how to tune a dellorto phbh carb!?

djneu-trix · Spanner Monkey Joined: 06 Dec 2006 Karma :

hi

does any 1 know anyway of working out what jet sizes etc i need if i make a engine larger? or is it just a gamble?

mallossi 170cc, dellorto phbh26 carb.

i only ask because i was reading a post and it says for a nsr125 normal jet size should be 138 well im running a 120. shouldnt mine be a lot bigger?

cheers
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pg

edd · Nearly there... Joined: 06 Jul 2005 Karma :

Normally you dont need to upjet for big bore kits, due to the fact that they draw more mixture in than the standard kit, but require it at the same proportions. Saying that why have you downjetted from standard?
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Bluespark Automotive - Diesel Tuning for Performance and Economy

djneu-trix · Spanner Monkey Joined: 06 Dec 2006 Karma :

i havent! it used to be a 110 jet ive now got a 120 in it! but im thinking i might have to go higher!
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pg

stu_m · Crazy Courier Joined: 27 Jun 2005 Karma :

the only real way to tel is get it on a dyno and the tuner will advise from there

but remember it will need running in before it goes on a dyno

Stu

djneu-trix · Spanner Monkey Joined: 06 Dec 2006 Karma :

yer i was planning to get it on 1 but the problem is i can only find in with in 30 miles of were i am, and ive tryed contacting them and they just dont reply!

does any 1 know of any within a 50mile radius of weymouth, dorset?

cheers
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pg

stu_m · Crazy Courier Joined: 27 Jun 2005 Karma :

try dynojet website they list all approved dealers

Stu