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Post by sailracer on Jul 4, 2013 12:17:03 GMT -5
This is why I still have my original scooter. I don't want to sell it, I want to work on it too. In the meantime, I got another one to use and improve on. It's kind of fun,as well as a challenge, and I'm not spending $1000's of dollars doing it so now I have one to use, and the other to tinker with. AND they are both inexpensive chinese scooters.
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Post by larry001964 on Jul 4, 2013 12:24:53 GMT -5
A water cooled engine yes maybe, the water cooling provides more consistent cooling, and prevents thermal oil breakdown, These air cooled engines are designed for small trips to the corner store, not cross country every day at wot, dealing with the traffic demands of 55 to 80 + mph. If your going to be doing a lot of driving you should get a 150 or bigger Why bigger ? simply because the bigger engine will not have to work as hard as the smaller one to do the same job.. Air cooling works fine if the metal in the engine isn't a cheese alloy Ive seen plenty of Kymco's go down for exactly the same reason, over stressing the engine. Part of my job as an Industrial Mechanic is failure assessment, I'm trained in it, and I'm pretty good at it... And what iv'e seen is there is very little difference in the metals used.... However when I bulit the stroker I did by only Taiwanese products, the reason was not because the metal used was of higher quality necessarily... It was because as I wrote the build I didn't want the quality of the parts coming into question... If I had had a failure with a cheaper products, many on scootdawg had a raging debate as to the quality difference between Taiwan and Chinese metals, any failure would have been blamed on the products used in the build, not what I actually determined to be the reason for failure.. I effectively removed that debate from my build.. |
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Post by scootnwinn on Jul 4, 2013 12:34:32 GMT -5
I'm trained professionally in tuning air cooled motors, I'm pretty good at it. I have owned a Chinese 150 and worked on/ridden more bikes than most people. I can tell you there is a difference. I have never seen Japanese steel or aluminum crumble or tear like bread. Its different I don't care what you do for a living its different. I used to ride the holy crap out of Honda XR650L it was air cooled and would take a beating and beg for more...
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Post by larry001964 on Jul 4, 2013 12:43:16 GMT -5
Then explain why the Kymco's go down ? They are being driven the same as there Chinese counter parts.. The metal fatigue is the same. If the metal is so much better explain why they go down ? What i'm seeing most often is rod failure at the crank shaft..
I owned a Kz 550 for many years, rebuilt it three times over it's life time, turned over almost 400,000 miles on it. Owned it from 1983 to 2009, bought it new, It was three years old on the showroom floor when i bought it ( now it's probably part of the can of soda people drink ) It has been recycled.. The reason why I didn't have that many failures with it and i did have a few, was simply because I maintained it very well... And it was a bigger engine doing the work..
When I tried forcing a 50cc to do the work of a 550, I had failures because I was over stressing the engine... Simply put IMHO 50cc 4t engines are not designed for that kind of a sustained load on them.
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Post by gitsum on Jul 4, 2013 12:57:16 GMT -5
Hey gitsum, Did you ever buy anything BRAND NEW? All your bragging about your rides, THEY ARE ALL USED- somebody elses leftovers. I but my stuff new. and it so happens that i could own any bike i choose NEW> I choose a chinese scooter because For what they are, they are a great valye  If I was bragging, it wasn't intentional, just trying to show what a value a lightly used quality machine can be compared to buying Chinese. I would never be as uncouth as you to state that "I could buy any bike I choose new". But since you asked, here goes. Since 2010 I have bought a new 2010 Honda Elite 110, new 2012 SYM Wolf Classic 150, new leftover 2009 Suzuki TU250X, new 2012 SYM HD200 EVO, new 2012 CPI Oliver City 50, new 2012 Tomos Nitro 150 and a new Honda CBR250R. And since you were making a point about your claimed ability to "buy any bike you choose new", I paid cash money for all of them, except the 2012 CBR250R, which I financed for my son and he makes the payments. If you would have just looked at the machines in my signature, you could have saved yourself the embarrassment of looking like a wanna be stuck up person. And if you're not embarrassed that's OK, 'cuz I feel embarrassed for you ;D |
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Post by scootnwinn on Jul 4, 2013 13:03:53 GMT -5
Since when was Kymco the highest standard of quality? They are ok but I have no experience with them personally couldn't possibly tell you why. Can you with certainty? Lots of things break for lots of reasons. The metal and welding on my Chinese ride was questionable at best. Never saw that with any other bike. Your extensive training and education should allow you to admit there is a difference. Maybe yours hasn't had anything fail due to metal fatigue. Mine ripped tabs off the frame like they were perforated. Who knows? Enjoy the ride. All brands of bikes are different that's why we all ride different ones right? Don't tell me its all the same that doesn't even make sense.
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Post by larry001964 on Jul 4, 2013 13:26:56 GMT -5
I em referring mainly to just the engine,
As for the frame and welding , LOL well I'm a much better welder than the Chinese machines for sure, I have to give you that one. I don't work on scooters for a living, but i do help a person out when they need it... Fawkes is pretty well known among the scooter riders at work ( there quite a few, recently they doubled the size of the scooters / motorcycle parking area, and it's still full almost a 2 to 1 ratio of scooter to motorcycles ).. So when something is wrong with someone's scoot I'm often asked.. If I can help them I do. Often this mean turning a wrench in my off time to repair the damage... So I get to see plenty of failures.. Many often give Kymco's a free pass just because they are Taiwanese but that's not what I'm seeing in reality...
