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stuff related to engines (size, power, lots of other stuff)

Discussion in 'General Motorcycling Discussion' at netrider.net.au started by kinch, Aug 9, 2008.

  1. Hi,

    As a newbie, I ride a 225cc bike. It's basically crap. Slow, ugly, small fuel tank - I could go on about the things I don't like about it. However, I specifically bought it because I wanted something to learn on that would give me good basics without the temptation to thrash it and do something stupid before I was ready. Now I feel like I'm stuck. The bike is a single cylinder, with a 12L fuel tank, and 5 gears. 4th gear will get me to about 50km/hr, 5th will handle 60-100 (but I really have to thrash it to get to 100km, and no matter what speed/gear, even a gentle rise will take 10-20km off my speed).

    I started looking for bikes, 500-750cc. Got a lot of good recommendations from the good folks here, unfortunately not many of them were available nearby (I'm looking for a recent model 2nd hand, since I'm pretty sure I'll drop it). Then I started thinking about all the other stuff related to engines, and had a ton of questions I couldn't find the answers to. Hence, the newbie post ;)

    So, let's talk engines. My 225 is a slow piece of crap. So what does 225cc actually mean in terms of output? I see things like VTR250s that look sexy - do they have the same low levels of power, or is the engine size only marginally related to performance? How does a 2 cylinder 250cc engine compare to a 1 cylinder 225cc engine in terms of fuel usage and output? On mine you have to rev the engine so high to get any type of speed (and forget acceleration, it's just not there) so that means more fuel usage than if you weren't revving it so high right ? So how does a 3 or 4 cylinder engine compare? There's just so much I don't understand about how the details of an engine (dize, etc) relates to real-world practicality.

    While browsing some bike sites, I stumbled across a Triumph Daytona 955i and a 600. I liked the look of them, a quick search found a couple that were nearby and within my price range. Some googling brought many favourable reviews (but of course, it won't matter if I don't like the feel of the bike right?) So, as a newbie coming from a 225cc gogomobile, is a 955i too much for me? I've heard that they're quite good with fuel efficiency, which is something I'm interested in for obvious reasons. I don't ride huge amounts, but that will change if I get a bike I like. I was reading a very interesting thread here about engine revs and what revs are 'good' to ride at etc. I would classify my riding as pretty conservative... I stick to the speed limit, I don't accelerate fast, and I'm happy to cruise along at low revs keeping the bike at a good speed.

    Sorry for the long post, I'll stop now before I bore you to death with all the other questions ;) Am I just overthinking this whole issue?
  2. mmm, just my opinion, but if you haven't yet been able to ride at 100kph for any length of time, or under all sorts of conditions, my advice would be to go for a 600cc bike, rather than hopping straight to a 900 - 1000 :).
  3. I agree with Hornet. Money is the main reason why I haven't upgraded yet.
  4. Well I can't answer all of those questions, but I can answer the ones about the engines.
    Lets assume all engines are 250cc. So that means total engine displacement is 1/4 of a litre. If you have a single cylinder engine, that means you have one big piston, and the one big cylinder that the piston moves up and down in. In a twin (2) cylinder engine (v-twin, inline, horizontally opposed) each cylinder is only 125cc, so all the parts are smaller. The same goes for a 3 or 4 cylinder engine. The more cyclinders, the smaller the pistons and all the moving parts. The smaller the parts, the faster they can move.

    So one of the reasons (theres many more such as gearing, engine tuning, fueling) your single cylinder bike won't go as fast as a 2 or 4 cylinder 250cc bike is because the piston can't go through its cycle as fast. Search up internal combustion egine on wikipedia, theres lots of diagrams that explain how it all works, and the process of the 4 stroke engine. Hope that helps with your understanding of engines :)
  5. Engine capacity (in cc) is not a particularly good guide to engine power, since there are a very large number of variables around engine conformation (number of cylinders, bore vs stroke), type of fueling, exhaust, etc., that effect power. There may well be 250s that would be a complete revelation compared to the bike you're on now. There's also torque as well as power, and the shape of the power curve, and gearing, and...

