air box drain tank?

[AllanB]

Back tinkering with the old NV400 again, sorry for those who are bored with this old bike.

I have it booked in for Thursday to get a new exhaust baffle made for the old girl, to try to get that Honda smoothness back and stop the loud popping on decel.

First I thought I would get the air system sealed up, when I found a few issues. First of all the air box has a big split/hole in it, which I am sealing up with some "stuff", but then I found something odd.

At the bottom of the airbox there is a hole (like a drain hole?), presumably to let the water in the airbox out, although with the intake fully under the seat, I can't see how water could get in, unless I rode through a river. But directly under this hole is a small tank...to catch the water??..it should be (but isn't at present) attached to the airbox with a big rubber gasket there.

Any idea what this tank is for?

By the side of it is the expansion tank for the rad, so it is not that and nothing else either feeds it, nor is fed by it.

Is this something dreamed up in the early 80's or do modern bikes have anything like this?

Edited September 22, 2015 by AllanB

[ktm jeff]

Rain / overspray from jetwash , can sometimes get into the air box . Tank may be to allow you to see what has drained out . Normally it is a hose , that looks "sealed" at the bottom , but has a fine split / cut in it . Squeezing the hose opens up the cut , allowing the water out . Either attach tank , or make "split hose" .

[CarolJadzia]

I guess you are talking about the extra box marked 24 in the image below? That is for the engine breather. It lets crankcase cases escape when the engine warms. It normally contains a filter screen to stop water going the other way but should also allow some fine oil mist to lubricate the carb sliders. Water does get sucked into the airbox a little through riding in mist and rain.

This is one of the reasons why keeping the standard air box can be better for the engine than fitting aftermarket K&N's or such like and it's also a reason why many air boxes are so big.

[AllanB]

Okay thanks, wow that is a lot of work just to see how much water got in and you would have to try very hard to get water in it even with a jetwash, unless you remove the seat.

It's a bugga to get to and reattach and even more difficult to remove without a hacksaw, if I did remove it I could transfer the one way valve tube to the airbox drain tube.

That parts list is for a later model bike with the smaller flat filter, can't get one for mine so using sponge wrapped around the old filter can, but seeing the difference in surface area and better flow through sponge, may put two layers of sponge on.

Cheers......

[CarolJadzia]

I think the problem is that as the engine sucks in air often it is heavily humid and the flow has a condensing effect so a lot of moister can build up as it condenses. I have come across many blocked airbox drains that are full of water. The other problem is what if a carb float jams? Often airboxes can fill with fuel if a carb float jams open, can be very dangerous.

The carb lubrication from the engine vent should not be underestimated as well.

[BSJ]

Most manufacturers put one of these valves in to drain water out of the airbox.

Edited September 22, 2015 by BSJ

[AllanB]

I think the problem is that as the engine sucks in air often it is heavily humid and the flow has a condensing effect so a lot of moister can build up as it condenses. I have come across many blocked airbox drains that are full of water. The other problem is what if a carb float jams? Often airboxes can fill with fuel if a carb float jams open, can be very dangerous.

The carb lubrication from the engine vent should not be underestimated as well.

Very good point Carol and at these sort of humidity levels and temperatures it doesn't take much to reach dewpoint. Here in the tropics condensate can be quite substantial and having that reservoir is a good solution since all the time the engine is running that drain valve will remain shut, trapping the water in the airbox.

My airbox is higher than the carb, so when one of my float chambers did overflow it filled my sump, I still don't trust it so I turn off the fuel tap, now that it is a simple manual one and not vacuum operated.

It goes in tomorrow to get a new baffle, so I may plug it temporarily until I figure a way of reattaching it.

"The carb lubrication from the engine vent should not be underestimated as well"...Please explain...

[CarolJadzia]

"The carb lubrication from the engine vent should not be underestimated as well"...Please explain...

The crankcase breather pipe connects into the airbox so that the engine can suck in a small bit of oil. This puts a fine mist of oil through the carbs which helps maintain them. Thats why the air box pipe connects into the box as well. Rather than just venting to atmosphere or a separate tank.

[BSJ]

"The carb lubrication from the engine vent should not be underestimated as well"...Please explain...

