Question about throttle on larger bikes

[Jiggles]

My 650's throttle is far more responsive than my 250 ever was but I'm also having an issue with it and I want to know if it's specific to the 650 or all larger fuel injected bikes. My 650 engine brakes like a mother ****er, when you release the throttle it's like you also stomped down on the rear brake. Compared to the newgen 250 it's an extremely significant and noticeable change. My pregen 250 also tended to engine brake rather hard but not as much as the 650. So first question.

1. Do larger CC bikes engine brake significantly more (not just a little more, alot more) compared to the 250? Or does it perhaps have to do with the cylinder size, i.e. 2x325cc vs 4x150-250cc?

Another issue I've noticed is that the 650s throttle is not that smooth. In lower rpm's it has three settings, decelerate, accelerate, and accelerate faster. Coasting is nearly non existent and the difference between accelerating and decelerating is so negligible that a small bump in the road can launch my balls into the gas tank. At higher rpms there is decelerate, coast and accelerate but there is still an issue. Any throttle less than coasting is full on engine braking, there is no slowing down while applying any throttle.

Because of these issues I feel like the 650 just isn't as suited for the twisties as my 250 was. I never intended for my 650 to replace my 250 in that aspect but it just kinda happened. So the question.

2. Do larger CC fuel injected bikes throttle's simply react that way in not feeling so smooth between off, coast, accelerate or does the 650 just have an anti-twisty throttle?

[massacremasses]

my engine break is also a lot more...

but its a single cylinder so idk if that helps....

[Jiggles]

Originally Posted by massacremasses

my engine break is also a lot more...

but its a single cylinder so idk if that helps....

It does not. I don't know how to say the opposite of thanks but if I had a word for it, it would be in place of this sentence

[Jono]

Maybe you just suck at controlling your throttle hand. It is probably all those energy drinks you slurp down.

[Jiggles]

That's a possibility which is why I am asking

[Mountain Dew]

I'm not sure what affects the amount of engine braking that occurs (piston size, stroke, compression ratio, etc), but I know that it's caused by the engine fighting itself because of the lack of air flow.

A quick check on Wikipedia states that different engines have different degrees of engine braking, but doesn't go any further than that.

[Mountain Dew]

According to my friend, the cam profile plays the biggest role in engine braking. Basically, the longer the valve duration, the more air that escapes. The less air that's in the combustion chamber, the less force the engine has to fight.

His words were: "An economy engine has a very high valve duration. Meaning it lets the air out early, etc. A high performance engine normally does not, so it keeps the air in longer and crushes it."

[csmith12]

My R6 is peaky, meaning... once it's really in it's power band in the higher rpm ranges, the more exaggerated reactions between roll on and off. It just kinda makes sense to me, the higher the rpm and heavier load, the more lurching around your gunna get. My old hardly had a stupid amount of engine brake at any rpm, but still, I was able to smooth it out with the throttle. My wife on the back of my bike will let me know if I am not mindful of this. Because her weight will become mine (on my back) or she braces on the tank with her hands and then complains her hands/arms when we are at a rest stop.

I find myself going between the 250 and R6 and treating the R6 throttle like the 250's. The R6 quickly reminds me that it's not the same, accelerating or decelerating. And the R6 doesn't know the meaning of coast.

Maybe Jono is onto something. Smoother on the throttle yo, because the problem will be even more pronounced while 2 up or carrying a heavy load.

Honestly though man, it don't sound like your really connected to the bike while on a ride through the twisties. Let's face it, an aggressive ride isn't "that comfortable" and if a bump or throttle roll off throws you into the tank, your not gripping hard enough. Maybe your a bit to relaxed. But if you want to be that relaxed then maybe you need to adjust the ergo's to accommodate the more relaxed riding.

Just thoughts... I am tired.

[Boom King]

I think it's related to more than just one factor but to put it in a simple answer, I think it has to do with stroke length. Longer stroke means more vacuum which means more energy required to pull a piston down on the intake stroke with a closed throttle. That's my basic understanding of the concept anyway .

As for your twitchy throttle, that could be the way the ECU is mapped out for the bike.

[Jiggles]

Originally Posted by csmith12

Honestly though man, it don't sound like your really connected to the bike while on a ride through the twisties. Let's face it, an aggressive ride isn't "that comfortable" and if a bump or throttle roll off throws you into the tank, your not gripping hard enough. Maybe your a bit to relaxed. But if you want to be that relaxed then maybe you need to adjust the ergo's to accommodate the more relaxed riding.

Just thoughts... I am tired.

