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Post by tuttlemon on Jun 25, 2020 8:00:24 GMT -5
I have a 150cc. I’m in the planning stages of boosting the performance of my bike. I came across a 4 valve head kit. I never seen this before. Can this be an upgrade, if so: how much of a performance upgrade would this add?
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Post by tuttlemon on Jun 25, 2020 8:03:28 GMT -5
Item description:
Scooter 4 Valve Head Kit & Cam Rocker & Cylinder Head & Bolt for GY6 G4 G3 125cc 150cc 152QMI 157QMJ GP110 4 stroke
Specification:
This product is suitable for GY6 58.5-61mm cylinder. Products using Japanese technology. Made in Taiwan, GY6 152QMI 157QMJ 125cc 150cc GP110.KBF4V.
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Post by fugaziiv on Jun 25, 2020 8:39:34 GMT -5
Unless it's Taiwanese, I'd say avoid. We've yet to find a Chinese 4v head worth stocking.
Matt
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Post by tuttlemon on Jun 25, 2020 9:30:50 GMT -5
But, realistically, a good/reliable/quality 4 valve would add performance? If so, how would that translate?
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Post by fugaziiv on Jun 25, 2020 9:35:11 GMT -5
But, realistically, a good/reliable/quality 4 valve would add performance? If so, how would that translate? Well, it would allow the engine to breath easier at higher RPMs. So the bike would perform better at the top, but it would require upgrading a few other parts as well, such as the intake, exhaust and carburetion to start. Because the powerband shifts away from the bottom with a 4v head, you'll probably be looking at weights/variator as well to capitalize on the added spin the engine can create. Doing 4V correctly on a gy6 is a big shift away from stock in actuality. Matt
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Post by fugaziiv on Jun 25, 2020 9:38:41 GMT -5
The real question is: What are you looking to achieve with your GY6?
Matt
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Post by tuttlemon on Jun 25, 2020 13:29:06 GMT -5
Top speed
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Post by fugaziiv on Jun 25, 2020 13:56:26 GMT -5
Right, I figured that much. Exactly how fast are you looking to go? Matt
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Post by rocketdogiv on Jun 25, 2020 20:27:38 GMT -5
I bought a cheap, relatively, Mainland Chinese 4 valve head. Not worth it. The casting is poor and the ports are rough. Taida, Taiwanese, makes a nice one but they are pricey $$$. You look like a big guy. Start with the simple things, lighter roller weights and an accurate tach, and work your way from there. Then put a 61mm big bore kit on it. Really the most power for the $$. That should get you and honest 60-65mph. Course with that comes a better exhaust and re jetting.
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Post by tuttlemon on Jun 25, 2020 23:06:29 GMT -5
I bought a cheap, relatively, Mainland Chinese 4 valve head. Not worth it. The casting is poor and the ports are rough. Taida, Taiwanese, makes a nice one but they are pricey $$$. You look like a big guy. Start with the simple things, lighter roller weights and an accurate tach, and work your way from there. Then put a 61mm big bore kit on it. Really the most power for the $$. That should get you and honest 60-65mph. Course with that comes a better exhaust and re jetting. I have upgraded the carb, deleted all the old intake stuff, and put a small foam UNI filter. I’ve rejetted the carb, and pit in some lighter roller weights. If you upgrade the cylinder, I’m aware you have to bore it out with the special tool, but: are there any other things you have to step up as well, like a different valve head, or anything?
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Post by tuttlemon on Jun 25, 2020 23:10:53 GMT -5
Right, I figured that much. Exactly how fast are you looking to go? Matt Mannnn.... sometimes I catch like 60-65 downhill and maintain it a little on flat ground, and that can be a little sketchy as far as suspension/bumps go. But, I’d like to maybe achieve 70-80 if possible? To have that extra power to pass quickly, or climb hills more proficiently.
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Post by rocketdogiv on Jun 26, 2020 0:58:24 GMT -5
You normally can put a 61mm Big Bore kit in a stock A Case Chinese scoot. Stock stroke and a 61mm bore is a little South of 172cc. Then you get into stroking it. More than 4mm in an A case is asking for interference issues. The largest an A Case can handle is 63mm when boring the case. If your not real careful you''ll cut into the oil passages. You could probably put a 6mm stroker crank in it if you checked all the clearances. You might have to grind a bit of the oil pump boss off. In an A case the most I would try is a 4mm stroke, over stock, and a 63mm bore. That will give you 193cc. There is such a thing as a B case. With those cases you can run a 232cc engine but it is $$$$$. Those engines will cost you thousands of $. Tuned correctly a 190 will take you to 85mph. But that will cost you as well. Add a good oil cooler too.
