What's y'alls thoughts on revmatching? I personally don't do it, but is it necessary for downshifting even when coming up to a light? I usually just clutch and drop a gear release clutch, clutch drop a gear release clutch till I'm at a light letting the motor do the majority of the braking. Someone told me that's hard on both the trans and the motor but I thought these bikes have a slipper clutch that helps with the wear on both. Granted I have downshifted into 1st on the freeway doing about 60ish to do a high speed run and I got a chirp from the rear tire (probably not the smartest thing for the bike). Whats yalls Thoughts? I mainly use the bike for commuting and have my youth days behind me so I'm curious have I been doing it wrong the whole time causing major wear?
Thoughts on revmatching
- Thread starter busanewb
- Start date
I'm trying to get past your downshifting into 1st @ 60 mph...have someone check your pulse. I don't think you survived.
I'm trying to get past your downshifting into 1st @ 60 mph...have someone check your pulse. I don't think you survived.
It's not something I did often, maybe 3 or so times. Where I live roll racing on a "closed track" is big and everyone starts in 1st gear
Mythos
Registered
"I usually just clutch and drop a gear release clutch, clutch drop a gear release clutch till I'm at a light letting the motor do the majority of the braking. Someone told me that's hard on both the trans and the motor but I thought these bikes have a slipper clutch that helps with the wear on both. "
Yeah, engine breaking is wear on the transmission and engine but it's part of using a manual transmission. You can hold the clutch and pop thr gears down as you slow but what fun is that? That's ok for commuting but it's for slow riding.
The slipper clutch is for preventing wheel lock/rear wheel hop at high rpm. It doesn't do anything when the clutch is disengaged. The slipper partially disengages the clutch automatically when the lever is released and there is a sufficient amount of back torque. It lets the clutch slip so the rear wheel won't lock. If you don't need to downshift fast or at high rpm, what you are doing is just fine.
"Granted I have downshifted into 1st on the freeway doing about 60ish to do a high speed run and I got a chirp from the rear tire (probably not the smartest thing for the bike).
OK, sounds like you probably will benefit from matching gearbox/engine speeds on occasion. The busa will have no problem doing 60 in first gear but that is definitely sport riding/racing territory.
Sounds like your slipper clutch didn't slip or else it took an instant to activate. I almost never feel mine come on. Only time is a hard downshift like that into first or maybe second. Normally, I would manually modulate the clutch on a hard downshift like that. You can use the clutch lever to soften clutch engagement just like the slipper is supposed to do. Try that. Release the clutch gradually feeling the back torque come on.
Does the downshift feel a little notchy or rough? It is bound to feel a lot smoother and lightening fast when you match the speed of the wheel/engine/transmission. The basic idea is, "how many rpm would the engine be turning at this mph for the gear I'm dropping down to?" For 1st gear 60 mph, I think that would be about 8,000 rpm? That's just a guess. I blip the throttle by feel. I don't pay much attention to the tach anymore. A rule of thumb is approximately 300-500 rpm increase in rpm for each gear you downshift. Make the shift while the rpm is at the proper speed for the gear and wheel speed. If you are down shifting at loweer rpm, you don't need to blip the throttle much, maybe just a couple hundred rpm or even less for very slow. High rpm, you probably need a couple hundred more. LOL that 1 st gear downshift is probably about as high of an rpm as I would downshift on a busa! Generally, I blip and downshift one gear at a time releasing the clutch between each downshift. Sometimes I downshift two gears, pulling the clutch lever a single time. Pull, blip, downshift, blip a bit higher, downshift, release clutch lever. Rarely would I need to downshift three gears like that but if I wanted to do it fast, I'd follow the same routine. Most of the time my downshifts are so fast, I don't ever let off on the throttle. Just pull the clutch with throttle on and the rpm will zip up just as I click down to the next gear and I let the clutch out still on the gas. Works slick, sounds cool, I love it. Practise this at lower rpm and when you get the hang of it, work up in the rpms to bang those 8,000 rpm downshifts! LOL hopefully you don't bang them. I have done that revving too high and dropping into 1st gear. Have fun. These engines are tough just use common sense, learn and do your best to be smooth.
Yeah, engine breaking is wear on the transmission and engine but it's part of using a manual transmission. You can hold the clutch and pop thr gears down as you slow but what fun is that? That's ok for commuting but it's for slow riding.
The slipper clutch is for preventing wheel lock/rear wheel hop at high rpm. It doesn't do anything when the clutch is disengaged. The slipper partially disengages the clutch automatically when the lever is released and there is a sufficient amount of back torque. It lets the clutch slip so the rear wheel won't lock. If you don't need to downshift fast or at high rpm, what you are doing is just fine.
