Jumping a 4 stroke...



26 replies to this topic
  • yz400fer69

Posted February 11, 2002 - 03:50 PM

#1

Hello, This is my frist post on this site. I was referred by someone off of the DRN forums. I recently went to a 4 stroke national race out here in Phoenix AZ. I noticed that alot of the 4 strokes were stalling there bikes going over the "smaller" jumps when they hit the back brake to move the front end down? Is there a certain technique to doing this with a 4 stoke? I ride a 99 yz400f and have not had to use the back brake in mid air yet? I see the 2 stokes do it with no problem but is there a key to this? Thank You

  • thumpsalad

Posted February 11, 2002 - 04:04 PM

#2

Well, depending on how long you are in the air, you can pull in the clutch and then nail the brake a little, then release the clutch. It's a lot to remember, but it's the only way I figured to stop stalling in mid air. Landings SUCK when you are stalled! :)

  • h_bomb

Posted February 11, 2002 - 04:10 PM

#3

You dont need to do it on a 4 stroke its all about body positioning,and your rpm range when you hit the jump.If you chop the throttle off the face of the jump it will make it nose down but I dont do it because you could easily go over the bars.

  • sirthumpalot

Posted February 11, 2002 - 04:12 PM

#4

It should be the same as a 2-stroke, be sure to pull the clutch before you hit the back brake. The front brake works the same way, just be careful if you land with your hand still on the front brake.

  • h_bomb

Posted February 11, 2002 - 04:26 PM

#5

Its not the same as a 2 smoke. :)

  • Phillip_Hutchinson

Posted February 11, 2002 - 04:50 PM

#6

Talk to your physics teacher. The laws of physics do not change simply because it is a thumper. Stopping the rotation of the rear tire during flight will cause the front end of the bike to lower. The effect works equally as well on a dirtbike or a quad, regardless of engine type. If you dont believe me just go to a SX race. Sat. in Indy almost every racer was brake tapping the long rythm sections, including the thumpers.

  • Shawn_Mc

Posted February 11, 2002 - 05:04 PM

#7

Its really not the same as a two stroke in as much as you can accomplish much of the same effect with the trottle because of the massive compression on the 426 as opposed to the normal 2 stroke. When ya back off the trottle on the 2 stroke, the rpm drop is almost nil in the air, ya do that with a thumper, the rear will wheel will almost slow to idle speed (in that gear). Its not the same, but its different too.

  • fastkevin

Posted February 11, 2002 - 05:23 PM

#8

Phillip, please remove that 4 letter word from your post :)

  • Phillip_Hutchinson

Posted February 11, 2002 - 05:35 PM

#9

Sorry. I'll try not to say that Q word anymore.

  • ben_suhard

Posted February 12, 2002 - 06:19 AM

#10

Whether it's a 2 or 4 stroke, it's best to pull the clutch in before tapping the rear brake, although I believe 4's can stall easier.

If you can jump without having to use the rear brake, you're doing it the best way. I never use the rear brake(although I know I should sometimes), but it would be a worthwhile skill to learn to get you out of trouble(I haven't mastered it yet, if I loop out I usually just freeze and hang on as tight as possible). I prefer to lean forward and if I lean to far just give the throttle a twist or two to bring the rear down.

Hmmm...I'm going to practice this brake tap next time I ride so that I'll be ready for the next time I loop out!

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  • Boit

Posted February 12, 2002 - 03:02 PM

#11

Depending on how you set the idle on your thumper, you can also blip the throttle as you pull in the clutch and tap the brake. I set my idle quite low so I automatically blip my throttle constantly during my air time. I haven't mastered the brake tap yet. I also tend to freeze. Dang it!

