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Everything you need to know about your TT-R 125

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Anyone who frequents this TT-R forum knows that the little 125 is the most popular bike here. There is a wealth of information on this site devoted to dialing in the little blue thumper. This thread will be a compilation of informational threads on the TT-R 125. If any users want me to consider adding more technical threads feel free to PM the link. Enjoy! :worthy:

Mods thread by user "Ovrrdrive"

http://www.thumpertalk.com/forum/showthread.php?t=170429

Tech tips posted by Moderator MNKevin

http://www.thumpertalk.com/forum/showthread.php?t=150064

TT-R-YZ fork swap by Chickenhauler

http://www.thumpertalk.com/forum/showthread.php?t=427335

Vendor Websites by ndawg22

http://www.thumpertalk.com/forum/showthread.php?t=318459

TT-R-YZ rear suspension mod by Smart Yamaha127

http://www.thumpertalk.com/forum/showthread.php?t=453702

Jetting and airbox PDF

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Great way to organizethis stuff, this will really help us guys trying to mod these bikes. My Daughter likes her bike much better with the air box and exhaust mods. I was ready to get rid of the bike. 2 carb cleans and 3 rides. crab was getting old. Now I may buy another for my son, i'll mod it before he rides it.

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Hey J, if I were to get together a good bunch of information of all of the aftermarket parts available for the TTR125, do you think you would add it in here?

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Hello,

First let me say awesome info on the TTRs nice to see people putting forth the effort on a bike that some don't consider is worth the time becuase it isn't a huge race bike. Have a problem with my wife's 05ttr125. Carb was gunked up from fuel sitting in it so took it apart and cleaned it real well, main jet and choke plunger were horrible. Well problem pre-cleaning was it wouldn't idle and coughed and spat. Well now it idles just fine but as soon as you give it gas it floods the bowl and dies. Was thinking the bowl is stuck but anyone have any ideas as to what the probalem might be? Any info would be greatly appreaciated.

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Guys, the whole point of this forum is to help fellow TT-R riders out. We can't help it if the newbs don't know how to use the search feature. The only thing you can do in that instance is lead the horse to water (so to speak)

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What have you guys done about cracked frames I got a cradle but still need to deal with the cracks are there any other braces I should weld on I do have a welder. thx

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Hey J, if I were to get together a good bunch of information of all of the aftermarket parts available for the TTR125, do you think you would add it in here?

Does anyone know of other performance parts to gain response and horse power out of the TTR 125 bike without increasing the engine displacement? I have installed a FMF power core IV pipe on wifes bike, opened the air intake box by removing the snorkel and cutting out the top, rejetted the bike with a 110 main and installed a UNI air filter. I don't want to change the fly wheel because she needs the engine braking for down hills on trail riding. Are there carb mods that would help gain performance?

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I would think that where you are in performance mods, the only really noticeable difference you're going to get would be from a big bore...

Is there a reason you don't want to go that route?

Honestly, I think that for just a little more than what you'd pay for a good aftermarket carb you could get a basic big bore kit can't you?

Everything else is just going to be slight increases in response. A big bore will be a measurable gain.

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I would think that where you are in performance mods, the only really noticeable difference you're going to get would be from a big bore...

Is there a reason you don't want to go that route?

Honestly, I think that for just a little more than what you'd pay for a good aftermarket carb you could get a basic big bore kit can't you?

Everything else is just going to be slight increases in response. A big bore will be a measurable gain.

I don't want to pull the engine apart. I concerned that reliability issues could arise. Wouldn't a big bore require to pull the engine completely out, then bore and hone the cylinder wall for the larger displacement engine to fit?

Secondly, how would you figure out proper jetting with a big bore kit?

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Anyone who frequents this TT-R forum knows that the little 125 is the most popular bike here. There is a wealth of information on this site devoted to dialing in the little blue thumper. This thread will be a compilation of informational threads on the TT-R 125. If any users want me to consider adding more technical threads feel free to PM the link. Enjoy! :lol:

Mods thread by user "Ovrrdrive"

http://www.thumpertalk.com/forum/showthread.php?t=170429

Tech tips posted by Moderator MNKevin

http://www.thumpertalk.com/forum/showthread.php?t=150064

TT-R-YZ fork swap by Chickenhauler

http://www.thumpertalk.com/forum/showthread.php?t=427335

You are the man!!!

Went through every single post of the first 2 links - in addition to a lot of excellent info there seems to be a other stuff too.... How about a locked sticky referencing these 3 threads that summarizes the basics like

17.5 pilot 107.5 to 112.5 mains seem to work well with just the snorkel removed and here is where to buy them: ________?

Just a thought - took a bit of time to read those 40+ pages...

Bunch of time went into getting this info - please don't delete.

Here is a copy of links towards the bottom of overdrives thread:

107.5 main https://shop.thumpertalk.com/ProductDetails.asp?ProductCode=WPS%5F1371075&CartID=

110 main https://shop.thumpertalk.com/ProductDetails.asp?ProductCode=WPS%5F137110&CartID=

112.5 main https://shop.thumpertalk.com/ProductDetails.asp?ProductCode=WPS%5F1371125&CartID=

17.5 pilot https://shop.thumpertalk.com/ProductDetails.asp?ProductCode=WPS%5F1300175&CartID=

20 pilot https://shop.thumpertalk.com/ProductDetails.asp?ProductCode=WPS%5F130020&CartID=

Spent all day calling around - there is no better place than TT to get those things...

Edit - January 20th 2007:

Regarding the fuel screw on the TTR125... I cannot find one at all. Only option seems to be to glue something on the end of the screw... The TTR125 is deceptively difficult to work on compared to what it should be. See attached pics for fuel screw - The first pic has the TTR125 fuel screw on the left and a Keihin FCR OEM on the right. Just for giggles the 2nd picture shows a CRF230 fuel screw on the right and an Keihin OEM & after market fuel screw on the left. As you can see they seem much much different. I did order extra O-Rings, Springs, and washers for the fuel screw of my Keihin FCR and they look like they would work just fine on the TTR125 & CRF230 for that matter - no guarantees though but they can be ordered from Sudco $15 minimum order so I bought 4 of each.

Keihin part nimber.............."description".............price

KE 021.041.......................1290-812 spring.......$2.31 ea

KE 021.042.......................16075-KG8 O-Ring.....$0.63 ea

KE 021.045........................0301-803 washer......$0.53 ea

Hope this helps someone.

.

TTR125 fuel screw on left fcr fuel screw on right 3 (Medium).JPG

CRF230 Fuel screw on right FCR on left and middle (Medium).JPG

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Just rejetted my wife's TTR125. It was extremely difficult to start cold. So much so that she could easily drain the battery just getting it started. After it started, it would run just fine. Quite annoying!

Changed the idle jet to 17.5

main jet to 112.5

fuel screw 1.5 turns out

removed air box snorkle

installed washers in exhaust

This thing is an entirely different bike. It starts immediately when cold......in like 2-3 seconds! It sounds much better and it has WAY more power. Thanks to this forum for the jetting info, couldn't have done it without it!

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ya, i have the same problem as the guy above, jason with the ttr 125 .. my 250 everytime i get on the throttle it coughs and acts like super flooded.. what could cause this? any adjustments??

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