Kookaloo and beyond!

[Bones]

Funny thing is that an r1 6th gear ratio is about the same as the fj's 5th and they also hang at 4000 rpm doing 100 km/h. So it must be the vibes causing us to want another gear and i agree sitting at 3500 is much more pleasant.

With 17/39 gearing mine sits at 110 kmh/70mph at 4000 rpm, smooth as glass and with instant acceleration. If I did a lot of touring or our roads had a higher speed limit than 110 kmh then maybe I might look at a change in ratios, but at the moment standard is just fine.

[Burns]

Can anyone tell me if this bike gets to 5th in the 1/4 mile with stock/near stock gearing?
My guess is no.

If that is the case, with  a taller 5th the bike would would still cut the e.t.'s of a stocker.


Yamaha sent this bike into the world with a very heavy bias for a top speed that most riders will rarely, and only occassionally use.

It was the gentleman racer of its day but now that examples are available at give-away prices it strikes me that there is a market for mods suited to riders with a more utalitarian application than that of the speed-deanons that were its original target market.

I think it is entirely possible to reach targets of 60mpg cruising at 80 mph; a 135+ mph top speed with a low 12 sec e.t.  and have ample luggage capacity, good wind protection and better than stock handeling and stopping.

Maybe Yamaha didn't intend for this to be a tourer but I reckon it could be a great one.

A taller 5th gear would certainly make a contribution to such a package.

I have two motors ....

[jr1349]

ooh wow, guess ill throw my hat into the ring, the drags question I can answer fairly accurately I think.

with 17/38 gearing, there was no need to pull top gear at the drags, unless you were making more power at lower rpm, which mine was at the time I think, so I did generally pull top gear, but I could go over the line at about 9k in 4th.

the drags is mostly about 1st gear, and top end power, as in, the sooner you can get out of first gear, the quicker your time should be, keeping in mind that you still want 500rpm in reserve when you cross the line, just in case you suddenly start making more power, this avoids you pinging the limiter for too long at the top of the track, which stops you accelerating.

so I used a gearing calculator and worked out that my perfectly consistent top speed could be easily reached with 16/46 gearing, leaving me about 1000rpm in reserve for more power, this making a huge difference in my 60 foot times, going from about 2secs down to 1.7secs, combined with a fork strap and some tuning, I went from 11.7 et's to 11.0 et's. more to this story yet to come this southern summer with pods now fitted and tuning being sorted.

in stark contrast to my drag gearing, I've been using 20/37 sprockets on the road, giving me 116kmh @ 3500rpm, I use dedicated chains for each sprocket set, providing I get can get one made, ill go for a 21t front with my next set of road sprockets, because it will pull it no problems, and my road riding style is generally short shifting and chasing economy, other than when I'm  scratchin through the twistes, which are few and far between over here, but the long road gearing doesn't effect the scratching anyway, you just use a lower gear in a corner than you would with stock gearing.

but that's what suites me, each to their own, and more power to ya. 

k

[Pat Conlon]

Kris, I'm not aware that a 19 or 20 tooth counter shaft sprocket will fit in our cases...

Can you take some pictures for us?  Do you leave your cover off?

Are you running a 530 chain?

[Burns]

From this drag racer's experience it is clear that the "stock/near stock gearing" answer is clearly "no".
It seems to me that a tall 5th gives you gearing that provides stock or better accelloration in all real world driving situations ("better" since you can pull shorter sprockets if you want) ("real world driving situations" being up to say 120 mph) with the obvious benefits purchased at the expense of a top speed that many will never use.

So, do the math. 

Do you ever go faster than your bike can go in 4th?  A few do, most probabaly don't.

Is it worth the expense/is the market cohort big enough to cut a decent ROI and justify development?  I leave those questions for those wiser than I in such matters.

But if (big IF) there are existing gears that fit those splines and would give the desired ratio, well I'd buy a set.

Anybody know how to chase that rabbit down?

[jr1349]

Kris, I'm not aware that a 19 or 20 tooth counter shaft sprocket will fit in our cases...

Can you take some pictures for us?  Do you leave your cover off?

Are you running a 530 chain?

it fits in mine, no problems, I'm using an RKxso 530 chain, I don't believe that there are significant differences between the sprocket cover and engine casings between the xjr's and fj's (I may be wrong) except to say that later model xjr's may have a speedo sensor in their covers, and I'm of the impression that the output shaft on fj's is a little different than on xjr's, with the xjr's being extended a little, probably to allow for the wider stock rubber on the rear of them, but the same spline and sprockets are used.

unfortunately I don't actually have a picture with the cover off of my 20t front sprocket fitted, (I have one of the bolt clearance on my 37t rear though, I will endeavour to take a picture of this in the future, ill be changing my gearing in a few months for my upcoming summer drags and ill sort a picture then.

however, if you measure your radial clearance (chain fitted) of your front sprocket, you will get an idea of what will fit, the diameter of any 520,525,530 sprocket increases by about 5mm with every tooth added, so 2.5mm (0.100") radially, so from an 18 to a 20t sprocket, your chain clearance in the area of you countershaft sprocket will reduce by about 5mm.

even with my 20t sprocket, my radial clearance is still at about 10mm, so as far as I'm concerned a 22t sprocket will go in there no problems, however, clearance in the event of a chain failure may be an issue for some.

basically with stock sprockets, if a chain lets go, you will have extra clearance for the chain to find its way out of there, and hopefully not pitch you down the road (no guarantee's though), with the reduction in radial clearance, you could argue that the broken chain may be more likely to get stuck, and pitch you down the road, and/or, do more damage to the engine casing, in such an event.
so the fact, in my case at least, that the 20t countershaft sprocket fits in the area, is perhaps not the only thing to consider.

personally I know the condition, strength, and maintenance, of my road chain is well up to the task, and am prepared to take the risk (if there is one) on my own terms, if anyone were to take on the fitting of a larger sprocket based on my experiences and opinions, they would have to assume the risks of doing so as their own. what I'm prepared to do, I do my way, I wont be held accountable for what others do.