  • Kirtwell

Posted February 13, 2002 - 10:37 PM

#12

I believe that if you are jumping you MUST know this technique. It's saved me alot of times.
It took me less than 15 minutes on a table top to learn it.
Now, I use it alot mostly when I seat jump.
I think a 4 stroke is harder due to the stall issue and I have stalled it in mid air. I idled up the motor a bit and adjusted my clutch out just a tad and practiced it religiously until I got over it.
I would discourage anyone from practicing using the front brake for dropping the front end. It does work...I've done it myself. But we are creatures of habit and bad habits are hard to break.

  • bbeakley

Posted February 13, 2002 - 11:26 AM

#13

The amount of drag on your clutch will make a big difference in how easily the bike will stall while you're doing this. If you have a little drag with the clutch pulled in and you stomp on the brake, you're far more likely to stall it (especially if idle isn't set very high). I know I'd have to rev my bike if I tried a brake tap. I'm still trying to get the drag eliminated after switching to the '01 clutch parts. I'm hoping when I move home in a few weeks and get some hours on the bike that it'll get a little better.

  • dav

Posted February 13, 2002 - 02:58 PM

#14

guys dont take this the wrong way but on my 450 which does not have the engine braking like the 400/426 it jumps just like a 250 tap the brake with the clutch pulled no stalling problems. i do wish the motor had more engine brakeing when going into a turn. i guess it just a trade off.

  • sirthumpalot

Posted February 14, 2002 - 01:28 AM

#15

I've got an '01 and I don't have any stalling problems either. It must be caused by something specific (not pulling the clutch all the way, having a dragging clutch, etc..). My idle is what I would consider no higher than normal for MX.

If your idle is too low then you're going to be much more suceptable (sp?) to stalling in lots of situations.

  • 98yz

Posted February 18, 2002 - 09:23 AM

#16

Using the rear brake in the air on the thumper is just as easy and the same as on the 2-stroker. I moved from a 00 YZ 250 to a 01 426 and race B class. I actually have to use the rear brake in the air less, but it works the same. If you do stall it either up shift and bump start it after you land (it does work), or remeber to keep the clutch pulled in.

  • Chris_Slade

Posted February 18, 2002 - 12:10 PM

#17

As far as brake tap goes...it's Exactly the same for both breeds of bike.
However, on a 4 stroke, you need to stay on the gas longer. I rode my dads 94 YZ250 when my hub blew last ride....and holy crap...I almost bought it many times because I would stay on the gas like my 520, until the front wheel left the jump, and I was WAYYYY nose high, and jumped out WAY too far. Almost wrecked every time. It scares me to ride a 2 stroke now!!! I'll take my 4 stroker for jumping smoothness anyday ! :)

  • therapture

Posted February 18, 2002 - 01:16 PM

#18

Due to the heavier weight (especially us porker YZ riders hehe), 4-strokes tend to be more stable in the air, even on potted jump faces, they tend to kick sideways less, conversely, a lighter bike is easier to straighten out as well if you DO get crooked. However, I like the added stability my stroker gives me, and I can jump it BETTER then my old 2-smokes due to the smoother, wider powerband. But the brake tap is the same! As long as you pull the clutch in and have your idle set properly, it is no different...

Gawd, I love these 4-stroke MX'ers...I never had it so good until now, what a wonderful machine to make a comeback into the world of MX on! :)
Now when the YZ hits 450cc and drops 15lbs, I will totally be in mx nirvana! Just hope they keep the same traits it has now...

  • yz400fer69

Posted February 18, 2002 - 05:49 PM

#19

Thanks everyone for all the replies. I am a beggining rider and haven't had to use the brake tap yet, but what do you do if it stalls in mid-air. If it drops the nose down that much by just tapping it then you will be in for a "rough" landing if the rear wheel just stops? Guess I will just have to see what happens when the time comes. And thanks again for everyones suggestions.

  • Dirtrider110

Posted February 18, 2002 - 08:06 PM

#20

I own a 99 yz-400f and i've never had a problem with it stalling in the air. I hit the jump let off the gas and the engine brake does the rest, no need to hit the rear brake if anything most of the time you need to bring the front up, not down.





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