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Post by ryan_ott on Sept 30, 2017 19:27:24 GMT -5
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Post by catchacuda on Sept 30, 2017 22:29:27 GMT -5
Good post!
Is that from seller gy6store? Looks similar to the one I bought, though my ports weren't quite THAT bad (1st pic). I spent alot of time filing and sanding the ports and smoothing the port edges. A quick hone, many thorough washes, blasts of compressed air and I deemed it worthy of installing. Also have my durations at 186 & 124. Could have saved myself some time by purchasing a quality kit...
What are your porting weapons of choice?
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Post by benji on Sept 30, 2017 22:39:45 GMT -5
I agree very good post! Please tell us the seller name. I got a cheap ruima kit from scooter assassins on eBay and it wasn't too bad for $50. Didn't look that tho haha.
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Post by benji on Sept 30, 2017 22:41:16 GMT -5
Not sure where those rings came from haha they don't look like there for that piston.
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Post by ryan_ott on Sept 30, 2017 23:00:03 GMT -5
The seller is motor99motor. It's just a cheap kit I'm sure the others may be slightly better but this was pretty funny. It's fine after some work, not that everyone has the ability to fix something this bad. Before you buy a cheap kit think twice about it. Strange enough the ports do line up at BDC. That's a plus.
Speaking of GY6 store I picked up a 47mm piston from him and it has a .3mm taper to it. The crown fits the bore,lol. Not to mention it's stupid design. I'll get pics tomorrow of it.
More eBay junk.
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Post by ThaiGyro on Oct 1, 2017 1:47:41 GMT -5
Wow! Thanks for the post. I am with you and your quest. I have been porting for many years, but never on such a rough beginning. Good luck...doesn't mean you can't get a good build.
I have used both Dremel and others...prefer more heavy duty equipment. I have a motor and flex drive set that is for the dental industry. (For making fake teeth) Speed is a foot petal, which takes some getting used to. Spins to 20,000 rpm, OK for polishing. The flex cable is narrower than Dremel sets, but takes the same bits. I no longer buy dental quality burrs. They are higher quality, but nearly 8 times more cost. I HAD super nice curved extension heads...45 and 90 degree, but somehow they went bye-bye when I moved to Thailand. Porting was very much better with them.
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Post by 90GTVert on Oct 27, 2017 6:50:46 GMT -5
I'm way late here, but it's not just the 70cc kits. I tried out a cheap 54mm kit some time ago. Actually, I ended up with 3 of them. They were of course a bit rough cast. The main problem I had with them was noise. I tried 2 of them (one arrived with a cracked skirt and was replaced by the seller) and both were noisy. Lots of clattering when the engine ran. I actually got it setup so it ran fine and made similar power to other mild builds. Eventually the noise annoyed me enough that I finally got out the dial bore gauge and mic and the clearances were significantly wider on the new cheap kit vs a new Taiwan made kit from Autotech355. The Taiwan kit was about double the cost, but it also didn't rattle and was better quality overall. 49ccscoot.proboards.com/post/281740/threadI think too often we get obsessed with price, when our strategy in modding should be more focused on at least maintaining and preferably improving quality when we buy aftermarket parts. I don't buy expensive stuff too often, but I don't have any plans for buying $60 big bore kits anymore. The Taiwan kit was about double that, but also came with a head, wrist pin bearing, exhaust gasket, and exhaust studs. There are still flaws in most sort of generic Taiwan made parts, but they seem to hold up well. There are flaws in plenty of big name parts too, at least when you're buying cast iron sport stuff like I have, but they tend to be more consistent. I wish Polini, Malosssi, etc... would make cast iron sport kits for the 90s. 90s are a bit worse to deal with low quality stuff, I think. The reason being, stroke lengths vary commonly being 42 and 45mm. Cylinders get labeled as short or tall and allegedly work with one or the other of the strokes, but sometimes I've had short cylinders work better with 45mm strokes than the tall versions that are supposed to be for them. They often require lots of setup time, figuring out spacing, milling, etc... to get them where you want them. Buying cylinders and using the same spacers and head and such each time for a quick setup would be nice. It could possibly be done with Hoca/SSP-G stuff, I've only owned 1 short and 1 tall from them though and I'm not sure how much anything changed when the Hoca/SSP change occurred. Autotech355 has definitely offered different products over the years for his BBKs, because I've owned 2 of his 70cc kits that were different and not all of the 90cc stuff comes the same either. |
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Post by 190mech on Oct 27, 2017 23:19:50 GMT -5
Nice job polishing that turd Ryan!!I too have been stung by the cheap(junk) 70cc kits..Most dont have a proper head included,thus the buyer happily installs his 50cc head and wonders why it runs soo badly..When the unknown alloy piston skirt shatters and packs the bottom end with metal,buyer is saddened by a complete rebuild which is out of his budget..So he buys a 139qmb 4 poke and lives happily ever after!!Spending a bit extra on a Taiwan kit(with head) would have lasted many,many miles...  |
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Post by aeroxbud on Oct 28, 2017 3:20:51 GMT -5
Very interesting thread.
The scary thing is a lot of people might not know so much as people on here. Just get it through the post, and fit it.
One of the main reasons I always buy naked brands. You do get what you pay for.
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Post by 90GTVert on Oct 29, 2017 10:11:51 GMT -5
he buyer happily installs his 50cc head and wonders why it runs soo badly..When the unknown alloy piston skirt shatters and packs the bottom end with metal,buyer is saddened by a complete rebuild which is out of his budget..So he buys a 139qmb 4 poke and lives happily ever after!!) This reminds me of the candy bar commercials where one decision snowballs to catastrophe. Buys cheap 70cc BBK > Installs improperly matched components > Runs poorly/blows up > Rides a 4T > Gets ran over by Duck boat tour when can't leave red light quickly enough  Senseless tragedy. |
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Post by gsx600racer on Oct 29, 2017 17:31:38 GMT -5
I usually steer clear of cheapo engine parts, think its the last place you want to skimp on. You get what you pay for most of time. My experiences so far have been with Malossi, Polini, & Airsal kits. Nice job cleaning up that cylinder.  |
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Post by houseoffubar on Jul 15, 2019 16:23:58 GMT -5
Again, thanks for all the good info. I am building a 70. Motor now, and was curious just how bad the really cheap BBK actually were. I will be spending some money😂
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Senseless tragedy. 
