Running without the airbox installed (temporarily) ??

[Longlivedixie]

So I am neck deep in my de-smog, electric fuel valve, petcock, fuel lines and carb work.

I put my fuel tank on with it in mind to put it together without the air box installed for a preliminary test run and leak check.  

It started fine, and no leaks, and the petcock and electric fuel valve seem fine.....thank goodness!! BUT, after I let it warm up a bit and started goosing it some, it would go up in RPMs (per normal) just a second......and then then wind down even with me giving it more throttle.

It ran fine at low RPMs, but giving it more throttle it just slowly would work its way back down to under 2K RPMs, then pick back running well.

Of course it making a big sucking sound when I would try to raise the RPMs, but it would just ease back down. like I had let go of the throttle almost.

I am hoping just the lack of an air box is causing this, and how it is acting is normal........not another problem.

I understand it would be running lean and not particularly good for it, but I am talking about only about 3 minutes of running.

Any thoughts??

THANKS!

[Bagger John - #3785]

If you're running inside a clean room, I wouldn't sweat a couple minutes without an air filter element in place.

If, on the other hand, you're in a dusty, gritty environment...don't. I'd be less concerned about leaning the motor out than I would sucking potentially harmful contaminants into the cylinders.

[JimC]

Not trying to derail the thread, but along the same lines as the OP.

I recently had my air box off and was wondering what would happen if I ran 6 separate air cleaners, one mounted to each carb?
I would imagine it would run a little lean, but that should be adjustable?
The main issue I thought about would be riding in a torrential rain storm and the air cleaners getting wet?

JIm

[Longlivedixie]

If you're running inside a clean room, I wouldn't sweat a couple minutes without an air filter element in place.

If, on the other hand, you're in a dusty, gritty environment...don't. I'd be less concerned about leaning the motor out than I would sucking potentially harmful contaminants into the cylinders.

No worries, thanks. Inside a storage building.

It may have been fuel starvation. That is kind of how it acted. I am wondering if I have my #2 diaphragm turned the wrong direction in my petcock conversion.  That may be it, I don't know.

[Paladin528]

The Valk is not tolerant of running with the airbox removed or tampered with in any way.  Honda engineers pretty much nailed it with the box.

[F6Dave]

Could it have something to do with the CV carbs?  Is there any way the airbox could affect the vacuum that lifts the slides and cause them to drop?

[Bighead]

The Valk is not tolerant of running with the airbox removed or tampered with in any way.  Honda engineers pretty much nailed it with the box.

It can be tampered with, witb no ill effects. Just ask attic rat. 

[Ricky-D]

There have been many posts over the years regarding the problems encountered with modifying the air box and related parts.

There have been no posts regaling any improvements in performance nor fuel economy as a result of modifying the air box.

CA, I think polished inside the air manifold pipes, and he can tell you the results.

As to anything else when it comes to messing with the air box is "pie in the sky" when looking for improvement.

I think the only real improvement has been with installing a "dial-a-Jet" system and I think CA can also tell you about that.

***

[Safety Steve]

All I know is Bob Smith aka Attic Rat does modify the air box, he opens it up so that is can breath better, he also rebuilds the carbs and I few other things and with the total package you get better MPG's and more power, just ask anyone who has had AR do his performance work on there bikes.  Now if the air box was the only thing modify with out anything else done I don't know what is would do, that is something you would have to ask Bob about.   

[Fazer]

Got mine back from Attic Rat Performance in late March and I would echo what everyone else that has had the work done says-- improved mileage, better running and for sure more power.  He cuts the rear top of the air box off, re-jets the carbs during rebuild, polishes and ports the valves (I don't know what porting the valves means, but I think he does it) and mills the heads.  He also polishes the intakes and replaces numerous o rings and hoses.  It sounds like a turbo when getting on it.  Bike was already fast, but now it's wicked fast.  Feels like the front end is getting light when twisting hard in third.

I agree with those before, me--a sixth gear would be nice.  I sure try to find it often enough.  (My previous bike, an '89 Shadow 1100 had only four gears.)

[pancho]

I am hoping just the lack of an air box is causing this, and how it is acting is normal........not another problem.

Put your airbox back on and see.

[Longlivedixie]

The Valk is not tolerant of running with the airbox removed or tampered with in any way.  Honda engineers pretty much nailed it with the box.

That dos not pertain to my question Sir. I had just done it for about 3 minutes under test conditions. No plans not to use the air box or modify it. The bike just ran counter to the throttle input with the air box off and I was wondering if that was 'normal'.

Thank you though.

[Longlivedixie]

Could it have something to do with the CV carbs?  Is there any way the airbox could affect the vacuum that lifts the slides and cause them to drop?

Me thinks ya have hit the ol' nail on the ol' head Sir!!  Thank you very much!!

