Jetting thread pitch


New Member
Aug 20, 2023
Hi everyone, I have a 1988 Yamaha blaster and I did a k@n air filter and vforce 4 reeds and need to re Jet my carb. I purchased multiple kits off Amazon and the thread pitch is different and won’t fit my carb.

If anyone has a link to a jetting kit that they used please send it to me.

Also does anyone know the thread pitch by chance?

And I only have the k and n air filter and vforce 4 reeds and everything else is stock. Any recommendations on what Jet size I need?

And no the Vito’s 240 jet kit doesn’t work because there jet kit comes with 300-340 jets wich are too big.
The best advice I can offer is to avoid Amazon (Chinesium) jets. Always buy genuine Mikuni (or Keihin if you are running a Keihin carb) jets.

I've always obtained my jets from Jetsrus. Assuming your carb is the original, here is what Jetsrus offers for the OEM Mikuni carb on your Blaster. These are genuine Mikuni jets

As to jetting recommendations for your reedvalve and K&N, I would start appx three steps richer on the main from stock and one step richer on the pilot. You'll probably end up pretty close to stock jetting once you dial it in, but it's best to start a bit on the safe side and work your way back.
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