I see the same metal you described in a earlier post.. I see the same type of metal stretching, heat damage, and brittleness as I do in Chinese scoots.. The mileage is virtually the same as their Chinese counterparts... I guess one can consider metal composition as part of design limits. And with that argument a better quality metal would require less metal and take more punishment. But what I'm saying takes the chinese metal's weakness into consideration, if one is going to do a lot of wot sustained driving, then a bigger engine will take the punishment better than the smaller one...
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Post by gitsum on Jul 4, 2013 13:42:07 GMT -5
A smaller engine produces less power, heat, friction, stress, and centrifugal force. Unless there is an inherent design flaw, a smaller engine should be able to run WOT for extended periods better than a larger one. This being true if the metal quality and engineering design are respectively equal.
You can't compare a smaller GM 2.4 liter economy engine with a million dollar Ferrari V12 model and expect the smaller engine to maintain the redline with the same durability as the much more expensive larger engine.
But I think we are talking more or less about a basic GY6 design.
Perhaps it's just bad luck with the Kymco 50's you've seen?
Maybe they are modified/derestricted and running a higher rpm than originally designed for?
Maybe a faulty batch of crankshafts were installed and you happen to see more than one?
For the most part, change the oil and keep the valves adjusted and Kymco air-cooled engines last quite a long time.
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Post by larry001964 on Jul 4, 2013 14:13:05 GMT -5
I think you hit on the very core of the problem Gitsum.
a smaller engine needs to run harder and more rpms to produce the same power and speed that a bigger engine does at half the rpms...
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Post by gitsum on Jul 4, 2013 14:36:57 GMT -5
I think you hit on the very core of the problem Gitsum. a smaller engine needs to run harder and more rpms to produce the same power and speed that a bigger engine does at half the rpms... Good point. If you own a smaller four-stroke 50cc and ride it consistently in a 45 mph speed zone, it would be WOT all of the time. A 150cc engine would be running easily and well below the redline under the same conditions, and as a result would have a longer engine life. But according to my theory, if you ran the 150cc in a 65 mph zone at WOT throttle all of the time, you would stress the engine harder than running a smaller 50cc engine at WOT. If both engines were a GY6 design made out of the same metal, the 150cc should wear out first because of the additional power and stress. However, both a quality made 50cc and 150cc engine should last a long time abused at WOT if the maintenance is kept up. |
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Post by scootnwinn on Jul 4, 2013 14:47:11 GMT -5
Most manufacturers somehow limit rpm so that even if you do hold it wide open always you are still within a safe rev range.
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Post by gitsum on Jul 4, 2013 15:02:12 GMT -5
Yes, this is done by either gearing or a rev-limiter, or both.
I prefer using gearing to limit maximum engine speed on a scooter.
If the CVT is tuned properly, you will run out of horsepower to push the scooter faster somewhere between the torque and horsepower peaks of the engine's powerband. Running WOT will keep the engine below the redline, unlike a rev-limited top speed where the engine is running all the way at the redline.
It seems like a lot of 150cc scooters are top speed limited by gearing, while a lot of 50cc scooters are top speed limited by rev-limiter. Probably because of the larger 150cc having a much fatter torque band, compared to a 50cc which makes most of its power at higher rpm's.
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Post by JR on Jul 4, 2013 20:46:44 GMT -5
I agree that the OP picked a strange place to post what he did. This is a predominately chinese scooter forum. We have and welcome all other scooters, motorcycles, atvs ect.
Ido really think we all know the chinese do not build the quality that the japanese, italians, indians build. I do know that the quality has improved over the years. When they first started sending 250cc water cooled scooters over here they were really iffy, now they are much better. The same is true of the gy6 scooters.
That said we all know that if you want to buy a chinese scooter it is best to be able to work on it yourself. If you can not work on it buy a used japanese scooter.
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Post by larry001964 on Jul 4, 2013 23:18:34 GMT -5
Hi Doug,
You know I don't make derogatory statements about anybody's ride, that's not what riding is about IMO. However I didn't like seeing to done by somebody who don't even or has never owned one... We can discuss quality, reliability, cost, maintenance, and any other issue without being derogatory to someone else ride... We may not agree with somebody else s opinion, but to make a blanket statement is not really fair and don't take into account other factors...
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Post by ramblinman on Jul 4, 2013 23:35:13 GMT -5
You think $800 was a good deal on a Chinese 50cc? Think again. I bought a 2007 Yamaha C3 with 750 miles for $1000. It was three years old and looked brand new without a scratch. 44 mph top speed and 115 mpg. Water-cooled and fuel injected, you could literally cruise at WOT forever, It was almost as fast as my two-stroke SYM DD50 that I bought for $500. Yeah, that's right, a Taiwanese built 49cc two-stroke with 1200 miles that I fixed up and invested $700 total into and it ran 47 mph. you found some terrific deals. unfortunately everyone isn't going to be lucky enough (or good enough at haggling) to get deals like those. and i didn't pay $800, paid $300 cause i bought it used like you. but if i could get a used SYM with only 1200 miles for $500 then obviously would have spent the extra $200. instead of bashing the forum for buying a cheap bike... why don't you locate some of these terrific deals for us so we can bask in the glory with you. |
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