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Yamaha R15: How I avoided an expensive clutch replacement

17th February 2025, 12:39 by Ananth Iyer

The throttle response has now come to the expected way. But I believe, the NGK spark plugs does require some time to come to its optimal performance.

BHPian sasta_rider recently shared this with other enthusiasts:

Clutch Plate Replacement (Avoided) and Installed NGK Spark Plugs:

Those who have read my previous post of this thread may recall that I was complaining about poor fuel economy. Why? There was an engine oil leak during my Bengaluru-Mangaluru ride, which I was unaware of due to the monsoon rains. I realised this only when I had parked her for a day or two, when there was oil spillage on the floor. I did feel lack of power during throttle response but all my attention was drawn by the faulty engine oil sump drain bolt. Somehow, I arranged the drain bolt and drain plug from Kasaragod, got her repaired at Sharief Bikes, Mangaluru where I did not like customer service. Since work was satisfactory, I did not speak a word. Surprisingly, they stole my 6 mm Allen key which comes by default in R15 v4 (under pillion seat). Just worse than Pioneer Yamaha, Kasaragod!

After this quick repair (which I was a little concerned), I had my return journey on 01-Nov-2024 (Friday). Day of the ride, I left Mangaluru at exactly 06:35 am. The route was one and only notorious "Mangaluru -> BC Road (pathetic roads) - > Shiradi Ghat -> Sakleshpura -> Hassan -> Kunigal -> Nelamangala -> Hebbal -> Seegehalli" where the roads are just horrendous. High road tax/tolls and third class roads for the public. Never mind! During most of the stretch, I did feel that the throttle response was not as satisfying as it was few months back. I was doubting Sharief Bikes: did they actually replace the engine oil? Did they do the work effectively?

During water break at Gundya, I did Google to find authorised Yamaha enroute Bengaluru, just in case, if I had to take her for a quick check-up under worst case scenario. Even if something would have happened, it was a state holiday (01-Nov). FNG was my only hopes. Thankfully, nothing unfortunate happened. I made it to my location by 02:10 pm, safe and sound! Surprisingly, that day, Bengaluru was literally empty. This is how I expect Bengaluru to be!

Quick stats of the ride back to Bengaluru, along with the machine herself:

Odo Start: 22790 km
Odo End: 23172 km
Trip: 382 km
1st Fuelling Point: MRPL, KPT, Mangaluru
2nd Fuelling Point: Bharat Petroleum,
1st Fuel Economy: 37.55 kmpl
2nd Fuel Economy: 37.99 kmpl

Note: I always calculate fuel economy by full tank to full tank method.

At Mangaluru, during the early hour that day!

Yes, that is me!

At my residence

Close-up of the beautiful dirt!

Once back at Bengaluru, I badly wanted her to be inspected by Vinayak Yamaha. I planned to explain them about the engine oil drain plug leak, the poor throttle response and lose brake levers. Let me say this, the brakes felt a lot more lose after Sharief Bikes worked on her. I wanted to go back and ask them "why is the brake levers lose when you had worked on engine oil replacement?" but did not get time due to work and family time. I just chucked it, believing nothing unfortunate would happen, which would have compromised my safety!

Before going to Vinayak Yamaha, I thought to do some research in YouTube, Google search and TeamBHP forum. What I found was a little concerning and was worried about the frequent expenses since recently for a 155 cc two wheeler! Below were the conclusions I had made up in my mind:
What all possibilities existed, to cause this poor throttle response?

Leaving the bike idle for almost 4 weeks separately between July and August 2024: moisture can accumulate in the clutch assembly, particularly if it's in a humid environment. It was monsoon during this time at Bengaluru. The lubricants in the clutch can dry out over time if the bike isn’t used. This can cause increased friction and wear when you eventually engage the clutch. If the bike sits for a very long time, the clutch plates can stick together, especially if the bike is stored improperly. Please note, the area I live, has a lot of dust! Other parts of the bike may degrade over time if not used regularly, which can indirectly affect clutch performance. For example, seals can wear out or oil can degrade, affecting overall function.
High speeds and aggressive riding (during my long rides till date) can generate more heat, leading to faster wear of the clutch plates.
Riding in back to back traffic: from few years, I have been travelling in back to back, slow moving traffic. Bengalurians can relate better. Be it when I exit/enter the city, travel to relatives place or even daily office commute. This can degrade the life of clutch assembly in general. Even the owner's manual does not say any specific interval when the clutch assembly needs to be checked/inspected!
Placing fingers on clutch while cruising: I do not have this habit at all since the day I learnt driving/riding.

On 04-Nov-2024, I got time to visit Vinayak Yamaha to get her inspected. Before that, I had plans since recently to upgrade to NGK Iridium spark plugs. Why?