The crankcase breather pipe connects into the airbox so that the engine can suck in a small bit of oil. This puts a fine mist of oil through the carbs which helps maintain them. Thats why the air box pipe connects into the box as well. Rather than just venting to atmosphere or a separate tank.

Do you just make this stuff up yourself or have you been listening to a professional bullsyte artist and pass it on without checking!

[CarolJadzia]

"The carb lubrication from the engine vent should not be underestimated as well"...Please explain...

The crankcase breather pipe connects into the airbox so that the engine can suck in a small bit of oil. This puts a fine mist of oil through the carbs which helps maintain them. Thats why the air box pipe connects into the box as well. Rather than just venting to atmosphere or a separate tank.

Do you just make this stuff up yourself or have you been listening to a professional bullsyte artist and pass it on without checking!

Actually we get taught this stuff when we go to college to get our city and guilds in motorcycle mechanics.

Maybe you should try learning something sometime instead of shooting your mouth off first.

Helps with not looking like a complete idiot troll.

Or maybe you have a better reason for connecting the crankcase breather hose to the air box? (See diagram above)

Excess crankcase pressure has to vent somewhere, it was decided long ago that venting it into the airbox was a good idea because as well as the vent needing to let gases flow in and out without letting contamination in, a little bit of oil vapour would lubricate the carb sliders and internals. This can often lead to issues when a fault leads to higher crankcase pressures and forces more oil out the vent pipe. Even Harleys vent into the carb as standard. Thats the way it is done.

http://www.sscycle.com/tech-info/tech-tips/top-end/how-does-my-new-ssw-breath/

[ktm jeff]

Actually Carol , your teacher was wrong , although i can follow the idea of the oil fumes = carb lubrication . Without putting fuel on the fire ( pun intended ) , those crankcase fumes are far more deadly than even the exhaust fumes ( no VW jokes please ) . These fumes couldnt be vented to air . So they get " re-circulated " . As a side note , research the problems with Exhaust Gas Recirculation ( EGR ) Valves . This isnt too good for the engine , as you in-addvertantly say in your line " leads to issues when higher crankcase pressure forces more oil out of the vent pipe " . It was so decided , to try to re-burn them , as you say , in a closed circuit , through the carb . But this itself causes many problems , with the carb "Sooting" up / "Gumming" up etc , and causing reduced air flow , disrupted air flow characteristics , and sticking butterflys / throttles . Venting these useless fumes into a charcoal canister is much better , but costs more .

[papa al]

Actually Carol , your teacher was wrong , although i can follow the idea of the oil fumes = carb lubrication . Without putting fuel on the fire ( pun intended ) , those crankcase fumes are far more deadly than even the exhaust fumes ( no VW jokes please ) . These fumes couldnt be vented to air . So they get " re-circulated " . As a side note , research the problems with Exhaust Gas Recirculation ( EGR ) Valves . This isnt too good for the engine , as you in-addvertantly say in your line " leads to issues when higher crankcase pressure forces more oil out of the vent pipe " . It was so decided , to try to re-burn them , as you say , in a closed circuit , through the carb . But this itself causes many problems , with the carb "Sooting" up / "Gumming" up etc , and causing reduced air flow , disrupted air flow characteristics , and sticking butterflys / throttles . Venting these useless fumes into a charcoal canister is much better , but costs more .

What components in the crankcase fumes are deadly?

Had a old Harley that vented to the chain so auto lube.

Saw no resultant deaths.

References to support your assertations?

(No irrelevant references as per Carlo please)

[ktm jeff]

papa , im no chemist , so you will have to look it up . There are many un-burnt hydro carbons and other fumes from the blow-by of the combustion process , not to mention the chemical reaction of the hot oil circulating the acidic and sulphuric by-products , that cause internal damage to the engine . A main reason for oil changes . Someone may know more of the chemical side if things , than me .

[papa al]

papa , im no chemist , so you will have to look it up . There are many un-burnt hydro carbons and other fumes from the blow-by of the combustion process , not to mention the chemical reaction of the hot oil circulating the acidic and sulphuric by-products , that cause internal damage to the engine . A main reason for oil changes . Someone may know more of the chemical side if things , than me .

My uncle and cousin died from CO from a car running in the garage.

Just wondering how crankcase fumes are more deadly.

