TTR 90 carberator

Okay beware with the ebay carb.

The Japanese made the stock carb easy to clean and replace rubber and brass parts.
If you must get the ebay carb please know they are jetted wrong, one size fits all is their plan, but jetting matters.
If you get the ebay carb you must change the jetting to match what you had stock with your original carb.

Example, you have 15 pilot jet, but they might put a 20 on the ebay carb and the 20 would make that bike to rich.
Double check the sizes of the actual jets match and the china carb can work fine.

First thing you need to do is measure the mounting flange from center to center of the bolt holes. They can be from 42mm to 48 mm center to center on the ebay after market carbs. Then determine what size your original carb is. Ebay offers a range from 16mm up to 24mm with varying flange center measurements.

For the money you could buy a couple of different size carbs, with the same flange width, and give each one a try. On a 70cc pit bike, I had good luck with an 18mm carb. Would not go bigger than a 20mm for a stock TTR 90.