Front suspension Bottom Out

[chefmatt]

Have an 89 fj1200, the front suspension is bottoming out and even small bumps. Can anyone recommend an econmical (re: cheap) spring? Other than fork seals and oil, what else will I need? Thanks for the help!

[FJmonkey]

Have an 89 fj1200, the front suspension is bottoming out and even small bumps. Can anyone recommend an econmical (re: cheap) spring? Other than fork seals and oil, what else will I need? Thanks for the help!

Not knowing what you currently have, you might be low on fork oil. Some history would go a long way if you want help... 

[chefmatt]

Don't know the history of the bike...bought it recently. No help, sorry

[chefmatt]

Should I have my mechanic check/top off the oil before spring replacement?

[Arnie]

Sonicsprings.com have some fairly economical single rate springs available.  Or, you could try Ebay if you know what you're looking for.  If your current springs aren't too soft (probable), you could add a longer preload tube which might be enough - for a while.
As FJMonkey says, check the oil level if its way low that would allow the fork to bottom hard.

[FJmonkey]

Don't know the history of the bike...bought it recently. No help, sorry

Time to crack it open then... I love the RPM solution, the RPM fork valves and new straight springs are awesome... Not a budget item but I see it as a safety item. Prop the front end up and pull off your fork caps. How much oil is in there?

[chefmatt]

How many ounces of fork oil do they need?

[FJmonkey]

How many ounces of fork oil do they need?

More of a measurement from the top with the forks compressed and springs removed. Try the search function....

[chefmatt]

got it thanks. thank you google, its 395cc or13.36oz.....

[Arnie]

Matt,

You're much better off measuring the distance from the top of the fork tube to the oil level.
If you try to fill by volume, you'll have to remove the forks and completely drain them of all old fork oil, this means rinsing with kero and leaving them upside down for a day.

Good height for fork oil starting point would be 150mm of air space with the springs removed and the forks fully compressed.

[skymasteres]

When I got my FJ the front forks were dry. It was freaking scary on the test ride when the bike bottomed out the suspension on the compression and the rebound stroke. Like Mark says, it's a safety issue to have a properly functioning suspension. You don't have to upgrade it to get a LOT out of the bike. But there are a LOT of potential improvements to be made. (Interestingly enough, Randy's front end solution isn't much more expensive than the Racetech solution when comparing retail prices. And the performance is much greater.) But either way you go, both are far better than the stock solution.  (I'm running the Racetech's and after months of building my skills and riding as much as I can, I can say that I'm ready to upgrade to the RPM solution.)

[movenon]

Cheap,  first thing is clean the forks, install new oil and see what you have.  IMO the first good improvement is getting the correct spring rate.  Beyond that the emulators come into play but now we are increasing the cost.

As far as cheap springs they are all priced about the same. You can go here and plug in your weight to get a spring rate. Scroll down to the yellow highlighted area and click it on.  http://racetech.com/ProductSearch/2/Yamaha/FJ1200/1986-89. 

I think Randy at RPM also carries them.   http://www.rpmracingca.com/products.asp?cat=39  Occasionally you run across a used set from someone wanting to go up or down with there spring rates.  You need to figure out what spring rate you want first.
George

[TexasDave]

I took route 70 in northern California down out of the mountains. It is a scenic highway with many curves and three tunnels running beside the Feather river. I was unhappy with the mushy front forks on all the curves. The PO had installed some kind of progressive springs that still did not do the job. Randy did his fork and shock mod and I couldn't be happier with the ride and handling now. I hope to someday make the same ride with the handling I have now. Dave

[Burns]

Have an 89 fj1200, the front suspension is bottoming out and even small bumps. Can anyone recommend an econmical (re: cheap) spring? Other than fork seals and oil, what else will I need? Thanks for the help!

What ya got here is  a "pig in a poke."  You don't know what's in the sack till you open it up, pardner.

Are the tubes bent or scored? Are Jimmy Hoffa's ashes in your sliders?

You gotta take the forks apart and look.


What you do know is that you have substantial wear on some 25 year old suspension units.  If you are bottoming-out you are probably beyond the spacer-and-add-oil "patch" and need to get things ship-shape.

You almost certainly need a basic rebuild.

First thing: get a manual and the tools that you'll need to remove and disassemble your forks.

When you get the tubes out of the sliders roll the tubes on a flat surface (pane of glass e.g.)  to check them for "true". If they are bent you need new ones.

You'll need to replace the seals, springs and oil.

Budget-out the best solution that you can afford (stock to RPM)and get your parts.

It is not hard to do. 

If you get stumped someone here will surely unstump ya.

[simi_ed]

2 points to add.  Bent tubes can be straightend, they do not always need to be replaced. 
Any true fork rebuild should also replace the bushings.  They wear out and will allow the forks to bind and become non-responsive to small bumps.  Who wants suspension that doesn't act on the small stuff?