650sx upgrades needed

[bored&stroked]

Later 650sx's used a 38mm carb and a diverter exhaust manifold that helped a good bit.
Aftermarket pipes don't feel any different then a diverter manifold stock pipe with pipe mods. I bet the factory pipe helps, but I never rode one of those.

 

[kevbo]

My experience, the smaller 86-90 carbs are too small. The 91-96 carbs are not. Jetting for the 38 will be 78 for the pilots and 140-150 mains. The 40 will need 80-82 pilot and 150-160 mains. The pilots are very sensitive and popoff changes affect their output noticeably. The main jets have a supplement adjuster so they aren't nearly as critical. More important is the impeller, just a little too much load will kill performance.

 

[Pro-pulsion]

I thought it was a good deal compared what others are selling for.

Kawasaki 650 Jet-Ski Mikuni 44 sbn Carb-Intake-Manifold upgrade 650-sx-x2-ts New | eBay

Mounting hardware to mount the carb on the manifold. Fits all of the Kawasaki 650 Jetski models from 1986-1995 including the sx-x2-sc-ts etc. This set up is a huge performance upgrade for the 650 models.

www.ebay.com

That's my build thread I did the stock pipe mod and documented the beans out of everything I did. At first I tried to stay on only freebie mods. Yes they made a difference. One of my friends had a stock 650sx and we did side by side tests. My ski was massively more potent. The stock exhaust mod is only as good as the carb supplying it. Without the airflow you won't feel it's true potential. I also tested it back to back with a WestCoast pipe, then added extra length, the diameter of the WC pipe I believe is too large. The stock mod pipe outperformed it by not a huge amount but a noticeable one.