    Bottom line is that a VTR250 would be a completely different and much better experience than what you're riding now, and might be at least one possible upgrade path.

    I'd concur that moving to something in the 500-600 range as a next step would make sense. You'll probably get a few people saying 'nah, go straight to the 1000', but given that what you've been riding is not the same as even most learner 250s I think a smaller step in power, weight and so on makes a lot of sense. Something like an SV650 - a v-twin with lots of torque as well as power - would be a very good step up, and there should be a fair few of them around Brisbane at a decent price.

    Up to you what you do with it.

    By the way, if you tell us what make and model of bike you're riding now it would be possible to look up some power and torque figures for it and some other suggested bikes to give you a sense of the answers to the questions you ask about engines.
  6. Thanks to all for the replies so far.

    jp86: I've read all the stuff on wikipedia, and I know all the theory behind how an engine works - the air is mixed with fuel, it's piped into the cylinder, the spark plug fires at a time determined by a timing chain, the piston drives the crankshaft, and so on. What this stuff doesn't tell me is how a 225 engine with 1 cylinder compares with a 600cc 2/3/4 cylinder :) I know the 600 will be 'bigger' and 'faster' but by how much? How does fuel consumption compare? etc etc. The so-called "real world" practical knowledge :)

    Bravus: The SV650 was a model I was initially very interested in, but I couldn't find any nearby... most of them were 2-3 hours away, and just not entirely practical for me to go there without knowing for sure that I want one. I haven't had a test ride on one yet (hopefully that'll change soon) and I'm hesitant about committing to a second hand bike without being a bit more thorough about my purchase (I didn't test ride my current bike either, and look what that got me). On that note, I can't find much info on my current bike. None of the major websites seem to list it, and I've only found a few mentions of it here. It's a Yamaha Scorpio.
  7. :LOL: www.productreview.com.au says "Pros: Very reliable and easy to start (Electric + Kick) Can sit all day 100Km easy Top speed I have managed to get on flat road 130kmh not bad for a single cylinder 225"

    Sounds like rose-coloured glasses to me :LOL:.
  8. So, the Scorpio (single) has a claimed power if 19 hp, which is probably optimistic.

    A VTR250 (v-twin) has around 32 hp.

    A CBR250RR (inline 4) has a claimed power of more than twice that of the Scorpio at about 40 hp.

    So as you can see, there's not a particularly close relationship between capacity and power. But it's more than number of cylinders that makes the difference (although this layout suggests it is!)

    An SV650 has 72 hp, so not quite twice again the CBR.

    A CBR600RR has 120 hp, so almost twice the power of the larger capacity SV.

    You have to remember with power numbers, too, though, that these are the peak on a curve, and some power curves are tall and skinny and others are broad and flat.

    Oh, there's a totally sweet sounding 2005 SV in SEQ right at the moment, on Bikesales... not that SVs are your only option at all.
  9. So, I've been shying away (just very slightly :p) from things like other 250s because I figured they'd be slow and lack power like mine... clearly with double the horsepower (give or take) it's going to be a different experience all together. But a 70+hp machine sounds so much more.... enjoyable ;) Hopefully next week I'll have a chance to ride some bikes and find out what their real power/acceleration is like... I'm still quite keen on an SV650, or the Daytona 600 (or 650, or 750). I'm kinda fussy about my bikes, in partiular the colour I want and the style of the bike.

    How does fuel consumption work with these engines. Is it directly related to horsepower? Or the engine size ? How does a 1 cylinder engine that's revving at 8k for an hour compare with a 2 (or 3 or 4) cylinder engine revving at say 3-5k for an hour ?

    p.s. Not just rose coloured glasses either ;) The bike does struggle over 80km/h. For 60-80 it's okay (although I've found that I hit 5th gear in about 10 seconds after taking off... is this normal?) but anything else.... I would still recommend it as a learner bike. But I think I'm ready to try out something new ;)
  10. I'd be really interested to hear more about your Scorpio because that is one of the bikes I'm looking at buying. I'm a learner, and though I've ridden friends' bikes it would be my first time mixing it up with traffic. I'm not looking for anything fancy, and I'm not likely to get above 60 kph very often either. It will mostly be commuting through 40 - 60 kph zones, with maybe the occasional foray into an 80 kph zone or onto the freeway.

