barryb1973 Posted April 22, 2016 Report Share Posted April 22, 2016 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 Quote Link to comment Share on other sites More sharing options...
lineaway Posted April 23, 2016 Report Share Posted April 23, 2016 I waited and no replies. Depends on elevation, but one step bigger pilot might work. Quote Link to comment Share on other sites More sharing options...
sirdabalot Posted April 23, 2016 Report Share Posted April 23, 2016 (edited) 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, 2016 by sirdabalot Quote Link to comment Share on other sites More sharing options...
smarty156 Posted April 23, 2016 Report Share Posted April 23, 2016 Can you get a stronger spring for the Keihin? Or would the spring from a Dellorto work (as they seem to be stronger)? Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted April 23, 2016 Report Share Posted April 23, 2016 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? Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted April 23, 2016 Report Share Posted April 23, 2016 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. Quote Link to comment Share on other sites More sharing options...
barryb1973 Posted April 23, 2016 Author Report Share Posted April 23, 2016 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 Quote Link to comment Share on other sites More sharing options...
steviet Posted April 23, 2016 Report Share Posted April 23, 2016 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! Quote Link to comment Share on other sites More sharing options...
sirdabalot Posted April 23, 2016 Report Share Posted April 23, 2016 Try high octane petrol first. Quote Link to comment Share on other sites More sharing options...
zuendapp Posted April 23, 2016 Report Share Posted April 23, 2016 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 settingsThe cure...... Head insert to lower the compression a littleNow perfectNot touched the carb or settings since I did this last year, I suspect the piston/cylinder was making a little too much compression! Quote Link to comment Share on other sites More sharing options...
smarty156 Posted April 23, 2016 Report Share Posted April 23, 2016 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. Quote Link to comment Share on other sites More sharing options...
heffergm Posted April 23, 2016 Report Share Posted April 23, 2016 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. Quote Link to comment Share on other sites More sharing options...
barryb1973 Posted April 23, 2016 Author Report Share Posted April 23, 2016 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 Quote Link to comment Share on other sites More sharing options...
barryb1973 Posted April 23, 2016 Author Report Share Posted April 23, 2016 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 Quote Link to comment Share on other sites More sharing options...
nigel dabster Posted April 25, 2016 Report Share Posted April 25, 2016 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? Quote Link to comment Share on other sites More sharing options...
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