4 valve vs 2 valve By dmartin95 (Read 2,312 times)

[jct842]

You can get a little more scoots with an airfilter/exhaust/jet mod. By tuning the rollers/sliders, bigger variator and belt you can get a little more and if you take the windshield off you can get back what you lost on top end. The extra 20 lbs might hurt take off slightly but should not effect top end,..... but the window will hurt top end.

[Alleyoop]

Nov 18, 2014 0:00:48 GMT -6 Bashan said:

Possibly Alley, this has never been done to my knowledge on a scooter, it will be an exciting experiment. But Pete has the knowledge and experience to make this work. If anybody can do it he can even though he has never touched a GY6. But he has built so many super bikes it is dizzying. By built I mean had most of the engine parts redone or made from scratch. The man knows combustion chamber technology, valve train technology including no spring actuation, piston machining from scratch, balancing and blueprinting. He has access to a dynamometer and can actually get some hard data before and after. I told Pete I'd help him with the GY6 since he has never taken one apart but I doubt he'd have much trouble. And the supercharger? I just passed out. Rich

I am not saying Pete does not know his crap, the OP wants a little more ump and that is just way out there for what the OP wants And yes it has been done one guy had the head setup and it was spinning at 14k. All I am saying it's a nice project to fool around with but not for your daily driver or even joy rider. That is a motor for weekend runs and the rest of the week to get it ready for the next weekend.

[Alleyoop]

As far as getting about 4-8 more mph on your top end Slap in some taller tranny gears, not much money about 50 bucks and a gasket and 1 or 2 gram lighter weights to get your rpms UP AND VOILA.

[Bashan]

True enough Dr. Oop on both posts.

[clonedrone]

Nov 17, 2014 19:23:19 GMT -6 jct842 said:

It would be nice to come up with a quality piston too! 150cc's and just 2 hp per cube would be dyno-mite. Might need a wheelie bar!

I've done some research on a Higher end Piston.
There have been some customs built for a customer several years ago.
A run of qty. 25 will still be pretty expensive.Dunno if there really is a market for a High end Piston at the price it would take.
The 61mm piston I have for my yet to install BB, stroker package is pretty darn nice, this is coming from more than 20 years in the high end Piston business.
I going to touch it up some and have a Skirt and Dome Coating applied.

[clonedrone]

And to touch on the Big Valve Two Valve head.
I received mine, Checking the Valve job the Head had oversize Valves in stock Dia. Seats.
This would have flowed like crap if I did not check this.
Willing to bet the Fake Big Valve Head would have made it Slower.
If it comes in a Box with a Label part # on it it's JUNK!

I sent Borg some Pics of the Finished product.

[cyborg]

And the cleanup of the head Clone did was a work of art,,, nice blending of the guide bosses and you could tell just by lookin at it it will flow 2x better than the stocker,,, nice catch of the big valves in stock seats,,,, fuking idiots,,,I'll get those pics to Rich,,, gotta post them,,, a stellar job Clone

[clonedrone]

Nov 26, 2014 12:26:18 GMT -6 cyborg said:

And the cleanup of the head Clone did was a work of art,,, nice blending of the guide bosses and you could tell just by lookin at it it will flow 2x better than the stocker,,, nice catch of the big valves in stock seats,,,, fuking idiots,,,I'll get those pics to Rich,,, gotta post them,,, a stellar job Clone

Actually a work of Ed.
Ahh shucks Borg, Thanks!
Taking a quick lookie at some volumes I didn't see any advantage to hogging out the Ports.
The most important thing to any cylinder head flow is the Valve job, so most time was spent on it.
If you could call it a valve job it had a Flow Bench Valve job, They just aren't very happy engines with that.
I removed as little as possible material to the ports and bowls.
Hoggin dem out would be like flushing a toilet into a straw.

[cyborg]

i don't even think thoses kinds of ports help even with a lite blower,,,i think what you did was just enough to make a big difference and still maintain decent intake tract velocities and proper cylinder fill,,,,probably to the point of inertia charge,,,,an added bonus,,,,,(and i will try to get those pics you sent me to Rich tonite)

[clonedrone]

Dec 1, 2014 13:44:33 GMT -6 cyborg said:

i don't even think thoses kinds of ports help even with a lite blower,,,i think what you did was just enough to make a big difference and still maintain decent intake tract velocities and proper cylinder fill,,,,probably to the point of inertia charge,,,,an added bonus,,,,,(and i will try to get those pics you sent me to Rich tonite)

Yes Sir, I'm all about the Velocity!

[dmartin95]

Bump....

What are the different ways to increase the RPM's of a GY6?

I found this link showing different cams can help attain higher RPM's... What are (if any) other ways to increase the RPM's?

LINK

[cyborg]

One of the limiting factors of rpm's of these smaller engines is port and carb size and combined with the exhaust ,, restrictive to say the least,, in my case on my 4 stroke 150cc genuine Stella a 20%+ Increase in overall power can be achieved with a 3mm larger carb and a freer exhaust,, this is dynamometer verified by pinasco who makes the "kit",,, that is a huge increase from just 3 or4 parts,,, this is not even cracking open the engine ,,,carb/exhaust/intake manifold and filter,,,,,that's all,,, I think similar results can be achieved the way Alley did his build,,, stroker crank and taller final drive gears,, makes for a nice combo,, I think he could have gone one better with a 4 valve head but he and I are in different camps on that point,, let's put it this way,, I've built over a dozen hipo engines in the last six or seven years all the builds but one were 4 valvers,,,, the 2 valve job ran great ,,made excellent numbers hp wise, had astounding torque production,, and also had severe fuel sensitivity,, I had to mix my own fuel,,, always carried a can of pure octane with me and avoided riding that bike on hot hot days,,,the four valvers ran milder grind cams had better flow and we're not fuel sensitive once broken in,,,,the limiting factors on the gy6 that I can see with my eyes and have gleaned from this and other forums ( I have not had my hands on the inside of a Chinese scooter yet) is breathing ( too small valves carb intake manifold and exhaust) and crank /rods and bearing material strengths and balancing,,, I've seen 20+ hp gy6 engines for sale on the net,, cheap too,,,well over 100% of stock engine production numbers so I know it can be and is being done,,,with a decent build ,,a larger variator ,and taller final drive gears such as alley did I can envision 55-60 cruising speeds with terminal speeds in the 70-75 range on a good day,,,,if it were my build its 4 valves