Free Power Doesn't Exist, But Here's An Inexpensive Power Boost For the It175
Free Power Doesn't Exist, But Here's an Inexpensive Power Boost for the IT175
About the only complaint we could muster about the IT175G was the pipey powerband. And Yamaha responded by telling us about a modification that not only eliminates most of the peakyness, but adds 2.25 bhp, too! The modification requires cutting the airbox and replacing the silencer. The airbox is simple and easy: first remove the right side number plates, then take a hacksaw blade or hot knife and open up the top of the box. More air can enter and breathing is better. The silencer mod is a little more costly and requires some welding. The first thing you’ll need is a silencer/spark arrester from a 1979 IT 175. It comes in three pieces and the cost of the parts is $39.46 plus tax. No, the part won’t bolt right on. The ’79 unit isn’t the right length and the mounting brackets are spaced differently. You have to cut the piece of pipe off the stock silencer, carefully position it to the front of the ’79 unit while it is bolted to the frame by the front mount, and weld the pieces together. Next the mounting bracket has to be modified like the one in the picture. It sounds complicated but really isn’t. Time required for the complete modification is around three hours, and the final result is more than worth it. The dyno shows a 2 bhp plus gain starting at 4000 rpm and, holding through 8000 rpm. Torque is also improved and the bike is much easier to ride. It’s no longer necessary to clutch the bike all the time or ride it like a 125 motocrosser to go fast.
We drag raced the two bikes, one modified, one completely stock, fully expecting the unmodified to be the fastest in a straight line drag. Wrong. The modified bike continually pulled the stocker by one length through the gears and topped out five lengths ahead and 5 mph faster (70 mph versus 75 mph). The simple modification improved the power more than anyone would expect from a full port job and custom pipe! If you already own a 1980 IT175G, try the modification, it’ll be the best $50 or $60 you ever spent.
