sprokets an stuff

[FJSpringy]

had a quick search and found some info but not really what I want

I have a 92 FJ1200 with the T/Ace rear end and for the last few years have been running 18/39 with a 530 chain.

My motor even though rebuilt (with cam timing and ignition timing mods) has a vibration (not real bad but annoying after a few hours) that starts at 3,200 rpm and finished about 3,700 rpm which, with the above gearing is right on our Australian highway speed limit of 110 kph. Once I hit 4,000 rpm the motor is so smooth you hardly know its running. The gearing is also a bit gutless down low.

I was thinking about 17/40 to raise the rpm to hopefully over the vibey bit and to give me a better take off from stop.

I modded my FJ as soon as I purchased it so have never ridden a stock FJ so have nothing to compare it to.

Any help much appreciated.

Dave

[roverfj1200]

Dave

I run 18 /40 with the GSXR rear and that puts me on 3800 at 100kph. My bike has no vibes at any rpm.

I have bee thinking of 17/40 to which should pop me up to 4000 at 100..

Cheers..

[Harvy]

Dave, is that your FJ on the UK FJ mod site?

Harvy

[FJSpringy]

yes it is, geez that was a long time ago

[Harvy]

yes it is, geez that was a long time ago

It sure was.

Actually reading that and other stuff on the mods site not long after I bought my FJ lead me to googling more info, which lead me to the Yahoo group, which in turn morphed to me being here.

So I guess its all your fault.....

Like, this is a great bunch of mates, most of whom I've never met in person, and I doubt you would find more motorcycle knowledge on many other internet groups (be it FJ or not!).

Are you still one the same FJ?

Cheers
Harvy

[FJSpringy]

yes it is, geez that was a long time ago

Are you still one the same FJ?

Cheers
Harvy

yes I am, but it has changed quite a lot since those days, still got the T/Ace rear but lots more mods, my mates still give me heaps about it 

[Bob]

The PM rear wheel I got came with a 46 tooth sprocket.  I now run 18/46 which translates to 100km/h@4250 and 120km/h@5000 ... it took some getting used to, but for most real-world riding it's a good fit.  In Ontario you get a big legal hit if you go 50km/h over the speed limit. 150km/h on the FJ is easy, so having the revs higher keeps me legal. 

There is, evidently, no law against getting up to speed quickly 

[Bob]

...and take a look the FJ Gearing.xls file in the files sections ... it's stored as FJ Gearing.zip

[the fan]

I am a big fan of the gearing commander site. With a little effort you can take a look at nearly any gearing/speed/RPM situation and easily apply it to the real world. Its even able to calculate in both MPH and KPH

http://www.gearingcommander.com/

Only the 89-93 model is shown, but to my knowledge the primary and transmission gearing has not changed so it should work for all models.

[FJSpringy]

thanks guys, I am going to put a 17 on the front and see how it goes, the chain is in good nick so won't be an issue.

[Arnie]

Springy,

You shouldn't be getting vibes all the way up to 4000 rpm.  Have you checked the front motor mounts are not seized?
Also check that all the bolts in the frame rail links (under the footplate and up near the front motor mounts) are tight and whole?

Rover,
Where did you get a 40T sprocket for the GSXR wheel?  I've not been able to find anything less than 42T.
This gives me gearing that is almost exactly the same as stock, and no vibes once over 3K rpm.


Cheers,
Arnie

[FJSpringy]

Springy,

You shouldn't be getting vibes all the way up to 4000 rpm.  Have you checked the front motor mounts are not seized?
Also check that all the bolts in the frame rail links (under the footplate and up near the front motor mounts) are tight and whole?


Cheers,
Arnie

Thanks Arnie,

I only get mild vibes between 3,200 and 3,700 and it appeared after the addition of the XJR1300 carbies and their tuning on the dyno, we never did get it as good as I would have liked under 4k, once you hit 4k the FJ takes off like a rocket, quite amazing for an old lump.

I agree about the frame rail bolts I checked them a while back the rear ones were loose so I did tighten them up, haven't looked at the motor mounts for years so I will have a fiddle with them later in the week.

Regards,
Dave

[higbonzo]

I have the 17-180-55 rear tire.  I run the 17 and 41 sprocket set up.  That puts the RPM's at 110 kph at about 4200.  I like the set up and it keeps the bike quick enough to keep it fun.  Although, I am thinking of getting another chain and sprocket setup to make the bike accelerated quicker.

Later.....

[pdxfj]

On top of the motor mounts, make sure you have the carbs synced.  That can also really help to smooth things out.

'92+ bikes have fully rubber mounted engines if memory serves me.  I seem to remember others saying the lower engine mounts on those years also seize up.  David R. said it was a PITA to get them out, but once everything is cleaned up and working the way it should, almost all the vibes were gone.

[Bob]

'92+ bikes have fully rubber mounted engines if memory serves me.  I seem to remember others saying the lower engine mounts on those years also seize up.  David R. said it was a PITA to get them out, but once everything is cleaned up and working the way it should, almost all the vibes were gone.

Yup... the difference is dramatic.  There are pictures in the gallery section under Misc FJ Photos.  And David R. documented the process well. It's worth the effort.

http://www.fjowners.com/index.php?topic=592.msg4349#msg4349

http://www.fjowners.com/index.php?topic=594.msg4348;topicseen#msg4348