[AllanB]

I think this is all a case of amounts, your uncle died as a result of being in a confined place with a lot of poisonous fumes. I am not chemist either, but would have thought it is all pretty poisonous, or carcinogenic, it just a case of quantity.

This policies of pumping shit back into the engine, hoping it would get reburnt, or just disappear was probably thought up by the same chuckwow (like Midgley or one of his mates) who put lead in Petrol and CFCs into fridges.

Yes, all these little tanks and pipes are gunked up to buggery and so is my driveway now, really 'orrible stuff too, like a 50 year old a smoker's lungs, I guess.

Edited September 25, 2015 by AllanB

[Lampang2]

Actually Carol , your teacher was wrong , although i can follow the idea of the oil fumes = carb lubrication . Without putting fuel on the fire ( pun intended ) , those crankcase fumes are far more deadly than even the exhaust fumes ( no VW jokes please ) . These fumes couldnt be vented to air . So they get " re-circulated " . As a side note , research the problems with Exhaust Gas Recirculation ( EGR ) Valves . This isnt too good for the engine , as you in-addvertantly say in your line " leads to issues when higher crankcase pressure forces more oil out of the vent pipe " . It was so decided , to try to re-burn them , as you say , in a closed circuit , through the carb . But this itself causes many problems , with the carb "Sooting" up / "Gumming" up etc , and causing reduced air flow , disrupted air flow characteristics , and sticking butterflys / throttles . Venting these useless fumes into a charcoal canister is much better , but costs more .

What components in the crankcase fumes are deadly?

Had a old Harley that vented to the chain so auto lube.

Saw no resultant deaths.

References to support your assertations?

(No irrelevant references as per Carlo please)

It's bypass gases that gets pass the piston and into the crankcase.

Mixed with some normal atmosphere that also in one way or another gets into the crankcase.

Can as well put the crankcase gases into the cylinder once again for another combustion.

As the gases in the crankcase may very well be depleted of most free oxygen you could die if you breathe that alone.

I don't know how that would be possible unless you do mouth to mouth with your crankcase, still very low volumes of gas inside a crankcase of motorcycle size.

[AllanB]

Actually Carol , your teacher was wrong , although i can follow the idea of the oil fumes = carb lubrication . Without putting fuel on the fire ( pun intended ) , those crankcase fumes are far more deadly than even the exhaust fumes ( no VW jokes please ) . These fumes couldnt be vented to air . So they get " re-circulated " . As a side note , research the problems with Exhaust Gas Recirculation ( EGR ) Valves . This isnt too good for the engine , as you in-addvertantly say in your line " leads to issues when higher crankcase pressure forces more oil out of the vent pipe " . It was so decided , to try to re-burn them , as you say , in a closed circuit , through the carb . But this itself causes many problems , with the carb "Sooting" up / "Gumming" up etc , and causing reduced air flow , disrupted air flow characteristics , and sticking butterflys / throttles . Venting these useless fumes into a charcoal canister is much better , but costs more .

What components in the crankcase fumes are deadly?

Had a old Harley that vented to the chain so auto lube.

Saw no resultant deaths.

References to support your assertations?

(No irrelevant references as per Carlo please)

It's bypass gases that gets pass the piston and into the crankcase.

Mixed with some normal atmosphere that also in one way or another gets into the crankcase.

Can as well put the crankcase gases into the cylinder once again for another combustion.

As the gases in the crankcase may very well be depleted of most free oxygen you could die if you breathe that alone.

I don't know how that would be possible unless you do mouth to mouth with your crankcase, still very low volumes of gas inside a crankcase of motorcycle size.

I think this pumping crap back into the engine, "hoping" it would get burned up, was a late 70's early 80's policy thought up by a non-engineer nitwit employed by the green chuckwows. Before that they used a mesh filter in the crankcase breather which became a bit of a mess as the engine rings wore, valves guides let by, etc. and crankcase pressure/flow increased.

It wouldn't be too bad if they put a filter in the line back to the carb and then allowed it to be changed at a service, mine has one but it appears to be riveted in. <deleted>?

The problem was exasperated more with cars where the fresh air intake was contaminated by the air under the bonnet (read hood) as a result of a ducting leak...Remember that "my dee!"

