just got a 2015 250 when under heavy load it was pinking slightly cant find any air leaks so lifted needle a notch from middle(richer)seems better just wondered if anyone had same problem or any other ways of improving running,also throttle is very light are they all like this or has someone been tampering with my spring thanks

I waited and no replies. Depends on elevation, but one step bigger pilot might work.

I went up to next size pilot jet, but still get slight detonation using BP petrol 95 RON. My 2014 did the same but I put up with it, as it only did it above 1/2 throttle, which I don't visit often. The bigger pilot definitely gives a bit more grunt at very low rpm and reduces stalling.

The throttles are very light on Keihin equipped Racing models possible due to the fancy throttle tube outer roller bearing they come with as standard.

Edited April 23, 201610 yr by sirdabalot

Can you get a stronger spring for the Keihin? Or would the spring from a Dellorto work (as they seem to be stronger)?

just got a 2015 250 when under heavy load it was pinking slightly cant find any air leaks so lifted needle a notch from middle(richer)seems better just wondered if anyone had same problem or any other ways of improving running,also throttle is very light are they all like this or has someone been tampering with my spring thanks

 

where are you?

Can you get a stronger spring for the Keihin? Or would the spring from a Dellorto work (as they seem to be stronger)?

 

spring?

Nothing to do with jetting.

There is another thread with the exact same question look it up will save waiting for replies.

spring?

Nothing to do with jetting.

There is another thread with the exact same question look it up will save waiting for replies.

im in uk,dont understand your reply

I have just picked up on this and I am guessing that you have a 250 gasgas racing like mine..

I had lots of pinking with loads of different combos of carbs (delorto n kiehin), jets and settings

The cure...... Head insert to lower the compression a little

Now perfect

Not touched the carb or settings since I did this last year, I suspect the piston/cylinder was making a little too much compression!

Try high octane petrol first.

It is my understanding that when GasGas had financial problems they cheapened the 2015 Race model and did not use the S3 2 piece head. To reduce the compression would need to purchase a S3 head and insert?

 

From what I have seen the Keihin carb is more sensitive to jetting and weather  / altitude changes. I have seen my bike run great in the morning and run lean in the afternoon.

 

Terry

 

 

 

 

 

I have just picked up on this and I am guessing that you have a 250 gasgas racing like mine..
I had lots of pinking with loads of different combos of carbs (delorto n kiehin), jets and settings
The cure...... Head insert to lower the compression a little
Now perfect
Not touched the carb or settings since I did this last year, I suspect the piston/cylinder was making a little too much compression!

 

spring?

Nothing to do with jetting.

There is another thread with the exact same question look it up will save waiting for replies.

My post was in response to this part of the post above mine:

"The throttles are very light on Keihin equipped Racing models possible due to the fancy throttle tube outer roller bearing they come with as standard."

Of course the spring has nothing to do with jetting. That's ridiculous.

The roller doesn't make the throttle any lighter. It just keeps it from dragging on the bars when you're doing something that involves applying pressure to the grip.

I have just picked up on this and I am guessing that you have a 250 gasgas racing like mine..

I had lots of pinking with loads of different combos of carbs (delorto n kiehin), jets and settings

The cure...... Head insert to lower the compression a little

Now perfect

Not touched the carb or settings since I did this last year, I suspect the piston/cylinder was making a little too much compression!

where did you get your head and insert struggling to find any on net thanks

The roller doesn't make the throttle any lighter. It just keeps it from dragging on the bars when you're doing something that involves applying pressure to the grip.

yes i thought that,its purely down to stiffness of sping isnt it

I wouldnt go down the expensive route unless youve explored jetting.

 

Usually a 3 slide and 128 main 45 pilot should be good. (from memory). Is that your setting?

Float level is important too.

 

IF and big if its head compression then any decent machine shop can skim a bit out?