TT250 carburetor?

[rojo_grande]

Decided to tweak a little on the carb this evening after work. Pulled the carb. Here are some pics of the slot I had to cut in the idle/pilot screw and the screw removed. Getting closer, idle/pilot jet is at 3/4 of a turn out from seated, 105 main jet, stock 38 slow jet, needle on top/leanest clip setting. No real hesitation/sputtering once warm but it feels kinda flat, no longer pulling hard once I get from 3/4+ to WOT. Starts with no choke with just a small bit of throttle and idles well. Will keep tweaking but have a minkuni on the amazon wish list just in case.

Rojo

[2LZ]

I wonder if CSC will eventually be selling real idle mixture screws since that's what's showing in the carb tutorial?

[2LZ]

Well, just ordered some jets. Since I have the 115/30 setup in my Rhino and it seems a bit rich, I ordered:

Pilot: 25 and a 27.5

Main: 110 and a 112.5.

If these don't balance properly, I'll rob the Rhino. Nice having the same setup on different units for swapping purposes.

I'll try to integrate the stock box first before installing the K&N style pod. Less hoses to plug off. The Mikuni doesn't have a vac port.

[rojo_grande]

Quick update. Rode the TT to work this morning. It ran really well. No hesitation or flat spots. Very pleased. Max speed at 59mph per GPS but still pulling and had to slow down for traffic.

Only thing I can think of is the cooler morning air at 58* this morning vs ~90* - 95* yesterday afternoon. Will see on the ride home this afternoon. Will pull the plug when I get home as well to see how its doing.

Rojo

[rojo_grande]

Originally Posted by 2LZ

I wonder if CSC will eventually be selling real idle mixture screws since that's what's showing in the carb tutorial?

Carb rebuild kits often have replacements that will have a real idle mixture screw. Let the amazon and ebay search begin (actually continue for all the various parts and farkles that might fit the TT).

Rojo

[pcspecialist]

Originally Posted by rojo_grande

Decided to tweak a little on the carb this evening after work. Pulled the carb. Here are some pics of the slot I had to cut in the idle/pilot screw and the screw removed. Getting closer, idle/pilot jet is at 3/4 of a turn out from seated, 105 main jet, stock 38 slow jet, needle on top/leanest clip setting. No real hesitation/sputtering once warm but it feels kinda flat, no longer pulling hard once I get from 3/4+ to WOT. Starts with no choke with just a small bit of throttle and idles well. Will keep tweaking but have a minkuni on the amazon wish list just in case.

Rojo

A lot of material to work with in that idle mixture screw, I'd drill a small hole in it and solder in a small Allen wrench to make it easy to adjust your mixture while on the bike.

[kohburn]

Originally Posted by 2LZ

I wonder if CSC will eventually be selling real idle mixture screws since that's what's showing in the carb tutorial?

makes me wonder what else is different between the bikes that csc used to test out and do the emission and what was delivered later.

[Ariel Red Hunter]

Originally Posted by rojo_grande

Decided to tweak a little on the carb this evening after work. Pulled the carb. Here are some pics of the slot I had to cut in the idle/pilot screw and the screw removed. Getting closer, idle/pilot jet is at 3/4 of a turn out from seated, 105 main jet, stock 38 slow jet, needle on top/leanest clip setting. No real hesitation/sputtering once warm but it feels kinda flat, no longer pulling hard once I get from 3/4+ to WOT. Starts with no choke with just a small bit of throttle and idles well. Will keep tweaking but have a minkuni on the amazon wish list just in case.

Rojo

I'm a little confused about where you have the needle attached to the throttle slide. If it is at the top of the needle, most lean setting, I would guess that the pilot jet is wrong, or the main jet is wrong. From the fact that the engine is flattening out at 3/4 to WFO, likely main jet. One way to test for this is to get up to speed in high gear, then reach down and give it a little choke - if the engine "comes to life" for a second or two, too lean a main jet. If it immediatly bogs, and sounds wooley, too rich. You should end up with the needle close to the middle slot, idle fuel or air screw out 1 1/2 turns, or close to that. If you are still running the stock exhaust, it can be hard to hear the change in exhaust tone, but the bike will respond as described.

[rojo_grande]

Originally Posted by Ariel Red Hunter

I'm a little confused about where you have the needle attached to the throttle slide. If it is at the top of the needle, most lean setting, I would guess that the pilot jet is wrong, or the main jet is wrong. From the fact that the engine is flattening out at 3/4 to WFO, likely main jet. One way to test for this is to get up to speed in high gear, then reach down and give it a little choke - if the engine "comes to life" for a second or two, too lean a main jet. If it immediatly bogs, and sounds wooley, too rich. You should end up with the needle close to the middle slot, idle fuel or air screw out 1 1/2 turns, or close to that. If you are still running the stock exhaust, it can be hard to hear the change in exhaust tone, but the bike will respond as described.

