Wow! Like a new machine!

[Dunnster 1,650]

Changed the oil & filter and also the air filter, castrol 4T 10w30, Honda oil/air filter and new sump plug washer. Took it for a quick spin to check for leaks and levels. Wow! What a difference, must be down to the new air filter. Manual states air filter change every 2 years, but I'm seriously considering an annual change. Just need to change the coolant and check the valve clearances, then it's free insurance and money spare for petrol, due to the cash saved on labour fees.

Anyone recommend a suitable coolant? Thanks in advance.

[embee 7,288]

Choice of coolant is a bit like oil, everyone will have an opinion. Main thing is to use a silicate free coolant, there can be some seal wear issues with silicate containing versions. The basic antifreeze aspect is pretty much common to all, 50% ethylene glycol 50% water (de-ionised or distilled recommended, or at least soft water. If your tap water is hard don't use it, clean filtered rain water is OK). The bigger differences are with the corrosion inhibitors, which is really what determines the service life anyway.

 

Colour means little, it is just a dye, but as a guide the pink/orange versions tend to be the long life ones. Considering the cost and the amount used you may as well use a high spec coolant, something called a 5yr coolant will probably be good. Something with G12+ is a good spec, as used by VW/Audi.

 

Many folk use Halford's 5yr coolant. Personally I use Toyota red in everything I have, it keeps things simple for me with only one coolant on the shelf. I've been very pleased with it, my Yaris coolant stays as clean as a whistle after 15yrs (changed every 3-4yrs typically).

 

I'd suggest not getting drawn into the "water free coolant" advertising blurb trying to sell you propylene glycol coolant with some wild claims about how much better it is than ethylene glycol. Yes it can be used as a coolant, but if it was "better" don't you think the major manufacturers would use it? Many years ago I did do some evaluation work with propylene glycol when working at a major car manufacturer. Just use a decent branded silicate free long life type regular ethylene glycol coolant.

Edited August 1, 2015 by embee

[Dunnster 1,650]

Thank's for the info embee, very much appreciated.

[Guest bonekicker]

Mike several members have been surprised at the difference in performance when fitting new air filters--was it just the standard Honda one? or aftermarket? 

[RussB644 379]

Interesting feedback on the air filter, out of interest what mileage had you done since last filter change?

[Guest chicken george]

Changed the oil & filter and also the air filter, castrol 4T 10w30, Honda oil/air filter and new sump plug washer. Took it for a quick spin to check for leaks and levels. Wow! What a difference, must be down to the new air filter. Manual states air filter change every 2 years, but I'm seriously considering an annual change. Just need to change the coolant and check the valve clearances, then it's free insurance and money spare for petrol, due to the cash saved on labour fees.

Anyone recommend a suitable coolant? Thanks in advance.

 

Hey Dunnster, although my bike is still under warrantee, I have decided to fit a K&N air filter instead of a stock filter. I agree that the bike felt better after this filter change (not sure if the K&N made a difference), so have decided to change the oil every 4k and oil+filter every 8k. Also an air filter clean every 8k rather than 16k (I’m averaging 20k a year).

This may sound like extra money. But I’m saving hundreds by not commuting into London on the train, and I’m willing to spend extra on additional costs.

I am doing all the servicing myself.

 

Cheers

[matt28 401]

Anyone recommend a suitable coolant? Thanks in advance.

 

I've been always using blue Honda coolant for my Transalp before, no problems at all.

Still have 3 never opened bottles, will use them during next coolant change at my NC.

 

 

Edited August 2, 2015 by matt28

[Guest TachyonMage]

Hey Dunnster, although my bike is still under warrantee, I have decided to fit a K&N air filter instead of a stock filter. I agree that the bike felt better after this filter change (not sure if the K&N made a difference), so have decided to change the oil every 4k and oil+filter every 8k. Also an air filter clean every 8k rather than 16k (I’m averaging 20k a year).

This may sound like extra money. But I’m saving hundreds by not commuting into London on the train, and I’m willing to spend extra on additional costs.

I am doing all the servicing myself.

