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Old Apr 21, 2012, 02:16 AM
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Joined Aug 2011
4 Posts
thanks for the help i'll get some oils and try .o and yer very shocking the power of the thing was amazing with the ripper motor just need to find a place big enough to open it up more than a second lol
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Old Apr 24, 2012, 04:32 AM
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Sweden
Joined Aug 2011
9 Posts
The rtr scratchbars angle and position are not the same as on the probike.You need to bend the scratchbars if you want it to be faster in the corners.
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Old Apr 25, 2012, 03:23 PM
Kungsangen, Stockholm, Sweden
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Sweden, Upplands-Bro Municipality
Joined Dec 2011
233 Posts
Assymetric steering input reaction

I have managed a few fantastic practice sessions and everything seems to be working fine but yesterday my bike seemed to be slower to shift from right to left, than to the opposite.
When I go left and change direction to the right, the bike is very quick to shift both lean and direction, even slamming the bars. When I do the opposite, right to left, it feels slow and unwilling to react to steering input. The problem gets bigger the faster I go. When the bike is in the turn, leaning, everything is good. It's just the reaction to steering input that seems to be affected.

I run my bike very close to original with 4900kv, a bit raked up fork (1 ZH leg), fork travel restrictors, lightscale brake disc, stock steering springs, only 1 damper filled(stock 600 oil), PMT 200's (massari inserts), 3000/1000 shock oil setup, stock springs, fairly high leaning angle and a homemade belt brace (The rear wheel sits straight as an arrow and no bending or beltskipping).
Nothing seems broken or otherwise wrong, though I haven't performed a detailed inspection yet.
My first thoughts concerned the steering springs, or the single damper being overfilled but it seems ok. It was suggested that I should replace the steering bearings (I know they are due for change but haven't come around to do it yet).
The servo is bluebird low profile and is ok as far as I can tell.

What's my problem?
Are there any theories out there?
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Old Apr 25, 2012, 04:10 PM
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United States, TX, Houston
Joined Dec 2009
1,122 Posts
Radio settings has been the problem down here. Even though some folks Know their radio inside and out, it always seems that when they try to change something they end up going to the wrong setting on the radio and changing the wrong thing thinking its the right thing. Lol, thats all i got for you.
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Old Apr 25, 2012, 05:05 PM
Kungsangen, Stockholm, Sweden
z_dad's Avatar
Sweden, Upplands-Bro Municipality
Joined Dec 2011
233 Posts
Quote:
Originally Posted by 621clay View Post
Radio settings has been the problem down here. Even though some folks Know their radio inside and out, it always seems that when they try to change something they end up going to the wrong setting on the radio and changing the wrong thing thinking its the right thing. Lol, thats all i got for you.
Thanks, I'll look into that. Have to rule everythig out.
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Old Apr 26, 2012, 12:50 AM
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Gartenzwerg's Avatar
Austria
Joined Jan 2007
630 Posts
Quote:
Originally Posted by z_dad View Post
The servo is bluebird low profile
That would be the first thing to check, in my opinion.

I only know that problem from my cross-bikes or the GPV-1. It happens when the fork legs are "twisted".

This should not be possible on an SB-5, but maybe it's worth a try to inspect the fork legs, and rebuild the forks?
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Old Apr 26, 2012, 05:28 AM
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Germany, RP, Nierstein
Joined Jun 2011
145 Posts
...maybe one of the steering springs collabsed and is too short / too soft now
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Old Apr 26, 2012, 03:03 PM
Kungsangen, Stockholm, Sweden
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Sweden, Upplands-Bro Municipality
Joined Dec 2011
233 Posts
Thanks guys, I'm making a checklist.
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Old Apr 26, 2012, 04:03 PM
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United States, TX, Houston
Joined Jun 2006
280 Posts
Check your end points on the servo - the servo horn should be symmetrical about the centerline at full throw in both directions. When adjusting the radio - I personaaly prefer to set the epa fixed on both sides and set the trim at 0. I then use the subtrim to center - that way I always have equal servo travel from center. The traditional way of setting your epa and using trim - will usually give more steering in one direction because you set the EPA before the trim and the end points do not adjust with it. This can be a big issue if your center is way off to start out.

Also check for any bInding or interference in the steering ( body, suspension swingarms, etc).

-rskip
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Old May 01, 2012, 12:02 PM
www.steliosh.net/rcmoto/
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Athens, Greece
Joined Oct 2003
3,249 Posts
A strange problem occurs to me lately!
The traction of the track is very good lately, so I am trying shorter and shorter crashbars (along with Clark's Lightscale longest wheelbase settings).
When I mount very short crashbars, my times go down, (happy me!) but the front wheel tucks inside during the exit of fast corners, leading the bike to the inside of the corner, usually ending in the grass...
I am running PMT treaded tires (stock rules) and it does it with either used or new ones.
I tried a slick front tire, a slick rear, (always PMT200, from Clark), combinations of all the above...
I even tried the shortest wheelbase positions of the swing arms, but still the same occurs.

