Hey guys! Do I need to reject my carb???

[Jaguar200]

Hey guys,
So I have a 170cc gy6 engine and I’m going to be upgrading from a 61mm jug to a 63mm. I’ll still be running all my other add-ons as well but since I’ll be going up in jug size, I must have to rejet my carb right? Or wouldnI need a new one at that point? So confused any help will be appreciated, thanks!

 

[950speed]

Rejet if it’s not a fixed jet size.

Do a plug chop to determine, then look at the plug, go up one jet size at a time

 

[JTSpeedDemon]

The typo in the title really threw me for a sec! I was thinking: "Why the heck would you need to reject your carb?!?!"

 

[mckutzy]

You don't nessisarly need to cut the plug to do a test... For the testing of these engines.... A top end of the plug is fine...

 

[Jaguar200]

So I posted this on my phone and it auto corrected the title on me, sorry about that. So is it the main jet or the pilot that I would be rejetting? And when I say a new one at this point, I mean buying a bigger carb

 

[950speed]

Just to clarify when you say “jug” don’t you actually mean the top end cylinder? I have never heard of it being called a “jug”

 

[mckutzy]

Yes..
Typically these type of engines can be upgraded with a big bore kit... new pistons,crank, bored housing(the jug) ect...
Often what is used on scooters for more power from the "49cc" to much bigger displacement...