ARH,
thanks for the tip.

Tried the choke procedure on the way home, bogged immediately. Not that surprising since I'm at 6,000 feet and trying to get it lean enough to run well at 8,000 to 11,000 feet. The stock pilot jet is all I have at the moment until CSC hopefully gets some more choices or another source is found. I have a few other keihin main jets to play with.

Rojo

[Ariel Red Hunter]

Originally Posted by rojo_grande

ARH,
thanks for the tip.

Tried the choke procedure on the way home, bogged immediately. Not that surprising since I'm at 6,000 feet and trying to get it lean enough to run well at 8,000 to 11,000 feet. The stock pilot jet is all I have at the moment until CSC hopefully gets some more choices or another source is found. I have a few other keihin main jets to play with.

Rojo

OK, we now know the main jet is too rich. Which is most likely why you have to have the needle in the most lean possible position. If, when you go leaner on the main jet, you don't have to raise the needle, it is almost certainly still too rich. In theory, when you get the main jet right, and leave the needle in the most lean notch, you'll have a case of "The blind staggers" in the mid range. When that happens keep raising the needle (richer) until mid range is good. I know the temptation is to make these changes all at the same time, but that rarely works. Change one thing at a time. The bike will tell you when you are right or wrong. These little singles are very much like little girls - When they are good, they are very good - and when they are bad, they are awful.

[rojo_grande]

Originally Posted by Ariel Red Hunter

OK, we now know the main jet is too rich. Which is most likely why you have to have the needle in the most lean possible position. If, when you go leaner on the main jet, you don't have to raise the needle, it is almost certainly still too rich. In theory, when you get the main jet right, and leave the needle in the most lean notch, you'll have a case of "The blind staggers" in the mid range. When that happens keep raising the needle (richer) until mid range is good. I know the temptation is to make these changes all at the same time, but that rarely works. Change one thing at a time. The bike will tell you when you are right or wrong. These little singles are very much like little girls - When they are good, they are very good - and when they are bad, they are awful.

ARH
Thanks again for the guidance. I feel like it's getting pretty close to where it needs to be. I have a 102, 100, and 98 main jets to play with now and JetsRUs has a lot of other choices, cheap and quick shipping. Agree on one step at a time. Probably won't get to the jetting changes until next week. Got a busy next couple of days at work and have a camping trip in the mountains (on the KLR) set up for the weekend.

I'll have to do it all over again if I end up getting an aftermarket exhaust.

Rojo

[2LZ]

Originally Posted by rojo_grande

ARH
Thanks again for the guidance. I feel like it's getting pretty close to where it needs to be. I have a 102, 100, and 98 main jets to play with now and JetsRUs has a lot of other choices, cheap and quick shipping. Agree on one step at a time. Probably won't get to the jetting changes until next week. Got a busy next couple of days at work and have a camping trip in the mountains (on the KLR) set up for the weekend.

I'll have to do it all over again if I end up getting an aftermarket exhaust.

Rojo

I thought setting up a carb for 3000' was a little different compared to basic sea level, but setting up your carb for "shuttle orbiting elevation" has to be a real challenge!

[rojo_grande]

Originally Posted by 2LZ

I thought setting up a carb for 3000' was a little different compared to basic sea level, but setting up your carb for "shuttle orbiting elevation" has to be a real challenge!

I'll finger it out eventually.

Sniped a Mikuni off ebay for $19 shipped the other day (purchased for a Hawk but never installed). Also found a Keihin rebuild kit that looks like it will at least get me a proper idle screw.

http://www.ebay.com/itm/291807976434...%3AMEBIDX%3AIT

Temped the hit the "buy in now" button on the exhaust.

http://www.ebay.com/itm/322065277975...%3AMEBIDX%3AIT


Rojo

[rojo_grande]

Originally Posted by 2LZ

I thought setting up a carb for 3000' was a little different compared to basic sea level, but setting up your carb for "shuttle orbiting elevation" has to be a real challenge!

Oops ! double post

[ughmas]

Originally Posted by rojo_grande

I'll finger it out eventually.

Sniped a Mikuni off ebay for $19 shipped the other day (purchased for a Hawk but never installed). Also found a Keihin rebuild kit that looks like it will at least get me a proper idle screw.

http://www.ebay.com/itm/291807976434...%3AMEBIDX%3AIT

Temped the hit the "buy in now" button on the exhaust.

http://www.ebay.com/itm/322065277975...%3AMEBIDX%3AIT


Rojo

good find on that pz30 rebuild kit.. the idle screw does look correct :O It is so cheap I had to order one myself will make tuning the carb for my exhaust much easier methinks