Well, here it is. The post you all have been looking for. If you own a TTR90, do this stuff....NOW!!!

Take the snorkel out of the top of the airbox, get a TwinAir filter, install a FMF powercoreIV with spark arrestor, and put a 95 Main and 15 Pilot jet in the carb. Install some Dunlop 773's, move the clip on the rear shock and make sure you have some good fork oil in the forks. If you do these things, you will see the biggest smile on your kids faces.

WOW, what a difference!!!!!!

This thing runs awesome, is not too loud and can really zip through the turns. My son logged about 60-70 miles on his bike today and was passing KX60's, KX65's a TTR125L and at one point a YZ85 on the local peewee track. By the way, my son just turned 7, is about 55lbs and has been riding for 2 years. While I cannot attest to the skill levels of the other riders, he was sure giving up a bunch in the power department.

His TTR has been transformed into a little 4-stroke rocket for about 200.00!

Do it now.

wow.your kid is awesome.

cool

I really hate the time I got rid of my TTR90 after i got rid of it they came out with the e-start on them

After that i got a XR80 i hade that for a while then i didnt fit on it any more so i sold it and then they came out with the CRF80

I am really mad at them i have a TTR125L now and when i get rid of it to move up to my next bike they will come out with the WR125F

I hope not or i am going to kill them

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Can somebody translate this for me please  

Bigmo,

Do you have a pic of your sons bike? My son who has a 90 wants to see it.

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Try www.yamaha.com

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Wow, I got it to work!

BIGMO,

What clip position did you put your needle on...? I have the jets you recommend, actually a 100 main... There was no listing for anything bigger than a 90, and places like Sudco do not exist down under, and well, the dealer had it in stock...

Anyway, I have been getting by on the needle raised one clip position, should I set it back down to stock...? I presume yours is in the stock position as you didn't mention any changes to it...

Cheers,

David

Left the needle in the stock position. The YAMAHA 95 main jet part number is 18A-14143-19-00

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Translation: Don't take Stock-Market picks from 125.  

Big mo where did you get the graphics for the tank ?
by the way the kids bike looks good !
thanks for the info!
john

The graphics were on the bike when I bought it, but I have seen them on Ebay from time to time. There is also a seat cover that matches the graphics, looks pretty cool.

BIGMO,

Have you considered a cam for the bike as well? - something that does not involve machining like big bore kits do...



David

Not really, I've gone about as far as I'm gonna go on the TTR90. I recently bought a KX60 that has twice the power and suspension of the TTR. I plan on keeping the TTR90 and the KX60 (TTR for trails and the KX for the track) around until he's ready for a KX65.

I will dread the day we get rid of the TTR. A great running bike that's bulletproof is hard to part with.

Bigmo , did your sons bike have a stutter about 3/4 throttle after this was done ?  My kids does, Im gonna bend a cheep screw driver today and adjust the magic screw to see if i can get rid of it. Man who ever engineered that was a genius  . I have a 100 main and 15 pj in it and it accepts it, looking at the plug its not to fat. pilot jet works at idle and first throttle response then the needle takes over to full throttle where the main works, this blubber happens at 3/4, makes me believe i need to move the needle ??   what do you think?
thanks for the info.
john

by the way i looked at the flywheel and theres not a lot to take off on this one i thought it would be best to leave it alone.

My son's runs awesome from idle to WOT. We do have the 95 main vs. the 100. Or maybe we just got lucky with the right jetting for temperature/mods/altitude.

By the way, make sure to clean your air filter EVERY ride. With that snorkel removed, it gets VERY dirty in there.

Here's the result. My 7 year old doing a no footer. Yikes!



One more.

Pretty cool , last weekend the foot peg cracked all the way around but a 1/4 inch , i told my son to stop jumping or he was gonna get hurt , he just couldnt stop so he would jump and hold his feet out (ouch)and land on his butt!. I wish there would have been stuff like that when i was a kid! .

see ya
john

One more. Here's the part number for the pilot jet. Yamaha part...

5HP-14142-15-00

Good luck!