Jetting a Mikuni 36mm on my 1980 Yamaha TT500

Bike: 1980 TT500G

Motor: bone stock

Exhaust: Super trap with  header

Intake: aftermarket high velocity

Carburetor: Mikuni Sudco 36mm

Air Filter: K&N (air box is gone)

This is my own Yamaha TT500. It is one of my favorite endure bikes ever. I managed to tag this TT500 so I use it on the street 95% of the time.

The bike is all stock except for the pipe, the intake manifold and the carburetor.

I purchased a Sudco Mikuni set up for the TT500 but I have a hard time starting the bike when it is cold.

Once it is warm, it runs like a champ.

I’ve tried every possible trick for cold starting and I finally decided to start playing with the pilot jet.

After a few changes, this is the best combo that I found:

Pilot: 30


Needle:center clip

The cold start routine is the following:

I open the petcock valve, I wait a few seconds to make sure the carburetor is topped with gas.

I open the choke, and I rotate the engine a few times pulling the decompressor. I do this to push gas into the cylinder.

Next, I close the choke and I turn the engine until I feel compression, then I bring it back up, then I pull the decompressor again to move the piston until the indicator is white (not at the beginning of the white strip, just in the middle), then I go back up one more time, and I kick hard all the way. That’s how I get it fired up.

With the 30 pilot, runs idles clean and take 1 1/2 turn approx on the air mix screw. I live in Florida, so humidity and hot weather is a factor to consider. ­čÖé