TTR125 Tech Tips, Mods, Questions/Answers, & Carb Jet Understanding

Will any of these mods work on the 230 with the GYT-R exhaust?How much difference will they make?

I have a ttr my self and i and am doing some mods and i found that this is the best place too look for those ty u soo much i needed this well lata

Hey guys,

I'm looking for a little help sorting out the jets i need for my carb swap.

I’m going to be using the carb from what I think was a 97 yz80. Marked on the side as 4ES10.

My dyno guy and I are trying to find the P-4 needle jet for this carb, and cannot find the proper one. Does someone have a part number that can be ordered?

The numbers on the jet I have are 332 Q-2 which means it's a 332 series right?

Well we cannot find this series in any of the Mikuni catalogs.

If you have the part numbers for any of the jets, needles, or slides that you have used I would really appreciate it. Then we can figure out where to go from there.

Thanks

Kevin

Kevin,

Your jetting 101 post is well written and very informative but I have heard a few arguments that would dispute some of the info in your post.Such as,back pressure in a stock exhaust is used to tune the bikes carb. so when changing from a stock exhaust to a free flowing after market exhaust you tend to lose this back pressure and would benefit from smaller jet sizes in the carb and not larger ones.I would like to hear your take on this theory as I am not sure I completely believe this loss of back pressure due to changing to a free flowing exhaust system would call for jetting a carb more lean.

Thanks.

Kevin,

Your jetting 101 post is well written and very informative but I have heard a few arguments that would dispute some of the info in your post.Such as,back pressure in a stock exhaust is used to tune the bikes carb. so when changing from a stock exhaust to a free flowing after market exhaust you tend to lose this back pressure and would benefit from smaller jet sizes in the carb and not larger ones.I would like to hear your take on this theory as I am not sure I completely believe this loss of back pressure due to changing to a free flowing exhaust system would call for jetting a carb more lean.

Thanks.

Well, I can't answer your question, but I sure can comment on it.

Regardless of what you have read on paper, in the real world after you open up the exhaust the bike will get leaner and require larger jets to compensate for the increased airflow.

All I have seen from the reduced back pressure is a slight gain of bottom end torque and improved throttle response.

Opening the airbox gives you more power up top, and opening the exhaust gives you more down low and improved throttle response. Do both and you have a bike that runs better than it did stock.

One thing you will quickly learn about this forum is that there is less emphasis on scientific theory and political correctness, and more emphasis on the seat of the pants dyno and things that "just work". The simple mods listed in here don't always work for everyone, but a quick read of a few key threads will help you understand they work for 99% of the posters here.

Kevin,

so when changing from a stock exhaust to a free flowing after market exhaust you tend to lose this back pressure and would benefit from smaller jet sizes in the carb and not larger ones.

I am not sure I completely believe this loss of back pressure due to changing to a free flowing exhaust system would call for jetting a carb more lean.

I am not sure if you think I am saying jet lean with a freer flowing exhaust, which I am NOT...You must jet rich to compensate.

As Ovrrdrive stated, if you are moving more air, you MUST increase the fuel.

Does it make sense to increase airflow, and cutback on fuel?

I don't have the exact physics formula's you are looking for, but I can give you a lot of thermodynamic and nuclear formula's we use in the military and commercial nuclear power industry :thumbsup:

A great way to test this is to cut your airbox up and keep the stock pilot jet >> an already lean engine will get leaner. Could it seize? I don't know about that.

I opened up the airbox and installed a K & N airfilter on my 1995 Honda Nightpig. When the bike was held WFO at anytime, the bike died while starving for fuel. Talking to BURNED, I went from a 112 mainjet to a 122 mainjet! My bike actually accelerates now, instead of stalling out!

I don't know how else to provide you with documented evidence you require... :confused:

Spend some time in the jetting forum. :thumbsup:

PA Kevin

TT Mod

A PM works best for attracting my attention. I am not subscribed to this topic and receive no updates.

my wife and daughter both have ttr125's I want to change the pipes and re jet what do you suggest they are 06's and in the book the pipes for ttr only go to 05 whats up with that????

i have a 05 ttr let want mods can i do for more power but im a little short on cash

Spend about $10 and get a few jets and follow the airbox mods/ rejetting / and exhaust washer mods from the other sticky. :crazy:

You can't beat it for best bang for the buck...

my wife and daughter both have ttr125's I want to change the pipes and re jet what do you suggest they are 06's and in the book the pipes for ttr only go to 05 whats up with that????

IMO...you might want to spend the $$ on better suspension on both ttr's then on pipes..What I'm reading on TT and local shops...there's not enough power gain over the modified stock pipe to justify a $250 aftermarket pipe..but I'm sure there's others here that might disagree....

Also if you go with new pipes others here would agree that a pipe for a 05 will fit a 06...no changes since 05.

Sangair

i have a ttr 125l and i have the airbox lid removed ,and i have the spark arrestor out wht size main jet do u think i should put in, also what setting should i put the clip on the neddle jet to get the most power out of my bike. Oh yea i dont know if its just my ttr but my clucth slips and haw i could fix that weither if it might be just springs or the friction/steel plates it only slip when u let out the clucth this really get on my nerves when i ride any advise whould be very helpfull thanks

i have a ttr 125l and i have the air box cut the screen out and the stupid spark arrester out and i was wondering if you had any suggestions on what size i should set the main jet to and if you had any suggestions on what position i should put adjust the clip on the needle jet to any thing would be very helpful thanks a lot

Jeff

how do you take a gause filter/screen out of a ttr125lw thanks

Just wanted to say thanks for this very informative post. I recently purchased a '04 TTR125 for my sons and have since added the powroll thrust chamber, re-jetted (17.5 pilot, 110 main), modded the air box (removed snorkel, screen, and drilled 3 1-1/4" holes)and am waiting for a high flow after market filter (bbr). I can't believe the difference these inexpensive and simple mods make. It took a little tinkering with the "air screw" to finally get the cycle to really pop. Throttle response is great now.

Can't wait to see what the air filter does.

This is a great site..thanks again to all contributers.

Does anyone know what number drill size (OR diameter in thousandths of an inch) corresponds to the 17.5 and 20 Pilot Jets and the 110 and 115 Main Jets? I have several smaller old jets that I can drill out and wanted to tune my wife's bike this weekend before she rides because it is not ridable in it's current condition and do not have the jet sizes that I need. Thanks.

Call Sudco and order them, it only took 1 or 2 days.

I've just purchased an 05 ttr125l for my daughter. I've already removed the snorkel from the air box and was wondering about jetting. I came to this site and bam everything is spelled out. After reading the entire thread, I have all the info I need to properly set-up the bike. I want to thank the mods and other contributors for all the info supplied. It will make my job much easier. Thanks again. You know who I'm talking about...

Well I just installed a 20 Pilot and a 112.5 Main jet into my 2004 TTR 125 and my bike started first push of the button and sounded real nice and I didn't even have the stupid choke on. Normally I would have to hold the choke in for 5 minutes or more until the damn thing would idle without dying. The gas was kinda old too. All I gotta say is for how easy and cheap this mod is its a no brainer. I didn't mess with the needle or the fuel screw either, but figure I will have to since I just ordered a two brothers aluminum exhaust system that I'll get in the mail tomorrow.

yea, just tweak the screw out a bit and you should be good, not much more from an exhaust after you just put them new jets in...

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