KX Riders
General => Riding Tips & Tricks => Topic started by: Hillclimb#42 on March 17, 2010, 04:49:05 AM
-
I have often been tempted with this concept, and try not to blurt out my ideals (opinion) on anyone else's thread, but am interested in your opinions, especially the ones based on facts about this. In hillclimbing, and I assume drag racing, along with many other forms of racing, the rear tire is spinning the whole race. No spin, or not enough wheel spin, will hook-up and wheelie which results in the on/off throttle, or crash, and you ultimately lose against anyone who didn't crash. UNDERPOWERED or OVERGEARED
Flip side of this is too much wheel spin and your bike never accelerates, and the back end won't stay behind you.
UNDERGEARED and NO TRACTION
Many factors are involved such as soil density, moisture content, and soil composition. The tire tread pattern, condition and air pressure, Gearing Choice, Power Supply, Suspension and Riding Technique are all factors really.
Power is basically Potential Speed in my opinion. Getting it to the ground is another art, also IMO, as with this whole thread, I guess. Far from an expert here. Presently, I have a basic set-up and will alter tire pressure 3-5 lb.s either direction, or switch 2 teeth either way on the rear sprocket, shorten or lengthen rear axle adjustment.
A little less air pressure and it will hook-up a little better, more pressure, it will spin a touch easier.
Longer suspension will help keep the front wheel down and help give a little wheel spin, shorter then would help give some traction to the ground ( I never try to shorten up a stock length bike)
2 teeth less on the rear and the bike is noticeably hooking up better, 2 more teeth and you will come out of any load sensitive bog and/or wheelie. (1 tooth bigger on the front is close to changing to three less on the back sprocket and vice versa, and is even more noticeable change than two teeth on the rear)
Suspension adjustments are aimed at keeping the rear tire putting power to the ground. Bumpy terrain needs a faster suspension and a big jump might need to be stiffer and slow to rebound. Suspension is an adjustment that I really need advice on. I usually leave it alone because of my ignorance of input and response with the adjustments to conditions, especially how it relates to the short hills that I race. The write-up by Paul, the former Administrator, about Race Sag and Static Sag really helped get the spring right and that made me alot faster. Thanks for that Paul.
-
Kyle,
On my 4t I gear so that I'm almost or in some cases may hit the rev limiter, of course you have to know your power curve with the mods you have, some bikes fall flat on their face once you hit a certain rpm, in other words understand where peak hp/torque are generated and gear for it. On the 2t again the mods you have may dictate where you want to run, as an example my 500 on gas will pull 15 counter and anywhere from a 47 to 51 depending on the hill, and if I ever get the 250 ignition tamed a bit maybe taller. on a stock length bike try to run as far back in the slots as you can, and if your still having issues with the front end coming up, pull the fork tubes up in the triple clamps 10-15mm, that will help keep the front end down. I also like to run a wide rim, you can go all the way to 3.5" that will flatten out the footprint giving you more traction, doesn't corner well but hauls in a straight line.
Hillclimbing is about momentum,once you lose it your ride is essentially over.
good luck
-
Kyle
You what about 15% wheelspin and 25% overgeared.
-
Very good suggestions, Don. I have seen the forks raised in the clamps a few times. Does that help a stretched bike also? I have seen the fat rims, (think I saw a 4" on a CR500)and the 18's with monster tread like the Terraflex on it. That's kinda THE hillclimb upgrade. I may get a fat rim eventually, just not ready, yet. When you say "depending on your mods" you still refer to me knowing where the bike pulls the best, right? Generally, tall enough to keep a load on the motor the entire climb, right?
Do you have a source for figuring spring rates with the bike extended? Will race sag and static sag settings be measured to stock axle location? I have heard of revalves, spacers, heavier oil. Is there any reason the stock shock wouldn't work with a stiffer spring for 6-8" stretchers?
Kaw Rider, not sure what that means, other than you are almost twice as concerned about being geared tall enough over having some wheel spin.
Thanks for your input guys. Working on some set-up plans, and need to be ready for adjustments.
