Fuel lines/ petcocks/ vacuum question.

[Slofuze]

Hi all....hopefully someone can set me straight on this. I've already used the search option, and I just want to be sure. I have an 89 750 Kat. I recently installed a new fuel line.... thinking now I should have done both since the airbox was a real PITA!!!.....does it matter which fuel line goes to which nipple? As it is now, the front nipple is for carbs 3&4, and the back one is for 1&2. The fuel line they sold me is much more pliable than OEM and I don't want to chance a kink to 1&2. Would it matter if I reverse them? I don't think it should, but I thought I'd check it out.
Second question...... On the back of the airbox there was a vacuum line with some sort of cap on the end. When I squeezed it to check for cracks I noticed it had a crack but I'm not sure if it was designed that way. By searching the threads I was able to read CP's posts on the matter, and I'm led to believe the crack shouldn't be there. Is that correct? I do know that one time I overfilled my oil level last year and some oil came out of that tube until I got the level corrected. I always thought it was some sort of overflow tube. I gather I might be wrong.
I'd appreciate any help or advice.
thanks
Nino

[gazoo]

i have a 95 kat750 . having the tank on and off so many times i hooked them up both ways . it did'nt matter fuel comes from both ends of the petcock when its on . the tube should be crack free and capped . hope this helps , be safe .

[Kreylyn]

i have a 95 kat750 . having the tank on and off so many times i hooked them up both ways . it did'nt matter fuel comes from both ends of the petcock when its on . the tube should be crack free and capped . hope this helps , be safe .

This is pretty spot on. It does not matter which side is hooked up to which.

Krey

[Slofuze]

Thanks guys.....making sure.

[ICEG]

if looking from the left side the nipple on the first two carbs should go to the back of the petcock (tank in standard position)
and carbs 3,4 go to the front
and vacum goes on the small nipple on the petcock

http://katriders.com/vb/showthread.php?t=72020

[The CyberPoet]

Air box drain tube should be sealed from end-to-end when the engine is running -- it's location is such that a vacuum pull on it would suck anything from around the hose into the airbox beyond the air filter, and thus unfiltered muck would go straight into the carbs.

The bottom end of that tube varies depending on the year of the bike, at least in the OEM form: pre-98's had a fold-over+clamp arrangement, while 98+ models have a cap that inserts into the end & clamps into place with a squeeze-clamp.

If yours is torn, replace it. You can use any fuel-resistant/heat-resistant hose you can score via the auto parts store as long as it will seal to the airbox end properly and can be either capped or folded shut on the other end (to close off any possible vacuum leakage).

Cheers
=-= The CyberPoet

[Slofuze]

Air box drain tube should be sealed from end-to-end when the engine is running -- it's location is such that a vacuum pull on it would suck anything from around the hose into the airbox beyond the air filter, and thus unfiltered muck would go straight into the carbs.

The bottom end of that tube varies depending on the year of the bike, at least in the OEM form: pre-98's had a fold-over+clamp arrangement, while 98+ models have a cap that inserts into the end & clamps into place with a squeeze-clamp.

If yours is torn, replace it. You can use any fuel-resistant/heat-resistant hose you can score via the auto parts store as long as it will seal to the airbox end properly and can be either capped or folded shut on the other end (to close off any possible vacuum leakage).

Cheers
=-= The CyberPoet

Just curious. But, if it's a "drain" tube, then what exactly is it's purpose if it's capped? Is it something that needs to be removed and held vertically (upside down) every once in awhile?..... or replaced periodically?

[The CyberPoet]

Just curious. But, if it's a "drain" tube, then what exactly is it's purpose if it's capped? Is it something that needs to be removed and held vertically (upside down) every once in awhile?..... or replaced periodically?

The idea is that you drain it when you do an oil change, to get out any fluids condensed in the airbox from the vapor-recovery hose from the engine. The drain tube effectively provides a larger "storage container" for excess fluids, to help keep the filter dry.

