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Post by scootypuffxl on Jul 13, 2020 21:59:24 GMT -5
So, after destroying 2 ebay and Amazon bbks and frying 8 starters and 3 crankshafts... what am I doing to put both my Chinese scooters back together? Taking a poll to see what parts go into the 2012 taotao (assuming) atm50 and the 2008 vitacci solana (assuming), 49cc scooters. Both have 100cc bbks,heads,a9 cam, aftermarket exhaust, orange cdis and coils, but one was built off ebay and one off Amazon... What are the best of what money can buy, and what's the slim budget build? Who has the secret sauce, and who can build a 139qmb on a budget? Let the polls begin!added afterwards, wont let mead to polls....
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Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
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Post by Petro on Jul 17, 2020 2:12:18 GMT -5
Budget in the short run, what you've already experienced. Budget in the long run, my signature more or less.
Most important to me is oil cooling, it even makes an Ebay kit last a while longer...
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Post by aeroxbud on Jul 17, 2020 4:30:05 GMT -5
A lot of people seem to think the 100cc kits put too much stress on the engines. When you double the capacity, the failure rate goes up. People do do it, but at that size the importance of a quality kit increases.
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Post by Mech Warrior on Jul 17, 2020 11:10:10 GMT -5
^ The realest shit i never wrote.
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Petro
Scoot Enthusiast
Posts: 149
Location: Gothenburg, Sweden.
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Post by Petro on Jul 18, 2020 14:02:09 GMT -5
A lot of people seem to think the 100cc kits put too much stress on the engines. When you double the capacity, the failure rate goes up. People do do it, but at that size the importance of a quality kit increases. One thing people doesn't take into consideration is the weight of the lot, especially the piston... I don't have the weights in my head but an 50mm Airsal (80cc) was 12% lighter than a 47mm Ebay (noname) one I had laying around. I regret I never put my current 90cc piston on the scale...
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Post by GrumpyUnk on Jul 19, 2020 8:48:56 GMT -5
My opinion is the orange ignition kits are of dubious value. A test, on site or youtube, indicates they tend to advance initial spark timing and add about zero to the performance... Makes them harder to start against the advanced timing, but adds nothing 'up top'. I doubt there's a lot of difference between the two setups. Some, emphasize SOME, name vendors purchase from suppliers who are supposed to meet certain specifications. The product they sell is NOT made by them, but from external sources. Its quality may vary. Or the retailer may tend to their garden, and insure that ALL product they retail is of proper quality. A customer does not know. Destoying BBKs and crankshafts can be done by multiple paths. Lubricant, heat, rpms, carburetion, and how the engine is 'treated' all play a part. Starting and letting things warm up a bit before going WOT is one way to improve longevity. Breaking in the new parts with variety of rpms and changing the load also helps. Using oil that is proper for the conditions is necessary to prevent premature failure. Choosing gearing to keep rpms somewhat in control rather than at redline for long runs and actually 'coasting' for a bit every now and then help. The mass of the piston is accelerated and decelerated at both TDC and BDC. More mass means more pressure on the crankshaft rod bearing, passed on to the end bearings. The force goes up with the square of the rpms, and the mass... I don't have it memorized. If you can minimize the mass increase for a given diameter/displacement, you will help longevity. The force of combustion is higher in total for a larger bore. I am of the opinion that the design was more for a 70cc-ish diaplacement, the 49cc being more 'legal' than practical. The market for 49cc engines being the 'moped' limit in many states, it is likely larger than that for somewhat bigger displacements. If you look at a cylinder, there is a LOT of cylinder wall in a 39mm bore, even a lot left with a 44mm or a 47mm, such that larger bores are possible without change to the casting process. The short story is larger bore and higher rpm are a recipe for shorter life. The parts used should be inspected and measured at the time they are assembled. The best assembly methods and procedures cannot prevent failures caused by poor quality parts. The closer you run to the edge, the more your engine life depends on quality to meet the more demanding requirements. Do be aware that upon first starting, the pistons and rings will generate a LOT more heat than when they have been broken in. The rings are trying to seat to the cylinder walls, the pistons are at their largest diameter, and so on. Keeping the rpms within reason for a while is a good practice. It likely does not hurt to run the rpms up, BUT, immediately back them down, so there is a bit of manifold vacuum to pull some oil up onto the cylinder walls to dissipate a bit of the heat just generated. Babying a little bit, but using them just the same, especially during the first few hours of operation is a lot better for longevity than running them up to 8,000 rpms and whizzing down the road right away... tom
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Post by bullybike on Jul 29, 2020 23:39:02 GMT -5
the secret sauce isnt necessarily expensive parts. You have to understand that with the cheaper kits what is lacking is finishing details. I can make a Glixal bbk just as good as a fancy pants brand ya know how? Prep. sandpaper . Soften up the edges of the piston, the skirt. Gap the rings really well and scuff up the cylinder walls. otherwise the engine has to do all the wear-in itself. After pulling my first build apart I found my ring was WAY tight and my top ring was all shiny near the seam. Also there was some glue from where factory mated the bottom case causing it not to seal and loose compression. Make sure all your mating surfaces are free of high spots and add a TINY amount of copper permatex between gaskets.
A slightly looser ring seal and lower friction piston equals less friction and a cooler runinng engine. People think those cheap kits are bad but its just they aint done yet.
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Post by bullybike on Jul 29, 2020 23:40:01 GMT -5
also only add one part at a time. throwing the whole spice drawer at it only works for chilli! 😉
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