-
Many climbs dictate what the Max length you can run, so if you have issues keeping the front end down you need to figure out how to accomplish this, the easiest is pulling the forks up in the triples. I run 3.5" rims, not sure I could fit a 4" in the swingarm, a 2.5 will help more than you can imagine if traction is an issue. I've been doing this long enough that I have a pretty good idea on what spring I need to run and have a fairly good selection to choose from. Revalves can be a great thing, the key is to find a suspension tuner that understand hillclimbing, typically you will run a stiffer spring and a little more compression and alot of rebound. You could go stiffer oil but I wouldn't go to stiff like 7.5 wt or maybe and thats a big maybe 10wt, there are some guys around here that are running 20 wt, but then you can see the results speak for themselves. I still set my race and static sag at the same position as if the bike were stock and look for the same numbers roughly 100mm race and 25-30mm static.
-
im not particularly up on suspension stuff but remember if you have a lengthened swinger,it acts as a longer lever so shock spring imo would need beefing up a bit.
-
You can put 4.25x18 sun rim on a K5 with no mods at all just shorter spokes , you can run the 5x18 excel on the K5 with an extended swingarm with a few mods, its what I run on the drag K5. You need to cut off an old spocket to use as a spacer to bring your spocket out for clearance from the side of the tire this will require yamaha sprocket bolts. then you need to mod the wheel spacers to move the rim to offset the rim to the brake side a quarter of an inch. the 5 inch rims put a whole lot of tire on the ground. the terra-flex is a little heavier tire if your interested in trying one I have 2 that are like new , they didn't work for drag racing my brother found out .CBX
-
Kyle
Also remember swingarm arm angle will affect the torque the motor has on tire. Just think about the angle you have going up the hill on the swingarm.
-
You can put 4.25x18 sun rim on a K5 with no mods at all just shorter spokes , you can run the 5x18 excel on the K5 with an extended swingarm with a few mods, its what I run on the drag K5. You need to cut off an old spocket to use as a spacer to bring your spocket out for clearance from the side of the tire this will require yamaha sprocket bolts. then you need to mod the wheel spacers to move the rim to offset the rim to the brake side a quarter of an inch. the 5 inch rims put a whole lot of tire on the ground. the terra-flex is a little heavier tire if your interested in trying one I have 2 that are like new , they didn't work for drag racing my brother found out .CBX
Yeah, maybe if your swing arm is wider than stock, All my swing arms are the same width as the stock swingarm, meaning there is no way you could add a sprocket width and clear, but I will keep that in mind if I ever want to go with a wider wheel. I use 530 chain on my bigger bikes, those that would use the widest wheel.
There is a balance between the traction and length, you can go more aggressive on the tire, and will have to go longer to keep a balance on the front end, shorter and a less aggressive tire will accomplish the same thing as a aggressive tire and length, the key is to know where that balance is. it does change from hill to hill and from morning to afternoon, you just gotta keep up with the hill.
-
Kaw Rider, thinking about the angle of my swingarm to the ground? You think its better to be parralel to the ground or to always stay above parralel. I would think swingarm getting flat would take away from force applied to the ground, but think the sag settings set all of that up. Am I missing something there?
I saw plenty of Terra flex tires on Hillclimbers. They are usually on big bikes. I don't think they work as well on 500's as a typical nobb. Its a very aggressive tread pattern and very heavy. It was too much traction for my buddies 750 triple, so I definately don't need that on my 500. Thanks for the offer, Cbx.
I found out that the longest I can be, Don. The axle has to be inside of the tip of rear fender. I'm able to get out even with the rear '93 Fender mod with this new set-up for the 600cc Class. Looks like I'll be racin the fastest guys and the conditions of the hill. With Stewart Power and the new Stretchers getting set-up, I am graduating to the Insane Racing. Most Fast Times of the Day come from the 600cc Class. Alot of guys thought I was nuts Hillclimbing a stock length 500, wait till they see me on this Green Rocket.
If you noticed my brake line stretched out, I am going to get a green Brake line and install the chain today. I hope that the racing season goes as smooth as the build went for this bike. No stressin' when you do your homework. Thanks for all of the help guys, direct and indirect advice as well.
-
bike looks real nice
-
bike looks real nice
Yes,very cool. :-D
-
looking good.how did you find the platinum pipe with fmf silencer when engine was stock?thats the combo im using next.did it make good top end power? decent overrev? thanks, k.