    My main reason for looking at the Scorpio (or the Honda CBR 125) is that I'd like my wife to be able to ride the bike as well, and she is only 5' 2" tall and quite petite. I read about the Scorpio initially in threads for short people looking for a bike where they can touch the ground comfortably.

    I'm aware that it is not a powerhouse, and also that it is not very pretty. What I'm looking for is a learner bike that my wife can inherit if and when I move on to bigger and better things. With that in mind, what do you think of the Scorpio, having ridden one for a while? Do you think a small woman would be able to handle it comfortably?
  11. The bike you're on is a gutless POS even in comparison to other decent 250cc bikes. A Kawasaki GPX250 puts out well over twice the power of the Yamaha Scorpio, and can easily sustain 150kph up a moderate hill if you so choose.

    This is the problem here. It's so much us as trying to inform you as to the differences between the Scorpio and a 600cc bike, mainly because the Scorpio isn't even on the same playing field as a decent 250cc bike for purposes of comparison.

    A VTR250 or GPX250 would kick the Scorpio's butt in every conceivable way, except for possibly fuel economy. A sporty 600cc bike is so far in front that even if you limited it to 1/5th throttle maximum, it would still kill the Scorpio in every performance aspect.

    If there's any lesson to be learned here, it's that you really want to avoid bikes with less than around 20hp, even for learners. The Scorpio has about 15hp, and that's being generous. All it does it frustrate the crap out of the rider when they can't even confidently run at 100kph with the rest of the traffic.
  12. Well I would safely say the difference in performance would be night and day. Keep in mind that most learner bikes have basic setups, as in the brakes, suspension. On a 600cc bike, it's obviously going to have a lot more power, but also better equipment to handle the power. In regards to fuel consumption, I wouldn't really worry about it that much. It's still going to be a lot less to fill up any bike than a car
  13. Any big, proper bike will be scarily faster than your 225.

    It will also handle better and have better brakes.

    Choose a model you really like, then buy the newest/lowest-kays one you can afford.
  14. Oooh... this is just the sort of stuff I wanted to hear. Hopefully early this week I can get out to some dealers and go for some test rides to find what I like and what I dont like... but now that I know anything I get will be soooo different from what I'm used to, I'm very excited to get some good hours on the road :D

    Thanks again to all.
  15. Re: stuff related to engines (size, power, lots of other stu

    I ride a '07 Scorpio. I usually changed into 3rd approaching 50km/h, and 4th at about 70 - this is still only using 5500-6500 rpm. To me it sounds like you may be gearing up to soon, and only using a fraction of the bikes power.
  16. Next time I go out I'll pay alot more attention to the revs, but I change gear about 5000-7000 (depends of course) and I think I still only get to 50 in 4th... I wish I could figure out a way to mount a camera onto my bike to show the revs, coz I'd very much like some other opinions on my riding style. I admit right now though, that I try to keep engine revs low and I don't like revving the tits off it unless I have to.
  17. Seems that there is big discrepancy between what MH is saying and your experience....I think we may also have to clarify one little thing....how much do you weight? :p
  18. Sounds like you're not using the engine to its capacity, as MH suggests. I weigh 95ish kg and have ridden a DR200, which has a smaller, less powerful engine that the scorpio and, while it isn't quick, it isn't as bad what you've been describing.

    With a bike like that you should be reaching near redline regularly, and often holding the throttle wide open. At first it will seem like you're over revving the engine, but small singles like that are designed to rev quite high.

    If you do decide to go the upgrade path (which i wouldn't recommend - you'll learn a lot more about cornering on a small bike like that) avoid anything with a 4 cylinder engine larger than 400cc, or a twin larger than around 650cc. 600 - 650cc single's are pretty good beginner (well, good for experienced riders too!) bikes, as they have plenty of torque. water cooled engines are generally more powerful than air cooled engines of the same size.