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Throttle Control


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After attending CSS in April I was lucky enough to get out on my local track (Miller Motorsports Park) this past weekend and try out my Level 1 and 2 skills on the big track. They all worked great, but I failed to adhear to rule 1, smooth, consistant roll on of the throttle and ended up losing the rear at the end of a corner and ending my day.

 

 

Just a reminder to all of you from a guy that has to look at his bike for a while and put it back together -> THROTTLE CONTROL IS PARAMOUNT!

 

 

Between Throttle Control and Picking the bike up at the end of the corner you can eliminate the majority of silly crashes.

 

 

 

Thanks again for the cornering lessons, I was so happy with my improved riding at that trackday. It's amazing what a little body position and proper eye control can do for a rider.

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Sorry to hear about the get off - that sucks :( . What bike were you riding?

 

So what exactly happened to cause the crash?

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...I failed to adhear to rule 1, smooth, consistant roll on of the throttle and ended up losing the rear at the end of a corner and ending my day.

Sorry to hear about the crash. I too would like to hear more about your throttle control trouble.

 

It's amazing what... proper eye control can do for a rider.

Vision easily is my most important factor these days. I can track almost all my mistakes back to visual errors. I never realized just how important visual skills were.

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  • 10 months later...

The issue for me was that in the turn previous to my crash I was passed by someone who I believed I could keep up with. So, as I was exiting the corner that I crashed in I was trying to "keep up" and the rider mentioned was already on the front straight and pulling away. Instead of keeping my wits about me and standing the bike up before really getting on the throttle I rolled on too quickly while still at about 80% lean... the results were as expected in hindsight. I low-sided, he continued down the straight. I could not keep up with him on foot, running in my track suit, in the gravel. :P Now my throttle control has become the focus of many of my corners. Also my '02 CBR 954rr has a fairly abrupt lurch when I first crack the throttle which I'm thinking I'm going to try to resolve with a Power Commander.

 

We'll see. Thoughts?

 

Here's a helmet cam video of the whole experience.

 

http://contour.com/v...on-2-race-group

 

Got passed - 1m 39s

Bad Decision with my right hand - 1m 58s

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Power Commander is probably the ticket to help with the "lurch" you describe, but a couple of other small things can be checked or adjusted which might help:

Check the amount of play in the throttle. If you have a lot of slack in the cable it can make the throttle response late and jerky.

 

Consider increasing your idle RPM, that can reduce the "chain lash" feeling when you come back on the throttle in a turn. (Be cautious on turn entries for the first lap or so after you do this, though - a higher idle speed can make you come into a corner a little faster than expectd until you get used to it.) I think last time this was discussed someone recommended to increase it 500rpm, then try it, then try another 500 rpm, and see how it feels.

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I had not even thought of that... I will be checking my throttle as soon as it stops raining in Utah. Thank you! That's probably something I'd be inclined to do before dropping $300 on a PC3... we both know I'm going to get that PC regardless but I'll feel better about spending the $ if I have at least tried to fix the problem on my own. The tricky thing for me is I am a 90% Street/10% track rider right now and it takes some luck on my part to find myself on a stretch of road where I can focus on my riding and not cars, rocks, cliffs, guardrails, deer and runoff streams across the road.

 

Thanks again for the advice though, much appreciated.

 

td

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........Now my throttle control has become the focus of many of my corners. Also my '02 CBR 954rr has a fairly abrupt lurch when I first crack the throttle which I'm thinking I'm going to try to resolve with a Power Commander.

 

We'll see. Thoughts?

 

Just something to consider when you deal with a powerful engine:

 

The torque applied onto the rear patch is directly proportional to the angular position of the throttle handle.

As soon as you twist it significantly, the pressure in the combustion chambers increases greatly and that force is immediately and entirely transmitted to the rear tire, even when you don't see any increment in the rpms'.

 

A jerking action between idle and a cracked open throttle generates much smaller torque increment that what has been explained above.

 

A trick to reduce both is to keep two fingers on the brake.

That way, you feel more control on very small openings of the throttle.

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Speaking of rusty, I go to VIR in a little over a month and I haven't even gotten to ride my bike yet this year. Actually the last time I rode was November 3rd. 5+ months of snow, salt and cold.

 

Rain, sleet and snow for a few more days. We have only seen a couple days with highs in the 50's all year and the forecast doesn't look like it'll get much better for atleast another week.

