rumors about down shifting???

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wizzardhw1

Member

Jul 8, 2006

7

0

• Aug 9, 2006

• #1

I reciently bought my first dirt bike kx125 used. I am a street rider and used to down shifting. Thats how I rode my kx125 and after 3-4 hours the crank siezed from. now it cost me big $$$$ to get it going again, just finniched it tonight. I was told that it siezed due to me down shifting, the reason being he said was because when you down shift your not on the throttle and since the lubrication comed from the fuel down shifting motor gets no fuel??? I does make sens to me but Im a car technician not bike.lol Whats the answer to down shift or not??????? Im running out of money fast cant afford another rebuild. lol
Thanks for any help.
:bang: :cool:

 

Okiewan

Admin

Dec 31, 1969

29,550

2,239

Texas

• Aug 9, 2006

• #2

If you are talking about down-shifting to slow down, that's not typical in MX.

 

High Lord Gomer

Poked with Sticks

Sep 26, 1999

11,788

35

• Aug 10, 2006

• #3

Gas and oil get drawn through the jets of the carb by the air moving through the card. From there it goes to the bottom end (carnk) area of the motor where it is then forced up, around, and on top of the piston into the combustion chamber. If your motor is turning high RPMs with the throttle closed, very little air is flowing which means very little gas and fuel are getting to the crank and then combustion chamber.

Two strokes don't provide anywhere near the engine braking of four strokes and it is very dangerous to them (as you've found out). Besides, engine braking is less predictable and less effective than using the real brakes. With an MX bike, accelerate until you have to slow down, then pull the clutch and use both brakes until they are on the verge of locking, turn, repeat.

BTW, welcome and what kind of street bike?

 

H

HajiWasAPunk

Member

Aug 5, 2005

807

0

• Aug 10, 2006

• #4

High Lord Gomer said:

With an MX bike, accelerate until you have to slow down, then pull the clutch and use both brakes until they are on the verge of locking, turn, repeat.

Click to expand...

we had been taught to not even pull in the clutch but to downshift while you're braking? I asked an instructor why they were constantly on anyone for pulling the clutch in coming into a turn and their response was always that it produced an incosistent flow of power to the ground making it harder to stay in position and stay smooth. They only suggested the clutch be used on the exit of the turn if you were a little out of the power (and then it was just a quick tap, not holding it in or even feathering it). Have I missed something though? We've never had a problem with my son's CR85 or my CR125 locking up as a result of downshifting coming into a turn (without the clutch pulled in).?

 

F

FruDaddy

Member

Aug 21, 2005

2,854

0

• Aug 10, 2006

• #5

I tend to rev a little whenever I pull in the clutch, this helps to lubricate things while I slow down.

 

RM_guy

Moderator

Damn Yankees

LIFETIME SPONSOR

Nov 21, 2000

7,058

214

North East USA

• Aug 10, 2006

• #6

HajiWasAPunk said:

we had been taught to not even pull in the clutch but to downshift while you're braking? I asked an instructor why they were constantly on anyone for pulling the clutch in coming into a turn and their response was always that it produced an incosistent flow of power to the ground making it harder to stay in position and stay smooth. They only suggested the clutch be used on the exit of the turn if you were a little out of the power (and then it was just a quick tap, not holding it in or even feathering it). Have I missed something though? We've never had a problem with my son's CR85 or my CR125 locking up as a result of downshifting coming into a turn (without the clutch pulled in).?

Click to expand...

If you leave the clutch engaged when braking hard you risk stalling the engine. The inconsistent flow of power statement has some merit but not if the motor dies in the meantime. The goal is to either be on the gas or on the brakes so I tend to have a finger on the clutch when braking into a turn and pull it in just before the apex of the turn when I am braking the hardest. The I wick up the gas and then slip the clutch it as I come out.

 

High Lord Gomer

Poked with Sticks

Sep 26, 1999

11,788

35

• Aug 10, 2006

• #7

You won't notice it on an 85 or 125 because those 2 strokes will restart easily once you let off the brakes. Older 4 strokes without auto-compression release cams won't restart as easily.

If you haven't stalled the motor when braking with the clutch out, that implies you are not braking as hard as you could. If you are really close to the edge of braking efficiency, you will occasionally lock the wheel. There's no way to find the edge without going over it. I prefer to try to dance around the edge of traction with the clutch pulled in.

Downshifting while on the brakes without the clutch pulled is *guaranteed* to produce a more inconsistent braking action. Try it on the street and you'll hear a chirp with each downshift when the wheel skids.

 

Masterphil

DRN's Resident Lunatic

Member

Aug 3, 2004

1,003

0

• Aug 10, 2006

• #8

I also pull in the clutch when braking, especially when I rode a 125. Why? A 125, produces very little power at low rpm. I turn the throttle on, then begin releasing the clutch. This keeps the bike on the pip and prevents accidental stalling. If you turn on the throttle with the clutch already out, you waste time if the clutch needs to be fanned. BUT, when I ride in the mud, I let the clutch out before I turn on the throttle, as it dosen't really take much to break the rear tire loose, even on a 125.

 

C

COMBEN

Member

Nov 7, 1999

166

0

• Aug 28, 2006

• #9

how about this,

When I used to do kart racing, the 100cc single speed clutchless ones, I used to hit the brakes into a corner and keep some gas on at the same time, seems a little wierd but it sure helps stop the engine stalling and helps to stop locking wheels into a corner, and when you release the brakes you are up on the power in an instant, it's called left foot braking in a car.

...haven't tried this on my bike but hey, I will try anything once :)

 

E

elliot-cr133

Uhhh...

Jul 4, 2006

96

0

• Aug 28, 2006

• #10

Masterphil said:

I also pull in the clutch when braking, especially when I rode a 125. Why? A 125, produces very little power at low rpm. I turn the throttle on, then begin releasing the clutch. This keeps the bike on the pip and prevents accidental stalling. If you turn on the throttle with the clutch already out, you waste time if the clutch needs to be fanned. BUT, when I ride in the mud, I let the clutch out before I turn on the throttle, as it dosen't really take much to break the rear tire loose, even on a 125.

Click to expand...

wow. thanks. that's a great explanation. i just began riding and started having problems with starting off, kept on stalling. but im getting the hang of it now, and reading this i think it might improve me alot more! again, thanks alot! great post!