View Full Version : 300 EXC power valve settings

18-11-2005, 07:21 PM
Gday all,

I am hoping there is someone more learnered than me on this matter. I recently bought a 2000 EXC 300 and love it, I just came off a Husky TC610 which handled like a drunk wilderbeast in the tight stuff! The ktm is a god send after that beast.

I picked this bike up and have finished restoring it to what it ought to be, but have one gripe, the person before me seems to have the powervalve set to open very high in the rev range, great for straight lines but not so flash in the weeds.

Has anyone had experiance with this type of powervalve tuning? I want to lower the point at which the powervalve does its job. My thoughts (extremely fuzzy logic) is that if the adjustment screw is screwed out that will decrease the spring preload on the actuator and allow it to work earlier in the rev range, am I right or barking up the wrong tree?

Any guidance would be helpful,

18-11-2005, 07:45 PM
wind it right out, then wind it in progressively if you feel you need to. there are instructions for doing it 'properly' that involve a tacho, powervalve covers, etc... but backing it right out is probably a good start.

18-11-2005, 09:40 PM
I had one and the best starting point with the engine is to get a DEL needle from prorider first if it hasnt already got one ,I couldnt get the spring right and think a diffenret spring would have been better but didnt have it long enough to try them, but you are right with your thinking.

18-11-2005, 10:06 PM

I figured I was on the right path after looking at the parts manual exploded diagrams, just nice to have someone else say it before doing it. Will wind it out a bit and give it a run to see if it helps, might carry a screwdriver to "fine tune" it next ride.


22-11-2005, 01:43 PM
might also help if you set the dimension Z in the specs.I think for the 300 it is 46mm(check the specs to be sure).This is the distance from the top of the barrel to the base of the powervalve flap at the rest position.You will need to remove the head to check this.It is set by a stop inside the LHS PV cover

07-12-2005, 09:47 PM
looks like i'm a bit late , the 2000 mdle power valve is a spring tensioner wind it in the higher the spring is compressed this also means that when the centifical "opener" has equeled the load on the spring the vlavle opens quite quickly giving a """hit"" or serge of power , lessen the tension the valve opens slower and earlier , so changing spings weights may make a difference to power delivery also ditch the 50 tooth sprocket on the rear and fit a 52 not great on fire roads, good in the tight stuff

14-12-2005, 04:46 PM
Powervalve problem fixed!

Was more to do with shit jetting and state of tune. But I did ease of the tension a bit. Much better now.

I running a 14/48 sprocket combo when in the more open stuff, and when I know damn well I am going to get dragged around tight single trail by my sadistic riding mate I run 13/48 for more instant punch and a closer gear ratio.

Still does not help me trying to keep up with the bastard! Bloody ex-racers!

14-12-2005, 06:35 PM
What jetting did you end up with ? I found with mine it was better to leave the powervalve in the optimal factory position (opening earlier and slower) and tweak the tuning via the jetting or other mods. Maybe even try a vortex dual curve cdi :D