I knew I only had an infantile knowledge of cam grinds, that's why I wanted to participate on another thread with my very incomplete ideas. This has really helped my education on the subject. You never know what you don't know until someone points it out. Thanks to all that are contributing to this interesting conversation...

 

Are cams the issue with the high 7-10.5k rpm range? I'd like my bike to not fall off so hard.

 

No , the main culprit for the drop in power after 7500-8000RPM is the ignitor on the carburated models and the ECU on the EFI models .
As far as the carb. models go there are a number of better igniters out there :
Kawasaki part No. 21119 - 1416 , used for racing , belongs to the SR model , my understanding i that has a 40 degrees max. advance .
Kawasaki part No. 21119 - 1533 and - 1579 . These are the stock australian and respectively the stock japanese units with a maximum advance of 35 degees .
As far as the EFI bikes go , I know there is a performance ECU made by Keihin , itīs part of the Kawasaki performance/racing products ( voids the waranty ) , but I donīt know the part number , max advance , nothing else . I asked about it at a few dealers in Spain but they donīt know anything ( as usual ) .
Tremor38 maybe you could weigh in on this , I think you have more experience with them ignitors .
If somebody knows anything about the ECU part numbers please shed some light on this .

 

For interest these are the numbers of the two ECU s.

OLD KLX250 2009

632B-190A-000
21175-0167 (part no.)
KEIHIN 8843-102784

NEW

638B-190A-000
21175-0304 (part no.)
KEIHIN 7052-100495

The Kawasaki part number is the middle set of numbers.


Marcelino mira aquí:
https://www.kawasakiforums.com/forum...s-31106/page9/

 

Would the sr cdi work on my 2009 250sf? And where could I find one? All I ever get by searching are links to a man that was trying to make an adjustable cdi

 

I'd have to do some digging as it was a while back, but the power drop-off in the higher revs can't be cured with an ECU alone. This has a lot to do with the weight and resistance of the engine's moving parts. The bike wasn't designed to be a screamer. It's more of a 'usable power' reliable type of engine that's designed for shorter shifting than the MXers are. To make any appreciable change to the shape of the power curve, you are talking big bucks.

 

When they changed the max ignition advance from 40 to 25 the max power dropped drastically . I donīt think that change was simultaneous with a increase in reciprocating mases ( mainly piston and rod ) .
I am FIRM in my belief that 25 degrees is totally inadequate after 7000 RPM .
If someone were to use a 35 degrees unit the power would mantain the same level after 7500 , not drop . If it were to use a 40 * it would rise all the way to 9000 - 10000 .
This is where you make acquintance with the next imitations on the bike : cam duration , carb diameter ( or throttle body diameter on EFI bikes ) , intake and exhaust shape and size and then , only after that , reciprocating mases .