New tt250 help

[Bobertj]

So bought new tt250 nice bike but having one issue basically when you try to give it 1/2 throttle or more the bike misses as it climbs through the rpm range if you feather it all the way through no missing only half throttle
Or more csc has been helpful sent me coil and new computer for the coil still same problem my
First thought was fuel and I’m still leaning towards this being
The issue any ideas? New to the forum thank you so
Much

[NzBrakelathes]

Have you checked valves? This might help a little
Second thing is tune the carb or look into carb check jetting that’s actually in it
I do have a set listed in my eBay store for first tune, this might be useful to you.
So you changed the CDI and coil? Any color smoke when it plays up?

[NzBrakelathes]

Do you have a timing light? See if it’s loosing spark when it plays up etc

[JerryHawk250]

Also try a new plug. The one that came on the bike may be defective or cracked. I agree, valve lash would be one of the first things to check.

[elkhunter338]

Originally Posted by JerryHawk250

Also try a new plug. The one that came on the bike may be defective or cracked. I agree, valve lash would be one of the first things to check.

I would second new spark plug. I had that happen in my honda car, new spark plugs, 10 miles later one failed. Replaced it and running good now for 40k+

Valve lash would be good check, mine were tight at 400 miles (I hope I did not damage valves) Bike runs great.
Dad's valve lash was spot on at 100 miles.

[Ariel Red Hunter]

Originally Posted by elkhunter338

I would second new spark plug. I had that happen in my honda car, new spark plugs, 10 miles later one failed. Replaced it and running good now for 40k+

Valve lash would be good check, mine were tight at 400 miles (I hope I did not damage valves) Bike runs great.
Dad's valve lash was spot on at 100 miles.

You make a good point here about damaging valves. If you ride at 60 mph for an hour at 6500 rpm, that means that the engine has fired 3250 times in one minute, to cover one mile. To put it simpler, that poor exhaust valve has been assaulted by 500+ drgree heat and flame 3,250 times in order to cover a mile. I think people should adjust the valves before they even start it for the first time. I know, I know. You want to declare "IT LIVES!!!" as soon as possible, but patience, patience!..ARH

[elkhunter338]

Originally Posted by Ariel Red Hunter

You make a good point here about damaging valves. If you ride at 60 mph for an hour at 6500 rpm, that means that the engine has fired 3250 times in one minute, to cover one mile. To put it simpler, that poor exhaust valve has been assaulted by 500+ drgree heat and flame 3,250 times in order to cover a mile. I think people should adjust the valves before they even start it for the first time. I know, I know. You want to declare "IT LIVES!!!" as soon as possible, but patience, patience!..ARH

You would think the factory could set the valves right, makes me wonder what else they screwed up.
Had I known I would have set the valves from day 1. But another bike my Dads. tt250 was perfect, set on the loose side of the spec.

I removed the side plate to rotate the engine, 1 out of the 3 screws was significantly tighter. Hmm they don't have a torque tools for assembly?

[Bobertj]

Thank you both for response so the valves are due in the next 40 miles so I’ll be doing them this weekend yes replaced both under warranty and also spark plug was the first thing I did to see and no improvement with all three those parts replaced. Changed the oil already bike is about to hit 500

[Bobertj]

Also idk what size jets are in it that’s was my thought maybe needs a different main
Jet since it’s only 1/2 throttle or more
I’m not to well with carbs but I’m
Decent with cars etc so

[JerryHawk250]

Try adjusting the idle mixture. It may be set to lean. Once you have the idle mixture set and it still does it then you can raise the needle up one notch.

[NzBrakelathes]

Originally Posted by Bobertj

Also idk what size jets are in it that’s was my thought maybe needs a different main
Jet since it’s only 1/2 throttle or more
I’m not to well with carbs but I’m
Decent with cars etc so

DO check my eBay store for some stuff that might help you etc
Valve adj set, first tune set, carb air screw adjuster all could be useful to you
I’m in the USA Saturday and have some products with me or it be 2ish weeks before I’m back
If you’re lucky I might be passing thru your area if you’re west coast lol
I have some items to drop off to customers already and it’s not the first time I’ve deluverrd in person

[Bobertj]

Ok I’ll check it out. Do I have to take the carb off to change the idle mixture ? Think the older models don’t have screw but I believe mine does

[JerryHawk250]

Originally Posted by Bobertj

Ok I’ll check it out. Do I have to take the carb off to change the idle mixture ? Think the older models don’t have screw but I believe mine does

The stock carb does have an idle mixture screw. It may be covered by with a plastic or brass cap that can be drilled out. It will be hard to adjust while on the bike but can be done. You want to adjust the idle mixture after the engines up to running temperature.

[Air_male]

and please make sure the choke is off

[Ariel Red Hunter]

Originally Posted by Bobertj

So bought new tt250 nice bike but having one issue basically when you try to give it 1/2 throttle or more the bike misses as it climbs through the rpm range if you feather it all the way through no missing only half throttle
Or more csc has been helpful sent me coil and new computer for the coil still same problem my
First thought was fuel and I’m still leaning towards this being
The issue any ideas? New to the forum thank you so
Much

My first thought is "too lean."...ARH