Fork tube extension

[Flyover Country Joe]

Hello all,
     Had a quick question, hope someone can help. I just finished rebuilding the forks this week. I forgot to measure the length of the fork tubes extending above the handlebar clamp. I put it back together and set the fork caps flush with the top of the bars & took it for a ride. It turned like a truck! I subsequently raised the tubes up in the triple clamps, they are now extended .435" from the top of the fork cap to the top of the handlebar clamp. I went on a 200 mile run today in the Ozarks, The steering is pretty manageable now, but hardly light. Could I get some measurements of fork tube heights from some of the members here? If I can lighten up the steering effort without getting headshake, how far can I go? Thanks!
                                                                                              Kookaloo, ya'all!
                                                                                                       Joe
1990 3CV 

[SlowOldGuy]

I have maybe 1/8 inch of the tube showing above the handlebar clamp on both of my FJs.

DavidR.

PS Joe,
Sorry I didn't hook up with you last month when we were in Arkansas.  Things got hectic at the last minute and I got distracted keeping everyone headed in the right direction.  We will be back in the fall.

[Flying Scotsman]

My 1990 is set flush but it wasnt when I bought it earlier this year.i have been thinking about going back to where it was to see what it feels like.If your bike steers like a truck I would see if you have enough air in the tires.Mine had low pressure and it felt like the brakes were on when I inflated them the diference was night and day.My 1990 now steers and turns just fine and also feels much lighter when moving it in and out of the garage etc.

[rktmanfj]

I experimented with mine (when I still had the stock fork) and at one time had them about !/4" from the clutch m/c.

Turn-in was a bit quicker, but not even close to the swap to YZF600 spec fork and wheels.

Randy T
Indy

[Arnie]

My fork tubes are up about 10mm from stock, and the rear ride height is about 2" higher than stock.
No headshake at all with this setup.  Note: I have 17" rear as well as 17" front wheels.

Arnie

[Flyover Country Joe]

I have maybe 1/8 inch of the tube showing above the handlebar clamp on both of my FJs.

DavidR.

PS Joe,
Sorry I didn't hook up with you last month when we were in Arkansas.  Things got hectic at the last minute and I got distracted keeping everyone headed in the right direction.  We will be back in the fall.
DavidR.
  I've got about 1/8'' of tubes showing as well. Looking forward to seeing you all in the fall.

My 1990 is set flush but it wasnt when I bought it earlier this year.i have been thinking about going back to where it was to see what it feels like.If your bike steers like a truck I would see if you have enough air in the tires.Mine had low pressure and it felt like the brakes were on when I inflated them the diference was night and day.My 1990 now steers and turns just fine and also feels much lighter when moving it in and out of the garage etc.

Flying Scotsman,

I thought tire pressure might have been it, but I had 35F/40R so i wasn't too far off.

My fork tubes are up about 10mm from stock, and the rear ride height is about 2" higher than stock.
No headshake at all with this setup.  Note: I have 17" rear as well as 17" front wheels.

Arnie

Arnie. I think I will raise the tubes a bit more, I'd like to raise the rear with new dogbones but I'm kinda short legged.

[andyb]

I'm up 10mm from stock (but also use a pinch shorter rear wheel, 17").  Strongly suggest raising the rear as much as you're comfortable to start off.

But before getting too far ahead of yourself... a different tire, particularly going between different profiles in the front, makes a spectacular difference.  The last Avon I had was magnificently stable but unhappy about doing anything but going in straight lines, where a BT010/11 (whichever it was) was twitchy and nervous going down the road, but hands-off stable when cornering. 

So, start with alla the obvious stuff.  Actually judging by what you've said you've done, I'd imagine this is all old hat to you, but if anyone later searches out the subject....


-Air pressure in the tires is adjustable
-Tires wear.  Square in the back does screwy things, and cupped fronts do even screwier things.
-Tires come in many a different profile, and it makes a very noticable difference (and don't start me on the Pirelli's I'm using on the other bike, they're awful because of this...)
-Tires also come in different sizes.  A 120/60 or 120/65 will lower the front a bit more, but a 110/80 might be better still due to the profile (CBA to do the math on height right now).
-Rear height can be raised to speed the steering up pretty easily on the dogbone equipped models.  Hard on the inseam for some of us though.
-Forks can be raised until they just about touch the master cylinders.  Stick a credit card in between them, raise them until they hit, and see where you're at.  If you really, truly want more, you can make handlebar risers (there's a link to plans in the files someplace?), but you're going to start having issues with ground clearance.  Alternately you can go to a different pair of masters that are not in the way of the fork tubes, but you'll end up scraping things eventually.
-What's your sag like on the front end?  Not enough will leave the front riding high, but stock springs tend to have the opposite problem.  Got aftermarket springs in?

Raise them a bit at a time and see what you think.  The FJ is generally really stable because of the conservative rake/trail figures, you'd have to go pretty crazy with things before you make it twitchy.

[Flyover Country Joe]

Andy,
    I agree that you would have to do something pretty drastic to get an FJ to get into headshake territory, geometry wise. I still have the stock springs in the forks, but added 2 washers per leg for a little more preload. Right now I've got preload adjusted full soft, really need to actually measure sag instead of just winging it. 1 kg/mm springs are probably my next purchase. I've got fairly new Lasertecs on it right now, in stock sizes, but would love to do the GSXR rear wheel swap ASAP. Actually having oil in the forks and new bushings and seals was a real revelation in how bad it rode and handled before! I got to get up to speed on getting pictures posted up, I've got some cheap fork tube protectors I put on during the rebuild that are just begging to be pointed at and laughed at! At least I only have $3.56 into the pair. Thanks for the input, I'll take all I can get!                                                                 Kookaloo, ya'all!
                                                                                            Joe