Always pay attention to what you take apart!

TheChairman · 05-25-2020, 01:23 AM

...and why you should have a good work space before tackling any project. *Long Winded!*

So I went to rejet my TT250 yesterday afternoon with the jet kit from CSC. No big deal, as I've cleaned or rejetted hundreds of carburetors over the years.

Now, I keep my bikes in a storage unit just outside of town because I don't have a garage. It's a big unit with lots of features like a 40w light bulb. I took with me a set of 1/4 metric sockets, an 8 way screwdriver, a 10mm wrench, and a pair of pliers. All I figured I would need because the screwdriver has Torx that fit the hex fasteners on the body panels perfectly.

Quickly pulled the bike apart and pulled the carb. No issues at all. Swap out the idle jet for the one in the kit, swap out the main for the 110 "middle" jet supplied, and dropped the needle clip 2 slots as it was only 1 slot from the top. No changes to the air mix screw, as it's stuck in there.

Reassemble, and it starts immediately with no choke. Fixed! No more lean hard starts. Idle is real low so I have to crank the screw like 3 turns. It doesn't change much, but whatever. So I give it a sec to build some heat and off I go. It's weird. It runs OK, but it sounds rich. Real rich. You know the sound, like the power stroke is muffled. Not a clean burn sound.

I turned around and went back to my storage unit. When I stopped with it running to open the door, it idled for about 5 seconds and then died. Outlet of the tail pipe is covered in spooge, and it stinks. Cat converters, even Chinese ones, do a good job of hiding the smell of unburned fuel. The plug is black as can be. Why? Everything went back together the same, and I didn't drill any jets or go big. Discouraged, I shut the door and went home.

Went back today assuming I had to do the right thing. I got on it and rode it to my shop 8 miles away where I have tools and a work bench. Managed to keep it running across the city. Got there, took out the larger idle jet, raised the needle one clip, and left the new main jet in there. Put it back together and then realized what I did and why it was so rich.

I hooked the fuel line up to the emissions port, and hooked the emissions line up to the fuel port.

Today I learned that you can make a rudimentary fuel injection system by feeding fuel directly into the throat of the carburetor. The bike will even start, run, and ride. Just a really rich.

05-25-2020, 01:23 AM	#1
TheChairman Join Date: May 2020 Location: Philadelphia Posts: 115	Always pay attention to what you take apart! ...and why you should have a good work space before tackling any project. Long Winded! So I went to rejet my TT250 yesterday afternoon with the jet kit from CSC. No big deal, as I've cleaned or rejetted hundreds of carburetors over the years. Now, I keep my bikes in a storage unit just outside of town because I don't have a garage. It's a big unit with lots of features like a 40w light bulb. I took with me a set of 1/4 metric sockets, an 8 way screwdriver, a 10mm wrench, and a pair of pliers. All I figured I would need because the screwdriver has Torx that fit the hex fasteners on the body panels perfectly. Quickly pulled the bike apart and pulled the carb. No issues at all. Swap out the idle jet for the one in the kit, swap out the main for the 110 "middle" jet supplied, and dropped the needle clip 2 slots as it was only 1 slot from the top. No changes to the air mix screw, as it's stuck in there. Reassemble, and it starts immediately with no choke. Fixed! No more lean hard starts. Idle is real low so I have to crank the screw like 3 turns. It doesn't change much, but whatever. So I give it a sec to build some heat and off I go. It's weird. It runs OK, but it sounds rich. Real rich. You know the sound, like the power stroke is muffled. Not a clean burn sound. I turned around and went back to my storage unit. When I stopped with it running to open the door, it idled for about 5 seconds and then died. Outlet of the tail pipe is covered in spooge, and it stinks. Cat converters, even Chinese ones, do a good job of hiding the smell of unburned fuel. The plug is black as can be. Why? Everything went back together the same, and I didn't drill any jets or go big. Discouraged, I shut the door and went home. Went back today assuming I had to do the right thing. I got on it and rode it to my shop 8 miles away where I have tools and a work bench. Managed to keep it running across the city. Got there, took out the larger idle jet, raised the needle one clip, and left the new main jet in there. Put it back together and then realized what I did and why it was so rich. I hooked the fuel line up to the emissions port, and hooked the emissions line up to the fuel port. Today I learned that you can make a rudimentary fuel injection system by feeding fuel directly into the throat of the carburetor. The bike will even start, run, and ride. Just a really rich.
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