VTEC 1, 2 or 3?

Life Cars & Motorcycles
21

Mine is black with gold rims…

@KawasakiRider,
Since you are very familiar with CB400, I need some more info from you if that’s ok…

  1. What oil should I use? 5W50, 10W50? any recommendation on the brand?
  2. How many liter needed to change the engine oil (with or without oil filter change)?
  3. The previous owner fill the bike up with 98 octan gas…Is it neccessary?
  4. Is it common to have the CB400’s handle bar elevated?

Thanks

22

1… What oil should I use? 5W50, 10W50? any recommendation on the brand?

  • 10W50 in summer, and 5W50 in winter. Never used any other oil than Repsol. If it is good enough for Motogp bikes than its good enough for me. Castrol is another good choice.
  1. How many liter needed to change the engine oil (with or without oil filter change)?
  • 2 bottles, not sure the exact measurement of each container of Repsol oil.
  1. The previous owner fill the bike up with 98 octan gas…Is it neccessary?
  • No, the engine will run too hot. Stick with 92.
  1. Is it common to have the CB400’s handle bar elevated?
  • I don’t see why you would have to. The ride position of the CB400 is already pretty upright as is. I did straight bars for my ZRX cause the tank was so big so when I leaned into corners my tummy was always bumping into the tank.

*Recommend getting some nice sticky tires. Don’t get touring tires. Dunlop and Bridgstone both make nice 400-600cc street/race tires.

23

Thanks a million for the info…

24

personally for a Jap inline 4, a fairly sophisticated engine with V-tech valves and what is a relatively high compression ratio at 11.3 : 1… I would use 95… but Kawasakirider is correct in saying don’t bother with 98, it’d just be a waste…

moreover in Taiwan I have my doubts that the antiknock performance of the gas is even close to the supposed RON numbers on the pumps… add to that the fact that apart from additives to increase octane rating, gasoline has or at least should have a combination of the following additives:

anti-oxidants ( inhibit gum formation, improve stability )
metal deactivators ( inhibit gum formation, improve stability )
deposit modifiers ( reduce deposits, spark-plug fouling and preignition )
surfactants ( prevent icing, improve vaporisation, inhibit deposits, reduce NOx emissions )
freezing point depressants ( prevent icing )
corrosion inhibitors ( prevent gasoline corroding storage tanks )
dyes ( product colour for safety or regulatory purposes )

to list but a few, I have my doubts in Taiwan’s 偷工減料 culture that 92 isn’t a gas that’s just engineered to a price point for terminally cheap junker drivers 'in 85 Honda civics…

25

95 it is then…thanks…BTW, does anybody know where I can get/download the english CB400 manual instruction?

26

[quote=“plasmatron”]I have my doubts in Taiwan’s 偷工減料 culture that 92 isn’t a gas that’s just engineered to a price point for terminally cheap junker drivers 'in 85 Honda civics…[/quote]For once, you’d be wrong.

When I worked for Chrysler I knew a BMW technician on rotation here who was having a hard time getting a car to run right. After checking everything down to the computer that controls the ashtray he started suspecting bad gas. He ended up sneaking some samples on the plane and took them home for analysis. Obviously this was pre-911.
The lab said the gas was as good as that in Europe and that wasn’t the problem.

I don’t know how China Petroleum pulls it off, but they do refine good gas. What may be more of an issue is how the gas stations store it, but those problems will show up on all grades.

27

stragely enough that’s not the first time I’ve heard that technically the gas here is fairly good, or at least on a par with the civilized world… I guess it’s just that it flies in the face of all that I’ve ever seen and experienced of Taiwan’s technical standards to such an extent that my conscious brain just won’t accept it as fact… perhaps it’s time for some shock therapy :s :laughing:

I still think that a V-Tech CB4 engine will be much happier drinking 95 though… :wink:

28

[quote=“plasmatron”]
I still think that a V-Tech CB4 engine will be much happier drinking 95 though… :wink:[/quote]Given the compression ratio, I concur.