"Granted I have downshifted into 1st on the freeway doing about 60ish to do a high speed run and I got a chirp from the rear tire (probably not the smartest thing for the bike).
OK, sounds like you probably will benefit from matching gearbox/engine speeds on occasion. The busa will have no problem doing 60 in first gear but that is definitely sport riding/racing territory.
Sounds like your slipper clutch didn't slip or else it took an instant to activate. I almost never feel mine come on. Only time is a hard downshift like that into first or maybe second. Normally, I would manually modulate the clutch on a hard downshift like that. You can use the clutch lever to soften clutch engagement just like the slipper is supposed to do. Try that. Release the clutch gradually feeling the back torque come on.
Does the downshift feel a little notchy or rough? It is bound to feel a lot smoother and lightening fast when you match the speed of the wheel/engine/transmission. The basic idea is, "how many rpm would the engine be turning at this mph for the gear I'm dropping down to?" For 1st gear 60 mph, I think that would be about 8,000 rpm? That's just a guess. I blip the throttle by feel. I don't pay much attention to the tach anymore. A rule of thumb is approximately 300-500 rpm increase in rpm for each gear you downshift. Make the shift while the rpm is at the proper speed for the gear and wheel speed. If you are down shifting at loweer rpm, you don't need to blip the throttle much, maybe just a couple hundred rpm or even less for very slow. High rpm, you probably need a couple hundred more. LOL that 1 st gear downshift is probably about as high of an rpm as I would downshift on a busa! Generally, I blip and downshift one gear at a time releasing the clutch between each downshift. Sometimes I downshift two gears, pulling the clutch lever a single time. Pull, blip, downshift, blip a bit higher, downshift, release clutch lever. Rarely would I need to downshift three gears like that but if I wanted to do it fast, I'd follow the same routine. Most of the time my downshifts are so fast, I don't ever let off on the throttle. Just pull the clutch with throttle on and the rpm will zip up just as I click down to the next gear and I let the clutch out still on the gas. Works slick, sounds cool, I love it. Practise this at lower rpm and when you get the hang of it, work up in the rpms to bang those 8,000 rpm downshifts! LOL hopefully you don't bang them. I have done that revving too high and dropping into 1st gear. Have fun. These engines are tough just use common sense, learn and do your best to be smooth.
Last edited:
Mythos
Registered
Yup, you need to learn to match speeds. Take the bike up to 60 in 1st gear and look at what rpm the motor is turning. That's your target for the shift from 2nd to first. It takes a little practice but as long as your a couple hundred rpm of right where you want to blip to, it works fine. I'm sure it is a lot easier on the bike than jamming it in at those speeds.
Yea... Im definitely going to practice revmatching then. 1st gear at 60 isnt something i do often. In your honest opinion you think much damage has been done the way I've been shifting? The bike is low mileage still, but I was reading horror stories about without revmatching while downshifting the compression in the motor is so high that the motor can let go.
The engine has a rev limiter.
You're not hurting it from higher revs.
Clutchless shifting, when done right, is not abusing the engine or transmission.
I'm talking about rev matching with clutch. Is that what I should be doing?
ali123
Banned
its pretty damn hard to hurt a stock hayabusa motor... ride that bike and learn it... the clutch has to engage the gear somehow...there are ALOT of 300-400 hp bikes that don't even have a lockup clutch.. just HD springs to hold all that power... I think ull be ok if u don't "revmatch"
It's more riding style, and preference.
Depends if you're cruising or riding agressively.
There is no "100% it must be done this way" method.
It is less of a shock to the clutch basket and transmission the closer the rpms are.
But, as long as you're not grinding gears, or popping the clutch at high rpms and speeds in low gears, it doesn't really matter.
You should be able to shift smoothly up or down without having to rev the engine.
By rev matching using the clutch I assume you mean feathering the clutch as was discussed above. While this probably won't hurt anything, clutches are a consumable part of the bike. All clutches will eventually slip, work the clutch harder and it will wear out sooner. However a worn out clutch is a relatively minor problem to fix.
Mythos
Registered
NO...I really doubt it. You should have heard the BANG I made downshifting that time I mentioned in my previous post. ...ID recall if it was revving too high or not high enough but I remeber I di not realize I was downshifting to 1st. I thought it was second. LOL I don't normally downshift to first at the speed I was traveling, probably close to 60 mph. No chunks of steel came out in the next oil change so no harm done. Just practice it by the book at lower speeds and see how smooth it is at 30, 40, 50 mph. If you got it, then go for your 60 mph target.
