Why are Chinese bikes slower?

[flumpy7]

So I've just bought myself an immaculate 2012 sinnis apache 125 to pop to work and back.

Doesn't seem to be the usual sub-standard Chinese stuff; chunky, decent quality fixings, nice plastics, polished alloy swingarm, discs on rear as well as front as seem to be pretty tough, nice alloy wheels and spokes. All together pleasantly surprised.

Anyhow....it'll only reach 55-60mph max, which is fine for my needs, but I was just wondering why.

I don't mean the usual 'cause its Chinese shit' comments, but i''m genuinely interested in the mechanical reasons why these replica engines cant match the speed of the original designs. I mean the apache is based on the GN125/DR125 motor. These could apparently reach 70mph and 75mph respectively so why cant the Chinese version? I believe the same is true of the myriad of cg125 copies.
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2012 Sinnis apache

[N cee thirty]

because they've been built cheaply so the state of tune has to be even less than the originals to stop it going bang, i assume.
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[callum94]

It could be due to the gearing, since every Chinese motorcycle I've owned hit 60mph@10000rpm in the highest gear (until I changed the sprockets then it would pull 60+ according to speedo)

I embarrassed a YZF-125 on my Sukida, I saw one pull up to me at a set of lights and when the lights turned green we went for it lol. He was hitting the rev limiter in every gear and I was still right next to him, the look on his face at the next set of lights

I want to race a YZF-R125 on my Honda since compared to the Sukida it gets to 60mph 6-7 second faster.
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Current: CBR 125R 2012 (Black)
Restricted licence (33hp): 09/12/12

[stevo as b4]

A lot of them seem to use cheap copy Mikuni/Keihin style slide carbs. I would be quite surprised if any of the air cooled 125cc singles based on the Honda or Suzuki OHC designs make 10bhp or more. Some of the original Japanese engines were closer to 12bhp after the the 1982 law's.

Even those Chinese copy engines based on the Honda CB125T don't seem to make much power, and some even have twin carbs. I suspect that they are built with cheaper lower quality parts and ancillaries generally, and not to Japanese standards of quality control.

[Carvel]

[Sable]

The Apache 'should' have a top speed of 65-70. Check your speedos accurate (heard of another Sinnis with a wonky speedo, fixed by warranty).

Trackstar is meant to be the slowest in the range and can manage 65mph.

[callum94]

[Nexus Icon]

Cheap carbs and, possibly, sloppier machining tolerances within the engine.

The predominant reason GP bikes and F1 cars can produce huge power figures without huge displacement engines is the ultra-fine tolerances and balancing within the units themselves. These give lower mechanical losses and the ability to rev higher.

It stands to reason therefore that poor machining of engine internals will result in lower power figures.

That and cheap carbs.
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Greetings from Shitsville!

[Derivative]

GN125 70mph?

Yeah, okay.

I don't know of any four-stroke 125cc motors that do 70. Maybe the Varadero, but that's a twin.

The CG doesn't do 70. No chance.

edited later: learner legals, the Superdream could probably manage it

[flumpy7]

[Sable]

[passifid]

[Derivative]

[ocatoro]

so it hurts less when it falls apart
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CBT - 17/09/12 * Theory - 23/10/12 * Mod1 - 05/03/13 * Mod2 - 25/03/13 * BOSH!
Current - None but shed project H100 (first bike )
Past - ER5, '93 ZZR600, '92 CB400 SF, ZZR600 (again), yellow Monster 620, Blackbird - black Monster 620ie - '96 ZZR600

[flumpy7]

I think a lot of people don't get the most out of 125's cause they don't rev them high enough and change gear too early. Although agreed, 4 stroke 125's are still seriously slow but then....you hopefully didn't buy it for speed.
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2012 Sinnis apache

[callum94]

[Timmeh]

Loving the cable routing for the throttle. Way to not go Honda.

All 4T 125s are teh slow, but that's good for people who are still learning.
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GSXR400 x2 | '94 RVF400 | '93 TZR125 4DL (again)
20:22:30 BLUEX5: i would love to be forced to undergo a**l plugging with different sizes
20:48:18 Temeluchus: comp you hunk of smouldering homos3x you

[passifid]

fastest 125 4t is still the vadero

followed probably by the yzf in common bikes as it has 1.2 whole kw(or about 1.6 hp) more which is about 12.5%

again its like argueing the heaviest fly, once they can manage 70 thats all i care about for a 125 speed wise
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CBT: 10/2011 | Theory:6/2012 | MOD1: 8/2012

[Lord Percy]

My GN125 was pushed very hard to hit 65. I mean, it was really pushed. A more typical speed was 50.

[callum94]

[passifid]

i thought we were talking about fastest bikes not fstest bike + rider combos because my mate comes in at around 7 stone and he would probably beat most people riding a 125 on an aubergine
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CBT: 10/2011 | Theory:6/2012 | MOD1: 8/2012

[callum94]

[-Monty-]

[passifid]

doesn't eat only really smokes and is about your hieght, and a very slim build anyhow, i have a 5 11 mate who is 9 st 3, he looks thin but not anorexic, but he has a womans build
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CBT: 10/2011 | Theory:6/2012 | MOD1: 8/2012

[TheSmiler]