Hi Guys,
I ride a Honda CBX250 Twister (known as CBF250 in some markets) and I am from South Africa.
I am having an issue with the carb that I am unable to diagnose.
First off, the bike has an aftermarket exhaust on it. The bike is also at 46 000Km. The motor was rebuilt by Honda by the Previous Owner. The carburetor is so clean, I will eat out of it. There's nothing wrong in the carb.
The bike had a #142 Main Jet in the carb when I got it. (factory is #138 - It was probably changed somewhere in it's life due to the aftermarket slip-on)
On partial throttle and idle the bike is very happy, no issues at all. After 3/4 throttle the bike starts to starve it feels like you're closing and opening the throttle continuously.
Now, here's what I've done in order to diagnose the problem.
1st, I removed the air filter to test - No difference
At full throttle with choke on - No difference
So I went up from the #142 to a #146 main jet.
It feel ALMOST perfect but it still starves at >3/4 throttle. again, air filter out and choke on with full throttle makes NO difference. - Choke makes it feel a bit worse though.
So I purchased both #148 and a #150 main jets in HOPE that I manage to sort the bike out!....
Installed the #148, it feels exactly the same as the #146. same applies to choke and air filter removal.
Also check the Float level.
I then installed the #150. Now. Now, it over fuels! The bike sputters and pops even at partial throttle (anything more than 1/2 throttle).
BUTTTT with the air filter removed, it revs freely to 10grand with no issues - which means that my #150 main jet is too BIG!
I am now currently lost for words.
I have stripped the whole thing down, checked the air box, all the hoses the carb, everything. I found a o-ring in the carb at the idle jet that was perished, It was replaced. Needle works perfectly and moves up freely when air is blowing over it. The diaphragm is perfect. The carb does not have an adjustable air jet and the needle and floats are non-adjustable.
It is a Keihin VE carb.
Guys please help me diagnose this issue!?
https://farm5.staticflickr.com/4344/...3cc5f11ff5.jpg
Thank you,
André
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