Flat on top - exc 300 2012

[adriano.ro]

My bike is in very good shape.

Carb specs:

40p NECW3 168. Main jet. Temp. Around 7C. 700m alt.

Dimension X 0

Squish 1.60mm

SXS  Front pipe.

 

Now, bike runs good, with good bottom and mid power but seams to not go on full WOT is just scream flat. Power valve is recently cleaned. Yellow spring inside.

Can pv  spring preload settings  effect the high rpm?

Smaller main jet?

Is like 75% on very good power and 25% power on top is weak.

 

 

 

[mog]

Yes the PV spring can affect all rpm ,and jetting makes a big difference

[adriano.ro]

9 minutes ago, mog said:

Yes the PV spring can affect all rpm ,and jetting makes a big difference

When I say pv spring effect I mean reduce the rpm! 

When I adjust pv tension , normally I adjust the speed of pv opening and not how far it will open.

[mog]

If you over preload the spring it will run very flat at high rpm

[Mike Sheetz]

168 seems a little lean at 7C, even at your elevation. I’d literally slap in a 178 and see what happens.

[Chas_M]

9 hours ago, Mike Sheetz said:

168 seems a little lean at 7C, even at your elevation. I’d literally slap in a 178 and see what happens.

 

I doubt that a 168 main would be too lean with the rich tapered Suzuki needle.

[pomoco]

If it has a screen type spark arrestor, take it out.

[adriano.ro]

Update. After 1 turn out on pv preload, bike revs higher,not much but higher.

About jetting.now I have 42p necw#3 168main as 1.5, very very good !!!!!!

 

BUT, for my higher power I need to go higher on gear ratio. I have 12/50, I was wrong about this ratio, I thought it was 12/50 =13/52 but no. 12/50 =13/54!!

So to have 13/52 I need to go with 48 rear sprocket.

[strokemetwice]

Why not just go with 13/52 if thats what you are looking for?  13 up front will roll smoother than a 12 and easier on the chain.  Front sprockets are cheap.  Your apparently buying a rear anyway so you may as well buy what you are looking for.  

[adriano.ro]

I prefer 48 because is smaller and lighter.