn't really come "on song" till you're over 6K rpm :-)
That's what Frank's daughter(?) calls Kookaloo

Pretty sure it's sister, not daughter.

Dan

[movenon]

68.3 mph/110kph @ 4000 RPM sounds like its in the ball park. What is the tooth count on your sprockets? RPM has an 18 tooth counter sprocket which would lower your RPM. Most of the rear sprockets are marked on the side with the tooth count if you don't want to count teeth.
Welcome to the FJ world .
George

[The General]

Does 4000rpm at 110km/hr sound right to you? ... or more likely, am I imagining a problem where there isn't one? - I'm prone to do that with a new-to-me second hand vehicle... you know what it's like, every little rattle has you imagining an impending catastrophic mechanical failure. 

4000rpm is perfect for me. Do you find a resonance point at around 95klm/hr? If ya in Victoria or NSW it`s good to be able to maintain 100klm/hr for occasionally long periods and your ratio is also good there.

If you are a Rockstar and attend a musical with a symphonic orchestra for the first time, the sounds will not necessarily be comfortable at first and definateley not a catastrophic failure - more of a developing crescendo!

Suggest you cruise at 110klm/hr in 4th gear for an extended period (seriously) so you begin to appreciate Bark. 

Note: We can orchestrate the toning down of the resonance point when you attend our annual concert. (In Bellingen this year  ) It`s really only a matter of "Get up and Go" (and there`s definateley more - above 4000RPM) - every good boy deserves fright!   

[andyb]

Because I don't know the OP's history, I'll point out that it isn't a car and it isn't a big, lazy twin.  It's gonna spin some going down the road, just be cheery that it isn't a 600 machine.  (Nothing sucks like 5krpm at 60mph, nevermind having to click down at least twice to make it sort of move....)

There's a bunch of factors to consider that will alter your speed/rpm ratio though.

One of them is really easy.  A smaller than stock front tire will give you lies on the speedo, though the speedo will lie a little to you anyhow.  While you're at it, ensure that the rear tire is of the appropriate size (150/80 on a 16, iirc).  Never trust the prior owners, or the shops where they took the bike!

Next, go ahead and ensure that you're running a reasonable gearing.  It's okay to cruise at 6krpm if you want, the engine will handle it easily if there's adequate airflow, though it can grate on the sensibilities of those with mechanichal sympathy.  Stock gearing is 17/40, give or take.  You can go up to 18 in the front if you have enough chain adjustment, which you should be okay on.  It'll shorten the wheelbase, which you probably won't notice much (the shock will feel fractionally stiffer, and the bike will turn a bit quicker).  Long gearing makes the FJ quite happy, a torquey and relatively low revving motor can pull extra gearing without blinking.


And then, the solution that I'm going to recommend, which is in two parts.

First off, if it's noisy and annoying you as you cruise.... Do you have an aftermarket muffler on it?  It's time to repack it.  You'll need a drill, a rivet gun, and some packing material.  It's an easy job that makes a huge difference, shockingly so.

The second portion is going to involve some finger waving... Why aren't you wearing earplugs?  Even with a helmet, the wind noise alone is LOUD.  You can and will damage your hearing permanently.  Wear them.  It's very alien at first, and after awhile you'll wonder how the hell you managed without them.

[dogtired]

I'll point out that it isn't a car and it isn't a big, lazy twin.  It's gonna spin some going down the road...

I know that the motor is free revving, like old 1960's GT Cortinas (4k revs at 60 mph) but there is a small part of me that is still living in the 60's that says "It don't seem right revving that hard..." even though I know it is not hurting anything, and much much smarter than me fellas designed it to run that way, that small part of me is still asking, "Why the hell can't I gear it to do 3,000 revs at 100kmh, it has more grunt than a trailer load of pigs, it could handle it."

So what if you have to knock it back a gear to pass in tight situations, and I know the bloody thing will start off in third gear, so stopping and starting wont worry it, surely there must be some advantage in giving it a higher top end? Like engine longevity, better fuel economy??

Am I making any sense?

[Harvy]

Dog, the highest gearing you are going to be able to fit on OEM FJs is 18/38......any bigger at the c/s or smaller on the back wheel is going to cause the chain to chew through something - either the sprocket cover or the top of the swingarm.

That will get you below 4000rpm at 100kph - I think its 3810rpm..... will have to check next time I'm out of the city, or on the freeway.


Harvy

[dogtired]

Thanks for that Harvy, can't really see myself doing it, changing ratios, but that small part of my brain keeps asking the question. I just keep telling it a smarter bloke than me designed the bike and to trust in their judgement, and engineering.
My 2012 Bonneville revs about the same as the FJ, but the FJ sounds a whole lot "busier" at the same speed. Twice as many moving parts and cylinder firings. Might just be a bit of adjustment on my part between the running noises of both bikes.

But oh my... the FJ is a whole lot more exciting post 6k revs than the Bonneville.
No one told me FJ's had warp drive...

[Steve_in_Florida]

No one told me FJ's had warp drive...

Ja! It's a happy day discovering that little secret!   

[DeltaFlyer]

Thanks for the feedback  I'm starting to feel a fair bit more comfortable now that I'm getting to know this bike better. I had a look at the sprockets, they're 17/39. There's nothing wrong with the bike, it was all just in my head. I have to stop worrying and learn to love the bomb-proof motor.

Had a day off on Tuesday so straight after breakfast, with no particular destination in mind I just said bugger it, I'm going for a ride. Ended up doing about 400km, taking in the whole range of riding from slow and tight twisties to wide open straight high speed runs. Man! this thing is a magic carpet ride! ...and yes, I did discover the undocumented warp drive system that is activated when the tacho hits 6000  scared the bejesus outta me! 

[DeltaFlyer]

Here is fun site to play with: http://gearingcommander.com/

Thanks for the link, that one's a keeper!