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Post by walleye1963 on Jan 17, 2020 1:56:51 GMT -5
hi guys been awhile.been saving sinse last year to get a new scoot.the one i picked is the icebear gen iv.what i need to know is can i put a ebay 47mm bbk on or do i have to spend $100+ for a hi priced one. i live in a small town so i wont be beating it up just want to keep up thanks guys.
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Post by 90GTVert on Jan 17, 2020 8:30:16 GMT -5
Plenty of people use cheap BBKs. Sometimes piston rings don't seal with them, but lots of people do fine with a cheap kit. You could consider using a seller like PartsForScooters that has some reasonably priced kits and has a good reputation for customer support.
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Post by SMALL CC TEK on Jan 18, 2020 0:11:44 GMT -5
Cheap kits work just ask around as to what works for your application . The Cheapest i would go is Naraku they have decent quality for the buck and a reliable parts stream , pistons rings etc ..
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Post by GrumpyUnk on Jan 18, 2020 8:26:43 GMT -5
I have installed over a half dozen BBKs. One made of part I gathered from different sources, the rest using 'kits' that had the required bits and pieces. The quality does vary, but I have not been disappointed for the most part. One vendor shipped two cylinders each individually wrapped in a plastic bag, enclosed in a bubble-pack envelope. The cylinders clanked and bounced against each other, causing chipping and scratching. The sent another pair of BBKs, shipped exactly the same, as an attempt to make good. I thanked them, and just used the best of the parts.
Others wrap them so you don't even want to open the package, much like a gift box. Quality on them was good also. The last few I have gotten, two were fine, wrapped as stated, the other was a bit tight with its piston fit to the cylinder. Most will have the piston free enough in the cylinder to fall in either direction of its own weight. This one was a bit tighter. I thought it too tight, so adjusted the piston diameter on the skirt area which was the tightest. Installed, and it seems fine.
All of them needed to have the ring end gap adjusted. They were all just a bit too tight. I guess better too tight than loose, as making them bigger is a bit difficult.
After installation, the engines seemed to run hot for a while, which is what I expected. They all ran well, and developed more power than the 39cc piston/cylinders produced. The apparent least unpopular size, the 63cc version, seemed almost as strong as the 47mm size. Of course, it was installed on a machine with a well broken-in final drive gearbox that got all-new bearings.
I am not 'into' riding these a lot, but like to work on them. Therefor, I did not investigate the higher priced options, but went for the lowest cost to get them running well and back on the road. I do not know the life expectancy of any of them, and cannot forecast. As far as I know, none burned oil, and all were strong runners.
I would repeat my choices because as far as I can tell, they seemed to work well. I inspected all the parts, and was positively impressed with the machined surfaces and the casting quality. I have no complaints except for the packaging method one firm used. A 72cc BBK is a 4.4 cubic inch displacement. Most riding lawn mowers have 7 times that displacement. A 139 can rev to 8-9k, while the mower engine will be limited to ~3500-3600rpm. Not a real comparison, but just a note that we expect a lot from a 'hummingbird' style engine. IMO.
tom
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