Idle Issue (I Think) on CB650

WingNut · July 3

I've got a CB650 that's over 10 years old, but it's only got about 4000 km on the clock and still looks practically brand new. So it's obvious I hardly ride it. I know, that's not good for a bike, but I just don't have the opportunity to ride it more often. It is what it is.

Anyway, I started having a recent issue with the idle in a way. It just started happening the last few times I drove it. I realize it can be many different things as the cause, but I'm just trying to get a rough idea of what might be involved in repairing it. I'll end up taking it into Big Wing I assume, but trying to get a rough idea in advance if this is going to be an expensive repair or not.

A friend who knows a bit about bike repairs told me the challenge can also be that some Service Centers might end up fixing a few different things, without really knowing what's the exact cause, and then you're spending a lot of money possibly repairing things that don't need to be repaired, before (hopefully) finally getting to the root of the problem.

Basically, when I first start the bike cold, the idle RPMs jump around (up and down) a lot, not normal. Sometimes it also stalls while it's warming up. Once it's warmed up a bit then the idol becomes a bit more stable and steady, but often when I'm driving in the low rev range of around 2500 to 4000 there's hardly any power when I first hit the throttle. I might even get on the throttle hard at those low RPMs and the bike doesn't respond for a couple seconds, but then suddenly lunges/jerks forward very hard. It's not fun.

Ever since I got the bike, since it was new in fact, I always felt there was some small dead zones in the lower rev range when I would hit the throttle hard. But I always thought this was normal because I was trying to give it too much power at very low revs. So maybe the problem has always been there to some degree and I was just thinking it was normal. I don't know though.

Any thoughts on what might be the cause though would be much much appreciated. If the ECU would show some error codes I guess that might also help the mechanics to diagnose the problem.

novacova · July 3

The only time I’ve ever experienced anything like this was water in the fuel and air leak.

London Lowf · July 3

I had similar inconsistent running on my low-mileage (800 miles in the last three years) scooter back home in the UK - a new spark plug sorted it out. A cheap DIY fix and worth a try.

WingNut · July 3

14 minutes ago, novacova said:

The only time I’ve ever experienced anything like this was water in the fuel and air leak.

Thanks. I already ran a couple of bottles of fuel injector cleaner through the tank. Didn't seem to make any difference. How would water get in the fuel tank though?

An air leak would be in one of the hoses? Normally one connected to where?

WingNut · July 3

11 minutes ago, London Lowf said:

I had similar inconsistent running on my low-mileage (800 miles in the last three years) scooter back home in the UK - a new spark plug sorted it out. A cheap DIY fix and worth a try.

Thanks. Spark plug was my initial thought too. Could be that I guess, but seems too simple. I would have to have all 4 changed I guess. I wouldn't be able to DIY that though.

novacova · July 3

21 minutes ago, WingNut said:

How would water get in the fuel tank though?

An air leak would be in one of the hoses? Normally one connected to where?

You mentioned that you haven’t been using the bike much, alcohol in the fuel attracts moisture. Or perhaps water in the fuel at the filling station.

There could be an air leak at the intake. The rubber boots get hot and can develop cracks/leaks. A way to check is to start the bike, get a propane torch (please don’t light it!) and blow the propane around the intake, if the engine starts to rev higher, then you found a leak.

WingNut · July 3

2 hours ago, novacova said:

You mentioned that you haven’t been using the bike much, alcohol in the fuel attracts moisture. Or perhaps water in the fuel at the filling station.

Thank you. Do you think there are any products made by STP or Liqui Moly available in Thailand that I can add to the fuel tank to dry out and remove any water from the fuel system?

2 hours ago, novacova said:

There could be an air leak at the intake. The rubber boots get hot and can develop cracks/leaks. A way to check is to start the bike, get a propane torch (please don’t light it!) and blow the propane around the intake, if the engine starts to rev higher, then you found a leak.