More background (vapor recovery: why, how):
All engines tend to blow some fuel-air mixture past the rings during detonation (typically a very, very small amount), as well as mixing some into the oil that's coating the cylinder walls. As the piston sweeps, this minor bit of fuel is mixed into the motor oil (unless the engine is already hot enough to vaporize it immediately).

As the engine heats up, any fuel in the oil vaporizes back out as well. Now we have a crankcase filled with fuel-enriched air. To keep this vapor mixture from hitting a potentially explosive (combustible) level of fuel-air mix (say something above about 8.5:1 air to fuel), pretty much all engines [since well before I was born] have a vapor recovery tube that ties the crankcase venting to the air intake system. The vapors are pulled through the crankcase and out by the virtue of the vacuum in the intake when the engine is running, and sent back into the engine to be burned again. On the Kat, that system is basically the tube from the top of the valve covers that runs to the airbox.

The same thing happens with oil that hits it's vapor temp (i.e. - heads, and esp. exhaust valves get really hot, oil boils & steams effectively) -- the oil vaporizes and is pulled around to the intake system as well (this is the primary reason that vapor recover is taken off where ever the valve area is, although there's also the fact that hot vapor rises to the top of the system). Oil that has been sheared in length by gasoline, water, acid, and/or mechanical action vaporizes more readily, so the system also has the benefit of removing the least desirable oil in the mix (but oil is heavy and rarely hits vapor temp).

Additionally, when the bike is parked & cools, the air in the crankcase may be subject to condensation (or repeat condensation), leading to water in the bottom of the oil system -- water which combines with the sulfated ash content in the oil to form sulfuric acid. This also gets vaporized back out and drawn off through the vapor-recovery system when the bike gets hot enough to boil it off.

OK, so now we have this combination of vapors headed back to the airbox under a vacuum and it arrives. The in-rushing air is quite cool by comparison, and the vapor wants to condense back into a fluid. Gasoline & water/sulfuric acid usually will get sucked into the engine to be re-ignited without issue because even in condensed form it's still tiny (unless you have a god awful lot of it, such as a stuck float), but the oil, being heavier & more prone to multi-molecule clumping, tends to condense and fall to the bottom of the air box (or slam the sides due to the pulsing action of the pressure waves)... This is why your airbox is always lightly oily on the inside. And from there, if enough builds up, it runs down to the drain tube.

SIDE NOTE:
These contaminants are also the primary reason we change motor oil at the intervals we do -- if the fuel & condensation could be kept separated from the oil perfectly, the oil would be good for 30k, 40k miles or possibly more as long as it didn't overheat (hit it's vapor temp) or get mechanically sheared too much. These contaminants (esp. the water) is the reason a bike that gets ridden regularly is so often in much better shape than one that was parked off for a long time, in spite of the fact that the one ridden more regularly has far more miles on it.

So, every oil change, you pop open the bottom of the airbox drain tube and drain out what's there. A healthy engine will get anywhere from a couple drops of oil to maybe a half a shot glass of fluid out every 3500 miles; a motor with bad rings will tend to have a lot more oil, and a motor with stuck floats will gush out either fuel or very thin, runny oil in great quantities. Bikes that have lots of water condensation from being parked up for extended periods of time may have a lot of water come out (often loaded with algae and bacteria and smelling nasty).

Hope that clarifies it all

Cheers
=-= The CyberPoet

[Slofuze]

The idea is that you drain it when you do an oil change, to get out any fluids condensed in the airbox from the vapor-recovery hose from the engine. The drain tube effectively provides a larger "storage container" for excess fluids, to help keep the filter dry.

More background (vapor recovery: why, how):
All engines tend to blow some fuel-air mixture past the rings during detonation (typically a very, very small amount), as well as mixing some into the oil that's coating the cylinder walls. As the piston sweeps, this minor bit of fuel is mixed into the motor oil (unless the engine is already hot enough to vaporize it immediately).