 

The increased idle speed I implemented when I raced and after several corners thought it was great and I always keep throttle cable free lay to nearly zero.

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The issue for me was that in the turn previous to my crash I was passed by someone who I believed I could keep up with. So, as I was exiting the corner that I crashed in I was trying to "keep up" and the rider mentioned was already on the front straight and pulling away. Instead of keeping my wits about me and standing the bike up before really getting on the throttle I rolled on too quickly while still at about 80% lean... the results were as expected in hindsight. I low-sided, he continued down the straight. I could not keep up with him on foot, running in my track suit, in the gravel. :P Now my throttle control has become the focus of many of my corners. Also my '02 CBR 954rr has a fairly abrupt lurch when I first crack the throttle which I'm thinking I'm going to try to resolve with a Power Commander.

 

We'll see. Thoughts?

 

Here's a helmet cam video of the whole experience.

 

http://contour.com/v...on-2-race-group

 

Got passed - 1m 39s

Bad Decision with my right hand - 1m 58s

 

I watched the crash about 10 times in a row, and I can't quite tell which end let loose. I assume it was the rear since you were on the throttle. It actually looks to me like a kind of mini-highside wipeout, which would be consistent with the throttle error. Do you think the rear slid then caught again, chucking you off, or did it just slide away out from under you?

 

That looks like a fun track!

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YellowDuck,

 

If you listen really hard over the wind noise you can hear my open the throttle and it sounds abrupt. I low-sided. The contributing factors were (I think):

 

1. I was at what I consider to be my own personal "full lean" (Peg drug in the middle of the corner so I'd assume that's about the limit)

2. I 'twisted the wrist' (haha) a bit too fast.

3. I'm 220 lbs and the bike is sprung about 70% stiff enough for my body mass.

 

What I remember from the crash (not that I got KO'ed, it just happened so fast it's hard to section out parts of it.) is that I was already cranking my head around to look down the straight and had located where I was hoping to exit. I wasn't paying attention to the SMOOTH part of smooth, consistant roll-on. I was knee-down so there was a small hip check to the track but it was only about 1' or less. I knew something went wrong when my elbow was down too and I (sort of) pushed with my right (inside) leg and there was nothing there. Once I knew I was off I thought "Tom, do your best starfish and get away from the bike" and immediately spread my legs and arms out in an attempt not to roll while on the asphalt. Bikes slide much faster than leather so it just took off away from me. Then as I was sliding I remember thinking "Damn, I'm sliding pretty fast and don't seem to be slowing." At that point was was on my back and has both palms down on the track and looking at the fast approching gravel. As I hit the striping I remember thinking about how gravel was going to be terrible to slide on and went for more of an "all fours" body position using my elbows and knees. At that point I rolled a bit and came happily to a stop.

 

Upon stepping through the POV footage on my home computer frame by frame I was able to see that my bike spun about 180 degrees to an orientation where the rear wheel and tail were leading the way. That tells me that the rear indeed slid out and the front was still achieving traction so the back end passed the front on the outside.

 

All in all I like to say it was the best crash I could have taken because the worst part was the emotions of injuring my partner, the bike, and there were no physical effects. I destroyed my right boot and discovered why you never buy Cyclegear brand gear (I was looking at my sock on the outside of my left foot when I stood up. Thank the man upstairs it was my sock and not my foot.

 

Also an interesting not about Cyclegear... they make "track boots" and sell them as such and love to brag about their 100% satisfaction guarantee and that you can return anything in any condition and they'll be glad to give you new gear... except if you're on a track. If you are on a track basically everything is void. Nice little loop hole they've got there. Needless to say I did not get any other gear there since and have invested in some SIDI boots that I trust would do much better.

 

and yes, that track is awesome. After my trip to other tracks I call it 'the country club' because it's so wide an there's not one crack or blemish anywhere. I and everyone else that rides Miller Motorsports Park are some of the most spoiled track riders in this country... except maybe the COTA crew, now.

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TD, You say that you had a peg drag. Was it the peg or maybe someother hard part. If that is the case would you think that maybe it might not have been throttle control but the unloading of the rear tire (off the ground or darn close to it) due to some part of your bike grinding into the track first?

 

Because of lack luster internet where I am currently. I intend on watching your video many more times and listening closely, when I get home ( in a few days). I am curious if grinding or dragging noise can be heard before the motor rev's away.

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The comment about the bike being way undersprung had me wondering the same thing. You wouldn't be the first one to have the shock near the bumpstop while cornering hard, then hit another tiny bump and lose traction.

