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Post by dragzooks on Jul 29, 2023 7:30:52 GMT -5
Howdy fellas/fellettes! Just got into scooters and found the site! Amazed at what you all are doing with these scooters. I’ve been dragracing 4 cylinder jap bikes last 25 years and I see the same kinda stuff I do being applied to scooters, it’s great, I love it. I’ve raced everything from kz1000 to gs1150 to busas. Stock to 600hp turbos, but now I’m building a little kymco super 8 50r I thinks it’s a 2016 white with red model. Someone swapped out the original engine for an older 139qmb that’s barely alive at this point. It’s a short case too so it’s got the 10” back wheel. The rest of the bike is pretty much stock and it has its correct 12” front wheel and bodywork still in 8/10 condition. I’m considering building this 150 (157qm Chinese engine) my buddy gave me and welding in some mounts. But after watching some of the two strokes like Brent’s and well that’s the only name I know so far, I’m not sure if even the most radical 4 stroke can compare.
So let me ask you guys this, can a big bore 157qm motor built with good stuff hang with a built two stroke Minarelli clone or would you need the Malossi rc one before the two strokes really rip like I seen in some of the videos. I should add in I’m a full time motorcycle builder/customizer/engine builder for last 15 years and have machine shop/welding/fab equipment and tons experience building these types things of engines, just not this particular genre if you will. I’ve built 1600cc busas and converted them to standalone injection with Holley or maxxecu, all kinda of one off machining stuff so I don’t mind a challenge. I just don’t know much about these Chinese engines or the Italian two stroke stuff (I’m assuming Italian by the name).
So if anyone wants to save me about of time digging around the internet and researching this stuff and prolly save me a dollar or two wasting money on four stroke China/Taiwan parts if it’s pointless, feel free to “educate” me! Btw, this is for blasting around town, not dedicated racer. But I don’t mind temperamental and running a little hot and all that comes with built motors. I wouldn’t know what to do with myself if I didn’t have to constantly fix something, 😂 😉 😉
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Post by aeroxbud on Jul 29, 2023 8:36:35 GMT -5
Welcome to the forum. You sound like you will fit in around here. Nowhere near the tuning potential, or parts availability with the four strokes. It's more expensive too. Not saying it can't be done. But at the sport, mid race and race level there are massive amount of parts available. I know you want some fire breathing monster. But for around town a good sports cylinder with a bigger carb. Expansion chamber exhaust, and a variator would rip. Believe me having to get over 10,000 rpm to make any serious progress in a town isn't fun for long. A stage 6 sport pro and a Yasuni R would give you over ten horsepower. In something weighing 200 pounds, that's fun. My favourite setup has to be the stage 6 street race with matching pipe. For longevity and power it can't be beat.  |
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Post by wiscootsin on Jul 29, 2023 21:49:34 GMT -5
between a 2 stroke 49cc minarelli build and a 157qmj build i think it really depends what you're hoping for. The 150cc 4 stroke wont ever have the fun appeal of shredding on a lightweight built 2 stroke.
Those kymcos came in a 125cc 4stroke gy6 version, and they ride very nice, maxing aroudn 55mph stock. You'd likely more easily get higher top speed throwing in a built 157qm.
But really depends what kind of fun you're hoping for.
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Post by dragzooks on Jul 29, 2023 23:24:03 GMT -5
That’s kinda what I gathered after watching some of Brent’s videos of his Malossi rc one ripping. Sounds like you wack it open and it goes right up on the pipe, the clutch lets it go right to peak power and the cvt responds as it should. In other words, he’s got it dialed!
Problem is I’m a 4 stroke guy. That’s what I know and have built for the last few decades. I grew up on two strokes though, so I do have some decent knowledge of them. Rm80 was my first dirt bike at like 13 or something and had ol Yamaha two stroke streetbikes too—lil 200 twin cs3 and a few ratty but fast ex chambered rd400s that were so temperamental it drove me crazy as a kid. I think it would be different with age and knowledge prolly no biggie to keep running.
So would you mind briefly breaking down the two stroke option? From my understanding there’s a Chinese two stroke that’s a 1pe40qm (or something to that extent-I’ve kinda got a grasp of how the Chinese engines are numbered with the bore size, pair valve or not etc etc) that is a clone of a Minerelli engine. Then you have aftermarket company’s such as Malossi making kit engines/parts with the RC one being top notch from what I’ve seen (but pricey). Can the clone engine be built up the same just knowing you’ve got cheaper castings and no meat to work with (I’ve seen the difference in the crankcase cylinder flange area ). All the parts interchange?
Is there a post you guys consider the Bible on the two strokes or does any of the aftermarket manufacturers have a good detailed explanation on their site of this stuff so one doesn’t have to muck around forever researching this??
I was thinking of building the 157qm spare engine I have. Taida (or whoever) 4 valve head, fully port it not just clean up the casting with sandpaper rolls but actually port it. Friend has flowbench I can use anytime and I have machine shop and mc dyno. Setup springs correctly, all the usual stuff for 4t engine builds. I was told the cams they sell are joke pretty much, no cam card and I watched a video where an NCY had like only a .001” more lift. I’ve been buying cams from web and megacycle for years and imagine I could sweettalk one of them into hard welding and regrindjng me a real cam. For that matter, such a simple cam, I could turn up a billet spool (that’s what a billet cam starts life as) outta tool steel and just have it ground. I know Isky does Briggs and Stratton cams so don’t see why they wouldn’t do one.
Anyway, I’m real good with injection and standalones and was thinking for about $300 for a microsquirt, a Grom throttle body and cheap fuel pump and lines and I could inject it and full control of mapping.
A 232cc 4 valve, good crank/rod be it stroker or not, sitting at 11:1 comp at least and with fuel injection should make for an interesting scoot. Or would the 2 stroke still blow it away???
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Post by 190mech on Jul 30, 2023 4:01:17 GMT -5
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Post by dragzooks on Jul 30, 2023 8:19:50 GMT -5
Thanks! Can you recommend a good supplier of the aftermarket parts be it 2t or 4t? I’m hooked up with all the motorcycle companies thru my day job but I haven’t seen anything specific to Gy6 4t or the 2t minarelli stuff in any catalog. I can get some Koso stuff from Parts Unlimited like Grom engine parts and various gauges but that’s all I’ve seen so far. I can make a lot of stuff myself but I’m gonna need to buy the heads, cylinders, cases and such. I saw someone saying it takes a while to get the Malossi stuff, does not anyone here stock it?
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Post by aeroxbud on Jul 30, 2023 10:11:44 GMT -5
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Post by geoffh on Aug 1, 2023 16:01:54 GMT -5
A bit late to this party  after much deliberation you simply don't,t get the aroma from a 4t. Geoff |
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Post by aeroxbud on Aug 2, 2023 5:19:22 GMT -5
A bit late to this party after much deliberation you simply don't,t get the aroma from a 4t. Geoff You will have to buy yourself one of those two stroke candles Geoff. Now the jog is gone. 👍 |
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Post by jbjhillbilly on Aug 5, 2023 13:56:58 GMT -5
If you really want to do a 4t, I’d see about finding a Genuine 170i donor engine.
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after much deliberation 