The mystery of the fading Nmax & a loss of power .

[DavidFL]

Continuing with my 2026 new year luck.

An Entertaining Story (for Some)

For the past few weeks, my Nmax scooter has been steadily losing power. This was well and truly confirmed on a recent ride with my son Jason, when we rode over Paradise Road to Chiang Saen. From there I turned back to Chiang Khong, while Jason continued on to Chiang Mai via Tha Ton, R1089 and R107.

The Nmax used to top out at 115 km/h. On this ride it was flat-out knackered at 95 km/h, and uphill it could barely manage 45–60 km/h. Meanwhile, Jason disappeared into the distance on the mighty Aerox, still pulling hard.

Clearly, something wasn’t right.
It was time to head to Chiang Rai and get the Nmax serviced.

I don’t service bikes in Chiang Khong anymore — parts availability is the problem. The local changs contact Sinthanee Chiang Rai, who then order parts from Bangkok. A week later, maybe, your parts arrive… all while your bike sits there in pieces and unusable.

In Chiang Rai I have two options:
Mr Kong at GTR (my favourite), or Sinthanee Yamaha.
I choose Mr Kong every time. I can jump the service queue, and Kong is often able to source parts independently. Sinthanee, on the other hand, keeps minimal stock and expects you to wait several days for parts from Bangkok — after you’ve already waited several days just to reach the front of the queue.
For me, Kong is the way to go.

The Ride Over
It’s a leisurely 100 km ride, and with a dodgy back there’s no rush anyway.
I chose the old road — R1174 via Phaya Mengrai. No hills, nice and flat, and perfect for a slow meander. The faster route via R1020 & R1421 was out of the question — I simply couldn’t maintain speed.

I set off with a maximum speed of 75 km/h, but every 20 km the power dropped to 40–50 km/h. I’d stop, have a drink, let the bike cool down, then set off again — briefly back up to 70 km/h.
After another 15–20 km, the power would fade again. Time for another break.
Repeat this process again and again and again…

The distance from Chiang Khong to Chiang Rai city is 100 km.
Total travel time: 4 hours.

Coffee Stop in the Middle of Nowhere

Somewhere in the middle of nowhere on R1174, I stopped at a little wooden Mickey Mouse coffee shop by the roadside.
As I pulled up, I noticed a not-unattractive woman sitting out front, so I called out in Thai:
“Is the coffee shop open?”
She shouted to another woman hidden at the back, who then appeared.
“You want coffee?”
“Yes, please.”
All of this was in Thai.

She came into the shop and asked:
“Do you speak Thai?”
I replied, “No,” and ordered a cappuccino in Thai anyway. 55 baht.

She brought the cappuccino and then asked:
“Are you alone? You travel by yourself? And you speak Thai?”

I replied:
I’m single
I’ve lived here a long time and like travelling alone

I then asked about them.
“We’re both single — 50 and 36.”
Both were attractive and still in good shape.

The older sister, the shop owner, said she had been single all her life, no kids, and didn’t want a husband.
“Oh — are you lesbian?”
“No, I’m not lesbian.”

She continued:
“My younger sister is 36 and single too. She’s looking for a boyfriend.”

The younger sister piped up:
“I don’t need much money either — 20 baht a day for food is enough!”

At this point, I immediately paid for all four coffees we had consumed and placed a 100-baht tip in front of the younger sister — for the next five days.
She nearly wet herself laughing.

I then upped the offer:
“How about 100 baht a day — let’s go to Chiang Rai for a few nights?”

Sadly… she declined.

But I shall return.
The banter alone was worth the stop.

 

[DavidFL]

Continuing with my 2026 new year luck.

An Entertaining Story (for Some)

For the past few weeks, my Nmax scooter has been steadily losing power. This was well and truly confirmed on a recent ride with my son Jason, when we rode over Paradise Road to Chiang Saen. From there I turned back to Chiang Khong, while Jason continued on to Chiang Mai via Tha Ton, R1089 and R107.

The Nmax used to top out at 115 km/h. On this ride it was flat-out knackered at 95 km/h, and uphill it could barely manage 45–60 km/h. Meanwhile, Jason disappeared into the distance on the mighty Aerox, still pulling hard.

Clearly, something wasn’t right.
It was time to head to Chiang Rai and get the Nmax serviced.

I don’t service bikes in Chiang Khong anymore — parts availability is the problem. The local changs contact Sinthanee Chiang Rai, who then order parts from Bangkok. A week later, maybe, your parts arrive… all while your bike sits there in pieces and unusable.

In Chiang Rai I have two options:
Mr Kong at GTR (my favourite), or Sinthanee Yamaha.
I choose Mr Kong every time. I can jump the service queue, and Kong is often able to source parts independently. Sinthanee, on the other hand, keeps minimal stock and expects you to wait several days for parts from Bangkok — after you’ve already waited several days just to reach the front of the queue.
For me, Kong is the way to go.

