Author Topic: Main jet size recommendations with aftermarket exhaust and cold air intake  (Read 431 times)

Marcos1323

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Hey guys I'm new here I just got a quick question I installed a aftermarket exhaust and a cold air intake on my 2009 kymco people 150 I've been reading and seen that you have to upgrade the main jet as well whenever you install a aftermarket exhaust/cold air intake and was wondering if any of yall know what size main jet to go up too I currently know that my main jet size is 110 any help with be appreciated thanks in advance.

Ruffus

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@Marcos1323 welcome here!
Before you change any jet on your carb please to a run test.
- speed did change contra before new muffler?
- speed change against before you installed a different air intake?

- change jets only if your scoot got slower
- experiment with jets only if your sparkplug is either greasy or too whitish.

In any other case leave the carb as it is, you might otherwise ask for trouble.
A real asassment is only possible with an emission tester.
Happy and safe scootering, Ruffus

Marcos1323

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Well when I got the stuff I just installed them with a bigger main jet size I did a 115 and was running a bit rich it kept backfiring tho it was cool I don't want that so I order a 113 main jet installed it today and honestly a bit of a difference top speed is now 65 but still a little rich backfires too but not as much as the 115 main jet tomorrow I'm going to install the original main jet 110 and see if a makes a difference also forgot to mention that I installed a performance cdi on it along with the rest of the stuff I'm just trying to reach a top speed of 70-75 mph hopefully it's possible

JJJoseph

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When doing mods on carbureted machines, you need to have a selection of main and pilot jets, at least half a dozen. three bigger and smaller main jets.  One size bigger and smaller pilot jets.  They're cheap, so don't panic. You're doing rocket science now, and you need to learn to tune your own jets when doing engine mods.  NOTE to future scooter hot-rodders: You can't adjust mixture on fuel-injected machines, so you have to leave everything in stock condition.  Good luck!

Ricksride

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Hey guys I'm new here I just got a quick question I installed a aftermarket exhaust and a cold air intake on my 2009 kymco people 150 I've been reading and seen that you have to upgrade the main jet as well whenever you install a aftermarket exhaust/cold air intake and was wondering if any of yall know what size main jet to go up too I currently know that my main jet size is 110 any help with be appreciated thanks in advance.
Which muffler/exhaust did you get? Any pictures? I just picked up the same year & model as yours. All advice is needed.
Thanks

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