jetting and porting

hey i recently ported my head.. just cleand it up and a little bit of shaping very minor... now i put it back together and it starts and runs great untill about just over half way thru the rev range and it stutter really bad...i can hear how lean it is..

i'm thinking this is due to jetting sizes...
my main jet was a 94 and i drilled it to 100..
goes a little better... but still dies top end...
my pilot jet is a 38...
was thinking of getting a 40.. due to the porting and lower vaccum at low RPM??

i have a 125cc 26mm carby and a bigger exhaust....

can anyone tell me there jet sizes who have porting done?
cheers

how do you ride ya bike, wide open throttle most of the time? if yes have you got it set to the richest setting on the needle. try this then ride it and slowly lean it out till its running right, if not i would go for a 102.5 but not totally sure as i have not ported my head yet

rich set on your needle?? wheres that up or down??

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The #38 pilot is good ----- your main jet should be #105 with the clip in the middle ...... you can make it slightly richer by lowering the clip to raise the needle or vise versa to lean her out a bit ......

Ported heads need slightly larger jets due to the more efficient airflow ...... most people are running stock ports .......

Honda XL/SL 125's run a #38 pilot # 105 main as stock

Honda XL/SL100's run a #38 pilot and a #110 main as stock so a bigger bore capacity doesn't mean a bigger main jet ......... an engine producing a higher vacuum signal will pull more fuel thru a smaller jet ......

My fully ported XR80's run excellent for all day long flogging in all temperatures with a #38 pilot and a #105 main in a 22 mm Keihin ..... the exact same carb as used by SL/XL 125/100's ........ great power , super high revs and clean running while keeping the engine temperature stable ...... for racing type power I go slightly leaner but there's a risk of melting the piston or detonation so the engine should only be thrashed around like that for short periods then allowed to cool down regularly .

A lot of people don't realise it but the fuel to air ratio controls how hot the piston and exhaust valve get ..... so it's better to run things on the richer side of lean if you want your engine to keep on performing reliably for a decent amount of time .

i'll go buy a 105 in the morning...

my needle is on the richest setting at the moment...

Waaaaaaaait a second!! What engine we talking about??125....with what valves??? What carb we talking about...Keihin 26??

ducar 125 (119cc) keihin 26mm carby 27mm inlet and 23mm exhaust.
ive played and ridin this bike these are your specs AGRO.

105 is way too big on this engine ...try a 100 #to 102#at max...the pilot might be good, if its idling fine and you can snap the gas....maybe try a 40#