I had 5 x 20t front sprockets made for my bike about 5 or 6 years ago, the USA company that made them said I had to have minimum 5 made or it wasn't worth their while, I'm endeavouring to chase down the company who made them for anyone who is interested, the name is on the tip of my tongue, but I think I still have the receipt with my spare sprockets so I will chase this down.
the 5 sprockets only cost about $150us, I've still got 2 unused ones (and no, at this point I'm keeping the unused ones, but Chris (fj1289, I think) has dibs on a good condition used one, if he still wants it.

I'm not trying to pull your leg you blokes, I'm using these sprockets, if your a little patient, I will to prove it to you.

this mob in oz can make these sprockets, my 37t rear is from them, although I was not 100% happy with the quality of it, they have at times said they will make me custom front sprockets any size I wont, but at other times they have said they wont, but try them if you want, in the meantime I will sort the details of the company that actually made my 20t front sprockets.

http://www.chaingangchainsandsprockets.com.au/

pics are of 37t rear sprocket clearance, and a wider view, and drag gearing fitted, this is what I have atm.


k

[jr1349]

found em, this is the mob who made my 20t front sprockets

thrust company sprockets, sugar grove, p.a.

http://www.thrustcompany.com/

k

[Burns]

this avoids you pinging the limiter for too long at the top of the track

Do the FJ1200's have rev limiters or is that a 13 thing?

[jr1349]

this avoids you pinging the limiter for too long at the top of the track

Do the FJ1200's have rev limiters or is that a 13 thing?

not 100% sure Burny, my guess would be if you've got an electronic ignition it will be rev limited (such as my xjr, which is at about 9500rpm, or redline, from what I can tell), but I think the 11's had points, but other than what my bike does, I don't know.

easy way to find out, pull it to the stop and see what happens, if its not breaking down by about 11 grand id say its unlimited, but if its anything like mine, it becomes quite obvious that its limited at about 9.5k.

the legends can use a specific control dyna ignition system which lifts the limit a bit I think, or with a dyna 2000 you can set your own limit's, but that's a ways down the track for me at least, ill see what I can do with the stock ignition first.

k.

[Burns]

I guess valve float would limit it at some point but I'm not THAT curious.
Seems like I recall that when the 'busa came out the Japs agreed to rev limit all bikes to keep top speed at 190 or so (40mph North of FJ1200 territory).

[Pat Conlon]

Kris, that is one bitchen XJR you have...

Thanks for the info on the 20t sprockets. I didn't mean to imply that I disbelieved you, I was just not aware that you could fit that large of a drive sprocket in our cases.

Re: Rev limiter, I think Randy or Bob W could comment on this. They have extensive racing experience.
I have not detected a ignition limiter on my bikes (doesn't mean that there isn't one) I've had them up above 10k and have not felt a studder.
I do have upgraded valve springs so valve float does not seem a problem.
We are of course, talking about the stock ignition. The Dyna ignitions have a programmable limiter.

[jr1349]

Kris, that is one bitchen XJR you have...

Thanks for the info on the 20t sprockets. I didn't mean to imply that I disbelieved you, I was just not aware that you could fit that large of a drive sprocket in our cases.

Re: Rev limiter, I think Randy or Bob W could comment on this. They have extensive racing experience.
I have not detected a ignition limiter on my bikes (doesn't mean that there isn't one) I've had them up above 10k and have not felt a studder.
I do have upgraded valve springs so valve float does not seem a problem.
We are of course, talking about the stock ignition. The Dyna ignitions have a programmable limiter.

cheers Pat, the old girl is actually pretty stock, particularly from a major components perspective, cycle parts stock, sundries like gearing and brake lines aside, and the engine internally is as it left the factory, save for valve clearance blueprinting, and an extra spring in the clutch, but I do like to play.

just to remove some doubt about the existence of 20t sprockets, some pics, I will show installed pics at later date.

in terms of fitting there is one caveat that I haven't looked into, my sprocket cover has some bits missing after I lost a chain a number of years ago, cant be seen externally but at the point where it curves around the oil filter housing I've lost some chunks of material, if a stock item means that a 20t wont fit I don't know, I have an undamaged one I intend to fit after returning to street gearing after this summers drags, ill look into if this affects the clearance at this point, and get some fitted pics for ya's.

k.

[mikedastonfj1100]

As Noel pointed out...You would think that after 30 years of riding the same bike, I would know what gear I'm in....occasionally I still reach for sixth.

I agree with that... I occasionally try to grab for 6th as a joke to myself... I laugh about it when I do it too....

[jr1349]

As Noel pointed out...You would think that after 30 years of riding the same bike, I would know what gear I'm in....occasionally I still reach for sixth.

I agree with that... I occasionally try to grab for 6th as a joke to myself... I laugh about it when I do it too....

I'm using 20/37 gearing and I still search for 6th gear every time I ride, I don't really care what gear im in as I mostly ride by feel, but there is no doubt in my mind that the fj/xjr engine will happily pull 110kmh (70mph) at 3000rpm, no doubt whatsoever, standing starts will be the only problem, but its only a problem if your in a rush.