I received so much information from the forum about jetting and performance that I wanted to report back my experience so far and keep a log of the progress for others to get a starting point.
A little background:
I have a 2008 that I purchased new from the dealer in 08. It now has 2100 miles on it. The base gasket leak is just starting to appear and it has generally been problem free for the past 3 years.
I built a motorized bicycle about 4 years ago and after I learned that I had to have a license and insurance just like a car I went and took the safety class for my license. After 2 days on a motorcycle there was no looking back. My motorized bike could do 30+ mph and after a front blowout I realized a mountain bike wasnt made to go that fast. So I purchased a TW200 new at the dealer to get a few years experience wanting a KLR or something someday. Now 3 years later I will probably never get rid of my TW200 because it is so much fun. But I wanted a little more power.
I had always noticed that at about 50 mph on an incline here in the central valley of California the bike would ping a little under a load. And on the flats it would surge at about 45 mph on hot days like someone was rolling the throttle back and forth ever so slightly. I never thought twice about it until I started reading some posts on the forum about jetting. Starting the bike on cold (40f) days was a chore. And after winter (Dec - Feb) storage I would have to use a squirt of fuel in the air box to get it started.
So I started with a teardown and noted that my main jet was a 126 not the 128 that a California model is claimed to have. hmmmmm
I went to the local dealers and none of them had any help with jets. All the 120 and 130 series jets were gone. Cycle gear had a 127.5 Large Round Mukini and 130 Large Round Mukini. I knew that the small rounds were the ones to get but took a chance because I had noticed pgilles had used large rounds. I also grabbed a 130 Keihin Jet because it looked so similar to a small Mikuni.
I received some spacers for the needle from a forum member. (Thanks MaineTW)
So with all that I started changing things.
I started with just 2 washers on the needle (.01 shims) .02 total. What a boost of speed and power. I rode it for about 3 miles and loved it.
So I went for more. 1 more washer added (.03) total. This time it was even stronger and pulled hard through the gears. Its like a brand new bike.
I decided to start jetting. I pulled the float bowl and put in the 127.5 Mikuni large jet and it wouldnt seat more than 2 turns. 1/8 inch from seating correctly. I wasnt going to push it. Same for the 130 Mikuni. So I installed the 130 Keihin small jet 130 and it went in perfectly. If I had to compare then I would say the 3 jets I have would be compared to Yamaha jets like this.
127.5 Mikuni = ~129.5 Yamaha Jet
130.0 Mikuni = ~132 Yamaha Jet
130 Keihin = ~131 Yamaha Jet
This is just my best guess based on my reading and the comparison I made with a loupe in my garage. They were all so close in size. The only one that was easy to compare was the 126 that I pulled from the carb. It looked smaller.
I dropped another washer in (.04) total and the Keihin Jet and my bike hauls a$$ now. I love it. I must warn that if you jet your bike take a day or so to get used to the new power. I pulled out of a corner today and the front end slipped a little when I punched it. The front likes to pull up with all the power. I cant wait to go to work tomorrow its that much more fun.
I ordered a Yamaha 125, 128, 130, 132 (They call it a 132.5 now) from the dealer to fine tune it in the next few weeks and try and narrow down just where the keihin jet falls in the order.
I also ordered a #34 pilot jet just to have it for future play use. And a South African or whatever they call the model needle jet with the five slots to adjust. Some forum members had speculated that you cannot get the needle with the slots and clip but my dealer ordered it and said they had 1 in the US and 5 in Japan so it was coming. I'm hopeful. The pilot jet that I ordered is from another model but from what I can tell it fits the TK carb. I'll let everyone know. Here are the part numbers.
Jet: Pilot #34 - 5LB-14342-17-00
Needle: South African model slotted needle - 5LB-14336-00-00
A few other notes. My screws didn't strip at all in the 3 times or so I had it apart because of the proper Japan screwdriver. I plan to switch them anyway but just wanted to mention it. Also, at first I removed the carb and getting it back in is a pain in the a$$. So I rotated it like some members suggested and that worked great. Just pull the tank, loosen the screws, and remove the throttle cable and rotate the carb.