 

Cheers

 

Hello George.

I am a big K&N fan, but did some research and found DNA filters, seen some rather interesting test results. As a result I bought one, will fit it at the next service cycle (hopefully a new can also, yet to decide which one though). From what I have seen the K&N filter (for this type of bike at least) doesn't seem to improve airflow as much as one might expect ... hence why you may not notice much difference.

DNA vs K&N vs OEM - 

DNA Air Filter vs K&N vs Stock - https://www.youtube.com/watch?v=Llu-E42wwFo

 

Interesting thoughts on the oil changes, will keep an eye on mine ... is there some indicator in the viscosity and sediment in the oil maybe? I mean if you change at 8000 and the oil is too thick and filled with too much stuff, maybe do earlier  and vice versa. How much does ride style and commute vs. open road influence this, any ideas?

 

Cheers, Jacques

 

[Dunnster 1,650]

Bonekicker, just the standard genuine Honda filter. On the difference it's made I might put a K&N in there if I'm going to change it more regularly.

Russ, just changining it due to maintenance schedule, mileage is 15,286 got the bike 2nd hand so unsure of the change, but I picked it up at 2 years old, so I reckon it's the one from new. It's a big air filter and a lot of it seems wasted space/ material, only a small intake but a huge filter?!

Chris, I can imagine it's a massive saving on commuter costs. I'll just keep to an annual oil/filter change, just debating on the annual air filter change, I don't do as many miles as you. So far it's been an easy thing to maintain. I'm no mechanic, but I like to know a jobs been done, taking my time and concentrating whilst doing jobs equals satisfaction and enjoyment. Plus getting to know the bike better.

Matt, is that the Honda type 2 or honda pro coolant? They seem similar, but one is cheaper.

Thanks for the replys, folks.

[embee 7,288]

Just a couple of comments on the airflow tests in the vid.

 

You can easily increase the flow for a given pressure difference (dP) by poking a hole in a filter. It doesn't really mean very much in isolation. Engines don't work on dP, they are displacement devices. If you increase the flow 10% on the flow bench for a given dP you won't get 10% more flow through the engine. Instead the volume airflow tries to be what the engine displacement will shift, but the dP will vary and thus the density changes. Bear in mind that 1.5" water (a typical flow bench setting) corresponds to about 0.4% of atmospheric pressure (1 atmos = about 10m or 33 feet water). If you set the same volume airflow and one filter produced 1.5" water dP, and another filter produced twice that, 3" water dP, the difference in density would be 0.4%, which would correspond more or less to the difference in power an engine would produce (simplification but OK for small changes). Do you really think you'd notice 0.4% power difference (0.2 BHP in an NC)? .... and that's if one filter produced twice the pressure drop of another, not 10 or 20% more.

 

The elephant in the room however is the filtration efficiency. No comment is made regarding this. Tests are normally done using a standardised dust (we used to use "Arizona fine", whatever that was) with a set addition rate and weigh the filter assemblies (not just the filter since the box can have a significant effect on the results). Capture rates for a stock filter will be 99.9 ..... something %. This is the abrasive road grit dust which will wear your bores and rings and valve stems etc. It's not good stuff to put into an engine. What capture efficiency do the various filter assemblies achieve?

 

Regarding the space and areas, a good airbox is designed largely for noise suppression, which is where the small spout comes in. There are empirical guidelines for airbox volume relative to engine size and individual cylinder size, but broadly the bigger the better (5x engine swept volume is nice but not always able to be packaged). The intake spout velocity is what keeps the intake noise suppressed, something around 50m/sec (mean airspeed based on 100% vol efficiency at max power speed) is a target. For an NC 700, at max power the nominal displacement is

(6250/60)/2 x 0.67 Lt/sec = 34.9 Lt/sec (call it 0.035 m^3/sec)

If the airspeed is 50m/sec, the area would be

V x A = F

50 x A = .035

A = 7 x 10^-4 m^2, or 700mm^2

That's a circle of about 30mm dia. (With fewer cylinders (and more pulsing flow) you might increase the area a bit relative to that figure).