Remember though, four-stroke compression ratios are always given as static figures. ie the swept volume divided by the volume of the combustion chamber and +/- any deck clearance and dome / dish in the piston crown. Valve timing is not taken into account. With very aggressive valve timing the inlet valve will close well into the compression stroke, reducing the dynamic compression ratio considerably.
Not to mention that with the very short flame paths in such a compact combustion chamber, you can get away with a lot. :wink:

29

Holy f**k! I didn’t understand a bit of that. But I concur. :notworthy:

30

and I thought I’m the only one who didn’t understand… :smiley:…

31

and I thought I’m the only one who didn’t understand… :D…[/quote]
I concur too. (Isn’t that what Leonardo DiCaprio said when faking it as a doctor in “Catch Me If You Can”?)

32

Paisay :blush: These fingers get the better of me sometimes… running off all over the keyboard like that. :blush:

33

Apologize for what? It was an amazing post… :notworthy:

34

[quote=“hsiadogah”]Remember though, four-stroke compression ratios are always given as static figures. ie the swept volume divided by the volume of the combustion chamber and +/- any deck clearance and dome / dish in the piston crown. Valve timing is not taken into account. With very aggressive valve timing the inlet valve will close well into the compression stroke, reducing the dynamic compression ratio considerably.
Not to mention that with the very short flame paths in such a compact combustion chamber, you can get away with a lot. :wink:[/quote]

cough… erm, well… naturally.… ah, i mean, ahem… that’s exactly what I meant of course… I just sort of, you know, thought that kind of stuff goes without saying… er… that is… um… right can I concur again?..

actually the only part I’m not sure about is what a more compact flame path on what is obviously a very compact <100cc cylinder’s combustion chamber allows you to get away with, ie compared for example to one of my GS’s 590cc cylinders that has technically 6 times the swept volume and probably comparably increased combustion chamber volume at TDC… I mean I understand that a shorter flame path technically equals quicker combustion (if you ignore the other variables) but what is it that this allows us to get away with? is it using lower antiknock value gas?

my apologies for being too dim to figure this out by myself… :wink:

35

[quote=“plasmatron”]
actually the only part I’m not sure about is what a more compact flame path on what is obviously a very compact <100cc cylinder’s combustion chamber allows you to get away with, ie compared for example to one of my GS’s 590cc cylinders that has technically 6 times the swept volume and probably comparably increased combustion chamber volume at TDC… I mean I understand that a shorter flame path technically equals quicker combustion (if you ignore the other variables) but what is it that this allows us to get away with? is it using lower antiknock value gas?[/quote]Yes. It’s easier to get a larger squish area (percentage wise) while still optimising the valve sizes (nozzle area) and position. Thus it’s easier to keep the chamber shape more open which helps equalize flame propagation, reduces dead spots, and also optimizes the surface area vs. volume.
Result: Increased HUCR (highest useful compression ratio) and the possibility to run with lower octane fuel. That in turn burns faster and also hotter*. Faster burning means you can use less ignition advance while still reaching peak cylinder pressure just after TDC. The advantage there is the rising piston is not spending so much flywheel energy tryin to compress a gas that’s expanding. That’s an efficiency gain which adds up to a lot at high rpms, quite relevant to a small-bore multi like the CB400.

*It’s easy to forget that higher octane fuel almost always has a lower calorific value. :wink:

36

excellent… I thought optimising squish area might be involved, although somehow wrongly assumed that the proportionally increased dome size would keep the ratio similar between cylinders of differing capacities… but I hear you on the benefits of getting away with less advance and also good point about the lower calorific value of higher octane fuel…

all hail hsiadogah: walking internal combustion technical manual :notworthy:

37

[quote=“plasmatron”]excellent… I thought optimising squish area might be involved, although somehow wrongly assumed that the proportionally increased dome size would keep the ratio similar between cylinders of differing capacities.[/quote]Yes, common assumption, but it’s not a linear relationship. Of course a lot also depends on the valve layout, size, included angle, ratio intake/exhaust flow and nozzle area ratio, bore/stroke ratio, stroke/rod length ratio blah blah blah. :dizzy:

all hail hsiadogah: walking internal combustion technical manual :notworthy:[/quote][ignatowski]I was right??[/ignatowski] :laughing: :blush: :wink: