EC300 still down on power

[19brendan81]

Hi Guys,

So I have this 2004 EC300 that was down on power when I bought it, which I knew but figured a fresh top end would bring it back. Since then, i have installed a brand new piston and ring, had the squish corrected, sent the carb to the states for boring and RB designs treatment. It goes heaps better than it used to, however compared to my mates 2008 EXC300 it is waaaaaay down on power, in all areas. I rode both machines back to back on the weekend and the difference is easily noticeable. My mates bike accelerates really hard, likes to get the front wheel up and is exhilerating to ride. My bike feels tame and pedestrian in comparison, with a weak transition to power and no real arm pulling power at all.

I am going to start playing with the jetting as per Ron Blacks suggestions however im worried that jetting alone isnt the issue.

My question is, should the power of this motor be broadly similar to the EXC300? If the answer is yes, what else could be giving me grief if I have done all of the following things:

1) brand new piston and ring (6 hours riding)
2) confirmed powervalve actuating correctly
3) squish corrected by head machining (RB designs)
4) Carb bored and improved and jetted to suit head and my specs (RB designs)
5) Clean air filter

Brendan

[djroggen]

What ignition do you have? Is it an MC ignition with a huge flywheel?

What kind does your plug look like?

What are you mixing your fuel at 32:1?

What kind of compression are you at?

Is your pipe crushed or blocked at the silencer?

You should be able to easily lift the front tire on a 300, there is definitely something causing the issue.

[19brendan81]

Hey DJ, thanks for the quick reply. In answer to your questions...

1) Ignition - no idea...think its stock. Its an Australian bike, identical to the one in this review... http://www.dirtbikeworld.net/Reviews...sGas_Text.html

2) Plug looks OK, a little rich I spose...but it idles well (really well in fact)...doesnt seem to fuel up, or blow smoke, nor is it particularly hard to start (4 or 5 kicks cold, 1 every time when hot)

3) Fuel mixed at 40 to 1.

4) compression is heaps better since rebuild will do a test when I get home to give you the numbers.

5) Pipe is stock and dent free

You dont spose its something like crank seals? They normally have other symptoms like oil coming in around the flywheel dont they?

[GMP]

If its all mechanically sound for sure, my $$ is on the CDI. Try and swap a different CDI. You can even use a KTM Kokusan CDI as they are electrically the same but in a different enclosure.

[PEB]

What do the reeds look like?

[stainlesscycle]

even with the heavy flywheel it should rip. is the slide opening all the way??? pv, ignition, or pipe restriction, or a reed issue is the only thing i can think of..



if it were crank seals, it would either race/climbing or hanging idle, or smoke bad.

[swazi_matt]

Same gearing?

[gasmonkey]

Pull the muffler apart and repack.

[19brendan81]

"is the slide opening all the way??? pv, ignition, or pipe restriction, or a reed issue is the only thing i can think of.."

Yep, slide functions perfectly. Will check out the reeds, I havent actually looked at them. If they arent shutting or are cracked they could definitely be the cause of the problem. The muffler could probably do with a repack...I think I will do that.

Its not gearing, the bike isnt running right...I can feel it. I'll be spewing if its the CDI...I thought when CDIs are broken the bike wont start at all, or will backfire and carry on...how would a CDI cause a general lack of power?

Brendan

[lonetree]

im pretty sure the cdi is responsable for all the advancing of the ignition so if its not working right, it could well be the problem. no idea how to test other than a swap with a working one.
you say its idling fine and starting good but also that its not running right.- whats it doing exactly? i presume its above idle where there is problems?
where in oz are ya? i have a 04 too...