The Ride Over
It’s a leisurely 100 km ride, and with a dodgy back there’s no rush anyway.
I chose the old road — R1174 via Phaya Mengrai. No hills, nice and flat, and perfect for a slow meander. The faster route via R1020 & R1421 was out of the question — I simply couldn’t maintain speed.

I set off with a maximum speed of 75 km/h, but every 20 km the power dropped to 40–50 km/h. I’d stop, have a drink, let the bike cool down, then set off again — briefly back up to 70 km/h.
After another 15–20 km, the power would fade again. Time for another break.
Repeat this process again and again and again…

The distance from Chiang Khong to Chiang Rai city is 100 km.
Total travel time: 4 hours.

Coffee Stop in the Middle of Nowhere

Somewhere in the middle of nowhere on R1174, I stopped at a little wooden Mickey Mouse coffee shop by the roadside.
As I pulled up, I noticed a not-unattractive woman sitting out front, so I called out in Thai:
“Is the coffee shop open?”
She shouted to another woman hidden at the back, who then appeared.
“You want coffee?”
“Yes, please.”
All of this was in Thai.

She came into the shop and asked:
“Do you speak Thai?”
I replied, “No,” and ordered a cappuccino in Thai anyway. 55 baht.

She brought the cappuccino and then asked:
“Are you alone? You travel by yourself? And you speak Thai?”

I replied:
I’m single
I’ve lived here a long time and like travelling alone

I then asked about them.
“We’re both single — 50 and 36.”
Both were attractive and still in good shape.

The older sister, the shop owner, said she had been single all her life, no kids, and didn’t want a husband.
“Oh — are you lesbian?”
“No, I’m not lesbian.”

She continued:
“My younger sister is 36 and single too. She’s looking for a boyfriend.”

The younger sister piped up:
“I don’t need much money either — 20 baht a day for food is enough!”

At this point, I immediately paid for all four coffees we had consumed and placed a 100-baht tip in front of the younger sister — for the next five days.
She nearly wet herself laughing.

I then upped the offer:
“How about 100 baht a day — let’s go to Chiang Rai for a few nights?”

Sadly… she declined.

View attachment 163079

But I shall return.
The banter alone was worth the stop.

To continue the story & the"fix."
I arrived in Ching Rai somewhat dehydrated & flustered at 6.30pm.
An evening of food & drinks with a delightful taxi driver followed to relieve the stress of the day.
The next morning I was at Kong's to weigh up the options - Sinthanee or Kong?
At Sinthanee the bike would go in the queue but at Kong's he said he do me a favour, straight away, & hopefully get it fixed in a day or two at the latest, parts depending.
I went with Kong.
After discussing the symptoms, we settled on the fuel pump and the coil, the most likely causes.
The coil was cheap & he could get a copy fuel pump.
Nothing ventured nothing gained, I went along with the quick fix, especially after a compression test on the fuel pump came up low.

"Everything else" was given the once over & checked.

I left Kong to his work in peace and carried on as normal, albeit sans a motorbike.
At 8.30 pm on round two of the taxi driver dinner, I get a call from Kong the bike is ok you can pick it up now if you want.
Nah I'd rather not be disturbed now, tomorrow morning is ok.
Tomorrow morning, 10am, the mighty Nmax is ready to go.
With a sweet smile on my face, I head off out of Chiang Rai city in the traffic and power down 1063 towards home via the Chiang Saen bypass.
Less than 20 kms later, oops, we have the same problem. WTF. Loss of power. Damn problem not solved. Grrh.

A quick U-turn and dawdle back to CR city at 50kph & the Yamaha dealer this time.
Let them have a crack at it with their diagnostic equipment & order some parts from Bkk.
Double bummer. And that's were we still are 5 days later. Time for a check-up in the next few days.
The only positive so far is that I had an enjoyable social taxi lift home, introducing the driver to Paradise Road.

Stay tuned...

 

[DavidFL]

To continue the story & the"fix."
I arrived in Ching Rai somewhat dehydrated & flustered at 6.30pm.
An evening of food & drinks with a delightful taxi driver followed to relieve the stress of the day.
The next morning I was at Kong's to weigh up the options - Sinthanee or Kong?
At Sinthanee the bike would go in the queue but at Kong's he said he do me a favour, straight away, & hopefully get it fixed in a day or two at the latest, parts depending.
I went with Kong.
After discussing the symptoms, we settled on the fuel pump and the coil, the most likely causes.
The coil was cheap & he could get a copy fuel pump.
Nothing ventured nothing gained, I went along with the quick fix, especially after a compression test on the fuel pump came up low.

View attachment 163080

View attachment 163081

"Everything else" was given the once over & checked.

