More low down power and smoother midrange

[Tonibe63]

Hi folks, a Gas gas newbie here and yes my first post is a plea for help-doh!!
Traditionaly I'm a 4 stroke trailrider who likes lazy riding and easy traction so it may come as no suprise that I'm not getting on with my 2008 EC250. I love the chassis, suspension, brakes, weight, ergos etc but I can't get on with the very on/off nature of the engine and the way it breaks traction waaay faster than my old reactions can cope with.
So is there anyway I can get more bottom end delivery, less stalling and a smoother more linear mid range? I don't mind losing a bit of top end as I don't ride at that sort of pace.
The bikes an 08 EC250, with an FMF gnarly front pipe, DEP rear silencer and the dual ignition switch isn't connected. It was running 12/48 gearing which I have changed to 13/48 which has helped a bit.
It's been suggested that I retard the ignition timing-would this help and if so how do I do it?
It's also been suggested that I fit 2 base gaskets to reduce the compression and alter the port timing-again would this work?
I've rebuilt a few engines over the years from singles to V8's but when it comes to 2 stroke tuning I'm lost so any help is much appreciated.

Thanks.
Tony

 

[stainlesscycle]

13/52 gearing will help.

what is your jetting currently? jetting can change power delivery drastically.. sometimes just a needle position change can give you the power you are looking for..

retarding the timing may or may not be enough to give you the grunt you are looking for..

 

[wence]

Fly wheel weight?

 

[HenrikSchmidt]

I recently switch from a 250CRF to a 250EC and had just the same problem,
I found that a ajustable powervalvecover is a good way to do it, then you can turn your power up again if you need it, even higher than stock

 

[eff]

13/52 gearing will help.

what is your jetting currently? jetting can change power delivery drastically.. sometimes just a needle position change can give you the power you are looking for..

Or change the needle. If it is one of the triple tapper needle, n1ef or so, it will hit much harder. Look for a single taper like a CCK or try a James Dean jetting kit. When I went to the LTR needle (not available now) it mellowed my bike out.

 

[HuskyDude]

I recently switch from a 250CRF to a 250EC and had just the same problem,
I found that a ajustable powervalvecover is a good way to do it, then you can turn your power up again if you need it, even higher than stock

...Now I wonder where a guy might pick one of those up??

 

[rosco]

I recently switch from a 250CRF to a 250EC and had just the same problem,
I found that a ajustable powervalvecover is a good way to do it, then you can turn your power up again if you need it, even higher than stock

Where do you get those at? I think I need one.

 

[jefgil123]

All you need is the CCK needle from Sudco.com $6 = bike becomes very linear.
I have a slower - acting throttle on mine and like it. $25 from Motion Pro. "CR" Throttle

A 10-12 oz.Flywheel Weight will also help A LOT if you have the 3.5 inch diameter ignition. The engine seems to like it a lot- just runs better. Don't do the base gaskets, it will run worse for low end- absolutely.
Don't mess with the timing, the switch does this for you (almost no difference).
Some like the Large Volume Power Valve Cover from "trusty.com"

You will LOVE it (IMHO).
Jeff Gillis

 

[Dude]

I recently switch from a 250CRF to a 250EC and had just the same problem,
I found that a ajustable powervalvecover is a good way to do it, then you can turn your power up again if you need it, even higher than stock

I have to say it cant go higher than stock only lower. Just like a wastegate with a controller it cant go under spring pressure set at the gate. All you can do is add more tension to open it later. Can't remove tension.

What i mean basically is you can make the valve open later but not sooner than stock.

 

[HenrikSchmidt]

I have to say it cant go higher than stock only lower. All you can do is add more tension to open it later. Can't remove tension.

What i mean basically is you can make the valve open later but not sooner than stock.

But if you reverse the force and "help" the valve to open it will open sooner and and the power is full all the way up.

I know the one from trusty.com, but i dont like to make the mods that is needed to fit it.
I have fabricated my own ajustable cover that's almost a bolt on, plug and play thing, I'm still testing it, but so far it have been working just the way I hoped.

