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TTR125 Won't start at all.

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Hi all. I posted Sunday in the general forum about the Mikuni flooding, and got some good information. Here is what happened. I cut the air box and it ran well but I changed the pilot jet to a 17.5 and the main jet to a 110. It started up and ran rough at high rpm so I put a 107.5 main jet in and the bike would not idle but ran. It stalled and I could not get it started again. I replaced both jets with the originals and checked the floats and the needle jet( by blowing in to the inlet with the carb upside down and could not blow air into the carb so I assume the needle jet is good). This was a tip I got from my last post.

I have good spark tested 3 times. Everything is connected correctly, gas adjustment screw turned out 3.5 turns, and the bike will not start.

I even tried to bump start it, I live on a hill but it still would not start, it didn't even sound like it was ready to start.

There is fresh gas in the tank and the carb is getting fuel. I had to empty the bowl each time I took it a part.

I do not have access to compressed air but blew everything out the best I could, didn't appear to have any trash in the passages.

Does not appear to be many things that could go wrong with the carb, simple design but I am at a loss as to why it won't start.

I will check the jet needle but I don't remember it being bent or flared at the tip.

I'm sorry this is a long post but I am determine to get the bike running.

Any suggestions?

Thanks

Phil

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I'd be at a loss too. Not sure I can be of help, but a couple of observations:

Changing the main jet should not have affected starting or the idle one way or another. Main jet only comes into play at 3/4 to full throttle.

3.5 turns sounds like too much to me. Stock, I think, the fuel screw was almost completely shut. I have mine at about 1.5 turns. And I'm using the 17.5 pilot and 107.5 main.

What altitude are you at?

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400 ft. I am going to take the carb apart again buy a can of compressed air and blow it out. I'm also going to reset the gas screw at 1.5 turns and see what happens.

Thanks for the reply.

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Getting it to start is all about the fuel screw and the pilot. 1.5 -2.5 on the fuel screw is where you should be at. But even that could very. Make sure you can see through the pilot. Also, is your air filter clean. That happen to me once. Undo the air boot and try to start it. See if that helps. ALso, could be an air leak.

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Thanks for the reply. I actually took the air filter out when I was trying to start it. How would I check for air leaks?

Thanks

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Thanks for everyone who gave good advise. Turned out to be the plug. It was so fouled even after I cleaned it and although it had good spark, it wouldn't fire.

So now I'm going to rejet the carb with a 15 pilot jet and a 107.5 main which seems to be popular. And keep a spare plug.

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If you are at sea level throw in a 17.5 pilot and a 110 main. Mine wouldn't start before that either. Now it starts right up and the fuel screw should be around 2 turns out.

Amazing difference. I also opened up the airbox and, pipe and changed the rev box.

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