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About preventec47

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  1. Is there any justification for buying anything other than LED headlights these days ?
  2. preventec47

    Recognize this engine ?

    Recently I have seen some new single cylinder models featuring "double balancers" what ever that means. I am glad mfgrs are working so hard to smooth the engines with all the latest technology. I wish we could get more technically accurate info from the cycle reviewers and mfgrs themselves about the vibration in the models they sell.
  3. preventec47

    Lets learn more and reduce our risks about Chinese bikes

    Do you know which Chinese company makes the NC250 such that you could contact them and they then tell you who they sell to in the USA so you have multiple sources of parts. ( I assume it is Zongshen Co ? ) On EBAY I notice lots of things now being sold directly from China without middleman...... or maybe the middleman is in China and simply an enterprising organization. Well then what about the chassis? Not enough to know it is a Husq clone. You/we need to know who is making them. Do you have all the parts schematics for your engine and chassis for when you need to buy replacement parts ? (Note to self): do google search for Usamotortoys, CSC, and Zongshen motors etc. http://usamotortoys.com/ https://www.cscmotorcycles.com/ http://californiascooterco.com/blog/?p=13319 http://www.zse.cc/home.aspx http://enzsmt.cyclonemoto.com/ https://www.alibaba.com/showroom/zongshen-motors.html https://www.aliexpress.com/popular/zongshen-motor.html https://www.made-in-china.com/products-search/hot-china-products/Zongshen_Motor_Parts.html http://www.cccme.org.cn/shop/cccme7023/index.aspx https://www.orionpowersports.com/orion-125cc-pit-bike-motor-engine/ http://www.advpulse.com/adv-bikes/10-adventure-motorcycles-you-cant-buy-in-the-usa/3/ https://en.wikipedia.org/wiki/Zongshen Martin Racing Performance Published on Jul 16, 2013 SUBSCRIBE 9K We had a dealer call today and tell us on the phone they could get the Zongshen parts for less money from Zongshen. I explained to him that we were the official scooter parts supplier since they closed the parts operation 9 months ago. All the private label importers Diamo USA / LS Motorsports, United Motors, Dixie, we have all their parts here inclusing Zongshen USA and ZMD branded parts. If you call the office this is the official recording. Call MRP. So if you have a store or repair shop make sure to open an account. MRP has the largest collection of scooter parts at the best wholesale prices. We don't dropship, we STOCK! We sell to dealers, distributors, exporters and traders. Call us about logistic services, drop shipping for your website, and more! To buy retail parts visit: http://www.gokartsusastore.com http://www.moxiescooters-store.com http://www.mrscooterstore.com http://www.superscooterparts.com http://www.scootertronics.com http://www.moxiescooters.com Web Site: http://www.martinracingdealer.com/ redirected to: https://www.racingplanetusa.com/ Online Parts Catalog: http://viewer.zmags.com/publication/d... Blog http://martinracingperformance.blogsp... 2015 https://www.cycleworld.com/2015/12/30/csc-motorcycles-rx3-cyclone-adventure-bike-motorcycle-review-photos-specifications 2016
  4. preventec47

    Balance shaft elimination

    If the spreadsheets were appropriate and accurate you would probably wind up welding on additional weights to the main crankshafts counterweights and to the balance shafts counterweights to optimize for your new heavier pistons etc.
  5. Here is a picture of an engine that is a couple of years old that was supposed to be a breakthrough in balancing and smoothness for a single cylinder. But I cannot remember the manufacturer. The engine basically has two crankshafts which have gears at the end which both intertwine with a main transmission power shaft. From what I remember nearly all of the vibration is canceled out in a remarkable way.
  6. preventec47

    Should i RK the 250RR?!

    I have a question about increasing the compression. Are you going to have to move up to premium fuel from regular octane ? Or it could be that you already are having to use premium fuel. Also do you race competitively or in any other way where someone is recording your time and thusly making it "worth it" to spend the money and experiment with making the power mods etc. Just wondering... . otherwise it is just for personal satisfaction. Just one small point. if the only thing you do is increase the compression with resulting power increase .... You will be increasing the heat output by the same percentage as power output. If you ever thought you were borderline on cooling and longevity is a primary desire, I would not make the change unless you know that you shouldnt extract the highest power other than for extremely brief periods so as to prevent heat build up. All engines have a maximum continuous power output beyond which heat builds in the motor faster than the motor can expel it. You always hear a lot about mods to increase power but rarely do you hear about cooling enhancements.
  7. preventec47