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TD, first I should have mentioned that it's good you weren't injured.

I got lucky and could actually review the video ( not many guest at the hotel, atm).

What have you noticed about the turn that you crashed in? Flat, banked, off camber, etc...

It is a banked turn. Where does the track return to flat?

Is it at some point in the turn or on the straight?

 

At 1:56 you check the throttle.

At 1:57 the grinding you mentioned.

At 1:58 you take the worm burner route into the gravel.

 

What happens to the suspension in a banked turn?

What happens to the suspension when you let off the throttle?

What do you think could happen if you were at a nice lean angle in a banked turn with the suspension travel bottomed out (dragging hard parts) and then applied the throttle while not realizing that the turn was going flat ?

 

I was knee-down so there was a small hip check to the track but it was only about 1' or less.

Could that be where the track starts flatting out?

 

btw I have not rode Miller Motorsport so I have not a clue of how the track really is. From the video I think you got sucked into that turn by the track designer.

 

Is it really a throttle control issue, or a combination of several factors that all came together at that moment to say " Hello." I tend to think it is the 'combination'.

 

What do you think?

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Duck(S),

 

This has been on my mind since the crash actually. I will elaborate more when I get home and have time to explain myself but the sum-total of the story is it may very well have been a hard part unweighting the tire. On my farings after the crash I noticed there are matching sections on either side where they plastics were dragging on the track during cornering, separate from the crash damage. Also my crank case cover shows signs of two distincly different slide directions. To quickly answer your ?'s about the track:

 

It is a banked corner.

At or near where I was the track returns to flat.

 

I'm glad to hear you all entertaining this idea as well because I've felt like it could have been a hard part and not my throttle for a long time. I was not sure if it was crazy to think I leaned the bike so far that the plastics and hard parts were dragging but the tire was still gripping. The quick rev increase could be because my rear tire has no resistance anymore since I lifted it off the track using my crank case cover as the fulcrum of the lever.

 

Pictures of my evidence to follow.

 

td

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The pictures are proving harder to get as the old farings are in storage and such. They're coming though... I may be able to find some action photos of my farings actually dragging (or at least it looks like it to me) mid corner.

 

What's really important out of all of this is how I find a way to not drag the bike anymore. I've invested in some Race-tech springs for my weight on the front end and am trying to figure out an economical way to upgrade the stiffness of the rear... Race tech rear springs would make me no better off than the stock rear spring for my body weight (225lbs dry with only socks on)

 

Any ideas?

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TD if you have not serviced your rear shock it may be due, or past. If Race Tech can not provide a better solution for the rear you may need to look at other sources aka Ohlins, Penske, etc...

Check the rear ride height even if the rear shock is in good order. Past that point it would be a good idea to "Ask the Cheif". You may get some good advise there.

It may be wise to check the front forks for straightness now.

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What's really important out of all of this is how I find a way to not drag the bike anymore. I've invested in some Race-tech springs for my weight on the front end and am trying to figure out an economical way to upgrade the stiffness of the rear... Race tech rear springs would make me no better off than the stock rear spring for my body weight (225lbs dry with only socks on)

 

Any ideas?

 

Sorry, I didn't get this. What do you mean race tech springs would make you no better off? You can specify any rate rear spring you like, and the higher the rate, the less sag (and therefore more ride height) you will get. You can reduce static sag by adding rear preload, but if your spring rate is too low you will still get too much travel and be dragging stuff under high cornering loads, especially in long corners where your compression damping setting isn't going to affect where the suspension ends up. If you are 225 nekid (plus socks) then for sure the shock is undersprung for your weight. Getting the spring rate right (especially in the rear) is easily the most fundamental and dramatic thing you can do to improve your suspension.

 

I don't know anything specifically about the 954, but I would be very surprised if the OEM spring was anywhere near correct for your weight.

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I checked the front forks for straightness and they're withing allowable run-out. I would go with an Ohlins or Penkse but I don't have the extra $ to fork out for my bike right now. As I sit and think about it I was thinking I could resolve the issue with my body position by getting off the bike more and *hopefully* be able to keep the bike more upright in the corner.

 

I'll Ask the Chief and see what he says about my front fork.

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YellowDuc,

 

What I mean by I wouldn't be better off with a Race Tech rear spring is that the stock spring rate is very close to the stiffest spring that they make so the benefit will be negligible at best.

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