The only solution seems to be 5mm longer crashbars, and the fenomenon disappears!
And then my times refuse to go below 24.14!!!!!! haha!
The bike has no problem turning right or left, and this occurs on both types of turns... usually very fast turns, like the end of the main straight which leads to a long uphill...
then on the other side, going downhill, letting go of the throttle, no brakes usually, when I push the throttle mid turn towards the exit, it will do it most of the times...
Any insight would be helpful...
Oh... I am running middle position crashbars...
And those +5mm crashbars that "work", are maybe 5mm shorter than what I used in Riccione in October...
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Old May 01, 2012, 04:47 PM
Kungsangen, Stockholm, Sweden
z_dad's Avatar
Sweden, Upplands-Bro Municipality
Joined Dec 2011
233 Posts
Hi Steliosh, I wonder. Do you use mechanical restricors for the fork movement?
If not, my guess is:
The longer wheelbase from the lightscale kit moves the CG forward. That puts a lot more push to the front in high speed turns. A high lean angle might make the fork come very close to a point where it actually folds into itself (You may have experienced this on a regular bicycle if you fall down and the handlebars tries to knock your teeth out as the front wheel folds.). With all that weight on the front and a completely crossed up fork, the bike may not recover from a slip or a bump (as seems to be your problem). Steering restrictors on the fork may help you recover better, as the fork does not travel so far from the effective angle.
My experince (limited) is that you need surprisingly small turning angles for the fork, to still make sharp turns.

I just had this thought and decided to share it before thinking too much.
It may also be completely wrong
Hope it helps

Micke
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Old May 04, 2012, 05:25 AM
www.steliosh.net/rcmoto/
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Athens, Greece
Joined Oct 2003
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It certainly makes sense, z_dad!
And, no, I do not run any restrictions on the forks, although I have turned down the ATL of the steering channel to about halfway, each side, after carefully finding the center with the subtrim.
I reverted to slightly longer scratchbars and the situation disappeared... anyway my track is not super on traction and it's quite bumpy at places...
Thanks for the input!
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Old May 05, 2012, 06:39 PM
Kungsangen, Stockholm, Sweden
z_dad's Avatar
Sweden, Upplands-Bro Municipality
Joined Dec 2011
233 Posts
Assymetric steering response

Quote:
Originally Posted by z_dad View Post
When I go left and change direction to the right, the bike is very quick to shift both lean and direction, even slamming the bars. When I do the opposite, right to left, it feels slow and unwilling to react to steering input. The problem gets bigger the faster I go. When the bike is in the turn, leaning, everything is good. It's just the reaction to steering input that seems to be affected.
Hi guys, thanks for the input on this issue, it has helped me in concentrating on the proper area.
I just finished checking, adjusting and testing.
I changed the steering bearings, they were shot, though not the main issue.
As I tested the steering spring tension, I discovered that the power of the springs, at the endpoint of servo travel, were different left from right allthough everything looked symmetrical and straight.
Something in my (cheap) Radio system made the fork do different movement depending on direction. After dialling the transmitter to make the fork movement equal, the problem disappeared. An additional source of trouble detected was the brake servo cable. It COULD get tangled in the steering restrictors due to routing (cured now). There is still sluggish response in high speed but I will be trying harder springs, hope to be fast soon.
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Old May 05, 2012, 07:24 PM
Kungsangen, Stockholm, Sweden
z_dad's Avatar
Sweden, Upplands-Bro Municipality
Joined Dec 2011
233 Posts
Steering restrictors

Quote:
Originally Posted by steliosh View Post
I do not run any restrictions on the forks, although I have turned down the ATL of the steering channel to about halfway, each side, after carefully finding the center with the subtrim.
Turning down the ATL does limit the movement caused by the steering input, but it's not helping if the bike dynamics is pushing your fork to its mechanichal endpiont, only mechanical restriction can do that.
Still, I admit, there is nothing that says this is your problem.

Anyway, this is a simple and cheap mod that is reverseble just as easy:

There are two 2.5mm threaded holes in your lower fork triple. You can use these, or rethread them 3mm.
Put 20mm screws fully through the holes from the bottom on both sides and threadlock them there. Use a plastic nut or similar on the tip of the protruding end of the screw. This nut will touch the steering stem to restrict the fork movement.
Differnt size, different angle.
Yes, they will bend with a lot of force but it's an indicator as if you're adressing the correct parameter. If you don't like it you can just remove these screws again.

I believe this helps me keeping high leaning angle in "notsoperfect" grip conditions.
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Old May 06, 2012, 12:24 PM
www.steliosh.net/rcmoto/
steliosh's Avatar
Athens, Greece
Joined Oct 2003
3,249 Posts
Looks like my problem is simple as this:
The track I am running has med to min traction, so the tires have to work REALLY hard to compensate...
The rear becomes a slick after about 20 batteries (20 ten-minute sessions) and the front after about 30 batteries sees chinks coming off!
I mounted a used (20-30 batteries) PMT200 slick front and suddenly I could do consistent 24-low lap times (struggled to do 25-low's with the used cut slick) and the fenomenon disappeared completely!
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