Right now I have the Keihin 130 installed and the 4 shims and its running top shelf. More to come.
A little background:
I have a 2008 that I purchased new from the dealer in 08. It now has 2100 miles on it. The base gasket leak is just starting to appear and it has generally been problem free for the past 3 years.
I built a motorized bicycle about 4 years ago and after I learned that I had to have a license and insurance just like a car I went and took the safety class for my license. After 2 days on a motorcycle there was no looking back. My motorized bike could do 30+ mph and after a front blowout I realized a mountain bike wasnt made to go that fast. So I purchased a TW200 new at the dealer to get a few years experience wanting a KLR or something someday. Now 3 years later I will probably never get rid of my TW200 because it is so much fun. But I wanted a little more power.
I had always noticed that at about 50 mph on an incline here in the central valley of California the bike would ping a little under a load. And on the flats it would surge at about 45 mph on hot days like someone was rolling the throttle back and forth ever so slightly. I never thought twice about it until I started reading some posts on the forum about jetting. Starting the bike on cold (40f) days was a chore. And after winter (Dec - Feb) storage I would have to use a squirt of fuel in the air box to get it started.
So I started with a teardown and noted that my main jet was a 126 not the 128 that a California model is claimed to have. hmmmmm
I went to the local dealers and none of them had any help with jets. All the 120 and 130 series jets were gone. Cycle gear had a 127.5 Large Round Mukini and 130 Large Round Mukini. I knew that the small rounds were the ones to get but took a chance because I had noticed pgilles had used large rounds. I also grabbed a 130 Keihin Jet because it looked so similar to a small Mikuni.
I received some spacers for the needle from a forum member. (Thanks MaineTW)
So with all that I started changing things.
I started with just 2 washers on the needle (.01 shims) .02 total. What a boost of speed and power. I rode it for about 3 miles and loved it.
So I went for more. 1 more washer added (.03) total. This time it was even stronger and pulled hard through the gears. Its like a brand new bike.
I decided to start jetting. I pulled the float bowl and put in the 127.5 Mikuni large jet and it wouldnt seat more than 2 turns. 1/8 inch from seating correctly. I wasnt going to push it. Same for the 130 Mikuni. So I installed the 130 Keihin small jet 130 and it went in perfectly. If I had to compare then I would say the 3 jets I have would be compared to Yamaha jets like this.
127.5 Mikuni = ~129.5 Yamaha Jet
130.0 Mikuni = ~132 Yamaha Jet
130 Keihin = ~131 Yamaha Jet
This is just my best guess based on my reading and the comparison I made with a loupe in my garage. They were all so close in size. The only one that was easy to compare was the 126 that I pulled from the carb. It looked smaller.
I dropped another washer in (.04) total and the Keihin Jet and my bike hauls a$$ now. I love it. I must warn that if you jet your bike take a day or so to get used to the new power. I pulled out of a corner today and the front end slipped a little when I punched it. The front likes to pull up with all the power. I cant wait to go to work tomorrow its that much more fun.
I ordered a Yamaha 125, 128, 130, 132 (They call it a 132.5 now) from the dealer to fine tune it in the next few weeks and try and narrow down just where the keihin jet falls in the order.
I also ordered a #34 pilot jet just to have it for future play use. And a South African or whatever they call the model needle jet with the five slots to adjust. Some forum members had speculated that you cannot get the needle with the slots and clip but my dealer ordered it and said they had 1 in the US and 5 in Japan so it was coming. I'm hopeful. The pilot jet that I ordered is from another model but from what I can tell it fits the TK carb. I'll let everyone know. Here are the part numbers.
Jet: Pilot #34 - 5LB-14342-17-00
Needle: South African model slotted needle - 5LB-14336-00-00
A few other notes. My screws didn't strip at all in the 3 times or so I had it apart because of the proper Japan screwdriver. I plan to switch them anyway but just wanted to mention it. Also, at first I removed the carb and getting it back in is a pain in the a$$. So I rotated it like some members suggested and that worked great. Just pull the tank, loosen the screws, and remove the throttle cable and rotate the carb.
Right now I have the Keihin 130 installed and the 4 shims and its running top shelf. More to come.
