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.

Megadan · 05-25-2020, 02:11 AM

It's rather amazing how stuff like that can happen. Not only happen, but actually work for a while. The vacuum must have been just right lol.

OneLeggedRider · 05-25-2020, 05:45 AM

When I bought my second place in Florida it was basically 13.5 acres of undeveloped swampland that came with gators, snakes, and all types of nasty insects just to keep you on your toes. Well I had to put in electric, a well and a septic tank, all of which I did myself. But for the first 6 weeks all I had was this ancient Onan generator that you had to wrap a rope around the flywheel to start it and hope for the best. I had traded a guy a dodge rear end for it and it turns out the carb was FUBAR, and so was the fuel tank.

I rigged up a plastic gas tank and mounted it on a stand above the generator so it would gravity feed, and got a citrus tree industry sprinkler head that had a valve to control the flow and set it up so it would drip into the intake.. And after a whole lot of fooling around it worked! Me and the wife had power to run a small AC, the refrigerator, and a couple of light bulbs for 6 weeks. She complained about the noise so I attached a 20 foot section of pipe to it going away from the house and slid a glass pack over the end. Where there's a will..

TheChairman · 05-25-2020, 08:32 AM

Quote:

Originally Posted by Megadan

The vacuum must have been just right lol.

It looks like the hole in the carb for emissions is very tiny. I'm guessing that it was just small enough that when the throttle was wide open, the fuel mix wasn't too bad. I had to hold the throttle somewhat open and really flog it to keep it running across town. When I got to my shop, the plug was dark brown, on the rich side of ideal. It wiped right up and runs fine as it is.

I also went ahead and ripped off the snorkel, as it's only glued in place and easily reinstalled. It sounds much better now. Gonna set out today to the store to grab some Autolites or NGKs and do some throttle chops. Maybe they'll also have a few vacuum caps so I can remove the canister.

One thing I ran into on mine is the rear tab on the tank is not formed correctly. The factory bolt is too short and won't align without practically sitting on the tank to push it down and it only grabs by a thread or two. I switched to an M8x1.25-50 and now there's a God's plenty of threads to get in there and hold it in place.

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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05-25-2020, 02:11 AM	#2
Megadan Join Date: Apr 2017 Location: Omaha, NE Posts: 7,993	It's rather amazing how stuff like that can happen. Not only happen, but actually work for a while. The vacuum must have been just right lol. __________________ Hawk Information and Resource guide: http://www.chinariders.net/showthread.php?t=20331 2018 Hawk 250 - Full Mod list here. http://www.chinariders.net/showpost....62&postcount=1 2024 Royal Enfield Shotgun 650 https://chinariders.net/showthread.php?t=34124
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05-25-2020, 05:45 AM	#3
OneLeggedRider Join Date: Nov 2018 Location: Stockport, Oh. Posts: 1,442	When I bought my second place in Florida it was basically 13.5 acres of undeveloped swampland that came with gators, snakes, and all types of nasty insects just to keep you on your toes. Well I had to put in electric, a well and a septic tank, all of which I did myself. But for the first 6 weeks all I had was this ancient Onan generator that you had to wrap a rope around the flywheel to start it and hope for the best. I had traded a guy a dodge rear end for it and it turns out the carb was FUBAR, and so was the fuel tank. I rigged up a plastic gas tank and mounted it on a stand above the generator so it would gravity feed, and got a citrus tree industry sprinkler head that had a valve to control the flow and set it up so it would drip into the intake.. And after a whole lot of fooling around it worked! Me and the wife had power to run a small AC, the refrigerator, and a couple of light bulbs for 6 weeks. She complained about the noise so I attached a 20 foot section of pipe to it going away from the house and slid a glass pack over the end. Where there's a will.. __________________ ~ Don't poke the bear ~ M.M.I. Dean's List graduate class of '95 and Specialty welder 2020 Ice Bear Terifecta 150cc Trike 2011 Honda Foreman 500ES 4x4 2001 Polaris Scrambler 400
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