Improved Ignition Performance (Iridium spark plugs provide a more efficient spark due to their fine wire center electrode)
Enhanced Fuel Efficiency
Longer Lifespan (Iridium plugs generally last longer than standard copper or nickel plugs)
Higher Heat Resistance (Iridium has a higher melting point than other materials)
Improved Cold Start Performance (Iridium plugs tend to ignite the air-fuel mixture more easily, which can be beneficial for cold starts)

I enquired about the availability of this product at multiple dealers:

LRL Motors (available online and AFAIK, they do not have a branch at Bengaluru)
Ryders Arena (they did not pick my call)
Ride Adventure (they did not have stock for R15 v4)
Htrz Modz, BTM Layout (they did have stock and I went there to get one, which costed ₹830/-).

NGK Iridium Spark Plug

My heart badly wanted to buy the Vesrah brake pads (front and rear) but since it costed around ₹1500/- each, brain did not agree. Additionally, the ceramic brake pad eats up the brake disc. Also, the price of this product was increased by ₹200/- recently. I did not find it worth anymore for my R15, but in future, if it is very much required, I might get one!

Then, I headed to Domlur. As usual, Mr. Chandar Singh (SA), attended my R15. He went for a quick test ride after I briefed him about the issue. I reminded him about the latest periodic service (8th). He then confirmed that the clutch assembly and the clutch ball has to be replaced which will cost around ₹4500/- (including labor). Since this work has to be carried out, the engine oil requires to be drained. Which means, engine oil and engine oil filter needs to be replaced afresh. I handed him the NGK spark plugs and he added the labor charges for this task as well. Thankfully, I had a free wash coupon I got during the Annual Maintenance Contract (AMC) purchase this year. The R15 did deserve a good wash after my recent ride. As usual, the chain clean and chain lubricant was added, to which I did not deny.

On 06-Nov-2024 (today), I did not receive any call from the ASC till noon. I decided to check with them (SA) by calling myself. Chandar Singh picked the call, I asked him if my bike is ready? What he replied gave me a sigh of relief and made me trust them/their work even more. He informed me that clutch plates and clutch ball did not require any replacement as they were in good condition. Hence, they topped up with fresh engine oil and engine oil filter. Big relief! Happy me, took the metro from ITPL, went to Domlur and took the delivery. The total bill turned out to ₹2189/-, invoice below for those who might find it useful:

Since I had been seeing how Toyota used to return the old components back to customer after service, I went and enquired about the old parts here as well. Since clutch parts were not replaced, all I asked was for the old engine air filter and stock spark plugs (which is also NGK but not of Iridium material). This is how the condition of both the components were:

Heck, heavy rat droppings on the air filters! This is when I started to recall the issues I faced during the rides. I hate this animal! The mechanic who worked on my R15 said "sir, the filter is completely destroyed by rats by pooping and urination!". What more should I say: I was speechless?!

Not an expert here, but is this how a degraded spark plug looks like? Was it a right decision to replace with NGK ones? Could this spark plug have clocked few more ignitions? Feedback much appreciated.

Clogged air filter never came to my mind at any point of time, even though I was very well aware about the dusty conditions in India. All my attention was diverted to other factors I mentioned above. Never in my dreams I thought a rodent can find access all the way up-to the engine air filter. Now, how to prevent this from happening again is what my concern.

When did rats find all the time to do this? I can now recall and confirm that it was during the period Jul-2024 & Aug-2024 (3 weeks each month). I did place Mortein's rat biscuits near to rear suspension (which is where the rats find an entry towards the battery chamber) & nearby area in my apartment at Bengaluru before going to hometown. I had even sprayed 3M's anti-rodent spray. Should I plan to get the entry points meshed? Next research (and a post maybe in future) will be on this fear. Another sigh of relief when the pocket does not get cut wide open.

I also learnt a new lesson today: while on the way back after taking her from ASC, near to Indiranagar 100 ft road, at the traffic signal towards KFC signal, I could see white (thick) smoke emanating from the rear brake pedal area. I did knew that after the service, few engine oil deposits which was spilled, get evaporated and this smoke pertains to that. But this lasted a little longer and I panicked mid traffic. As the signal turned green, I took to the side and inspected for any drain bolt leakage again this time. But could not find any. Slowly, put my hand (being aware of the hot silencer) to feel for any kind of lubricant spillage. Could not find because I was not able to see behind the fairings. Immediately captured the video, sent to my SA and asked if this was normal. He consoled my tensed mind saying this is normal. Since the clutch assembly was removed and new engine oil was used, there would have been a little more spillage than usual. Once heated for some time, it should evaporate. If it still persist, get the vehicle tomorrow. We can check. Even after this conversation, when I was near the Swami Vivekananda Metro signal, the smoke was coming. Concerned fellow riders pointed out to me and I signalled them all is well. From there, the smoke did not turn up. Another quick relief. Thank goodness!

The throttle response has now come to the expected way. But I believe, the NGK spark plugs does require some time to come to its optimal performance. My R15 turned off thrice at multiple occasions when I was moving ahead from a stand still. From then, I managed to give a little more throttle feedback while moving from stand-still to avoid bike turning off mid-traffic. Will post more on this after few weeks maybe.

As a quick summary, till date, below parts were changed/replaced during different occasions/intervals:

Please note: I did not include oil change, oil top-up etc because they are taken care during all the periodic services.