I never intended my 650 to be a twisty bike, I bought it as a commuter and wanted to have the 250 for the twisties but things have changed. So I'm trying to see if I can make my 650 into a good twisty bike and when I get the 1000 that will be my commuter. But the throttle on the 650 just doesn't feel right for the twisties. And I'm talking about when you're in a turn and precise throttle is needed, I just can't hit that precision with the 650 because the throttle is so, idk, twitchy.

I haven't ridden a 600 or any other larger CC bike so I have nothing to compare it to. It could be that they are all like that and it's something I just need to get used to or it could be that the 650 just doesn't have the precision that I need for a dedicated twisty bike. If that's the case then there is no point in having two commuters and I would likely get rid of it and probably replace it with another 250

[choneofakind]

Jiggles, I think that also a large portion of what you're seeing here isn't the difference between a 250 and a larger bike, its the difference between a carbureted bike and a fuel injected bike. My 250 is the same as your 650 with the low end throttle on/off feeling, engine braking glory, and the better throttle response. It was not like that when it had carbs. I'm liking it more as I get used to it. I'm also getting smoother at using the friction zone more to help with making gradual throttle at slow speeds where I would be experiencing that choppy on/off sensation. I've also had to get better about making tiny tiny throttle inputs and being more controlled in my right instead of just whipping the throttle open and shut.

carbs are analog, fuel injection is digital. That on/off feeling is to be expected. The glorious engine braking is because the fuel is cut off during engine deceleration, and the throttle response is quicker because the mixture is always closer to perfect and the engine can rev more freely.

I think (since both bikes are marketed as sport bikes) that they likely are both about the same level of cam shape/valve timing/general aggressiveness of the engine, meaning that I think a comparison to a high strung efi aggressive inline 4 isnt really fair.
Posted via Mobile Device

[Jim Moore]

Originally Posted by Jiggles

IBut the throttle on the 650 just doesn't feel right for the twisties. And I'm talking about when you're in a turn and precise throttle is needed, I just can't hit that precision with the 650 because the throttle is so, idk, twitchy.

That's simply the nature of a bigger, more powerful bike. The little Ninja can tolerate gross (meaning large, not disgusting) throttle movements in mid-turn. There is so little power available that it's very hard to do anything to upset the bike. That what makes it such a good learners' bike.

With a bigger bike smaller throttle movements make bigger changes, which can upset the bike in a multitude of ways. It can be seen as twitchiness, or can break the rear wheel loose in more extreme cases. That's why liter bikes (and 600s) make such crappy starter bikes.

Bottom line, it's not the bike. It's you. You need to recalibrate your throttle hand to the power delivery on the new bike. Squeeze the tank with your knees, relax your upper body, and keep a loose grip on the bars. That will help. If you're moving the throttle when you hit a bump it's a pretty good indication that you're holding on too tight.

As a note, the 650 is more twitchy than the 250, but it's pretty mild when compared to a 600 at the upper end of the rpm range. And a 600 is pretty mild compared to a liter. Appalling, really.

[lgk]

i had the same feeling but i realized my arm was moving in my datalogs.
the fuel injection adjusts almost instantaneously to throttle inputs, my arm moving caused the choppy throttle.

[csmith12]

Originally Posted by Jiggles

I never intended my 650 to be a twisty bike, I bought it as a commuter and wanted to have the 250 for the twisties but things have changed. So I'm trying to see if I can make my 650 into a good twisty bike and when I get the 1000 that will be my commuter. But the throttle on the 650 just doesn't feel right for the twisties. And I'm talking about when you're in a turn and precise throttle is needed, I just can't hit that precision with the 650 because the throttle is so, idk, twitchy.

I haven't ridden a 600 or any other larger CC bike so I have nothing to compare it to. It could be that they are all like that and it's something I just need to get used to or it could be that the 650 just doesn't have the precision that I need for a dedicated twisty bike. If that's the case then there is no point in having two commuters and I would likely get rid of it and probably replace it with another 250

Then go for it brah! Maybe the 650 isn't for you. Try to ride a few others before you make a final decision. And if your still not feeling the 650 for the twisties, then sell it and get whatever you will feel comfortable on. I see nothing wrong with wanting to toss around a 250 in the corners where one would feel more 100% in control with a higher margin of error and having another bike for more relaxed riding, commuting, touring or whatever.

Not everyone needs the throttle control of a racer and I am not telling you to never get any better, getting better is going to happen all on its own, but if it's currently not your thing..... No big deal, just don't let it be your handicap going forward.

[R1Chronicles]

Originally Posted by Jiggles

1. Do larger CC bikes engine brake significantly more (not just a little more, alot more) compared to the 250?

Yes due to compression

Originally Posted by Jiggles

In lower rpm's it has three settings, decelerate, accelerate, and accelerate faster. Coasting is nearly non existent and the difference between accelerating and decelerating is so negligible that a small bump in the road can launch my balls into the gas tank.

