can anyone offer any practical advice on how to "smooth out" the power delivery on an 03 290. i have tried a 3 tooth bigger rear sprocket and a slow throttle, but its still a bit flighty. this is a request for a mate of mine who cant stop launching the thing. selling is not an option. (my suggestion!) any advice that has been tried and has worked will be gladly recieved.

thanks

paul

I had a 2003 290 which was virtually brand new and it was too pokey (too fierce for the previous owner,that's how I came by it).

After messing about with sprockets and a slow throttle I set the timing back and it calmed the power delivery .Voila!

My dad had a 2003 model which he found a little bit overpowered!! We changed the front cog from a 10 tooth to a 9 tooth and also put slow throttle on, made big difference and much more rideable. Even for a 67year old novice. Has since changed to Scorpa 250 and feels much more at home.

Two or three cylinder base gaskets will also dull it off. Sherco provide several different thicknesses.

Two or three cylinder base gaskets will also dull it off. Sherco provide several different thicknesses.

this will work but you will lose some torque as well as it will lower the compression. I softened my 07 290 by retarding the timing 5mm and going one notch richer on the needle (lower the clip by one groove) and fitting a larger pilot jet (one number). THese things are all relativley easy to do and you can change it back if he doesnt like it. You could also fit an inlet spacer ?

retarding the timing 5mm

is meaured on the base plate ? i.e. 5mm rotation measured at the outer edge.

did you need to alter the pilot jet because of the ignition change, or was this an extra measure?

thanks for the reply

is meaured on the base plate ? i.e. 5mm rotation measured at the outer edge.

did you need to alter the pilot jet because of the ignition change, or was this an extra measure?

thanks for the reply

Hi Paul,

Mark the timing plate where it is before you alter it.

The way I see it is ...the only time you need to be accurate with the timing is when you're looking for peak performance(which we're not).

Retard the timing all the way just to see how the power feels,if you encounter some running problems (excess heat ?)then advance it in small increments until you're happier.

There is a wide range on that timing plate and you can totally change the nature of the beast.

Okeedokee,

Wayne

P.S. I only ever changed the pilot when I put Boyesen reeds in.

Here is the last word on the matter from Copemech......Timing

Edited April 20, 200818 yr by HAM2

is meaured on the base plate ? i.e. 5mm rotation measured at the outer edge.

did you need to alter the pilot jet because of the ignition change, or was this an extra measure?

thanks for the reply

carb mods were additional, mark the stator plate and rotate past the allen bolt at the top if you know what I mean. If you search this forum copemech posted a good diagram last year which I used as a start point.

I had a problem with the power of my 07 290, tried a smaller front sprocket and slow action throttle but it was still too snappy,

I fitted 3 standard thickness base gaskets and now it is perfect, was a doddle to chang them too.

hope this helps

Definately the best way(as described by ham2) is to put a slow action throttle on and retard the timing.I have a 04 290,it always uused to kick back and was way to snappy.Now its really soft,but still loads of power,which is more controlable.

Edited April 22, 200818 yr by dabomb

I should write a 10 page blog on my personal experience with all this, as over the years I have tryed most things to tame the 2.9's to my personal liking.

Long story made short, with the exception of my '03 bike, which had soo much power that I ran the 44T rear on just to slow it down, I have never NOT been able to tone the 2.9 down to a rideable state for me with just timing changes and the Boyesensn along with some proper jetting. The timing change WILL help prevent kickback and stalling, and allow low chug down!

Slow throttles I do not like as there is not that much difference if your bike is too twitchy to begin with, it will still put you on your ass when it hits the power!

A 2.9 is still a 2.9! And if you get your hands on one they are an exciting bike to ride, weight, performance, design and sturdy reliability, it is all there in one package!

Although I have never stacked base gaskets, this has been an option. Basic rule of thumb it 3 maximum of the standard gasket which measures about .5 mm as I recall. So an addition of the maximum two would have a change in port timing of 1.0mm and a significant change in compression. Two things are happening here! I wish we had some specs before and after on compression from those that have done it! Sherco has made available the "shim" gaskets in .2,.3,and .4mm thicknesses as well. But my impression is that these are simply used to adjust for manufacturing tolerances on the latter bikes.

I should end by saying that my '05 2.5 was still the favorate! With the long headpipe! Sweet, another option!

all MHO! Your mileage may vary!

I think the standard carb is a bit to blame especially on the pick up. On a 290 a Kehin carb seems much smoother off the bottom end, though madder at the top.

A slow action throttle means you have to twist your wrist a lot further back for sharp log or rock hops which can be awkward.

An O-Ring chain will tame it down a bit also. Worked great on mine....just watch your blocks.

i felt the same way about the 2.9 having too much sh..! i went to a black throttle, then i did the timing, got v-force reeds, went fat with the jetting, and after getting used to it i got rid of it all, (except the v-force reeds) and after a month or two of a pooch i jacked my bike up in to a scream machine! quick throttle leaned out carb., and the best mod. a set of j-peg half back foot pegs! your whole center of gravity changes! you don't feel like you are on stilts, my guess is to keep the bike stock change your pegs and get used to the power, well maybe keep the black throttle!................................john

i felt the same way about the 2.9 having too much sh..! i went to a black throttle, then i did the timing, got v-force reeds, went fat with the jetting, and after getting used to it i got rid of it all, (except the v-force reeds) and after a month or two of a pooch i jacked my bike up in to a scream machine! quick throttle leaned out carb., and the best mod. a set of j-peg half back foot pegs! your whole center of gravity changes! you don't feel like you are on stilts, my guess is to keep the bike stock change your pegs and get used to the power, well maybe keep the black throttle!................................john

Just out of interest,what year is your bike?