Yamaha FZS 180 CC Big Bore Long Term Review!

I just returned from a mechanic after giving my 2012 Yamaha FZs for tuning the carburetor.

It all started 2 years ago with a feeling of my bike being under powered. As usual I was planning to do some upgrades to the bike to 'extract' few more horses from my bike.

Numerous searches and some novice advice made me think of a big bore kit for my bike. Stock engine was 153 CC. A leading motorsports tuning shop in Bangalore was providing 180CC big bore along with other upgrades like head work, Free Flow Exhaust, Racing carb etc. Based on some reviews I found online and a friend's experience with the same I contacted the tuner. His claims on the upgrades were convincing enough as he even had videos in YouTube on the acceleration of an upgraded FZ. Moreover he promised me better than stock reliability for the upgraded engine. I agreed to do the upgrade and started gathering funds for the same as I was studying at that time and had no source of income. I borrowed from my parents and took the bike for work. For around 11k I had 180 big bore, mesh stock air filter and something what he called valve polishing. The bike was running good. I was said not to cross 5k RPM. I followed the run in. But after the run in I started feeling that the tuning is not all perfect because it had glitches. The engine used to knock below 3000 RPM, and low end was sluggish. But the high end was good enough. I once tried a 40 kmph pull against a Duke 200 with pillion on it and Duke could not catch it till 100! 

Everything was going like a dream. Eventually I felt like the low RPM engine knock is a burden.So I took my bike to the tuner again for the head work which he did not do previously. He did the head work for some 3k and installed the head and then the bike would not cross 4k RPM. His mechanic did everything he could do on a carb. Tried all sorts of jets available. Reset the carb 5 or 6 times.  But no use. One incident that's worth mentioning here is that I went in at 10 in the morning and they made me wait till 6 in the evening to start the work. He and his mechanics were so curious to work on some racing Honda CItys. I went after he agreed he is free t0 do work and it will take only a couple of hours. But ended up making me wait there like a dog for around 15 hours on one day. Finally they started singing songs that I have to upgrade to a racing carb as well. I did not allow as I was not prepared for that upgrade. Later on after making me wait till 1 at night, they put on this so called racing carb after some exchanging of words. They did some sort of tuning and bike was running somehow. I said them it is OK and left the place marking in my mind I will never return back to that hell. I could never ride my bike after 6k RPM. I somehow managed to commute with it. Later on I did some work myself and made in a run-able condition. The bike had lost its refinement it had in stock. 

After some 25k kms, I was on highway cruising at 100kmph for an hour or so and I heard some knocking noise from engine, which ended up as a worn out crank. As a chain reaction or not when the engine was opened the piston and bore was seized, valves were broken as well. I put the stock piston and bore back,fixed everything and had the bike running. On removal of upgraded parts during the repair there were some things I noted. The race spec carb was Pulsar 180s carb. There was literally no considerable changes done on the head. The piston rings he provided with new piston were so weak they were breaking like biscuits! All together it is perfect to say I f***d up my bike big time.

To all those people out there who wants to modify their engine for more power, I would like to give some advice. It is after years of Research and Development and after many prototypes, a manufacturer settle down with one model which is the optimal balance of efficiency, performance and reliability. It is not that Yamaha made the stock FZ's engine to be 153 CC by mistake or they did not knew how to make exact 150 CC out of it. It is a result of numerous trial and error methods by which they devised the particular engine capacity. Yes, you can extract more power out of the engine through various means. But it changes the equilibrium! Know this racing engines are rebuilt after few races! Don't compare them with street bikes! If at all you need more power, buy a bigger vehicle! That's the right way. But at least for super-bikes manufacturers sell authorized performance parts. These have some technical research done before they say it is good to be fitted on their vehicle. So there is no big risk!