I would see if I could get a different throttle body to smooth out the bike before selling it. Some stunters will change out the TB for a more controller throttle, more play less response.

[choneofakind]

Originally Posted by R1Chronicles

Yes due to compression

Can you cite that fact? There's many factors that go into how strongly an engine brakes.
Posted via Mobile Device

[sombo]

Part of the engine braking would have to include the compression ratio as well. I have noted that my pre-gen had much better engine braking than my HD does. As for throttle response on bigger fuel injected bikes. I have found them to be quite smooth. My HD's throttle is very smooth and responsive. When I tested the 2012 650 I felt as if it was just fine for smooth response. Then you have the large touring and sport touring bikes like the FJR1300 from Yamaha and Goldwing from Honda. The Honda's throttle response was very smooth, very strong, and the bike overall is a joy to ride. The FJR's throttle response is so slippery smooth that it's like turning up the power on an electric motor. It had no rough spots at all in it's response.

So I would say it's probably more leaning towards the riders themselves as to how smooth a throttle response on a larger FI bike can be. Yes, the mapping of the engine will have a major effect on it, but for the most part they are usually pretty smooth when you have good throttle control.

[alex.s]

@Jiggles if you want less engine brake, turn the idle up. F1 cars run at an idle of 5000rpm

[Boom King]

Originally Posted by R1Chronicles

Yes due to compression

Yes but any pumping loss during the compression stroke is almost completely recovered during the power cycle of the engine. Compressed air is like an elastic or spring. In other words, a 12:1 compression ratio turns into a 12:1 expansion ratio when the piston rebounds with nearly the same force. Energy just doesn't disappear; it's simply stored or converted into some other form or state. Some of that energy is lost when it is converted into heat during the compression cycle but it's a very small percentage.

Most of the engine braking or pumping loss occurs during the intake stroke against any air flow restrictions such as a closed throttle. In this situation, the piston is trying to depressurize the cylinder against a flow restriction or vacuum. This creates a great restriction to crankshaft rotation.

Pumping loss also occurs at very high RPMs with wide open throttle. The intake can no longer pass the amount of air necessary to fill the cylinder to full pressure at each intake stroke in order to maintain optimum engine/power efficiency. This is where devices such as turbochargers can help. They pull in air at positive pressure to help push the piston down on the intake stroke, adding more torque.

Again, I'm no expert or anything and this is my basic understanding of the concept so if I'm missing anything or mistaken anywhere, please chime in.

[blackoutt]

Bigger displacement typically = more drag and most likely higher compression and cylinder pressures. Also the difference in power on roll on make a huge difference, think about comparison of throttle control in a slow car to a fast car. Slow car you floor it and barely get thrown back in your seat so letting off isn't much of a change in accel. Fast car you floor it and take off like a rocket, you let off and the change in accel is massive too. Sounds like you need to work on throttle control, on my g/fs 250 it's easy to get away with being sloppy, but on the R6 in the power band it's a VERY fine control rolling on and off or it bucks terribly, ruining weight distribution and becoming very uncomfortable.

[Kevin2109]

Originally Posted by Jiggles

1. Do larger CC bikes engine brake significantly more (not just a little more, alot more) compared to the 250? Or does it perhaps have to do with the cylinder size, i.e. 2x325cc vs 4x150-250cc?

2. Do larger CC fuel injected bikes throttle's simply react that way in not feeling so smooth between off, coast, accelerate or does the 650 just have an anti-twisty throttle?

1. Not all the time, my bike engine breaks less because of its slipper clutch

2. If its tuned well, the throttle bodies are much more responsive then the 250. My 636 is really smooth if I make it perform that

[Jiggles]

Ok well if it is just me then I'll kelp the 650 instead of trading for a 250

[Jiggles]

Originally Posted by alex.s

@Jiggles if you want less engine brake, turn the idle up. F1 cars run at an idle of 5000rpm

I already read your dumbass comment Alex! You don't have to mention me 3 hours later

[alex.s]

Originally Posted by Jiggles

I already read your dumbass comment Alex! You don't have to mention me 3 hours later

y u no listen?

[Jiggles]

Y u no hav gud advice!?

[R1Chronicles]

Originally Posted by choneofakind

Can you cite that fact? There's many factors that go into how strongly an engine brakes.
Posted via Mobile Device

Lazy statement by me, higher compression/volume = more work required, when the energy is removed it creates inefficiency inversely proportional to each other. Which would be very noticable from a 250 to a 600 based on the different work load required. I'll refrain from generic statements in the morning.

[Kevin2109]

Originally Posted by R1Chronicles

Lazy statement by me, higher compression/volume = more work required, when the energy is removed it creates inefficiency inversely proportional to each other. Which would be very noticable from a 250 to a 600 based on the different work load required. I'll refrain from generic statements in the morning.

have you ridden a modern SS?