50m/sec speed converted into dynamic head (equivalent to pressure drop if you like) across the intake spout is about

dP = 0.5 x density x speed^2

dP = 0.5 x 1.2 x 50^2 = 1500 Pa (pascals)

1 atm = 10^5 Pa approx., so if you lost all the dynamic head it would be about 1.5% pressure drop, but in reality you get maybe half back in stagnation, so the actual loss through an intake spout is typically between 0.5 and 1%. Again, would you notice 0.5%?

 

A good cleaner airbox is designed to direct the flow at one area of the filter. This deposits a large percentage of the dirt in one place, leaving the rest of the filter relatively clean and therefore extending the service life. Air will spread out to utilise the whole surface area (at the sort of speeds seen inside an airbox anyway), the denser dirt tends to carry on in the direction of the intake spout.

 

 

Personally I use standard OE air filters in wanything of any value, but it's your choice. You can leave the filter out, it's cheaper and will flow more air.

Edited August 2, 2015 by embee

[Dunnster 1,650]

 Personally I use standard OE air filters in wanything of any value, but it's your choice. You can leave the filter out, it's cheaper and will flow more air.

Thanks for posting that info embee. I think after a few thousand miles, the filter will be clogged, but still doing its job, might aswell just stick to the schedule changes. I use OE oil filters, brake pads etc, too. If you do the jobs yourself, your saving on the labour anyway, so parts price isn't an issue.

Cheers, Dunnster.

[embee 7,288]

Thanks for posting that info embee. I think after a few thousand miles, the filter will be clogged, but still doing its job, might aswell just stick to the schedule changes. I use OE oil filters, brake pads etc, too. If you do the jobs yourself, your saving on the labour anyway, so parts price isn't an issue.

Cheers, Dunnster.

As a rule of thumb we used to use an increase in dP across the filter of 5" water at rated airflow as the service life. The thing which really used to clog filters was the HC/soot mix you used to get in industrial/urban areas but generally speaking the concentrations of these is a lot less than it used to be (problems for humans now are NOx and particulates, a lot of it from diesel traffic, but that's another thread). In reasonable air quality areas a real world service life of around 25k miles is pretty reasonable usually. That works out at about £1 per 1000miles for air filters, compared to around £60 for fuel on an NC so you're dead right, do it yourself and the cost is trivial.

Edited August 2, 2015 by embee

[matt28 401]

Matt, is that the Honda type 2 or honda pro coolant? They seem similar, but one is cheaper.

 

 

It's type 2, paid £8 per litre at Honda Garage.

[Dunnster 1,650]

It's type 2

Thanks Matt

[Guest TachyonMage]

Personally I use standard OE air filters in anything of any value, but it's your choice. You can leave the filter out, it's cheaper and will flow more air.

 

Thanks for that Murray (embee), you clearly know the drill way more than I do ... They had me at "more air flow and 99% filtering", clearly I now know there is a lot more to this than those 2 points  

[Guest motorboy]

Just a couple of comments on the airflow tests in the vid.

 

You can easily increase the flow for a given pressure difference (dP) by poking a hole in a filter. It doesn't really mean very much in isolation. Engines don't work on dP, they are displacement devices. If you increase the flow 10% on the flow bench for a given dP you won't get 10% more flow through the engine. Instead the volume airflow tries to be what the engine displacement will shift, but the dP will vary and thus the density changes. Bear in mind that 1.5" water (a typical flow bench setting) corresponds to about 0.4% of atmospheric pressure (1 atmos = about 10m or 33 feet water). If you set the same volume airflow and one filter produced 1.5" water dP, and another filter produced twice that, 3" water dP, the difference in density would be 0.4%, which would correspond more or less to the difference in power an engine would produce (simplification but OK for small changes). Do you really think you'd notice 0.4% power difference (0.2 BHP in an NC)? .... and that's if one filter produced twice the pressure drop of another, not 10 or 20% more.