View attachment 163082

I left Kong to his work in peace and carried on as normal, albeit sans a motorbike.
At 8.30 pm on round two of the taxi driver dinner, I get a call from Kong the bike is ok you can pick it up now if you want.
Nah I'd rather not be disturbed now, tomorrow morning is ok.
Tomorrow morning, 10am, the mighty Nmax is ready to go.
With a sweet smile on my face, I head off out of Chiang Rai city in the traffic and power down 1063 towards home via the Chiang Saen bypass.
Less than 20 kms later, oops, we have the same problem. WTF. Loss of power. Damn problem not solved. Grrh.

A quick U-turn and dawdle back to CR city at 50kph & the Yamaha dealer this time.
Let them have a crack at it with their diagnostic equipment & order some parts from Bkk.
Double bummer. And that's were we still are 5 days later. Time for a check-up in the next few days.
The only positive so far is that I had an enjoyable social taxi lift home, introducing the driver to Paradise Road.

View attachment 163083

Stay tuned...

A few days ago I had a missed call from Yamaha.
Must be the Nmax ready finally, I thought.
I rang back multiple times but never got an answer.
I then used line to contact them, and again no response to a phone call of a chat message.
TIT I thought.
Never mind, pop over Friday, leave the Vstrom at Kong's for the suspension linkage service & ride the Nmax back to CK.
Simple & good planning.
BUT
The NMax aint ready yet! WTH I thought.
I asked to speak to the chang who was servicing the bike.
He came out with another employee who could speak English.
The chang explains everything to the English speaking employee & tells him to explain to me.
I said, no. You can explain to me direct in Thai. We don't need a 3rd person, you can talk to me in Thai, Oh Oh oh sorry.
So they claim to have checked most things so far, fuel pump, coil, air filter, ECU, sensor, belt and the current theory is fuel throttle body.
They're still waiting for a throttle body from Bkk to try on the bike first. If it works I have to pay for it. If it doesn't work, send it back and move onto the next theory, whatever it is.
Meanwhile I will keep working my way through the brilliant Chiang Rai music pubs.

 

[DavidFL]

A few days ago I had a missed call from Yamaha.
Must be the Nmax ready finally, I thought.
I rang back multiple times but never got an answer.
I then used line to contact them, and again no response to a phone call of a chat message.
TIT I thought.
Never mind, pop over Friday, leave the Vstrom at Kong's for the suspension linkage service & ride the Nmax back to CK.
Simple & good planning.
BUT
The NMax aint ready yet! WTH I thought.
I asked to speak to the chang who was servicing the bike.
He came out with another employee who could speak English.
The chang explains everything to the English speaking employee & tells him to explain to me.
I said, no. You can explain to me direct in Thai. We don't need a 3rd person, you can talk to me in Thai, Oh Oh oh sorry.
So they claim to have checked most things so far, fuel pump, coil, air filter, ECU, sensor, belt and the current theory is fuel throttle body.
They're still waiting for a throttle body from Bkk to try on the bike first. If it works I have to pay for it. If it doesn't work, send it back and move onto the next theory, whatever it is.
Meanwhile I will keep working my way through the brilliant Chiang Rai music pubs.

The ongoing Nmax saga.
A return to my now non-favourite mc dealer.
"We've got the bike running well we want you to come and test it."
It's certainly running better, maximum 107kph, with the old fat GTR fellah on boar.
Yes ok, but I used to get 115kph out of it easily, plus it accelerated a lot better.
What's the solution, you've reached?
Oh we think it is the fuel pump you installed. We've swapped the fuel tank & pump from another bike. So if you can wait yet another week, while we will order a new one from Bkk.
But what happened with the throttle body you ordered from BKK?
Oh, that didn't do anything. No improvement. So now we think it is the fuel pump.
You have to wait for a new fuel pump from Bkk now!
WTF.
I'd like to burn my bridges with the Yamaha dealer but can't yet!

 

[ADV]

The ongoing Nmax saga....
It's certainly running better, maximum 107kph, with the old fat GTR fellah on boar.
Yes ok, but I used to get 115kph out of it easily, plus it accelerated a lot better.

Maybe it's durian and cheese extra weight? }}}}555{{{{

 

[DavidFL]

To continue the story & the"fix."
I arrived in Ching Rai somewhat dehydrated & flustered at 6.30pm.
An evening of food & drinks with a delightful taxi driver followed to relieve the stress of the day.
The next morning I was at Kong's to weigh up the options - Sinthanee or Kong?
At Sinthanee the bike would go in the queue but at Kong's he said he do me a favour, straight away, & hopefully get it fixed in a day or two at the latest, parts depending.
I went with Kong.
After discussing the symptoms, we settled on the fuel pump and the coil, the most likely causes.
The coil was cheap & he could get a copy fuel pump.
Nothing ventured nothing gained, I went along with the quick fix, especially after a compression test on the fuel pump came up low.