[alex.s]

Originally Posted by Kevin2109

have you ridden a modern SS?

he owns an 07 r1.... his name is r1chronicles... im just making an assumption here but i would say yes.

[Kevin2109]

Originally Posted by alex.s

he owns an 07 r1.... his name is r1chronicles... im just making an assumption here but i would say yes.

Thanks captain obvious!

Most SS's have slipper clutches, they dont engine break like the 250 does because of this.

[alex.s]

07 r1 i think was the first r1 with a slipper clutch

[Alex]

Either Motorcyclist or Sport Rider tested that engine braking / compression myth a few years back, and had some surprising results. The myth is that large capacity twins have tremendous engine braking, while high-revving smaller 4's have much less engine braking. They tested a number of different bikes, including a large twin Ducati, a literbike, and a 600. The methodology was to take the bike to exactly halfway in its rev range in top gear (half of redline), and measure the g force of deceleration after completely letting off the throttle (while staying in gear). The same tests at the same speed were run, but then by pulling in the clutch and measuring deceleration, to be able to remove air resistance and other related friction from the equation.

Bottom line, it turned out that all three bikes had almost identical engine braking forces, from the large v-twin to the tiny, free-revving 600.

Now back to present time though, and the engine braking effect is starting to be monkeyed around with intentionally by the electronics. Racebikes are working on tuning that rear wheel deceleration for corner entry almost as much as they used to work on the traction control on the way out. In years past it was just turning up the idle, but it has become much more sophisticated; read this month's Roadracing World magazine where Chris Ulrich describes it in detail on a WSBK spec customer Ducati.

[Alex]

Originally Posted by alex.s

07 r1 i think was the first r1 with a slipper clutch

Nah - the 2004 ZX-10R had one.

EDIT: Sorry, I read this as the first SS with a slipper. It very well may have been the first one on an R1, I don't know.

[Alex]

Originally Posted by Kevin2109

Most SS's have slipper clutches, they dont engine break like the 250 does because of this.

The slipper clutches have nothing to do with engine braking on the street. None of the deceleration comes anywhere close to enough force to cause the clutches to slip in any way. The main reason SS's feel like they have such limited engine braking compared to the 250 is that they are geared so much taller that the engine isn't revving nearly as fast at the equivalent road speed.

[alex.s]

Originally Posted by Alex

Nah - the 2004 ZX-10R had one.

EDIT: Sorry, I read this as the first SS with a slipper. It very well may have been the first one on an R1, I don't know.

yeah i just meant for the r1

[alex.s]

Originally Posted by Alex

read this month's Roadracing World magazine where Chris Ulrich describes it in detail on a WSBK spec customer Ducati.

i hear dorna is going to start providing electronics packages for all the motogp prototypes and CRT bikes because the CRTs were having so much trouble matching the electronics capabilities of the factory prototypes

[R1Chronicles]

Originally Posted by Kevin2109

have you ridden a modern SS?

Try this out tell me if I'm wrong, in first gear accelerate a certain distance, dump the throttle leave it in gear no clutch and turn it off (remove the energy source) let it pull it self down. You shouldn't get more than 1/1 to 1.5/1 glide ratio. "Inversely proportional", kinda sorta, but had a lot of fun typing that sentence.

The point being your going to notice a bigger difference with an acc/de-acceleration between a 250 and a 600 and won't experience a free glide while de-accelerating while in gear.

Yup, 07R1 has the Slipper which will allow it to partially disengage to remove rear wheel chatter (keep traction), the 07 also a more basic ECU than the newer models.

PS, if you turn it off, don't start it until you've come to a complete stop, gas build up can cause an ugly backfire (abnormal explosion in the cylinder) which can cause damage. Fun to do with old cars you don't care about. (i know, electronic fuel pumps)

[alex.s]

Originally Posted by R1Chronicles

PS, if you turn it off, don't start it until you've come to a complete stop, gas build up can cause an ugly backfire (abnormal explosion in the cylinder) which can cause damage. Fun to do with old cars you don't care about. (i know, electronic fuel pumps)

you mean like this?

Link to original page on YouTube.

i heard its good for your exhaust valves to have something explode behind them.

[R1Chronicles]

Originally Posted by alex.s

you mean like this?

lol

[R1Chronicles]

Originally Posted by Alex

but it has become much more sophisticated

Thats what I love about the 07/08R1, the last generation of the R1 were it's mostly human controller. Ya make a mistake and the electronics won't save your arse, keeps me a little more honest when driving it hard on streets (I never speed, wink). I've only low sided the rear end once .... lol ... (but it was snowing earlier that day)

[ajcadoo]

Coasting solution: Clutch In.