[papa al]

Crankcase hydrocarbons vented into the intake system will be burned.

This is a good thing.

[AllanB]

Crankcase hydrocarbons vented into the intake system will be burned.

This is a good thing.

I doubt very much whether any of this has any combustible qualities, this mixture of engine oil vapour and carbon deposits entering the carb has very little in those terms, it just clogs the engine. I remember when this "green technology" came in, engine bhp rates dropped and they blamed it on this nonsense.

Perfect example was the Mk3 and Mk4 Triumph Spitfires, the Mk3 was only 1300cc with no crap recycle system and produced 75bhp. The Mk4 was 1500cc and had it and produced just 63bhp, making the Mk3 easily the fastest of all 4 marks giving a 100mph (Advertised as "Top down, Toe down, Ton up") and at the time the new system was blamed for this loss of power.

I seem to remember the same story with the Ford Mustangs of the day.

Edited October 8, 2015 by AllanB

[Lampang2]

Crankcase hydrocarbons vented into the intake system will be burned.

This is a good thing.

I doubt very much whether any of this has any combustible qualities, this mixture of engine oil vapour and carbon deposits entering the carb has very little in those terms, it just clogs the engine. I remember when this "green technology" came in, engine bhp rates dropped and they blamed it on this nonsense.

Perfect example was the Mk3 and Mk4 Triumph Spitfires, the Mk3 was only 1300cc with no crap recycle system and produced 75bhp. The Mk4 was 1500cc and had it and produced just 63bhp, making the Mk3 easily the fastest of all 4 marks giving a 100mph (Advertised as "Top down, Toe down, Ton up") and at the time the new system was blamed for this loss of power.

I seem to remember the same story with the Ford Mustangs of the day.

"Green technology" has done wonders for air pollution.

BMW S1000RR-15 puts out 199 hp / liter with all regulations in place, so not a problem for power.

I guess triumph struggled for other reasons.

[AllanB]

Crankcase hydrocarbons vented into the intake system will be burned.

This is a good thing.

I doubt very much whether any of this has any combustible qualities, this mixture of engine oil vapour and carbon deposits entering the carb has very little in those terms, it just clogs the engine. I remember when this "green technology" came in, engine bhp rates dropped and they blamed it on this nonsense.

Perfect example was the Mk3 and Mk4 Triumph Spitfires, the Mk3 was only 1300cc with no crap recycle system and produced 75bhp. The Mk4 was 1500cc and had it and produced just 63bhp, making the Mk3 easily the fastest of all 4 marks giving a 100mph (Advertised as "Top down, Toe down, Ton up") and at the time the new system was blamed for this loss of power.

I seem to remember the same story with the Ford Mustangs of the day.

"Green technology" has done wonders for air pollution.

BMW S1000RR-15 puts out 199 hp / liter with all regulations in place, so not a problem for power.

I guess triumph struggled for other reasons.

Yes, I should have put a sarcastic smiley next to the words green technology instead of inverted commas, there was noting green about the particular technology. Today is different with cats and what-not.

No, at the time Triumph was successful and the Mk3 was really great car, I was a teenager when I got my first, a 100mph (on the speedo) with the roof down, going across Europe, not many kids were doing that.

[papa al]

Crankcase hydrocarbons vented into the intake system will be burned.

This is a good thing.

I doubt very much whether any of this has any combustible qualities, this mixture of engine oil vapour and carbon deposits entering the carb has very little in those terms,

Engine oil vapor and carbon are eminately combustible.

[ktm jeff]

papa al , combustible , yes , but so is finely ground custard powder , but i aint putting that in my tank .

[papa al]

papa al , combustible , yes , but so is finely ground custard powder , but i aint putting that in my tank .

The first internal combustion engines used powdered charcoal.

Petroleum products proved more popular.

Not familiar with custard powder.

Have cooked over buffalo chips.

Corn chips n potato chips make good fire starters.

[AllanB]

papa al , combustible , yes , but so is finely ground custard powder , but i aint putting that in my tank .

The first internal combustion engines used powdered charcoal.

Petroleum products proved more popular.

Not familiar with custard powder.

Have cooked over buffalo chips.

Corn chips n potato chips make good fire starters.

Moderator please step in and stop this...where will this all end?....Someone will be mentioning farts next....