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Discussion Starter #1
Tomorrow i am installing a Vance Hines muffler and dyno jet kit. My 2007 has no mods at all right now. Should I do an airbox mod prior to these upgrades? The airbox on my sons KLR looks like swiss cheese it has so many holes in it and it runs much better than mine. Should I do an L mod or just cut holes? How do you do and L mod. I know you cut an L shape in the box but I don't know how big or where exactly.
 

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Discussion Starter #3
Thanks for the info. Should I do a stage one or two jet? I presume the both have larger main jets. They are rejetting it tomorrow at the kawasaki dealership
 

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Dwell -

What SLO-KLR said. +1.

I'm a believer in not doing irreversible mods, so I recommend poking 1" holes that you can pop plastic plugs into if you don't like the results, or if you put a really loud muffler on and find that later on you want the stocker back on and have to rebalance the airflow. Ask me how I know about that...

photo deleted


Notice how that forward hole is only half a hole? Be careful where you cut - I miscalculated and got half the hole on the carb side of the baffle and had to patch it. Oooops. Fortunately it is made of ABS, so making a patch and cementing it in was easy. The plugs for the holes are available in those bins/drawers of miscellaneous hardware at Home Depot, Lowes, ACE, etc..

Are you also going to pull the snorkel out? It's usually done with the L-Mod.

Tom
 

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Discussion Starter #5
Good information. Thanks. What is the snorkel? I am relatively new to motorcycles. I used to ride as a teenager and took a 30 year hiatus to raise kids.
 

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Tom what's that right angle piece left of your +ve battery post?

Have you tried the "MC" mod yet (advancing exhaust Cam one tooth. It works great on my 09). :)
 

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salty_monk,

That is the fitting where the hose from the canister of the vapor recovery system goes. When I removed all of that I capped it off by simply inserting a vacuum cap (backwards) into the fitting.

Removing the fitting would have been more difficult and irreversible.

Interestingly, if you were install the IMS 10 gallon tank you would need that fitting to be intact. The vent for the tank goes there.

I haven't done the MC mod yet. I will, but probably not until I do a valve clearance check.

T
 

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I've got an FMF pipe on my bike, and was told the original owner rejetted the carb.
Sounds like I'm a good candidate to do this as well.
I like Tom's idea of using 1" holes and removing the snorkel, I'm thinking if I only drill four - that still looks like a lot of airflow to me, compared to the opening of a carburetor.

The usage of the term "snorkel" makes me think that this exists in the bike like a snorkel on a Jeep - to make sure no water gets sucked into the bike.
I'm not really planning on going off-roading in mud, much less trying to ride my bike across Lake Erie, but for the benefit of this thread - is there any risk to removing this? Is that the intended stock purpose of that part?
 

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It's a bit of a mystery how it works.

One school of thought is that it does keep water from the intake, as the internal air box construction has a dam and a well sort of arrangement. I'm not sure how effective it is if you really submerge the bike.

Once water gets into the air box and reaches the bottom of the snorkel, no more water can get in, and there is a smallish drain to let the water out.

There are some thoughts that the snorkel's purpose is to reduce intake noise.

I don't know which is true; I've never had an air box apart.

T
 

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I have a supercharged Honda civic that I bought new I'm 95 and has since turned into an autocross toy... I still have it believe it or not.

One of the first things I had done to it while still naturally aspirated was to remove the factory airbox and replace it with an inexpensive kit that was simply an aluminum tube and reusable K&N filter.

On the Honda, the only purpose for the airbox was to muffle noise. The motor roars without it - a nice roar lol.
(Or roared - sort of disappointingly muffled that roar with a supercharger blocking the intake path :( )
And it did make a just-noticeable amount of peppiness to that small motor.

I'd be less concerned about additional noise on the bike and more concerned about efficiency at any rate - I'll have to take a look at this one. Thanks!
 

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Sometimes I feel compelled to do research thereby adding to the vast body of knowledge, or adding entropy to the universe depending upon your point of view.

I'm going to have to go with the theory that it's there to reduce noise.

Though hard to see in this photo, the "dam" rises no higher than 5" from the top of the air box (as measured by the scale that looks like it's in the background), while the snorkel descends no further than 2 1/2". The air box is about 6" deep. I think if there were a dam that cam to within an inch of the top of the air box a case could be made that water could be trapped.

I'm no hydrologist, but it seems like there's not much resistance to water flow.

Somebody correct me if I'm all wet...



T
 

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Think of the shape and how it directs air flow and also the overall shape of the airbox.
Again....this is old news and has been documented before elsewhere.

But I am not looking up past threads over at .net or the World for you. Sorry.

Please keep up the great work.....but if you do find the thread it will answer all your questions. The same thing goes for the pumper carb and where to get the one you are looking for to easily fit the KLR. But without providing the threads and all of the paperwork so to speak....you call BS on me.....All I'm saying is, in the past 7 years this has been hashed out before and resolved.

I'm not saying this to upset anyone but it will make the job of figuring out these issues that much easier. I used to have all of this stuff bookmarked and saved but with 2 hard drives dying, I no longer have this information to share. Plus like others I can no longer search on .net.
 

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willys-

I did go do a search, but I couldn't find anything. There seemed to be a lot of posts about removing it and sometimes some conjecture about what the purpose is. Nothing definitive or conclusive about the purpose, though.

The search function, like most forums (including this one) isn't the smartest so it could be that the right thread just didn't come up. Or it could be my search abilities.

T
 

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The thread discussed the flow of the air over the noise reduction. It seemed as if the shape of the box was creating some turbulance with they fixed by using the snorkle. From what I remember of it. This was close to 7 years ago now.
Taking off the side door was also discussed and was found that it also ruined the air flow characteristics of the airbox. It allowed too much air to flow into the aircleaner and thus required you to rejet etc to compensate for it. Again it was dropped as a non worth while mod. I think Cary was involved with this discussion, I may be mistaken but......it has been a long time ago. The aircleaners were all getting flow tested around the same time and the results were posted. It was proven that the best way if you needed to gain more flow was the top opening mod, either using the 4 1" holes or the "L" mod. But they disregarded the removal of the door.
Hope this helps......don't ask me to prove or explain this as I do not know thermadynamics well enough any more. I used to but with lack of use come loss of information.
 

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I'll search the L-mod.
I'm going to guess, blindly, that it involves removing the snorkel and replacing it with a less obtrusive L-shaped thing.
Now off to go see how good my guess is. :9:
 

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See post #4 in this thread. Just don't do it quite that way...

T
 

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Take my advice...do not cut a "L" into the top of your airbox. Drill 4 1" holes in the same location as they can be plugged with electrical fuse panel plugs from a good hardware store. I don't think they are actually 1" in size, so go and buy 4 plugs first then bore the holes so the plugs fit snugly. This is reversable, easily.....the "L" mod is NOT! It will give you the same basic benefit without the distruction of your airbox.
 
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