View attachment 163080

View attachment 163081

"Everything else" was given the once over & checked.

View attachment 163082

I left Kong to his work in peace and carried on as normal, albeit sans a motorbike.
At 8.30 pm on round two of the taxi driver dinner, I get a call from Kong the bike is ok you can pick it up now if you want.
Nah I'd rather not be disturbed now, tomorrow morning is ok.
Tomorrow morning, 10am, the mighty Nmax is ready to go.
With a sweet smile on my face, I head off out of Chiang Rai city in the traffic and power down 1063 towards home via the Chiang Saen bypass.
Less than 20 kms later, oops, we have the same problem. WTF. Loss of power. Damn problem not solved. Grrh.

A quick U-turn and dawdle back to CR city at 50kph & the Yamaha dealer this time.
Let them have a crack at it with their diagnostic equipment & order some parts from Bkk.
Double bummer. And that's were we still are 5 days later. Time for a check-up in the next few days.
The only positive so far is that I had an enjoyable social taxi lift home, introducing the driver to Paradise Road.

View attachment 163083

Stay tuned...

The ongoing Nmax loss of power story.
After 35 days at the Yamaha Sinthanee dealer, I've got the Nmax back.

The dealer has tried their best, with a few altercations with the old GTR fellah.
I've now been to Chiang Rai 3 times = 600 kms - to check on the bike, because there's hasn't been one courtesy phone call from them, & they don't reply to line contact phone calls or messages they gave me!

1. It was a throttle body causing the trouble. I disagreed, but they insisted.
One was ordered from Bangkok. A 10 day wait.
It made no difference = total waste of time.

2. After another week they borrowed a fuel tank & fuel pump off another Nmax they were servicing, to the best of their ability.
The top speed increased. So they ordered a new fuel pump from Bkk. Wait another 10 days.
Top speed back to 95-100 kph. Progress.

3. At the same time they borrowed a CVT variator off the other Nmax they were servicing, Top speed came back to 115kph.
So they examined the Variator on my bike. It was from an earlier model Nmax, not the right one for my bike?. Why didn't we see this 3 weeks ago?
OK, lets order the right one from Bkk - wait another 7-10 days.

4. The bike was "ready to go" & ok to ride home they said.
I set off sitting on 90-100kph to play safe.
But after 40 kms the power was fading again, down to 70-80KPH maximum.
Stop & let it cool down for 15 minutes, then set off again.
Good for another 20 kms & repeat once. I lumbered into Chiang Khong in the dark @ 60kph after a couple of convenient bamboo bar beer stops to let the bike cool down.

On the positive side the top speed is acceptable when you first start off, but once the bike warms up it fades & then continues to fade more frequently after stops.

Valves & a water pump cooling system issue have been suggested by me, but discounted by the Yamaha changs.

A brow beaten English speaking chang who prefers not to use any language with lung nowadays. 55
One month has been enough for both of us. His supervisor now deals with lung.

Oh well back to Chiang Rai slowly in another 10 days, to fit a new variator.
At least I have the Vstrom in for a suspension - linkage rebuild.

But I have to wonder how the hell I rode the Nmax to Sawankhalok & back.
(A CSL Dinner ride: Chiang Khong - Sawankhalok - Si Satchanalai & Return.)
It definitely is not that the bike was never good.
Something has worn out?

 

[ADV]

I think the N Max has a coolant temperature sensor that feeds data to ECU.

If the coolant sensor is faulty and sending incorrect data to ECU this might lead to improper fuel/air mixture adjustments.

Also has the thermostat and fan operation been checked?

 

[DavidFL]

I think the N Max has a coolant temperature sensor that feeds data to ECU.

If the coolant sensor is faulty and sending incorrect data to ECU this might lead to improper fuel/air mixture adjustments.

Also has the thermostat and fan operation been checked?

The ChatGPT SUGGESTIONS

FAST DIAGNOSTIC ORDER (what I would do)

Step 1 (MOST IMPORTANT)
Check exhaust backpressure / catalytic blockage

Step 2
Check valve clearance

Step 3
Inspect cooling system thoroughly

Step 4
ECU scan for stored codes

The Sinthanee Yamaha changs do not consider any of Step 1-Step 3 to be possibility.
Step 4, the ECU has been checked?
Re Step 3, a water pump that that was replaced at Kong's prior to the loss of power issue. But Sinthaneee disregard this as a indicative of a possible overheating cause.

With the correct CVT Variator fitted I believe we will have a top speed of 115kph back.
BUT the loss of power - overheating(?) still needs to be solved. However 40 kms is better than 15 kms, so we have made some progress = I remain positive but Effing frustrated in the process.