New bike doing well, got my best result in my class two weeks ago. Got a minor problem which seems carb related though, starts fine, idles fine, jets recommended sizes but it will bog down easily if the throttle is opened really quickly. For instance if you try and left the wheel from low rpm's by throttle alone rather than rev up a bits and clutch, it bogs completely. Once its up and spinning response seems fine. Haven't checked needle position, what should it be?

Oh and while I'm typing, what grade of fork oil should i use and how much per leg?

cheers

Jon

Hi, they are a bit of a pain when it comes to the carb. Check you have a 17.5 pilot jet and a 102.5 main jet as they were modified to run these and set float height to 18 mm. turn carb upside down put it on a good flat surface and remove gasket and carefully measure from base of carb to top of float (which is of course bottom of float as carb is upside down set to 18 mm . Set mixture screw to 1 and half turns out. blow out 2 small jets in back of carb and make sure they are in the right places 145 top 80 at bottom. Whilst your at it remove choke from carb clean it up on the end of the cable spray with wd 40 and refit it and make sure there is plenty of free play when its all back together. You can go to Birkett Motorsport website for any other 4 t set up info. Cheers

Sorry cant help with fork oil ring Birketts 01229 716806

Edited July 24, 200719 yr by bo drinker

Hi, they are a bit of a pain when it comes to the carb. Check you have a 17.5 pilot jet and a 102.5 main jet as they were modified to run these and set float height to 18 mm. turn carb upside down put it on a good flat surface and remove gasket and carefully measure from base of carb to top of float (which is of course bottom of float as carb is upside down set to 18 mm . Set mixture screw to 1 and half turns out. blow out 2 small jets in back of carb and make sure they are in the right places 145 top 80 at bottom. Whilst your at it remove choke from carb clean it up on the end of the cable spray with wd 40 and refit it and make sure there is plenty of free play when its all back together. You can go to Birkett Motorsport website for any other 4 t set up info. Cheers

Sorry cant help with fork oil ring Birketts 01229 716806

Yep checked the jet sizes, (bought 'em then stripped carb and found they were already in there) float height fine, etc. Had another fiddling session this evening, checked what the needle pos was: lowest clip with 2.5mm plastic washer underneath, some evidence of prior fiddling there too. Is the white plastic spacer meant to be there? Will be ringing Bkts tomorrow (busy today when i tried). Also tried resticting the air box intake with a rag, that seemed to make it a little better on brisk WOT response, may try a next bigger jet.