Knocking sound from my Yamaha Fazer: Should I open the engine or not

While running the bike under load, there's a definite knocking sound from the engine that's audible till 4,000RPM, post which it reduces considerably.

BHPian ads295 recently shared this with other enthusiasts.

Hello all,

I purchased a preowned 2011 Yamaha Fazer a few months ago.

The bike has done approx 30,000km.

While running the bike under load, there's a definite knocking sound from the engine that's audible till 4,000RPM, post which it reduces considerably. The noise is more audible after the engine has warmed up than when it's cold.

When I handed the bike for a service to the local Yamaha service center (right after I purchased it from the first owner), they were very impressed with the condition of the bike and felt that I got it for a real bargain (₹34k excl. RTO expenses). The mechanic said the engine was unopened and said the bike was well kept.

Now, the ASS guys keep telling me over and over that the bike is fine. I showed them the noise clearly (we even went for test rides on my Fazer and another one they had in for service) and they even admitted to hearing the noise which was not present in the other bike. But they said this is normal and discouraged me from getting the engine opened. (I got the impression they were almost scared they couldn't put it back together).

My mechanic who services my other vehicles said he can open it up and fix it himself.

My question for all the experts here: do I need to open up the engine at this point, considering that I just purchased the bike? I would surely like to avoid the expense, but if it's going to ruin something else in the engine, I want it out of the way now.

Bear in mind that the bike has done a genuine 30,000km only, and the rest of the bike works flawlessly. There's no spark plug fouling, there's no smoke from the exhaust, and I get a fuel efficiency of 45km/l, something even the first owner didn't get when he owned it.

So is it necessary to open up the engine, in your opinion? Except for the noise, there are no obvious problems right now.

Here's what BHPian MT_Hydrabad had to say on the matter:

Congratulations for your purchase.

I have the very same bike from the very same year. It has run 23 or 24k kms and is being rarely used.

I haven't heard the sound file you shared, but understand your problem.

Use a good company 20w50 engine oil and the sound will reduce.

The manual prescribes 20w40 or 20w50 oil.

The sound may be coming from the valves or the timing chain. As you have recently bought it, you are over cautious, continue to ride it for a few thousand kilometers and see if the sound increases.

Here's what BHPian Suresh Stephen had to say on the matter:

If the bike is not consuming oil and there is no lack of power, I suggest you run it as is. Avoid opening the engine. You can avoid running the bike at the RPM range where it is creating this sound. One possibility is that the bike could be running lean. Try a re-tuning and make the bike running slightly rich. it may consume more fuel, but it will run cooler and you can possibly get rid of this noise.

Check out BHPian comments for more insights and information.

Seat belts save lives