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CaptainKnobby

Question on changing gears on a 4-stroke?

14 posts in this topic

Ever now and then during a race I catch my self down shifting either in the air or sometimes on the ground without pulling in the clutch on my 06 450f. I did this kind of downshifting when I had yz 125-250 two-stroke but was woundering on a 4-stroke is this bad while racing during the heat of passion when your arms are tired and you can barely hold on> your should you try no matter what and pull the clutch in to change to a lower gear instead of just mashing the gear shifter down? Will this hurt anything?:applause:

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no clutch needed! Just chop the throttle a bit before upshifting.

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also search clutchless shifting....

i have done a lot of research and i have learned a lot about Constant Mesh transmissions. go onto the site that i provide.

when downshifting without the clutch, you need to let off the throttle but no completely, you need to apply just a little bit of throttle to match the engine speed and the speed at which the bike is moving...so when you downshift, it will make a smoother transition as well as prevent the gears from grinding due to the load or torque put on the gears. You will know if you did it wrong if you feel a sudden shift in momentum and a sudden feel of going over the bars.

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for upshifts i dnt use the clutch and all i do is let off, shift, and then get back on the gas. No need to match the rpm's to the speed the bike is moving (neutral speed; applying gas but not gaining any speed is a sign that the speed of the engine is close to the speed of the bike). doesnt really need to be exact....the important thing is there is no load.

Im not saying switch to clutchless shifting, it depends on the riders style, i dnt use it on upshifts but i usually use it for downshifts, buts thats me. Everyone else is different, with the clutch, you can eliminate the fear of adding any load to the transmission. But im just saying it won't harm anything, so its ok to do, but just ride the bike the way you want to

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Would down shifting in the air have any effect on the gyroscopic force on the rear tire.. I mean causing it to spin slow and possibly induce an endo effect?

Just wondering?

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That's not gyroscopic, but yes, dropping a gear is like tapping the brake, but not as effective, because the change in speed is less (slower, vs. stopped), and will drop the nose just a little.

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i never used that technique to bring the front end down, especially on the 4 strokes, but i remeber on the 85's the nose would be high up and i would have to kiss the fender basically....and it wasnt the body position, its the weight of the front end and the speed that i was going to clear gaps.

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Good info Racer24!!!! I rarely upshift without the clutch but I downshift often without useing the clutch. After reading your info Iam downshifting without the clutch quiet well I just didnt know if this was harmfull or not but now I understand it more and feel more comfortable about it.

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Good job....just take it easy...i think its a little bit harder when it comes to downshifting...really when you apply some gas to match the speeds its usually around 1/4 throttle. In the Crf250r forum i said the same thing i told you...

Also my gearing ratio made 2nd and 3rd more useful by making it "longer," so now it feels like i dnt have to upshift right way and i dnt hit the rev limit very fast. Now i can pretty much carry through most turns in 2nd or 3rd with little or no clutch and i barely have to downshift. Coming off from a 2 stroke, 4 strokes have a lot more torque to carry through in each gear. I moved down in the rear to a 47 for my kx250f....i also used a 49, and that made more acceleration but 2nd and 3rd, mostly 2nd couldnt be used in turns

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Yea I usually take it easy when downshifting>I do it normally when Iam in the air off of a jump that leads into a tight corner where a lower speed is needed.

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The Yamaha 450 has one of the nicest gearboxes ever in my opinion. I do supermoto and rarely use any clutch for up or downshifting. My bike is a '05 model and only had to replace the box once in two and a half seasons of hard racing. Even under full load one can just hit next gear without clutch. I know this sounds very harch but most of the time i use it like this with no problems.

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if your downshifting its because you need to slow down. If you need to slow down you should be breaking. If your breaking the clutch should be pulled in anyways.

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