    Lets learn more and reduce our risks about Chinese bikes

    Well that is why I posted the message. There are ways we can reduce our risk.. Sometimes what you get is a big savings if you have done your homework right. I believe if we can determine which chinese mfgrs are are producing hundred thousands a year for their own market which dwarfs the USA, then we can probably piggy back on their experience and economies of scale. Of course there will be some that paid a lot for their brand name bikes and done want anyone else to save lots of money. We just have to accept that and work around it.
  8. Ideally this forum could be a clearing house of info regarding the many chinese mfgrs and the ones that are attempting to sell bikes into the USA. Somewhere I saw a list that looked like at least fifteen different companies offering bikes and there must be many more that sell components only. At the small end I read about many companies literally copying a Japanese model so that all or some components would be interchangable. We need to know what companies and which models use what kind of parts because I feel that is the best way to reduce our worst case risk of getting a bike that becomes worthless because of a single component that cannot be replaced etc. What we reallly need is a catalog of all the mfgrs and bikes and components and then some info as to compatibility .... exactly the way our american auto parts stores do it. It is likely some of the USA distributors or importers have learned all this info the hard way and that is their proprietary advantage. Somehow we have to feel our risks are minimized and the cheapest way to do that is distribution of info I feel. Somewhat related..... it would be good for some semi formal feedback channels so we can have our own built in consumer reports regarding how well and how long these bikes last and specific companies could begin to earn good reputations. I would appreciate any other ideas Thanks Scott in Atlanta, GA
  9. Wille said, "Been riding and wrenching for almost 50 years and almost exclusively on singles both 2 and 4 cycles from 50 to 650 cc. " _________________ Great Willie ! then you would know. I am not criticizing anything, I am just curious if some engines are different because they use more or less or different vibration canceling techniques...... then which manufacturers and models use which techniques ? My thought was also that as you say todays single cyls can be as large as 650cc and I just dont remember any single cyl models from 30, 40 or 50 years being that big. Maybe there were some and maybe those were the motorcycles that made your hands go numb after riding a while due to the vibration. My original premise/question was that maybe singles are (partly) more popular in this era because the mfgrs figured out better how to reduce vibration and preserve longevity and build bigger motors etc. Can you tell me which models use separate spinning balance shafts ? Have you ever noticed a single cyl engine that seemed to have an over sized fly wheel compared to multicylinder bikes of same displacement etc. I have no experience with motorcycles.... all my experience is in aviation and torsional vibration can bring down planes. What is different is that propellers flex and if they can flex a little for each combustion pulse then the force ( can) builds just like when you take three jumps on a diving board. It is called harmonics and is the same as control surface flutter like the flapping of a flag on a pole except that the vibration is rotary in nature. I'm sorry this is way off the topic but I was wondering why/how chains are prevalent in motorcycles and basically forbidden in propeller reduction systems for airplanes.
  10. What puzzles me is that none of the 6 or 8 big name motorcycle mfgrs that market single cyl motors mention as any attempt to be competitive what measures are being taken to minimize vibration. So are we to assume they "ALL" use exactly the same methods ? There could be a company that uses flexible components, counter weights, and balance shafts along with heavy flywheels to make the smoothest possible single cylinder motor and have a significant advantage "smooth running and longer lasting" yet I never see any mention in advertising literature or vehicle spec charts or website descriptions etc. Again this puzzles me. Maybe it is something they are all trying to hide. Do they all have a secret agreement to not mention vibration ? Recently I found three mfgrs "BEFORE 1920" using 4 cylinder motors to largely cure vibration woes. One was 1905 ! I will soon share some photos and info on these motorcycles when I gather the info. From memory one is the ACE motorcycle co, and another was the Henderson motorcycle co.
  11. preventec47

    Getting back into riding need help

    I was under the impression that some of the still carbureted and air cooled 4 strokes with lower compression are not so hi strung and since effectively a being a little de-tuned are longer lasting, more reliable, have extended maintenance intervals and are easier to work on. Well of course the tradeoff is performance. You normally cannot have it all ... well sometimes if you pay a boatload of money etc. I would assume the redline rpms ( hence max power ) are less but I do not know that for sure. I basically always believed ( with no real experience ) that the lower end cranks and bearings etc on 2 strokes wore faster and needed as much or more maintenance than the top ends of 4 strokes due to the diluted lubricants moving through the spinning components.
  12. Somewhere in the very early 1970s I went into a Harley Davidson dealer and learned a lesson about kick-start. Their large bike electric model was called the XL and the kick start model was called the XLCH. The CH, said the salesman, stood for "Charley Horse" in the leg muscles when kick starting..... Thats the only thing I know about Harley Davidson bikes. OH... and an old term "Kick-Back" is not heard much these days but I recall the big bikes were responsible for a broken leg or two.
  13. preventec47

    New helmet after crash

    The crash also had a long lasting effect on your brain function and decision making if you want to throw it away. Have you ever heard of an NFL football player needing to replace their helmet after a hard hit ? No Never. Same thing.
  14. preventec47

    New helmet after crash

    There are some plastics that age and degrade over time. The word "plastics" is very broad and covers a thousand compounds and formulas and I cannot believe they would make helmets out of stuff that degrades in five years. I think it has to be a scam by the helmet companies to get us to spend more money. Yes I know for a fact some plastics become brittle but there are many other compounds including fiber reinforced resins like fiberglass or epoxy based carbon fabrics etc that have long lives. I have a carbon hockey helmet that is about 25 years old and I dont doubt its strength. On the other extreme, I have high school football shoes and helmet where the facemask and cleats on the shoes crumble like ritz crackers or potato chips.. However after 35 years the helmet still seems tough and hard..... BTW... helmets do not prevent damage or concussions by reducing the inertia forces.... They minimize injury by dispersing and distributing point load forces over larger areas. There is no detectable difference in the inertia. In order to alter the inertia you must have a greater distance ( and greater time at a certain speed ) to reduce the deceleration. Think about the crumple zone on cars. If the car crushes 3 or 4 feet then that is an example of greater distance and time for deceleration. A helmet would have to be as big as a beach ball with a crush zone to reduce inertia.
  15. Yea that little 50cc race bike is impressive. I wonder how fast they go on the race track ? It looked like at least 60 mph. Hows that for legal on the streets without license ?