Converting a GY6 2 valve to 4 valve - By dmartin95 (Read 8,698 times)

[dmartin95]

The other night I finished my first 4 valve conversion. I recorded the whole process but am not done with editing yet. I will add the videos in the coming days...



The kit I purchased was a Taiwan kit, but not the Taida kit. I also own the Taida 4 valve which is a higher quality and comes with all the right stuff, unlike this kit... For those who clicked the link you will see it comes with 4, 213mm cylinder stud screws, but only 2 are the right size. You will also need 2, 218mm studs. I acquired them from a Taida 218/225 kit. In addition, you will need to increase the chain to a 46 (aka 92) link chain.



The other upgrades Consisted of a 58.5mm BBK bringing it up to a 155cc, installed an 11 pole stator, Hoca Premium Gasket set and this Taiwan CVT set.



I fired her up and after finding the right Jet setup (#35 and #108 in Keihin PD24J) she runs smooth as butter and in my first test runs I hit 58MPH and was only at 6000RPM's with plenty left to go... I can't really get into her until shes gets broke in.



The components were around $300 with another $25.00 in gaskets and various other materials. It's one of an upgrade without having to cut the case....



Here's some pics:





And here's a video of me starting her up:

[Alleyoop]

Martin , it is not running as good as it should it is bogging on you when you open the throttle that is the HOLLOW SOUND BOG you hear. It needs a little more fuel, you can try Richen the Fuel Ratio on the carb.
It should rev up nice and quick without hesitation and or bogging and come down quick to idle.
Alleyoop

[cyborg]

What threw me was the pipe that looks like a 2stroke expansion chamber,,,all in all not a bad build ,,,a little more tuning and it's going to be great!!!!

[jojo]

Awesome man.

[dmartin95]

May 12, 2015 19:17:44 GMT -6 Alleyoop said:

Martin , it is not running as good as it should it is bogging on you when you open the throttle that is the HOLLOW SOUND BOG you hear. It needs a little more fuel, you can try Richen the Fuel Ratio on the carb.
It should rev up nice and quick without hesitation and or bogging and come down quick to idle.
Alleyoop

I can try a 110.... Right now it has a 108 and 35.... Anything larger than the #35 she spits fuel out the exhaust... A #114 main and she was smoking out the exhaust... My sweetspot has to be in between the 108 and 114. What do you suggest?

I should get another video with the stock air filter. It's sounds completely different. Then again, I suppose it would because it would be taking in way less air....

I thought that "hollow bogg" sound was from the acoustics of my air duct....

I have an O2 sensor... I need to get out to a muffler shop and have my bungs welded on... Once I get the O2 sensor I can eliminate the guess work...

[dmartin95]

May 12, 2015 20:46:21 GMT -6 cyborg said:

What threw me was the pipe that looks like a 2stroke expansion chamber,,,all in all not a bad build ,,,a little more tuning and it's going to be great!!!!

Are you talking about the part on the end of exhaust? The red part? 

It is an expansion chamber. It comes off in the event I want to open it up for more air... It was sold as a performance exhaust and the ad said you remove the chamber when you're going to race... I only selected it because it matched the colors of the scoot.... 

For a first time build, it was a challenge. When you're building something like this, You can't just log onto a web forum and ask questions... Like who would've known that I would need to acquire longer studs? Or split the case and install a new chain, what's the length, etc etc... I was in over my head but managed to pull it off...Even though she still needs a little fine tuning, I was quite proud of myself when I heard her fire up for the first time.

[jojo]

Im still patiently waiting to see you bust out that gy6 200 B case and see what you do with it. dmartin95

[dmartin95]

May 13, 2015 10:47:30 GMT -6 jojo said:

Im still patiently waiting to see you bust out that gy6 200 B case and see what you do with it. dmartin95

That will be coming up real soon...

That will also have a 4 valve head... It will also be liquid cooled...232cc (76mm & +8.8mm stroker), Dr pulley, Ecotrons EFI and just about every other performance upgrade one can think of... I'm gonna race that one.