I would feel a bit nervous spraying propane gas around or into the intake myself. I think there are 4 of the rubber intake boots though on my bike. So if the mechanics were to find an air leak at the intake and all 4 rubber boots need replacing, would this generally be a difficult and/or expensive job?

novacova · July 4

12 hours ago, WingNut said:

Thank you. Do you think there are any products made by STP or Liqui Moly available in Thailand that I can add to the fuel tank to dry out and remove any water from the fuel system?

Personally don’t use those products, many of them are alcohol based. Though some folks swear by them. & personally only use clear fuel, non ethanol fuel in the tank, the yellow nozzles @ caltex ptt & pt in the 600cc & 300cc since those two don’t get ridden much anymore.

12 hours ago, WingNut said:

would feel a bit nervous spraying propane gas around or into the intake myself. I think there are 4 of the rubber intake boots though on my bike. So if the mechanics were to find an air leak at the intake and all 4 rubber boots need replacing, would this generally be a difficult and/or expensive job?

Propane is fuel and won’t cause any harm. You can do the same with a can of carb cleaner. Personally I’d try to figure out the source of the issue first.
Generally I work on my own vehicles, so not sure what it would cost you, maybe ~1500฿ for the parts?

WingNut · July 4

37 minutes ago, novacova said:

Personally don’t use those products, many of them are alcohol based. Though some folks swear by them. & personally only use clear fuel, non ethanol fuel in the tank, the yellow nozzles @ caltex ptt & pt in the 600cc & 300cc since those two don’t get ridden much anymore.

Propane is fuel and won’t cause any harm. You can do the same with a can of carb cleaner. Personally I’d try to figure out the source of the issue first.
Generally I work on my own vehicles, so not sure what it would cost you, maybe ~1500฿ for the parts?

Thank you for the additional feedback. This morning I spoke with the service department at Big Wing. The guy mentioned a few possible issues, nothing air intake or boot intake leak related, but unfortunately some of the words he used to describe the possible problem also weren't familiar to me.

When you talk technical stuff in Thailand they often have their own reference words that they have created from English words which are then hard to decipher if you don't know the reference. One thing he mentioned was something about cut off it sounded like. I think that might be something electronic to do with the throttle control. A possible issue I read about online before was something to do with the Throttle Position Sensor (TPS). So maybe that's what he was referring to. Wouldn't be a really expensive repair I don't think. He also suggested spark plugs as a possibility.

He said the erratic idle I have when first starting the bike is not unusual if the bike sits a lot. But the power delay in the low rev range is not normal he said. Also, since the engine warning light isn't showing up on the display, he said there most likely won't be any ICU error codes that can be used to try and identify the problem.

Anyway, I've got an appointment now for them to go through it and try and find the problem. Unfortunately the queue is about two weeks out from now, but there is actually no rush on my part. I don't drive it during the rainy season anyway.

The cost will only be around 320 Baht he said for them to try to identify the issue. Seems worth to me it rather than messing with it myself and getting my hands dirty. I can do simple things like battery changes and small adjustments myself, but this would probably be over my head anyway. And since it could be a few different possible things, it seems better to just take it in. Do you agree?

Anyway, I'll update this post again after I take it in to Big Wing to let you know what they find. Thanks again.

Agusts · July 4

Also check battery voltage, see if it changes when idling is not stable. Someone mentioned it to me when I asked about this...

I'm guessing the voltage is shown on CB650 dash display......? On my Forza 350 when idling the rpm needle just very slightly (maybe 100rpm) moves up and down - at all times, cold or hot, and the battery voltage disolayed also changes about 0.1v to 0.2v. I am told the battery is weak...!

I don't have other symptoms and the bike starts okay, so not tackled the issue yet..., I personally think it might be other issues too.... Never seen weak battery does this on other bikes over the years...!?

novacova · July 4

55 minutes ago, WingNut said:

One thing he mentioned was something about cut off it sounded like.

You think he meant the kill switch? The symptoms don’t seem to resemble.

The tps should throw a code.

As usual, difficult to diagnose without inspection. Hope everything works out for you.

WingNut · July 4

1 hour ago, Agusts said:

Also check battery voltage, see if it changes when idling is not stable. Someone mentioned it to me when I asked about this...