-
Thanks guys.
kwakman, I started with a stock pipe and silencer, but eventually flipped the bike and destroyed the silencer, fender and sub-frame. Picked up the Platinum pipe after reading here on kx riders how well it performed. The FMF silencer was just a simple decision. I didn't like the pc silencer's looks or sound. I felt a noticable increase in power with the new exhaust, and it sounded healthy like I wanted. As far as overrev, I don't think I can give a good report. My 500 seemed to rev about 3/4 as much as my 250, so I had to gear it to be fast. This being my first 500, and every upgrade adding a little power, I really have no base reference. I had a crank issue that probably kept the motor from revving high, which has since been resolved, during the rebuild.
Pro Circuit, V force Reeds, Wiseco, ...ect., everything Stewart has stated as being strong reliable performance upgrades has been just that.
-
Bike looks excellent. I agree with you on the pc vs fmf. I have a pc spark arrestor on one 500 and fmf turbine core on the other 500. I can't confirm performance exactly because of the different engines. Ones an 87 and the other is a 93. I am going to try swapping silencers and see which works better on what bike. I like the sound of fmf though. I'm looking forward to some hill climb videos Hint Hint :D Don't have much for climbing around here unless I go way north. Keep up the good work. Good luck in racing.
-
I have not had the opportunity to run anything on a dyno, but I have good friends that swear by them. During a recent "Dyno" conversation, one such buddy said that his bike made more power in 1st gear. Somehow, the dyno showed better numbers in 1st over 2nd, so he always gears the bike to suit pulling 1st gear. Most people hillclimb in 2nd gear, rarely having a shift and even more rare for someone to pull third out of the hole. This concept of one gear showing better numbers than another gear, confuses the crap out of me. I always thought, "a motor has this much power and the transmission is the equasion of a final drive ratio of the primary gear and sprockets."
Is it possible for a bike to have better dyno numbers in one gear over another, or is this a misconception or even a bad theory of reading the dyno power/torque numbers? I read on another thread about which gear the bike will be dyno'd in, and it got me wondering how that impacts the readings, and if it gives accurate ones with this variable....? Thanks again for the education.
-
The actual traction thing vs. what your bike can actually pull is huge. A few years ago we had a sand drags race here and the quad four stroke classes had everything from 8 paddle tires to like 16 paddle tires. The guy on the 8 paddle tire won that class overall. He got spanked by the unlimited Banshee winner in king of the hill though, but nonetheless, he was set up for that dune... Most "stock" quads pull best on an 8 paddle.
Later, I talked to the guy at skat-trak and even with almost 80 hp on the rear tire he still recommends a 10 cup paddle for the mighty KX5 in the sand, not 12 or 14 like some people think... Just food for thought.
-
i have 8 and 14 paddle paddles tires i think the 8 paddle turbo paddles hook up great my 14 scat track paddles seems okay for real low speed loose climbing
-
ive tried just about every paddle out there 8, 10, 12, 14, hookers, vipers, turbos and dominator.hillclimbing in loose conditions we use 14 paddle, viper on the 450, hooker on the 490, dominators on the 650 and 1000. in really hardpacked conditions we'll run a knobby, IRC M5B seens to work the best the terra flex has to stiff a sidewall.
-
You guys will get me dq'd, :lol: :lol: No paddles in Amatuer/Semi Pro Hillclimbing. Everything has to be originally a nobby tire. On the KDX I have a cut tire. Its a Budds Creek where I took all of the square nobbs off and left the rectangle bars. Basically removing every other row and leaving a tire with short paddles (sort of). This technique allows a little more spin right off the log. That allows you to pull a little taller gearing and still has some good hook up on the rough stuff at higher speeds. I won't have the same isuue getting the tire spinning with the 500, I'm sure. I was just fishing for some new ideas for adjustments. I guess the theories don't vary as much as I expected.
Here's the closest that I can get to paddle tires....