I can repair anything on a GY6, but this is the first time I actually split the case and built one from the ground up... Now that I have some experience with these GY6's you're going to start seeing the builds turn out faster. It boosted my confidence when she fired up... It's a really good feeling when you build a motor yourself and it actually fires up.... 

[jojo]

Oh no doubt for sure. I'm still pecking away at my gy6 200 it sucks when you are getting progress and then hit a stopping point bc of misc parts needed here and there.

[dmartin95]

May 13, 2015 11:07:25 GMT -6 jojo said:

Oh no doubt for sure. I'm still pecking away at my gy6 200 it sucks when you are getting progress and then hit a stopping point bc of misc parts needed here and there.

I don't remember, Is your 200cc one that came stock with your scoot or are you building it?

[jojo]

The scooter was given to me in pieces from a friend. The motor is the scrappy dog gy6 200 B.

[Alleyoop]

May 13, 2015 10:36:28 GMT -6 dmartin95 said:

May 12, 2015 19:17:44 GMT -6 Alleyoop said:

Martin , it is not running as good as it should it is bogging on you when you open the throttle that is the HOLLOW SOUND BOG you hear. It needs a little more fuel, you can try Richen the Fuel Ratio on the carb.
It should rev up nice and quick without hesitation and or bogging and come down quick to idle.
Alleyoop

I can try a 110.... Right now it has a 108 and 35.... Anything larger than the #35 she spits fuel out the exhaust... A #114 main and she was smoking out the exhaust... My sweetspot has to be in between the 108 and 114. What do you suggest?

I should get another video with the stock air filter. It's sounds completely different. Then again, I suppose it would because it would be taking in way less air....

I thought that "hollow bogg" sound was from the acoustics of my air duct....

I have an O2 sensor... I need to get out to a muffler shop and have my bungs welded on... Once I get the O2 sensor I can eliminate the guess work...

First try just Turning the Fuel Ratio Mixture Screw on the carb COUNTER CLOCKWISE to richen it up and see if you can get enough fuel to satisfy the amount of air coming in. When turning the Fuel Ratio Mixture you are looking for the HIGHEST IDLE with every 1/4 turns. Also wait for about 10 seconds after the 1/4 to allow the motor to catch up with the new setting. As far as the MAIN JET wait until you get the bog out from the low end, then you can work on the top end part.

REMEMBER YOU ARE LOOKING FOR THE HIGHEST IDLE OUT OF THAT SCREW.
Alleyoop

[dmartin95]

May 13, 2015 11:17:52 GMT -6 jojo said:

The scooter was given to me in pieces from a friend. The motor is the scrappy dog gy6 200 B.

Oh yeah! Now I remember.... How's yours coming along?

[jojo]

Well I don't want to thread jack you here. But I'm working out some little links here and there. If you don't mind I'm going to PM you.

[dmartin95]

May 13, 2015 12:40:51 GMT -6 Alleyoop said:

May 13, 2015 10:36:28 GMT -6 dmartin95 said:

First try just Turning the Fuel Ratio Mixture Screw on the carb COUNTER CLOCKWISE to richen it up and see if you can get enough fuel to satisfy the amount of air coming in. When turning the Fuel Ratio Mixture you are looking for the HIGHEST IDLE with every 1/4 turns. Also wait for about 10 seconds after the 1/4 to allow the motor to catch up with the new setting. As far as the MAIN JET wait until you get the bog out from the low end, then you can work on the top end part. 

REMEMBER YOU ARE LOOKING FOR THE HIGHEST IDLE OUT OF THAT SCREW.

Alleyoop

Can you expand on what you mean by "looking for the highest idle"?

I totally follow ya on adjusting A/F screw to richen it up.... But I'm having a hard time separating RPM's with Idle in the context of your post... When you increase the idle, RPM goes up.... With the current setup I have now if adjust higher my RPM's increase and i'm already at 1800 rpm when at idle... Stock RPM idle was 1700

So can you expand on what you're saying because I'm pretty sure I'm not understanding exactly what you're saying...