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drz125l mod issues.

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Hey folks, I'm new to posting here but have creeped around a little reading through back posts and what not. Read all the mods for the drz-125l which is my wife's bike.

Well, last week I did the airbox mod and installed a twinair filter instead of the stocker fat foam. Also, cut the center of the exhaust cap out, careful not to ruin the spark arrester. Did not like this mod though, the sound is just not quite there, but breathes better no doubt. Ordering one of those billet caps instead.

Anyways, went to the local shop and the owner recommended just jetting to 105 and leave the pilot stock. He said his bike runs better with just changing the main jet. He actually rides the same bike with the intake mod but without the exhaust mod. Also, I didn't drill out the brass plug in the carb either. Is it really necessary?

Well, the bike ran great at first until it got hot. Then it started dying and really hesitating when trying to throttle it. Now its hard to start and hesitating without it even heating up. I'm suspecting the jets need to be richened. So I ordered the 107.5 main and the 20 pilot which I hope to install next week.

Does this seem to be right? We ride the bikes at around 1000 feet and below. I'm a little new to four strokers as well. Im used to working on my 2 stroke RM250.

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If it runs good cold, but not hot, then it is probably running rich already. Although with carburetion, you can easily be fooled.

I would recommend that you drill out the brass insert to get access to the pilot screw. I would also recommend replacing the needle with the one in the Yamaha TTR-125. It costs about $20 and gives you a clip for adjusting mid-throttle jetting. If you are going to be modifying the intake and exhaust (which is highly recommended) then you need better control of the jetting. The DR-Z125 has quite a bit of potential, but you need to increase the adjustability of the stock carb.

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Naw, it doesnt run good cold now either. Theres a bit of popping too. Thats a lean condition correct?

The TTR pilot, is that needle located behind the brass plug? What do I ask for when I go to Yamaha?

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The DR-Z pilot screw is located behind the brass plug. This is the fine adjustment on the pilot jet. The pilot system (the screw and the jet) dominantly affect the idling characteristics.

The TTR-125 needle is part number 5HP-1490J-00-00. You can see it online if you go to Yamaha's website www.yamaha-motor.com and click on "Parts and Service | Parts Catalog" on the control bar. Any year TTR125 should have this needle, but I just obtained this number using a 2003 model.

The airbox mods that you have done will tend to lean it out, which makes more sense. A hard time starting points at the pilot system. Do you have a hard time maintaining an even idle? Does the idle tend to "hang up" at a higher RPM and eventually drop down to a lower RPM?

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Actually, there really is no idle now. When I throttle it, the motor hesitates, then revs, then hesitates, then dies out. Its just running really bad. When I first changed the jet, I rode it for about fifteen minutes at home. It ran fine. Then we took it up to the track and rode it around a couple of times and the power felt much better. Then my wife got on it for a few minutes and it now just runs terrible. And has stayed that way. Im assuming once it got really warmed up it showed its true colors. Im just hoping I didnt screw it up doing the mods, my wife will kick my butt. Also, when I got it back home, I had to use the choke to start it, which Ive never had to do before.

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I had a similar problem with mine. It ran ok for a while, then changed personality to where it would hardly idle. The pilot screw (under the brass insert) had been set all the way in at the factory. I was able to get it idling just fine after adjusting the screw.

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I just want to make sure. That brass insert is towards the motor end of the carb on the underneath? How far from the cap is the screw? Dont want to mar the screw. What does turning the screw adjust? Amount of airflow to gas? Sorry, so many questions.

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What does turning the screw adjust? Amount of airflow to gas?

Here is a link to a pdf describing the Mikuni VM carburetor and tuning of it.

www.mikuni.com/pdf/vmmanual.pdf

What Suzuki calls the pilot screw is called the air screw in the pdf manual. It is also located at a different place on the carb, but it does the same thing.

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:excuseme:bottom line guys the bike is very very anemic even after an aftermarket pipe, jetting,etc.bbr made my wifes bike into a rocket,without the big bore kits etc. you will get nowhere but:thumbsup:its worth it, there very fun play bikes

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