[Frankenstein87trx250]

Hi everyone I'm new here I have a 87 honda 250 two wheel drive and just for giggles I put a 300 carb on it and it runs great it has great throttle response idles good and runs like a scalded dog until I shift too fourth it acts it's bogging down it ran fine with the original carb on I was just curious any idea waists going on Tia

 

[Goober]

How’s the plug look? Light gray or brown? Starvation maybe try a larger main jet.

Sooty? Too rich.

 

[Frankenstein87trx250]

I'm a truck driver headed home right now I will look asap I do know it sorta burps back thru the carb every now and then

 

[SamUK]

Emulsion tube is wrong or the jet that sits within it. As said above, you can confirm this by the color or the spark plug