 

[ramcclure200]

Dido the throttle with different reels, I rode a buddys 300 with one and it made it a dog (for me) perfect for him.

 

[Dude]

Right but opening a valve before there is sufficient vacuum is pointless. Its liek throwing a 45 dcoe on a single cylinder and wondering why it does not work wot off idle. Big hole no vacuum to draw fuel to create venturi effect. I wanted to try a adjustable pv but had my doubts that it would be benicial. Otherwise why not just pin the valve open then.

 

[noobi]

Right but opening a valve before there is sufficient vacuum is pointless. Its liek throwing a 45 dcoe on a single cylinder and wondering why it does not work wot off idle. Big hole no vacuum to draw fuel to create venturi effect. I wanted to try a adjustable pv but had my doubts that it would be benicial. Otherwise why not just pin the valve open then.

Adjusting the powervalve to open sooner or later is a pretty big thing for KTM

 

[Jakobi]

Right but opening a valve before there is sufficient vacuum is pointless. Its liek throwing a 45 dcoe on a single cylinder and wondering why it does not work wot off idle. Big hole no vacuum to draw fuel to create venturi effect. I wanted to try a adjustable pv but had my doubts that it would be benicial. Otherwise why not just pin the valve open then.

Sure you could pin it open. It would run.. Nothing nothing nothing whaaaam!! Not very realistic and defeats the purpose. But would work never the less.

 

[Dude]

sorry i was not trying to argue or be a ass. What i am trying to convey is the power valve is tuned to open where it does. Making it open sooner does nothing but cause lag. Sort of a spool up issue. Now making it open later is a different story. remove some shims and prolong the low end grunt to its max. then POP it opens. According to my tach i have setup on my 240 the pv slams open right at 5,500 and starts to open at 4900. FWIW YMMV.

All i was trying to say is opening it earlier in the rpm range will hurt it more than anything. There is just not enough velocity at that rpm to change the harmonic....I digress

 

[Dude]

Or change the needle. If it is one of the triple tapper needle, n1ef or so, it will hit much harder. Look for a single taper like a CCK or try a James Dean jetting kit. When I went to the LTR needle (not available now) it mellowed my bike out.

Are you saying the cck hampered performance or just made it linear. I threw in a cck right when i bought mine and yanked the triple. Wondering if its worth it power wise to trough it back in or if its just a feel difference on the power onset.

 

[HenrikSchmidt]

Just like on the KTM's you could benefit from ajusting when the pv open, and it's not pinned open in high pos. it's only helped to open a little sooner so you still have vacum to make it run off idle, but dont expect to run slow tight, tech stuff in the high pos. but as you can ajust it on the fly, just turn it down in the woods for low down power and turn it back up for the open sections.

You're right that you have almost no bottom end power when you open the valve sooner, but for a dessert ride or a mx track it's not an issue since you almost pin the throttle wide open all the time for that kind of riding.
Anyhoot I don't use the high setting, but I really like the down low trials like power it gives me when i turn it down.

I did not try re jetting yet but it's my plan to try it soon, but what is best, the JD kit or the cck needle?

 

[Jakobi]

Obviously none of us ever achieve the perfect mixture of air/fuel from idle to top with our jetting..

Different needles just provide different mixtures at different times.

A richer mixture will feel more torquey and tractable, where a leaner mixture will rev harder and faster.

While one may make more power, it might not be of benefit due to the way its delivered. Sometimes less is more.

The tapered needles have transitions where the tapers change and the jetting changes.

 

[Dave]

...Traditionaly I'm a 4 stroke trailrider who likes lazy riding and easy traction so it may come as no suprise that I'm not getting on with my 2008 EC250...

No offense, but you've got the wrong bike. A 300 with 2k-3 ignition is what you are looking for.

 

[eff]

Are you saying the cck hampered performance or just made it linear. I threw in a cck right when i bought mine and yanked the triple. Wondering if its worth it power wise to trough it back in or if its just a feel difference on the power onset.

CCK should make it linear, not hamper. I am using the LTR needle, but from others on the forum I have heard the the CCK is close to the LTR needle.

FWIW, I had a hell of a time with jetting until I switched to the LTR needle.