I'm guessing the voltage is shown on CB650 dash display......? On my Forza 350 when idling the rpm needle just very slightly (maybe 100rpm) moves up and down - at all times, cold or hot, and the battery voltage disolayed also changes about 0.1v to 0.2v. I am told the battery is weak...!

I don't have other symptoms and the bike starts okay, so not tackled the issue yet..., I personally think it might be other issues too.... Never seen weak battery does this on other bikes over the years...!?

Thank you. I actually had a battery issue on this bike in the past after I changed a battery and didn't seat one of the cable screws properly. But symptoms were very different. Sometimes bike just wouldn't start or power would just cut. After I tightened the screw down properly the problems instantly went away. I doubt this is a battery issue though this time the problem I'm having now.

WingNut · July 4

1 hour ago, novacova said:

As usual, difficult to diagnose without inspection. Hope everything works out for you.

Cheers. I agree. I'll keep you posted. I am starting to remember now that when I first noticed the problem late last year I had did some digging online and watched a few YouTube videos and various sources were pointing to a possible TPS issue. But I never investigated that possibility further. Then, I began traveling, and doing some other things, and kind of just forgot about it. So, now, six months later I am back at it. Hopefully I get to the bottom of it this time. 😊

liddelljohn · July 9

On 7/3/2024 at 1:09 PM, WingNut said:

Thanks. I already ran a couple of bottles of fuel injector cleaner through the tank. Didn't seem to make any difference. How would water get in the fuel tank though?

An air leak would be in one of the hoses? Normally one connected to where?

E10 gasohol 95 has water in it , if you dont use the bike the water seperates out rusting the tank and polluting the injectors

liddelljohn · July 9

Also need to change air filter , fuel filter and reset TPS which is easy if dealer has computer oh do a fresh oil change and filter too

WingNut · July 18

UPDATE: Well, I think the idle and power fluctuation issues have been resolved now on the bike. But not without a bit of drama first.

I had made an appointment with the service center at the dealer to look at it as I had mentioned above. So the night before the service appointment I started the bike up, after it had been sitting still for 4 months, and I took it out to put some air in the tires and go for a quick ride to make sure it was still running well enough to get it over to the dealer in the morning.

Well, it started right away on the first press of the starter, so it was looking good, but then the engine seized on the Don Muang highway in the middle of nowhere and I had to get a flat bed truck to come and pick me up and take the bike over to the dealer at around 1AM. Maybe I'll do a separate post on that later.

Anyway, turns out it was only a spark plug issue. They changed all 4 plugs and now it's running perfectly again. They also thought that the starter relay might have had a problem, but I talked them out of changing that part because the starter never had any issues in the past and so we just went with the spark plug change.

I also had an engine oil change done and the oil filter changed. The oil in the bike was practically unused but was getting old. so seemed like a good idea to change it.

The mechanic also recommended I change my battery because I was running an inexpensive RR brand battery and he said that the battery wasn't really holding a full charge and was also fluctuating on power. So he suggested I change to an FB. So ordered one from Lazada (at 1/3 the price of the dealer) and it should arrive within 2-3 days. I've got the bike parked now and I won't drive it again until I swap in the new battery.

Other possible causes of the problem came up during discussions with the mechanic. He had thought maybe the clutch had burned out and was slipping, but the clutch is fine. Also, he was going to run some pressure tests on the fuel system to see if maybe the fuel injectors, the fuel pump, or the fuel filter might be gummed up, but after we changed the spark plugs it seemed like all the problems went away. So most likely there aren't any problems with the fuel system.

I'll try and drive it more often now and see how it goes. Hopefully with the new spark plugs and the new battery all those issues I was having will now be a thing of the past.

Agusts · July 18

Lucky for you not too pricey..., I totally forgot to mention that a few years ago I had about 3 months of idling problem that nobody could diagnose. Honda put it on computer and just about every other mechanic checked every thing, including spark plugs, battery, water in fuel, and fuel injector etc., electric etc. without any luck.

