Feels like I'm bottoming out. Preload adjustment?

[bamarama]

When leaving my condo parking lot, there's a small dip between the lot and the road for water runoff. When I hit this, it feels like bikes frontend bottoms out (substantial jarring in my wrists). The previous owner had the bike lowered by the guys he bought it from, but couldn't tell me exactly how they did it (adjusted something while he was standing there apparently). Is it possible that the front (and possibly rear) preload was adjusted to lower the ride height, which now for a taller and heavier guy is allowing the frontend to bottom out? Any other suggestions? I'd like to get the ride height back up a bit, but more importantly I don't want the bike to bottom out on me.

Thanks,
bama

[Black_peter]

If they lowered the front by just sliding the forks in the trees then that would not effect the bottoming out.

If they monkeyed with the springs..
(I doubt is that is a several hour affair to change)

try this:
tie a string or rubber band around the fork slider
(shiney part) push it down to the dust seal.
Make it tight enough to stay where you slide it but
not too tight, don't use anything that would scratch..

Now drive by the spot you feel bottoms the forks.
If the marker is at the very top,
right against the bottom tree, you are bottoming out.

[bamarama]

After taking an extended look at the front end, it's very clear that they lowered the bike by lowering the triple clamp on the forks, because the marks from where the clamp used to be reside about an inch and a half to two inches above the top edge of the clamps now. The bike is indeed bottoming out on the top of the tubes, and the black covers on the top of the tubes are pretty beat up (cracking on edges). How difficult of a job is it to adjust the clamp back up on the forks? Also, is there any way for the rear end to have been lowered in similar manner as the front and is there a way that I can figure it out?

Thanks,
bama

[The CyberPoet]

My advice:

Odds are that the bike hasn't had it's fork oil and oil seals changed in the last two years -- my guess, based on your description is more like 5 years. Either change it yourself (search the threads for the how-to; change the oil, and both the oil seals and the dust seals), or ask your local dealership/garage to do so. When the forks go back in, ask them to put them back to the stock position (or put them there yourself). This will increase both the travel range (because they were dropped too far) and the viscosity of the oil (which will increase the compression rates a bit, reducing the tendency to bottom out). It will also restore the bike's geometry so it handles like it should (at least if there are no glitches in the back-end).
Depending on how worn the springs are (or if they have been cut down at all), you may want to replace them as well ($110 in parts or so, + S&H). I sell Ohlin replacement springs that are about 20% stiffer than stock, and you can also get RaceTech brand at about the same pricing in a variety of stiffnesses.

Cheers
=-= The CyberPoet

[bamarama]

Thanks for the advice. As soon as I get my centerstand back from the powdercoaters, I will change the fork oil and oil seals and restore the position to original. How do the Ohlin springs change the handling of the bike? Would you recommend them over stock springs? Also, you got any advice on how to check for back end adjustments?

I really appreciate all yalls help. bama

[The CyberPoet]

Thanks for the advice. As soon as I get my centerstand back from the powdercoaters, I will change the fork oil and oil seals and restore the position to original. How do the Ohlin springs change the handling of the bike? Would you recommend them over stock springs? Also, you got any advice on how to check for back end adjustments?

The springs compare to new stock springs by saying they take 25% more effort (or force) to compress any specific distance, thus reducing brake dive and front end dipping on weight transfers (coming off throttle, rolling into turns, etc). The flip side of that is that they won't suck up tiny bumps as well (you'll get more road info transmitted to the handlebars). If you are a light-weight rider (say 150 lbs or under), you probably wouldn't want them; if you clock in around 200 lbs or more (with gear, typical load, etc), then they should improve the feel of the bike.

Your springs are an unknown, and so I can't honestly compare them -- they might be stock, they might be stock that have been cut down, they might be stock that are weakened over years of use, they might be aftermarket, they might be cut down and weak, etc... there are just too many variables for me to be able to give you an honest answer. If you get them out, and have a good scale and tape measure, you can calculate how they are -- put the spring into a piece of PVC tube cut to the same length as the spring (and just slightly larger than the spring), set the spring & tube on the scale and zero the scale out. Take a smaller piece of pvc designed to fit inside the larger piece, cut it to an inch in length and push down until the spring compresses 1" in length (which should make the two pieces of PVC flush) -- and look at the scale. The reading should be approximately 65 lbs for a healthy stock spring (someone else posted that number -- I haven't verified it). A weak spring will read less, an aftermarket will normally read more.

If you search, you can find where I already posted the length and girth of the stock springs in one of the threads -- if needed, I can remeasure it for you.

Cheers
=-= The CyberPoet

[bamarama]

Thanks for the info CP. I'm 6'1" 215lbs. myself, so I'm guessing stiffer springs would be beneficial, as currently the bike feels kind of floaty. As soon as I can get the bike up to work on it and I get out of the Christmas time non-gift money lockdown, I'll probably get some new springs to pop in when I do the other stuff to the front end. Thanks again.

bama

[Ninja_Vidal]

My advice:
Depending on how worn the springs are (or if they have been cut down at all), you may want to replace them as well ($110 in parts or so, + S&H). I sell Ohlin replacement springs that are about 20% stiffer than stock, and you can also get RaceTech brand at about the same pricing in a variety of stiffnesses.

Cheers
=-= The CyberPoet

Hey Cyber, are you still seling springs? I'm looking to get my fork Seals replaced, and my mechanic said I should think about replacing the springs while I'm getting that done.

200lbs. , 1993 Katana 600.

Any recommendations on Fork Oil?

thanks,

Vidal

[The CyberPoet]

Hey Cyber, are you still seling springs? I'm looking to get my fork Seals replaced, and my mechanic said I should think about replacing the springs while I'm getting that done.

200lbs. , 1993 Katana 600.

Any recommendations on Fork Oil?

thanks,

Vidal

Yeah, I'm still selling the Ohlin springs.
As for oil, how often do you ride 2-up? If the answer is rarely, stick to OEM weights; if the answer is often, bump it up by 5 weight. Personally, I think a blend of 10 and 15 weight to arrive at an effective 12.5 weight is a good compromise.

Cheers,
=-= The CyberPoet