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Mr Cross
Mr Cross,
Category: Motorcycle
Satisfied Customers: 48
Experience:  Expert
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Just up graded my apriia rs4 50cc to a 70 big bore kit but

Customer Question

just up graded my apriia rs4 50cc to a 70 big bore kit but need advise on what size jet i need
JA: How long have you had your RS4?
Customer: just brought it been standing for 4yrs
JA: What have you tried so far?
Customer: at the moment it has a 98
JA: Anything else you want the Electronics Expert to know before I connect you?
Customer: which thought may be wrong
Submitted: 13 days ago.
Category: Motorcycle
Expert:  Virtual-mod replied 12 days ago.

I've been working hard to find a Professional to assist you with your question, but sometimes finding the right Professional can take a little longer than expected.

I wonder whether you're ok with continuing to wait for an answer. If you are, please let me know and I will continue my search. If not, feel free to let me know and I will cancel this question for you.

Thank you!
Expert:  Mr Cross replied 11 days ago.

Hi, it is not a case of guessing  jet sizes as all engines run differently, in order to get the air/fuel ratio right it will involve extensive testing using various different jets, needle settings and air screw adjustment. In order to monitor how lean or rich the bike is in testing you would have to use the plug chop method. I would suggest getting this done professionally.