Then as problem started after a service when I changed spark plug, I suspected it, and just bought another plug and after 3 months the bike idled normally again...!?!?

I put it down as either the plug was faulty or they tightened it too much - the last change I specifically asked them not put all their weight on it, as Thais do...! 🙄

WingNut · July 18

2 hours ago, Agusts said:

Lucky for you not too pricey..., I totally forgot to mention that a few years ago I had about 3 months of idling problem that nobody could diagnose. Honda put it on computer and just about every other mechanic checked every thing, including spark plugs, battery, water in fuel, and fuel injector etc., electric etc. without any luck.

Then as problem started after a service when I changed spark plug, I suspected it, and just bought another plug and after 3 months the bike idled normally again...!?!?

I put it down as either the plug was faulty or they tightened it too much - the last change I specifically asked them not put all their weight on it, as Thais do...! 🙄

Yes, thank goodness, not a pricey repair compared to all the other things that could have been much pricier. Thank you also for the additional info. Yes, it seems spark plugs can be very delicate. In Thailand they can also corrode very easily or get moisture inside and then they won't fire properly. I guess in the future, if something like this happens again, first move is to change spark plugs and then go from there.

I think also good to be sure you are using quality plugs. I think the Honda dealer put in Denso branded plugs which they only charged 98 Baht each for plus labor.

novacova · July 19

15 hours ago, WingNut said:

They also thought that the starter relay might have had a problem,

Keep a relay handy, as they can suddenly go dead. Just replaced one that went completely dead on me, luckily I was parked on a hill at the time.

WingNut · July 19

2 hours ago, novacova said:

Keep a relay handy, as they can suddenly go dead. Just replaced one that went completely dead on me, luckily I was parked on a hill at the time.

Thanks. They wanted around 1,700 Baht for the OEM part, plus labor to install it. So that's why I passed on it. Mainly because the starter works perfectly and so I didn't see any reason to replace the relay. Perhaps the mechanic was misunderstanding my ailing battery as being a starter relay problem when he first started trying to diagnose the problem. And in the end he also confirmed the relay is still working fine. Thankfully I've never had one go dead, but I agreed with him that if engine power problems persist in the future that we would replace it next time. If all goes well, the new FB FTZ10S battery I ordered will arrive tomorrow and I will install it straight away. Then hopefully the bike will be fully running perfectly again. ✌🏼

The most expensive part yesterday ended up being the oil filter which they charged 600 Baht for. It takes a 15410-MFJ-D02 filter. I checked on Lazada and it would still be 500 Baht if I bought one myself.

WingNut · July 23

Finally got a chance last night to take the bike out for a full send after the spark plugs were replaced and after I dropped in the new battery a couple of days ago. The power is amazing now. I think there might have even been some low-key spark plug issues for 5-6 years already because there were times when I would be driving at higher speeds, get on the throttle, and then there were some slight pauses in acceleration. But all of that is gone now.

In the past I had thought that maybe the acceleration delays were occurring because I was trying to accelerate too quickly when in higher gears and with low revs. But I realize now that this wasn't the issue at all.

Korat Kiwi · July 25

Methylated spirits absorbs or mixes with water... It can be used to 'extract' small amounts of water in a fuel tank.

Otherwise as previously stated, if your machine can run on E10 fuel then a tank full of that can do the same job.

Regarding plugs and batteries, I now always go the iridium type of plugs. Cleaner burning and virtually last a lifetime.

I've been looking for Lithium iron Phosphate (LiFePO4) batteries here without much success.

Back in NZ I put LiFePO4 in all 3 bikes that I had. They have a way lower discharge rate compared to SLAB ones, heaps lighter, smaller and often more CCAs.

Sure they are more expensive but I like the insurance gained by knowing when I hop on a bike, it will start anytime and every time. Generally they will last about 10x longer than sealed lead acid batteries.

OK that's my 10 cents worth to the discussion...

WingNut · July 30

On 7/25/2024 at 1:53 PM, Korat Kiwi said:

Regarding plugs and batteries, I now always go the iridium type of plugs. Cleaner burning and virtually last a lifetime.

