EC125 Power Valve and Oil

[oldschool07]

HI,

I've recently bought an EC125 and I'm in process of sorting it out. Is it possible to get the power valve to start opening earlier? I've had a look under the cover. The seems to be alot of play in the joint where the actuator rod meets the arm on the power valve rod. Is that normal? Probably 2-3mm? I've had a look at the guide on this site but it doesn't cover the 125.

What gear oil would you guys recommend running?

Cheers

Ross

[iancp5]

If it opens earlier wont you get less power at low revs?

I use either Putoline Light Gear Oil or ATF.

[oldschool07]

Not sure Ian kind of why I wanted to try it. But it dosn't look like there tune able.

[Caravan Monster]

Originally Posted by oldschool07

HI,

I've recently bought an EC125 and I'm in process of sorting it out. Is it possible to get the power valve to start opening earlier?

Are you looking to get the bike to a)pull harder / cleaner at low rpm, or is it b)bogging in the low to mid range before it goes 'on the pipe' ?

If a), you could try retarding the ignition, but be careful about running too lean and this will sacrifice top end. A heavy flywheel is another option, I believe, but one I have no experience of, so won't advise any further about that. Different expansion pipes, reed valve spacers and jetting mods are other options.

If b), the bike isn't running properly, which could be caused by many things.

[oldschool07]

Hi The bike runs fine looking at the power valve mechanism then the power valve opens it snaps open what i would like to have is a more linear and gradual opening. But looking at the mechanism I don't think I'm going to get it.

I've swapped the expansion chamber over for the FMF one I got as a spare with the bike but haven't had time to test ride it yet.

[noobi]

On my 07 125, the powervalve was always snappy when I watched it opening, but the bike made very linear power for a 125. The powervalve is similar in design to the jap 125s, so any technique on modifying those could probably be applied to the gg.
You didnt say what year yours is?

[GMP]

The 125 PV is not like the 250/300, its a lot like the Yamaha YZ125 and the non-linear operation is normal. By design its more like a switch than a linear opening valve. For best low end from the 125 get your jetting right with the FMF pipe, and run 13/52 gearing if you ride technical woods.

[Zman]

Good news - The YZ 125 power valves do work in the GG 125 engines. They are a direct swap.

Bad news - I cant say exactly which years cross over. They are 1999 or later, but im not sure which ones for sure because I got them used.

[Rick]

Food for thought....RMATVCM......when youn click on a pn# it tells younall applicable models thatvpart fits......I've never seen a GG 125...but I've heard the motor is YZ copy.............VForce reeds....RB carb mod for TMXX shouls wake it up! Did wounders for my YZ!
oh...ya ....squish too!

[motopsycho87]

Your best option would be to find a thicker gauge spring. Search for the inner diameter, thickness and length of what you have, keep the number of could in mind too. To get more progressive you would need more cpils and a thicker gauge wire.

125s tend to be pretty gutless down low and power valves are generally a compromise as opposed to a solution. As re you certain your jetting is correct? I feel you'll get more out of your bike by fettling the jetting and correcting head squish than altering PV opening rate.

Also I think the reason this bikes open the valve in one his is that due to it being a spring loaded mechanism, anything between full open and full shut would result in 'fluttering' which will give very spontaneous and unpredictable running.

Hope this helps.