As long as that is normal, I am good as far as my mods and lack of fuel line problems.......so far anyway.

I will report back when I get her al put back together.

[Longlivedixie]

I am hoping just the lack of an air box is causing this, and how it is acting is normal........not another problem.

Put your airbox back on and see.

Yes......I was TRYING to see if I had any problems with all my other mods before I put that contrary-assed thing back on, so I would not have to yank it off again and re-do something.

At the time, I was thinking my petcock mod may have been causing fuel starvation, or one of my other mods was causing that bizarre behavior.  I THINK I am good to go though........that it is 'normal' for it to act all crazy without the airbox. It is very odd to have a engine throttle down with more gas being applied.

Hopefully I will have it running by tomorrow.......if the levees hold and the Arkansas river does not carry me away.

[98valk]

I am hoping just the lack of an air box is causing this, and how it is acting is normal........not another problem.

Put your airbox back on and see.

Yes......I was TRYING to see if I had any problems with all my other mods before I put that contrary-assed thing back on, so I would not have to yank it off again and re-do something.

At the time, I was thinking my petcock mod may have been causing fuel starvation, or one of my other mods was causing that bizarre behavior.  I THINK I am good to go though........that it is 'normal' for it to act all crazy without the airbox. It is very odd to have a engine throttle down with more gas being applied.

Hopefully I will have it running by tomorrow.......if the levees hold and the Arkansas river does not carry me away.

u actually were reducing fuel by opening the throttle with no air box, air filter restriction.  the throttle only opens the throttle blades more.  with no restriction into the carb mouth, fuel is not drawn up through the jets and needle well which also cause a restriction of fuel flow. using much larger jets, reduces the restriction and allows fuel to flow with no air box. same principle when individual air filters are used on each carburetor which requires much larger jets. It is all a balancing act btwn air box/air filter restriction and jet restriction to get the air fuel ratio the engine wants.

[Longlivedixie]

I am hoping just the lack of an air box is causing this, and how it is acting is normal........not another problem.

Put your airbox back on and see.

Yes......I was TRYING to see if I had any problems with all my other mods before I put that contrary-assed thing back on, so I would not have to yank it off again and re-do something.

At the time, I was thinking my petcock mod may have been causing fuel starvation, or one of my other mods was causing that bizarre behavior.  I THINK I am good to go though........that it is 'normal' for it to act all crazy without the airbox. It is very odd to have a engine throttle down with more gas being applied.

Hopefully I will have it running by tomorrow.......if the levees hold and the Arkansas river does not carry me away.

u actually were reducing fuel by opening the throttle with no air box, air filter restriction.  the throttle only opens the throttle blades more.  with no restriction into the carb mouth, fuel is not drawn up through the jets and needle well which also cause a restriction of fuel flow. using much larger jets, reduces the restriction and allows fuel to flow with no air box. same principle when individual air filters are used on each carburetor which requires much larger jets. It is all a balancing act btwn air box/air filter restriction and jet restriction to get the air fuel ratio the engine wants.

Thanks much for that good info!!

I appreciate it!

RON

[Longlivedixie]

Well.......I finally got her put back together.  The modified de-smog seems to be fine. The new electric fuel valve seems fine. The petcock conversion to manual and the elimination of the number 6 cylinder vacuum line seems fine.

Sadly though, the carbs did not clear up with the soaking with some pure 'Mechanic in a Bottle'. It is running better, but she still has carb issues.

Probably won't make any difference, but I will take her out for some miles with a very strong dose of some carb cleaner and see what happens.

Thanks for everybodies help and advice!

RON

[gordonv]

It is running better, but she still has carb issues.

Probably won't make any difference, but I will take her out for some miles with a very strong dose of some carb cleaner and see what happens.

+1

Remember, try different types of cleaners. Others have reported each cleaned a little bit more of the problem away.

Remember you want to run the engine in the rpm range that is giving you trouble.

[Longlivedixie]

It is running better, but she still has carb issues.

Probably won't make any difference, but I will take her out for some miles with a very strong dose of some carb cleaner and see what happens.

+1

Remember, try different types of cleaners. Others have reported each cleaned a little bit more of the problem away.

Remember you want to run the engine in the rpm range that is giving you trouble.

Yes thanks.  I posted my questions about the carb cleaner issue on another thread. I wanted to get some input from folks about what brands they have had luck with.

Yes, when I ride her I keep her in the RPM range where she is having the issues. That is the lower rpm range. I also shoot some extra gas to her occasionally with the fuel enricher. Just hoping against hope that she will clear up with some riding.

I am a bit cautious about taking her on a long trip and seeing what happens since I fear she may be running lean in the cylinders with carb issues. I only go about 8 miles.

BTW.........I did a compression check on her and all is well, thank goodness!!

Appreciate your help!

RON