I've been looking for Lithium iron Phosphate (LiFePO4) batteries here without much success.

Back in NZ I put LiFePO4 in all 3 bikes that I had. They have a way lower discharge rate compared to SLAB ones, heaps lighter, smaller and often more CCAs.

Thanks. I don't know much about plugs and batteries.

The plugs they put in were from the Honda dealer. So I assume they are up to snuff. But if it makes a big difference, then I'll go for iridium plugs next time.

The ones they put in there this time are the Denso U27FER9 plugs. For my bike, I think the Denso IUH27 Iridium Power plugs would work too, but not sure about availability of those in Thailand. The NGK Iridium IX CR9EIX plug would also fit my bike and they are only 100 Baht each (or less) I think. So I will go for those the next time they are due for replacement.

On the battery, I put in a FB FTZ10S battery, which was the one recommended to me by the dealer. FB is an aftermarket battery brand made in Thailand, but seems quite reliable.

I'm not sure if any Lithium Iron Phosphate motorcycle batteries are available here. I doubt it. They would probably be quite expensive though if they were available because seemingly not much market demand. So, on batteries, I think I'll stick with the one I have in there and replace it every 2-3 years as recommended. They are only 1,500 Baht a pop.

Agusts · July 30

Iridium plugs are usually in 700b+ range each, even NGK original is like 300b, I think 100b plug is fake, watch out for those on Lazada, I had 3 months of headache probably due to a bad plug...

WingNut · July 31

12 hours ago, Agusts said:

Iridium plugs are usually in 700b+ range each, even NGK original is like 300b, I think 100b plug is fake, watch out for those on Lazada, I had 3 months of headache probably due to a bad plug...

Thanks, I wasn't aware there are fake plugs for sale on Lazada. I see now that most of the Lazada sellers are selling the NGK plugs for 300-360 Baht each. Can I assume those are real?

Also, I want to do a fluids flush soon on brake fluid and coolant. The last time Honda charged me 600 Baht for half a liter of their Honda branded Dot 4 fluid, which seems expensive. And I forget how much they charged me for the coolant they used. This time though I want to buy the fluids myself and only pay them for the labor as I think it will work out lower cost that way.

I think I'll need .5 liter of brake fluid again. Would either of these 2 Dot 4 fluids on the links below be good?

https://s.lazada.co.th/s.pZAlV

https://s.lazada.co.th/s.pZAMX

Also, for coolant, I believe I need around 2.5 liters for my bike. I also read that I need an ethylene glycol-based coolant that is silicate-free and designed for use in aluminum engines. I'm not sure, but I've seen Honda branded coolant for about 65 Baht a liter on Lazada. Will this one on the link below work?

https://s.lazada.co.th/s.p0Z0w

WingNut · July 31

I just found my receipt from the last fluids flush they did in 2021 and the coolant sold by the dealership is also 60 Baht a liter. So not worth buying it elsewhere I think. Maybe I'll just take it from them again I'm thinking.

But 600 Baht for half a liter of Honda Dot 4 brake fluid is too much when I can buy it myself for around 100 Baht. I will likely order half a liter of that Brembo Premium Dot 4 fluid I linked above and use that for the brake fluid flush.

Agusts · July 31

Best is to check if seller is LazMall seller, they are usually okay. Or see how many of the item they have sold already, and their reviews.

Be honest for a one off thing, that are critical, I resigned to go to Honda. Although rumours around, some of the small Honda shops could knowingly or unknowingly stock grade A or B copies...!!!

Big Wings I think are much better run and manged, with fairly well trained mechanics though...

Buy plug from Honda, I think it's 400 or 450 and include putting it on the bike...

I doubt Honda shop let you bring your own fluid, any fluid, but specially Dot 4 brake fluid. They make most of their money on these stuff. Also safer to just go with theirs for the sake of a few hundred baht. Coolant fluid is cheap even at Honda shop.

