michael whiteman
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50cc Bicycle Engine Full Kit Bike Motorized 2 Stroke Petrol Gas Motor Max 38km/h | eBay
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Don't be certain you'll get what you see in the add when ordering from E-bay sellers. May be true on Amazon also. The kit I ordered from this seller above came as a total surprise. I noticed things in his add that made no sense. Looking at the main picture #1, I saw that it has a belt drive trans. Then in #2 it shows a chain drive trans. Again in #7 it is a belt drive for a tapered shaft engine which you'll find to be a rare combination for an E-bay kit. Now I'm really confused so I contact the seller and he replies that #8 is the trany that comes in his kit. What he sent me was a belt drive trany that fits a straight shaft engine which I also received. I'm upset because my end goal was to purchase a GruBee trans in the future, but now it will not fit this straight shaft engine. After getting over all this (and this is totally my personal opinion) I concluded that the clutch bell support on a straight shaft engine is of a superior design, even though it limits you to this one transmission. I tried to contact the seller 4 times with no reply at all. I get E-bay involved and they get back to me saying all I can do is send it back. I explained that if I did, he would be paying the shipping and that seeing as I decided to keep it I would like to be refunded that cost of shipping to make up for the false advertising and the lies he told me. You can guess... E-bay just laughed at that. So my advise to all of you who are considering this...........buy from a reliable dealer who knows exactly what they are selling and can help you if there are any issues involved with your purchase. The extra expense will be well worth it for sure. I am totally convinced now the E-bay sellers just get a sealed box from the manufacturer in China and stick it on their warehouse shelf until the day they ship it to you. They never open it and wouldn't know what they were looking at if they did. Go to their "store" page and look at all the other Chinese junk they're trying to sell us.
The scary thing still with the belt drive trans. is you can not determine if the engine it's attached to has a tapered or a straight shaft without removing it and the advertising pictures seldom, if ever, show this. There is an early and a later transmission casting. The later improved casting shows the 4 nuts being exposed around the shaft under the chain sprocket. On the earlier casting you see nothing but a protrusion in the aluminum that contains a threaded hole on the inside. Look closely at pic #1 and you can see one of the four protrusions.
This trans below is for a tapered shaft engine
This trans below is for a straight shaft engine
Let me stop here and clarify to newcomers that when you read or hear "straight shaft" engines there are 2 different ones to consider. The most commonly referred to is the Hausheng from China. Their shaft measures 15mm ( 0.595” ) and has a threaded hole in the end. Sometimes it's called 5/8"......but be aware that it is .030 less than 5/8”. The Predator at Harbor Freight is the other engine that has a 5/8" straight shaft.
Now if you want to learn about chain drive transmissions take a look at the BikeBerry website. Although they have a poor reputation for customer service they do a very good job explaining their product. Ordering a single item form them is probably safe. Everyone has an opinion about their kits. Watch the video comparing a single chain and dual chain trans. and you'll learn all about them.
No matter what trans you decide on you will need to know the gear ratio to determine your top speed, and choose a rear wheel sprocket.
There are many speed calculators on the web to choose from that will help in determining this. Do this first so you can decide if the trans and sprocket in the kit you are considering will give you the performance you're expecting.
Belt drive trans have a 20T and a 100T pulley ratio 5:1
Single chain trans have a 9T and a 27T sprocket ratio 3:1
Dual chain trans have a 6T and a 41T sprocket ratio 6.83:1
I sincerely hope this gets you started in the direction you want and not end up like I did. For me it was a welcome mistake in the end. michael
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