Has anyone done the yz80 carb upgrade on the TTR125L


Has anyone done this upgrade that the sticky thread refers to under above with the yz80 carburator? I got a 'vm26' mikuni carb. Having trouble figuring out which replacement jets to order. I'm not a 'jet' genius i guess :banghead:


Bill w.

7. YZ carb mod

The last generation of round slide carbs from the YZ80 make great improvements to the TTR for little $$$ and fit right up with no modification. (2.5mm can be milled off the engine side for a perfect fit, but is not necessary.) They are particular about jetting, but make very good power. Look on Ebay and in junk yards for a clean model from 1982 to 2001. They are all basically the same and can be had for as little as $20. Strait from a YZ, they will be very rich on top and bottom, and lean in the middle on the TTR. A good place to start with rejetting is a 20-22.5 pilot and 140-150 main. The best needle is still undecided, but any of the richest Mikuni 4 or 5 series needles could work. (The stock YZ needle seems to fall just on the rich side of the middle of the charts in the Mikuni catalouges.) Slide sizes could also be changed. The YZ's slide is a #3. A #2 or even #1.5 could work well? Many folks have opt'ed to replace the stock O-0 needle jet with a P-4 size and keep the YZ needle. This seems to work well too. But remember, jetting will be different on nearly everyone's bike, so what works great for one, may not work as well for another. These are all just generalized places to start. Getting your bike finely tuned is half the fun. But overall, the YZ80 carb mod is very much worthwhile for the added power and response. It also enables the use of a pod filter, which is impossible with the stock carb. All necessary jet's and needles can be found here: http://www.sudco.com/ and here: http://www.mikunioz.com/

It says to try a 20-22 pilot jet and a 140-150 main jet. The needle and slide info sounded a bit vague however.

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