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ttr 90 revs out of control

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My buddy let his oldest son rebuild his youngest sons ttr90. Now when you start it, it revs out of control. I thought I had read this was caused by an air leak. What could be causing this? What should he check? Any help would be much appreciated.

Thanks Ed

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A air leak can cause the motor to not return to idle right when you let off the throttle but normally doesnt make it take off out of control. What I would check first is to make the the slide isnt in backwards, as that is very common at making the motor do what you described and a easy mistake to make.

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A air leak can cause the motor to not return to idle right when you let off the throttle but normally doesnt make it take off out of control. What I would check first is to make the the slide isnt in backwards, as that is very common at making the motor do what you described and a easy mistake to make.

good advice, also make sure there is slack in the throttle cable.

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Thanks for the replies. It can't be the slide reversed as the carb was not taken apart. I was helping them and trying to adjust some slack into the throttle cable but was unable to. I looked in the manual that come with the bike to see if his son had rerouted the cable (he did this on his yz125 and had problems) but didn't find a cable routing diagram. Not saying it wasn't there but I had been awake about 27 hours and wasn't at my most alert. The bike does speed up when you turn to the left. Hope to get this corrected so the poor kid can ride again. Thanks for the help and any more would be great

Ed

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whenever i cut the bars left on my old ttr 90 the idle went up its the way the cable is adjusted ; my bet on the revving is an air leak like everyone else said but where its at is the hard parttry listening for a whistle sound also

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If it is revving when the bars are turned to the right, i would say almost certainly the throtle cable, air leakage is not going to be affected by the bars being moved :)

Make sure the problem gets fixed and fixed properly, a young kid on a bike that may rev out is not a good situation, it can only end badly, kids panic a lot quicker than adults

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Pull the air intake tube off the carb and visually verify that the carb slide is all the way down in the carb and isn't stuck half way open. Aside from the carb slide not sitting all the way down I dont know what It could be.

Did you get the timing right??

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Thanks for the replies. It can't be the slide reversed as the carb was not taken apart. I was helping them and trying to adjust some slack into the throttle cable but was unable to. I looked in the manual that come with the bike to see if his son had rerouted the cable (he did this on his yz125 and had problems) but didn't find a cable routing diagram. Not saying it wasn't there but I had been awake about 27 hours and wasn't at my most alert. The bike does speed up when you turn to the left. Hope to get this corrected so the poor kid can ride again. Thanks for the help and any more would be great

Ed

ok so turn left to go faster and turn right to slow down, problem solved! :) j/k hope u get er fixd soon

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forgot to mention it the first time but depending on what you did the fuel screw may be able to do it worked on my cousins lt125 when it started to rev to low we adjusted the screw now its to high but hey you pop wheelies when you put it in gear :)

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If it is revving when the bars are turned to the right, i would say almost certainly the throtle cable, air leakage is not going to be affected by the bars being moved :)

Make sure the problem gets fixed and fixed properly, a young kid on a bike that may rev out is not a good situation, it can only end badly, kids panic a lot quicker than adults

I don't know about that. When I was little I had a gocart with no brakes. My dad fired it up and I went riding. The throttle stuck wide open. Now granted it wasn't incredibly fast but I went flying around the lawn. Under the volleyball net dodged the horseshoe pin and then finally hit a stump. Of course mom wasn't home, you should have seen his face. I was all happy though. :)

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