-
Well, should have been asking how to hook it up in the slimy mudd. The race was a rainout, basically, but being the first race of the season, noone even mentioned not racing. Everyone spent their money and was ready to do it. It was beautiful weather on Friday, when we went down to get the festivities started early. The benefits of having a stock bike, is blazing some trails, when you show up before everyone else. :-D
Friday night into saturday it poured. A small river was running down the hill an hour before the event. Anticipation was definately turning into Procastination for everyone. With the help of a couple guys and a box blade on a tractor they managed to clean off some of the slop in the hole and on the first breaker. The second breaker was unreachable with the tractor. the mud there was at least a foot deep to walk in. I have video of all of it, but am having trouble with the editing software. One step forward and two steps back with this computer software stuff for me. It was a brutal night of wrecks and wash-outs. I managed to win the 200 cc Class and the 400 cc stock length class, then like 9th of 17 in the 600cc Class, on the 500. The 600 class is the crazy fast class, here. I started with a 14- 49 that launched out of the hole, but I could not get it to hook up on the last part of the hill. It landed in the mud and sounded good, but could not hook up. The new stretchers were working against me a little on their maiden voyage. I could spin the wheel with little effort, which is important in the hole, but it wanted traction for the slimy deep mud. Its runnin' awesome, but a stock length or shorter extensions would have been a big help.
Again on Saturday night it rained like cats and dogs, and we awoke to a lake with grass in it, that we were calling the spectator area. I got up early and changed gearing in hopes of finding some traction. I went down to a 13-49, shortened the adjuster bolts and let out some pressure to about 8lbs. It went faster, but was unable to hook it up enough still. It was even muddier than on Saturday, but not sure if that was the right gearing choice either. Lots of guys and girls wiped out on Sunday, but I managed to keep them rubber side down. 2nd on the 200, but not 100% sure on the stock class and the 600 class, because Payout was closed by the time, I got there. I know I had second in the 200 class because of the enveleope that was waiting on the window. Stock classes are last, and on Sunday everyone is ready to get going home. :| I was close to the top 5, but not close enough as they say. I have the footage, as soon as I can get my software fixed, I'll post a link.
Preparing for this weekend, I'm even shorter, about an inch, with a better tire, and doing the anti-rain dance :lol:. But in Indiana/ Illinois, I might as well learn to race in it.
-
Got it edited with the new software. Still working out some bugs, it appears. Finally got my pc to update and download the software. Only took 4 days. :lol: The playback on youtube is very small for some reason. I'm sure its user error. I will try to fix it.
Here's the abbreviated race. I have about an hour worth of footage, but max on youtube is 10 min.s.
Here's the link to my half a** vid. Anyone know what I did wrong right off the top of your head? My sanity is being tweeked to a point that I'm not sure I will come back from.
http://www.youtube.com/watch?v=V_89b8DokkI
-
Everything has to be originally a nobby tire.
skat trak vulcanized paddles start out as nobbys
-
Why not just run a Terra-Flex ? CBX
-
Fixed it.
http://www.youtube.com/watch?v=4IUs1ar0k2c
Terra Fles is a big heavy stiff sidewall tire. It takes alot of ponies on our hills to turn that tire, and be fast. Although for those conditions it would have probably been ideal. The 500 is gonna work in normal conditions alot better. White City this weekend. King of the Hill Race. Close as we get to the guys in Joplin. You guys have any sick days built up?
-
White City was another super muddy mess. The 500 was fast enough to get me into the King of the Hill. That is a one round shoot out between the top ten riders of the day. I was 7th fastest of the day. I had a very good ride that the time was missed on, which happens occassionally. Sometimes you get a better ride, but usually its a touch slower like mine was. I wound up 5th fastest in the King of the Hill round. I was a little discouraged to be honest. I was holding the 500 tapped for the entire ride, and even though they missed my best time, I didn't feel like it was good enough to win the class or the event. It felt overgeared, but I was already running 13-49. I knew I could not be low on power unless I had a prioblem of some sort. I just knew I needed about 5% more power. I made me a little check list of things to look at and go over, and wow, did I ever find the problem.
My serious brainfart. When I was in there checking out the goods of my newly rebuilt motor, after my break in ride, I somehow got the powervalve arm outside of the double washer deal. Yep, that's right. Three races with no powervalve hooked up. I almost passed out when it dawned on me, how fast this bike is. I don't know how much power that i left on the table, but I am thinking alot more than I needed to win the event. :-o This bike is going to be sick fast. I really wanted to post better finishes, but am prepared to dial it in, and realistically figured 4-5 races before I get it set-up just right. I think the powervalve is going to help. :lol: