Gilera runner 180 2t FXR problem

I have a gilera runner fxr with everything stock except s6 vforce 3 reed valve, phbg 21 (85 jet), runner 50 airbox with malossi sponge, 13.5g rollers and red clutch springs. I used to have a original runner 180 exhaust non catalyzed but because it was too loud i put on the catalyzed hexagon exhaust. The bike runs fine but it hase really slow acceleration simmilar to 50cc runner. What could be the problem?

 

Personally I'm not too sure, sorry buddy but just wanted to say I've been wanting a runner 180 for years now. Have you found it fairly reliable (apart from this)?

 

If it ran better before the exhaust, I'd assume the hexagon exhaust is what makes it sluggish.

50 airbox on a 180 might be a bit restrictive too, but hey if it works it works.

 

I have just built my runner. I heard that its reliable.

 

I just found out thet the exhaust is from aprilia sr150 2t. The exhaust shouldnt be a problem because these exhausts are not restricted like 50cc exhausts

 

Probably the airbox.
How is the intake diameter on the airbox compared to the carb?

 

I used the same airbox before and it was fine but then later it started acting like it had a weak spark and the spark plug was wet. Maybe the stator is broken.

 

Do a compression test. It should be above 150psi.
get the standard 125/180 airbox fitted as found on the ST125's
It'll go better with a 25 or 28mm carb jetted to suit

 

The compression is fine when i fitted the old exhaust it was a lot better. It was a completely different bike. It looks like something is in my exhaust that is blocking it.

 

If you have a build up of carbon and soot blocking your pipe you can clean it with a mixture of caustic soda and water. Be careful handling that stuff though (caustic soda, not water), it's pretty toxic stuff!

 

Is it a used exhaust?

 

Like milo said, could be carbon blocked up the cat.
Use caustic soda then get some heat in it.
That should open it up.
You will probably destroy the cat in the process though

 

I will probably just cut it and clean it then weld it back together.

 

Better option that!