Does the dealer have another one you could drive? Its possible that with a 125 motor, and your weight, and a non cv carb, that snaping open the throttle is too much for it. Try to drive another one and see if it acts the same way. I know on older motorcycles,( with non cv carbs) its easy to overwhelm the motor with a heavy hand and low rpms.
Its also possible the vent, in the carb is plugged, but if its done the bog since new...thats probably not it.

 

this may be dumb...... but do valves affect any of this? intake opening enough? i have heard complaints about valve adjustment problems on these. (can't see exhaust valve being it, but intake???)

factory setting for the air/fuel is 2 1/2 turns out. you can fine tune from there, but mine seems to run good there. let us know how this turns out. assume air filter is clean!?

 

I thought the same thing so I checked and double checked the valves and they are right on. It is still at the dealer right now so we'll see what they say.

 

has to be the jetting, my 110 mojave did the same thing so i just kept playing with the jets/air screw and snorkle and finally with a new foam filter and the needle clip adjusted ahnd a J&R pipe its fine, matter of fact better then before.

 

I got the little Grizz back from the dealer after almost two weeks and the dang thing doesn't run any different than it did when I dropped it off. Maybe Hondabuster is right and it is always going to hesitate. Once again this is what the worst case scenario is. I can be stopped in gear with the engine idling, pin the throttle wide open to try and spin the tires and it will do one of two things. It will either kill or it will almost kill then it will start to go and once it is going it will take off. It will run great all day long as long as I don't try a full throttle start. Can anyone elses breeze do a full throttle start from a dead stop and take right off ?? I am going to call Yamaha today and see what they say, Not that that will probably help.

 

Did they try a smaller main jet? Try removing the air box lid, and try nailing it...my guess would be the leaning out, will make the thing take off quicker.
I remember years ago, on motorcycles, this was a very common problem. This was the early 70s and most street bikes were 50 cc and up. The small ones didnt like too much throttle before the revs built up, or itd bog like that. These were motorcyles before modern cv style carbs.
Hows it go, when your boy, nails it?
What did the dealer do...or try, to make it better?

 

If I have it in neutral and nail it to rev it up it will still kill or bog way down before it slowly revs up. It does the same with my boy on it also. I have know idea what the dealer did, In fact I wonder if they actually did anything. They say they cleaned and adjusted the carb just like they did the other two times. I am really disappointed in the way in takes off and I am also a little dissapointed in the dealer. I am thinking the tech. isn't very good. I am going to call Yamaha although I doubt that will help.

 

I talked to 3 different Yamaha dealers today and everyone of them said If I pin the throttle from a dead stop it is going to fall flat on its face. They all say it is normal do to the type of carb and the size of the engine. One dealer said they got one to not hesitate, But then it wouldn't idle so there is not much that can be done. Oh well, At least I know it isn't something wrong.

 

I will make a mental note to see what mine does, and let you know. does it do this cold, or when it's at normal operating temp?

 

It does it at normal operating temp. I talked to Yamaha and all I got out of them is try another dealer and if they say it's normal then they know best. Imagine that, The factory doesn't know if it is normal or no. I can live with it if it is normal, But if it's not I would like it fixed. If it is not normal a new problem has arrived. The last time the dealer had it (which was time 3 for the same problem) they kept it for almost two weeks and the warranty expired. I would think they would still have to cover an on going problem wouldn't they ?? All the dealers I have spoken to say it's normal, But if you could see what yours does that would be appreciated. Thanks to all of you that are trying to help. I have learned more and received more help from people on this board than I ever thought I would.