 

The elephant in the room however is the filtration efficiency. No comment is made regarding this. Tests are normally done using a standardised dust (we used to use "Arizona fine", whatever that was) with a set addition rate and weigh the filter assemblies (not just the filter since the box can have a significant effect on the results). Capture rates for a stock filter will be 99.9 ..... something %. This is the abrasive road grit dust which will wear your bores and rings and valve stems etc. It's not good stuff to put into an engine. What capture efficiency do the various filter assemblies achieve?

 

Regarding the space and areas, a good airbox is designed largely for noise suppression, which is where the small spout comes in. There are empirical guidelines for airbox volume relative to engine size and individual cylinder size, but broadly the bigger the better (5x engine swept volume is nice but not always able to be packaged). The intake spout velocity is what keeps the intake noise suppressed, something around 50m/sec (mean airspeed based on 100% vol efficiency at max power speed) is a target. For an NC 700, at max power the nominal displacement is

(6250/60)/2 x 0.67 Lt/sec = 34.9 Lt/sec (call it 0.035 m^3/sec)

If the airspeed is 50m/sec, the area would be

V x A = F

50 x A = .035

A = 7 x 10^-4 m^2, or 700mm^2

That's a circle of about 30mm dia. (With fewer cylinders (and more pulsing flow) you might increase the area a bit relative to that figure).

50m/sec speed converted into dynamic head (equivalent to pressure drop if you like) across the intake spout is about

dP = 0.5 x density x speed^2

dP = 0.5 x 1.2 x 50^2 = 1500 Pa (pascals)

1 atm = 10^5 Pa approx., so if you lost all the dynamic head it would be about 1.5% pressure drop, but in reality you get maybe half back in stagnation, so the actual loss through an intake spout is typically between 0.5 and 1%. Again, would you notice 0.5%?

 

A good cleaner airbox is designed to direct the flow at one area of the filter. This deposits a large percentage of the dirt in one place, leaving the rest of the filter relatively clean and therefore extending the service life. Air will spread out to utilise the whole surface area (at the sort of speeds seen inside an airbox anyway), the denser dirt tends to carry on in the direction of the intake spout.

 

 

Personally I use standard OE air filters in wanything of any value, but it's your choice. You can leave the filter out, it's cheaper and will flow more air.

Wow my head hurts after reading all this and I'm sure your right  so if your saying  K&N BAD  stock filter GOOD  I'm with you can't let more air in without letting other things in too

[embee 7,288]

I can't say whether any aftermarket filter is bad, I haven't seen any independent data regarding filtration efficiency, and they don't tend to advertise how effective their filters are at filtering compared to OE versions, perhaps for a good reason.

[Guest bonekicker]

We think any aftermarket items must be either cheaper or a improvement---for them to spend time & money to develop it ??? but who knows???

[TheEnglishman 401]

We think any aftermarket items must be either cheaper or a improvement---for them to spend time & money to develop it ??? but who knows???

 

The fable of the Emperor's new clothes comes to mind.

 

Interesting seeing the science and maths - thanks embee

[Guest GeoffThai]

Its very dusty here in NE Thailand, took my NC750 in today to the main Honda dealer for a 12k/annual service and I asked for the clutch filter and air filter to be changed as well as "extras". They did the clutch filter extra but when they removed the air filter it was close to new condition, so they cleaned the casing and re-installed. I was tempted by the K&N publicity but after the good info from Murray, I will stick to stock Honda.

[Guest Rama5]

Where abouts in thialand are you we was in chiang mai in April very hot

[Guest GeoffThai]

Hello Rama5, we live in Tha Bo near Nong Khai. Have a look for Vientiane the capital of Lao and we are just over the river on the Thai side and down a bit. Weather strange this year so still rainy season here and hot, we normally a bit cooler in summer and warmer in winter than Chang Mai. Yes, April was hot this year and we still waiting for cooler weather.

I would like the odd run through the Kent countryside to refresh my English battery!

Going up in the hills here is good as the traffic is sparse and temp drops a bit. General riding requires extra concentration for the odd dog,child, grandpa, hole, snake, truck coming wrong way etc but is very relaxing afterwards !

Stay safe

Geoff