Advancing timing on gy6

[padly1995]

Hello,
i want to advance timing on my gy6 scooter, by making holes on pickup sensor wider.
I just want to be curious about the position, so i have a question:
To advance timing i must move pickup to the left right (towards the exhaust)?
As much as my logics works moving pickup to the right would be retarding the ignition?
I just saw a picture on the web that is making me crazy :S

What do you think is advancing timing on 75cc gy6 even worth of doing?

Thanks!

[padly1995]

One more quiestion...
While ago my oil seal on crankshaft started leaking, so i repleaced it, but when it was leaking scooter was going a little bit faster and it was also reving higher... So if i install oil breather effect would be the same, right?

[bull]

Originally Posted by padly1995

To advance timing i must move pickup to the left right (towards the exhaust)?
As much as my logics works moving pickup to the right would be retarding the ignition?
I just saw a picture on the web that is making me crazy :S

What do you think is advancing timing on 75cc gy6 even worth of doing?

Thanks!

Originally Posted by padly1995

One more quiestion...
While ago my oil seal on crankshaft started leaking, so i repleaced it, but when it was leaking scooter was going a little bit faster and it was also reving higher...?

To advance timing move the pickup / crank sensor counter-clockwise as viewed with the fan cover off, looking at the flywheel.

advancing timing on 75cc gy6 : yes, but you must use premium fuel or detonation will occur

oil seal on crankshaft started leaking = most likely the performance gains were because the oil was originally over full, don't trust the service manual or the dip stick for correct oil level at full. i put in 550cc of oil and it runs best as a rule of thumb

[padly1995]

Originally Posted by bull

To advance timing move the pickup / crank sensor counter-clockwise as viewed with the fan cover off, looking at the flywheel.

advancing timing on 75cc gy6 : yes, but you must use premium fuel or detonation will occur

oil seal on crankshaft started leaking = most likely the performance gains were because the oil was originally over full, don't trust the service manual or the dip stick for correct oil level at full. i put in 550cc of oil and it runs best as a rule of thumb

Hy, thanks for anwser.
I use 100octane petrol, that is available on every petrol station in my country. Is this enough?

Ok, thank you for telling me that, i have always putted in 700cc, so the dipstick was on top haha.

Thanks again!

[bull]

Originally Posted by padly1995

I use 100octane petrol. Is this enough?

It MIGHT be.

Years ago in the USA the only octane # that was used is what is termed the RESEARCH Method (to one derived in a lab) and we had premium grades ranging from 98 to 101. There was so much variation in the FIELD (at local gas / petrol stations) and the government was getting complaints. The government ordered everyone to use the same calculation methods for consumers knowledge.

That method is ((R+M)/2). Where R = Research and M = Field.

An interesting point about fuels (gas / petrol) before, all stations had 3 grades EXCEPT Sun Oil Company (Sunoco) which had a blending pump or dispenser and you could buy grades from 190 (sub regular) to 260 (super premium- 110 R). Sunoco still has this capability as they normally sell 4 grades with Ultra being their super premium.

Some stations have their Nascar racing fuel which I understand is around 120 per the new grading system. However the wholesale cost is in the $5 to $6 per gallon, while regular is under $2 per gallon retail.

[blueboy5000]

The gy6 139, 152, and 157 all use exactly 750ml of 10W40 oil. The oil vent line must always be unobstructed, and allowed to vent to open atmosphere, or an "open" catch can.

Leaking crankseal after changing seal ( and most times, before changing crankseal) is 99% of the time due to worn crankshaft bearings.

Physically altering the magnets or pick-ups, or repositioning them, in the Hall-Effect igntion system is a bad and imprecise method that can damage the engine, and CDI. The best way to advance timing is to use an "advanced curve" CDI.

[bull]

Originally Posted by blueboy5000

The gy6 139, 152, and 157 all use exactly 750ml of 10W40 oil.

Sir, please pardon me but I believe your information is flawed. All of the GY6 139s I've serviced (a few hundred now) held exactly 600 - 650ml of oil to fill to top of cross hatch markings on the dipstick. Through testing I found that as a rule of thumb 550ml reduces the friction of the engine and allows it to perform better without adverse effects. Friction robs power from the engine which the rider does not get to use.

As to 10W40, by all means use what works for you, but ask yourself WHY are many of the car makers like Mercedes specifying 0W20 and 10W30? The answer obviously is friction reduction.

Originally Posted by blueboy5000

Leaking crankseal after changing seal ( and most times, before changing crankseal) is 99% of the time due to worn crankshaft bearings.

If as you suggest, the crankshaft bearings are usually the culprit, then why did a totally new scooter have an oil leak from the crank seal on another scooter forum admins test scooter. His bearings were tested and they were within specification. Here is the link to his project on a new scooter, please read all his testing / troubles.

http://49ccscoot.proboards.com/threa...ences-upgrades

From testing I have found the scooters develop extremely high crankcase pressures and this coupled with, what I believe is too much oil, is most likely the culprit for blowing oil past the seal.

Originally Posted by blueboy5000

Physically altering the magnets or pick-ups, or repositioning them, in the Hall-Effect igntion system is a bad and imprecise method that can damage the engine, and CDI. The best way to advance timing is to use an "advanced curve" CDI.

If as you suggest that repositioning the pickup / crank sensor is a bad idea and can damage the engine, then how come the American auto makers used this approach to automatically advance ignition timing using vacuum from 1974 to the mid 1990s and had no problems with it.

The above referenced forum thread goes into great detail about testing CDIs on page 15 of that thread. He also included a video so that others could see.I have personally confirmed his test results as they are repeatable by anyone.

Here is a chart that he created to show the results of his testing:





As to the idea of an user adjustable "advanced curve" CDIs, I have not tested one yet, but from research I understand it offers a full advance upon starting OR at higher rpm. These are the only options with them.

[tvnacman]

here is a viable option
http://www.nycscooterparts.com/#!pro...-cdi-nycsp0007

check out the video with the timing light.

John

[blueboy5000]

Being a professional scooter tech, who has also serviced hundreds of gy6 bikes, I stand by my statements.