Quote by: Matty

I know that in countrys with strict emmission/pollution laws, manufacturers of carburetted motorbikes often use restrictors in the intake manifold and exhaust manifold to enable the bikes to pass emission laws. Once these restrictors are removed the engine performance increases greatly as the bikes can now breath easier.

Does anybody know if the new fuel injected Yamaha Spark 135i has these restrictors and if so are they easy to remove ???
Any advice appreciated.
Thanks Matt...

He Matty,

You can relatively easy enhance the performance of your Yamaha Spark 135i by modifying the airbox and go for a sport exhaust pipe. With the exhaust pipe make sure that it doesn't make to much sound...

Of course if you want more you can go for a more aggressive camshaft... but that will likely mean that in the lower rpm's you will have less power...

Yes, you're right, the Yamaha Spark 135i is not easy to find performance parts. I once saw a guy who had a Yamaha Spark 135i with a Honda CBR150R sport exhaust muffler attached to it... He told me that the exhaust pipe was custom made from stainless steel.

It looked impressive and the sound was surely amazing...

Quote by: Matty

I dont want to fit an after market exhaust pipe can to my bike unless it is manufactured to fit my model.
i have seen on Utube some Spark 135i using Yoshimura pipes. looked on yoshi website but dont see my bike listed.
Somebody must know where i can find a good exhaust or know someone who does know.
please help...

You probably right about not using just any exhaust pipe. For Yoshimura, did you contacted the Thai distributor/representative of Yoshimura in Thailand?

Real Moto Sports
372 Ramkamhang 146,
Sapansoong,
BANGKOK 10240

Sorry have no email or telephone number...

Also keep in mind that the Yoshimura pipe you saw could be fake...

Quote by: Mick

G'day! I own a 2007 Yamaha Spark and I also would like to find out if my model has intake and exhaust restrictors? What mods help with the airbox? Different filter or modify the airbox unit? Have seen loads of performance parts for the bike but unable to contact via e-mail given in another forum.....anyone stock off the shelf performance parts for this bike? Thankyou!

Through each of the little rectangular holes on the "dress plate" on the back of the stock muffler, carefully drill a tiny pilot hole only 1/16" deep into the back round face of the muffler. You will find your drill hits an internal plate that 1/16" in----- DO NOT PENETRATE THAT NEXT BAFFLE!!! Then drill out the holes to 7/32". This will leave the rectangular holes intact on the back dress plate. The sound is quite soft at 40 in third gear. When you get on it, it is quite louder and sounds quite fine. You can cover the main exhaust hole with your thumb and romp it with no pressure felt on your thumb. The new small holes let all gases out fine. So between the two you have half the restriction. Grind or cut the four plastic rivets that hold on the perforated screen inside the air filter element and get rid of the screen. Take off the rubber air "snorkle" that goes into the air box. This was to soften the sound of the intake pulses. Install an Irridium plug. One more tooth on the rear sprocket. This will gear it down minutely, but you will go faster because it was geared taking gas milage into account at the factory, and not looking for top end. You will feel the difference. If you want to go beyond this, buy a new bike, unless you just need a hobby. Happy trails! : )