If it were me I'd just buy a bigger scooter. A 250cc scooter. By the time you upgrade and tune a 150cc A Case you could have bought a 2400 dollar 250cc that would do 85 mph. Just saying.
There's an old racer quote. "How fast do you want to go? How much money do you have?".
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Post by tuttlemon on Jun 26, 2020 8:01:06 GMT -5
You normally can put a 61mm Big Bore kit in a stock A Case Chinese scoot. Stock stroke and a 61mm bore is a little South of 172cc. Then you get into stroking it. More than 4mm in an A case is asking for interference issues. The largest an A Case can handle is 63mm when boring the case. If your not real careful you''ll cut into the oil passages. You could probably put a 6mm stroker crank in it if you checked all the clearances. You might have to grind a bit of the oil pump boss off. In an A case the most I would try is a 4mm stroke, over stock, and a 63mm bore. That will give you 193cc. There is such a thing as a B case. With those cases you can run a 232cc engine but it is $$$$$. Those engines will cost you thousands of $. Tuned correctly a 190 will take you to 85mph. But that will cost you as well. Add a good oil cooler too.
If it were me I'd just buy a bigger scooter. A 250cc scooter. By the time you upgrade and tune a 150cc A Case you could have bought a 2400 dollar 250cc that would do 85 mph. Just saying.
There's an old racer quote. "How fast do you want to go? How much money do you have?". I really appreciate all the info and specs, man. From you as well, Fugaziiv! So, as confirmation: my stock valve head will fit up fine with upgrading the cylinder(BBK)?? I watched some videos, and I recall something about piston clearance and the valves..
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Post by fugaziiv on Jun 26, 2020 8:35:23 GMT -5
You normally can put a 61mm Big Bore kit in a stock A Case Chinese scoot. Stock stroke and a 61mm bore is a little South of 172cc. Then you get into stroking it. More than 4mm in an A case is asking for interference issues. The largest an A Case can handle is 63mm when boring the case. If your not real careful you''ll cut into the oil passages. You could probably put a 6mm stroker crank in it if you checked all the clearances. You might have to grind a bit of the oil pump boss off. In an A case the most I would try is a 4mm stroke, over stock, and a 63mm bore. That will give you 193cc. There is such a thing as a B case. With those cases you can run a 232cc engine but it is $$$$$. Those engines will cost you thousands of $. Tuned correctly a 190 will take you to 85mph. But that will cost you as well. Add a good oil cooler too. If it were me I'd just buy a bigger scooter. A 250cc scooter. By the time you upgrade and tune a 150cc A Case you could have bought a 2400 dollar 250cc that would do 85 mph. Just saying. There's an old racer quote. "How fast do you want to go? How much money do you have?". I really appreciate all the info and specs, man. From you as well, Fugaziiv! So, as confirmation: my stock valve head will fit up fine with upgrading the cylinder(BBK)?? I watched some videos, and I recall something about piston clearance and the valves.. Well, no. Generally you'll want a matched head to the big bore kit you choose. If you go with a 61mm kt, you'll want a head made for a 61mm kit. The added benefit here is if you get a good one, the ports will typically be much, much larger which has an added power benefit. If you went with this cylinder: www.partsforscooters.com/169-485-SSP-G-Drop-In-61mm-CylinderYou'd want this head: www.partsforscooters.com/169-204_SSP-G_61mm_Cylinder_Head(You'll have to bear with my examples. I'm out of stock on all of this stuff at the moment. It's been a crazy spring with COVID related supply chain issues and all... ¯\_(ツ)_/¯ ) However, to back up to what was said previously: if you want to get up over 80 reliably, A GY6 isn't the best option unless you just want to throw money at it. A reliable 80+mph build isn't cheap, and a cheap 80+mph build won't be reliable. A well built 61mm GY6 is for the most part a reliable 65mph-ish bike, with a bit of headway above that when you need it. When you see people posting about a 190cc bike topping 90, that's full tuck, short sprint, WFO. They aren't maintaining that speed for any notable distance. Personally (and keep in mind I have easy access to pretty much anything you could want to throw at a GY6), If I needed a bike to do an easy 80, I'd be looking at something a 250cc+, and probably closer to 500. Some 250's don't crack 80 without room to run. Matt
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Post by FrankenMech on Jul 15, 2020 19:22:59 GMT -5
If you really want to go fast buy a motorcycle. The suspension and frame on a scoot really are not safe at speed.
A scoot is like an old girl's bicycle, real wobbly.
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