I was going to buy Brembo Dot 4 from Lazada too, and get corner shop to change it. But a friend said Brembo brand is the most copied spare part in all Asia...!? I said do they copy and make fake brake fluid too..., he said who knows, do you want to risk it for 10 dollars saving... 🙄

WingNut · August 1

12 hours ago, Agusts said:

Best is to check if seller is LazMall seller, they are usually okay. Or see how many of the item they have sold already, and their reviews.

Be honest for a one off thing, that are critical, I resigned to go to Honda. Although rumours around, some of the small Honda shops could knowingly or unknowingly stock grade A or B copies...!!!

Big Wings I think are much better run and manged, with fairly well trained mechanics though...

Buy plug from Honda, I think it's 400 or 450 and include putting it on the bike...

I doubt Honda shop let you bring your own fluid, any fluid, but specially Dot 4 brake fluid. They make most of their money on these stuff. Also safer to just go with theirs for the sake of a few hundred baht. Coolant fluid is cheap even at Honda shop.

I was going to buy Brembo Dot 4 from Lazada too, and get corner shop to change it. But a friend said Brembo brand is the most copied spare part in all Asia...!? I said do they copy and make fake brake fluid too..., he said who knows, do you want to risk it for 10 dollars saving... 🙄

Thanks for the insight on the Brembo fake fluid.

I discovered that Motul and Shell both have their own official stores on Lazada. So presumably nothing fake from them. Dot 4 fluid is around 200 Baht for half a liter from either of those two brands.

Motul also offers an LV Dot 4 fluid, which has lower viscosity and possibly better for ABS systems. It also has a higher boiling point than the Honda Dot 4 fluid. Higher boiling point might also be advantageous in a hot country like Thailand.

Yes, Big Wing is good. Mechanics are good and aren't hacks. They know what they are doing from my experience. Labor isn't cheap though at Big Wing like it is at the other small Honda dealers. Big Wing charges 535 Baht an hour for labor. So they might let you bring your own fluid because they will still make a few hundred Baht changing it out for you.

When they changed my oil, oil filter, brake fluid, and coolant back in 2021, they charged me 800 Baht just for the labor alone.

Agusts · August 2

17 hours ago, WingNut said:

Thanks for the insight on the Brembo fake fluid.

I discovered that Motul and Shell both have their own official stores on Lazada. So presumably nothing fake from them. Dot 4 fluid is around 200 Baht for half a liter from either of those two brands.

Motul also offers an LV Dot 4 fluid, which has lower viscosity and possibly better for ABS systems. It also has a higher boiling point than the Honda Dot 4 fluid. Higher boiling point might also be advantageous in a hot country like Thailand.

Yes, Big Wing is good. Mechanics are good and aren't hacks. They know what they are doing from my experience. Labor isn't cheap though at Big Wing like it is at the other small Honda dealers. Big Wing charges 535 Baht an hour for labor. So they might let you bring your own fluid because they will still make a few hundred Baht changing it out for you.

When they changed my oil, oil filter, brake fluid, and coolant back in 2021, they charged me 800 Baht just for the labor alone.

Good info about big wing, I used to have old model 300 Forza and they would not accept me there. Now I have 350 Forza, I will try to see if they work on this one..., I think I heard 300cc+ is they threshold...

Yes, official stores on Lazada are all good, I have bought many items from Samsung, Motowolf and Philips official stores amongst others and they were all genuine with full guarantee etc.

WingNut · August 4

On 8/2/2024 at 8:11 AM, Agusts said:

Good info about big wing, I used to have old model 300 Forza and they would not accept me there. Now I have 350 Forza, I will try to see if they work on this one..., I think I heard 300cc+ is they threshold...

Yes, official stores on Lazada are all good, I have bought many items from Samsung, Motowolf and Philips official stores amongst others and they were all genuine with full guarantee etc.

I'm not sure if Big Wing works on any bikes that are smaller than 500cc. They may also not stock any parts for bike models that they don't sell. But you can check with them first.

You can send them a text via LINE directly to their service department. Their LINE ID: bigwingbkk

You can also call the service department at 02-790-3940.

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