Rev matching or not has nothing to do with compression in the motor; engine breaking has everything to do with compression whether you rev matched or not. It was probably the slipper clutch's reduction of full engine braking that you read about.
You can soften the decel two ways: fether the clutch or keep on the throttle. If you need to slow down with hard engine braking, let the clutch out slow. yeah, that's wear on the clutch plates as much as slipping the clutch in a drag launch but that's what clutch plates are for. They wear out eventually. Feel how hard the pull is. Feel it, listen to it...is the engine whinnying like a horse? are you flying onto the handlebars? rear tire lifting, locking? The slipper should take care of all that but if isn't for one reason or another, you need to be the slipper yourself by modulating the lever out slowly so the clutch grabs the transmission gradually. by gradually I mean 2 seconds or less--for less severe downshifts, you can let the clutch lever out in a half second or less. It all depends on how hard you feel the back torque. This is a common road race technique. Personally, I like to do this and I may disable my busa's slipper clutch. If you don't want to scrub speed but just want the stronger acceleration of a lower gear, roll into the throttle as you are releasing the clutch lever after the down shift. This is the same technique you use when taking off from a dead stop but you'll be doing it rolling. As mentioned before, I don't let off the throttle at all if I want more git up and go, I just squeeze the clutch lever, click down one gear and release the clutch lever. It's very fast and I don't slow down at all. NO back torque, you're still on the gas and the bike keeps pulling forward, not back.
You can combine both softening techniques when decellerating. Let the clutch out slow and open the throttle a bit at the same time (3:05 n the video below). There's no rule you must engine brake at 0 throttle. Partial engine braking works too. There;s lots of downshifts in this video. You can hear what's happening with the blip. All engine braking downshifts. I coulda used an on the throttle downshift for the little "race" at the end but I didn't know he intended to race. LOL I still had him! He was a big boy on a small bike.
I would. I've never dared a clutchless downshift but I hear people say they do it. It works better at certain rpm than others. I'm too scared to try it and I like rev matching so I use the clutch every time, pulled all the way to the grip or at least halfway I think. LOL I don't try to not use the clutch but doing the real fast downshifts, it probably clicks in before I get the clutch pulled all the way. As long as it is smooth, no problem.
Mythos
Registered
There probably is a limit to how high in the powerband you should downshift to. I rember my Kaw owners manual recomending no higher than 7000 rpm but you know those owners manuals. LOL do not exceed 3000 rpm for the first 2000 miles, shift to 6th gear at 35 mph!! yeah, right. I'd say you'd be pushing it downshifting into the 9000 rpm range. Never tried it. The busa does keep making more hp all the way to redline so starting closer to the top might give you an edge in a rollon race.
I beat the sh*t outta my gen2 for 17k miles, and I couldn't hurt it.
This is a dyno chart from long ago of my Gen 2 with a Yoshi full exhaust. Going by this, I would try to get into first at the 6.5K to 7K area. You will pull hardest when the torque is max, which happens at around 7.5K rpm. The green area is going to be max pulling power. Note the point of the highest torque & HP comes at just around 9K. The high HP mark comes at somewhere around 10.5K but note at this point the torque is dropping off fast. So you should drop into 1st gear to get the rpms in the 6.5K+ area. If you hit 1st and the bike is say at 8.5K, you're going to have to shift immediately back into second to keep the engine in the max torque area. Now I'm no drag racer, so this could all be B.S. Lol! But if I were in a roll on I would drop into 1st at 6.8K and shift to 2nd & 3rd in the 9K area. I would let the upper gears breath more, maybe out to 10K-10.5K or so. I have seen the bike lose 2-4k in the shifting process which is something to consider as that could drop you out of the max torque powerband. That's why quick shifters are so great. I set my redline to 11.5K in the ECU but as you can see the engine is losing bacon pretty fast above 10.5K, so no real reason to be up in those revs. Obviously these numbers apply to the dyno chart for this bike/configuration, yours maybe different.
Just my analytical 2 cents.
Just my analytical 2 cents.
Fallenarch is right about the tradeoff of being in a lower gear and having to shift very soon, vs. being in the next gear and saving the shift time. As for the best rpm range for acceleration, it is going to be the upper rpm's. Considering the error in the Busa tach, your best acceleration will come by shifting close to the 11,500 mark on the tach on a stock motor Gen2 with exhaust and flash. Now that I have an autoshift on both my bikes I set them at 10,800 rpms. I flash my ECU with an 11,200 rpm redline. The bike drops about 1400 rpms on each gear change so I'm operating at a real RPM range of 9400-10,800 for best acceleration. If I am index racing and need to slow down I short shift for repeatable results. It's much smarter than trying to let off like some guys do.
Similar threads