As the engine heats up, any fuel in the oil vaporizes back out as well. Now we have a crankcase filled with fuel-enriched air. To keep this vapor mixture from hitting a potentially explosive (combustible) level of fuel-air mix (say something above about 8.5:1 air to fuel), pretty much all engines [since well before I was born] have a vapor recovery tube that ties the crankcase venting to the air intake system. The vapors are pulled through the crankcase and out by the virtue of the vacuum in the intake when the engine is running, and sent back into the engine to be burned again. On the Kat, that system is basically the tube from the top of the valve covers that runs to the airbox.

The same thing happens with oil that hits it's vapor temp (i.e. - heads, and esp. exhaust valves get really hot, oil boils & steams effectively) -- the oil vaporizes and is pulled around to the intake system as well (this is the primary reason that vapor recover is taken off where ever the valve area is, although there's also the fact that hot vapor rises to the top of the system). Oil that has been sheared in length by gasoline, water, acid, and/or mechanical action vaporizes more readily, so the system also has the benefit of removing the least desirable oil in the mix (but oil is heavy and rarely hits vapor temp).

Additionally, when the bike is parked & cools, the air in the crankcase may be subject to condensation (or repeat condensation), leading to water in the bottom of the oil system -- water which combines with the sulfated ash content in the oil to form sulfuric acid. This also gets vaporized back out and drawn off through the vapor-recovery system when the bike gets hot enough to boil it off.

OK, so now we have this combination of vapors headed back to the airbox under a vacuum and it arrives. The in-rushing air is quite cool by comparison, and the vapor wants to condense back into a fluid. Gasoline & water/sulfuric acid usually will get sucked into the engine to be re-ignited without issue because even in condensed form it's still tiny (unless you have a god awful lot of it, such as a stuck float), but the oil, being heavier & more prone to multi-molecule clumping, tends to condense and fall to the bottom of the air box (or slam the sides due to the pulsing action of the pressure waves)... This is why your airbox is always lightly oily on the inside. And from there, if enough builds up, it runs down to the drain tube.

SIDE NOTE:
These contaminants are also the primary reason we change motor oil at the intervals we do -- if the fuel & condensation could be kept separated from the oil perfectly, the oil would be good for 30k, 40k miles or possibly more as long as it didn't overheat (hit it's vapor temp) or get mechanically sheared too much. These contaminants (esp. the water) is the reason a bike that gets ridden regularly is so often in much better shape than one that was parked off for a long time, in spite of the fact that the one ridden more regularly has far more miles on it.

So, every oil change, you pop open the bottom of the airbox drain tube and drain out what's there. A healthy engine will get anywhere from a couple drops of oil to maybe a half a shot glass of fluid out every 3500 miles; a motor with bad rings will tend to have a lot more oil, and a motor with stuck floats will gush out either fuel or very thin, running oil in great quantities.

Hope that clarifies it all

Cheers
=-= The CyberPoet

A huge "THANK YOU", CP. In my "bucket list" is to meet up with the KR crowd at The Gap soon and I hope you'll be there.

[The CyberPoet]

A huge "THANK YOU", CP. In my "bucket list" is to meet up with the KR crowd at The Gap soon and I hope you'll be there.

This information is now integrated into the KR Wiki as the following entries:
Vapor Recovery System
Airbox Drain Hose
Vapor Recovery Hose

PS - I plan on being at this year's rally.

Cheers
=-= The CyberPoet

[Slofuze]

This information is now integrated into the KR Wiki as the following entries:
Vapor Recovery System
Airbox Drain Hose
Vapor Recovery Hose

PS - I plan on being at this year's rally.

Cheers
=-= The CyberPoet

I'll be riding north to Sault Ste. Marie,Ont. (where I grew up) this summer. The Gap and all the great members of KR will be in my thoughts. Ride safe CP, and all of you reading this thread. Til then...peace
Nino