YT125-175 swap problem

[RyanRX7]

Ok so I did the cylinder and head swap to my YT125 and it took a little doing to get it running. What I had to do was use the 125 carb instead of the 175 carb and hook the fuel pump up to the smaller 125 carb. When I used the 175 carb and pump it didn't have any power. With the 125/pump combo it seems to have a good deal more power, but I have to run it without an air filter, if I put an air filter in it runs like crap again. Any ideas guys?

[RyanRX7]

No ideas on this carb issue guys?

[4cylinders]

hey, almost sounds like a plugged muffler. pull the muffler off and try it, if you can. clean out the insert.

[smokinp]

what does the plug look like?sounds like its not getting enough air...

[hotroddal]

sound like a plugged air filter if it runs like crap with it on and runs nice without it on.

[85_ATC_200S]

Sounds like a jetting/ air-fuel ratio problem to me. What i would do is mess with jetting, get a high flow air filter or something along those lines, and also clean your head pipe and silencer out. Like he said it could be a plugged muffler. Just my 2 cents.

[TrikerR]

yea did you rejet cause u r trying to feed a 175 engine with a 125 carb which didnt need to put in as much fuel.