Youz guys have inspirted my to start moding my klx. I've got quite a bit of not so high dollar stuff coming but I couldn't just sit here so I improved, I think, my previous setup.

I've seen the hi flow snorkles and high $$ hi flow exhaust systems but thought I'd see what I could do with the stock setup for now. I might be missing something but why buy a freer flowing snorkle when there is so much room to generously perforate the air box? (see video)

To open the stock exhaust I took a 1/2 inch drill bit through the existing center then drilled 7 3/8 inch holes around the perimiter. 3 of the seven went through the first baffle in the spark arrestor. I don't think it has a bad exhaust note but I am going to add a billet tip with screen.

Anyway, here's what it looks like and how it sounds with the no dollar mods. You guys are much more familiar than I am with what works but these free mods seem to open her up a bit and let her breath and I think I like the exhaust note too.

3 pics of my evening ride and a short video of airbox perforation mods with sound. (volume check)

If I can got Botophucket to work...ARG!!



http://s295.photobucket.com/albums/m...t=KLX250-1.flv

 

If you haven't rejetted - now is the time. The lean running stock carb with the extra airflow could cause you some problems!

 

I'm still unclear as to the proper re-jetting.

I hear about different jet sizes but don't know what size is best for me at about 2500 ft.

I've also got a Uni filter on the way. YOU GUYS ARE COSTING ME.. but I luv every foot pound of it!!

What are my re-jet options. Where is the best place to buy either jets or a kit?

What is this "big bore" kit I hear about?

Sorry for all the newbi questions. I've searched other threads and have found some great info and some information overload.

So how does it sound to you? Seems much throatier than pure stock.

 

Please don't take this the wrong way, but...what the hell did you drill a bunch of holes in your airbox lid but leave the snorkel in? I'm actually very puzzled right now.

As for your exhaust. Your on the right track if I understood you correctly. You drilled the baffle out then took a smaller bit around drilled around the main exhaust exit hole right? You should just cut the hole around entirely. Then get one of those billet ends off of ebay. They look nice.

And yes, you must rejet. You have the advantage of being at 2500 ft. that gives you an ever so slight edge. But... if you have stock jetting you were already lean, now you drilled out your exhaust and airbox you have to be lean. If I were you I'd grab some duct tape and seal those holes in your airbox lid back up temporarily until you can get a bigger set of jets in there.

Fuel is what gives you power, not air. Air is whats required in order to burn the fuel. Too much air however, and the mixture is off.
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VAPORGENIE PORTABLE VAPORIZER REVIEW

 

all that work on the new airbox lid when you really just have to remove it and place it on your junk rack in the garage. You should've first rejetted the carb as you're running way lean now, leaner than stock which is bad. You could damage your engine if you run it too hot.
The bad thing about the stock muffler is first, it weighs a ton. Second, it has a catalytic converter inside that no matter how many holes you drill, still stops flow. If you want a cheap stock system, just buy the KLX300R full system. It will bolt right on but make sure you get the header as well as it's a bit longer than the 250S's.
Buy the Keihin N1TC needle, and a 128 or 132 main jet and do the carb mods.

 

I'm here to find out what's what so if you've got something to say, I'm all ears. I only ask that it's backed by some reason.

I don't understand what difference leaving the snorkle in would make. Some people take the lid off completely. I question why some people buy a hi flow snorkle instead of drilling some holes. It seemed to be the simplest way to increase intake flow and provides a more even and turbulent airflow, and probably a tad cooler air than a hi flow snorkle that draws air from behind the radiator, under the tank and over the top of the engine.

What I ended up doing after looking at the intake air source was cut the top of the snorkle back almost all the way to the bend and turning it around. I'm putting closed cell foam under the seat over the front half of the airbox to divert hot engine air around the airbox and draw air from the sides and rear. It may not do a bit of good but I can't see where it hurts anything.

If what I've done to the air intake is counter productive there must be a reason. What is it?

As far as the re-jetting goes, that makes sense. While I've gotten things apart I'll do that.

I also removed the smog bog and routed my cranckcase vent to the top hole in the airbox because it's already bigger and it's higher which seems to me would be an advantage from both oil and water getting into the engine in the event of a spill or a wet spill. Since I already enlarged to original crank vent hole in the airbox I'm going to run a short piece of hose up to the top of the airbox with a small air filter on the end.

The exhaust and header are also on the list but I'll be patient for the right deal. It only makes sense that if you pack more air in you've got to make room for it to get out.

I've got a high energy coil and have decided to run an iridium plug.

With a re-jet and 13 teeth up front I'm sure I'll notice a big difference!!

Thanks for the suggestions.

 

What I meant by all of that is why didn't you just take the snorkel out? See, what you did is a permanent modification (drilling holes). You would have to either buy a new one, rig that one by taping it up, or use some sort of plastic weld on it to reseal the holes, but it will never be the same again if you want to turn it back to the way it was.

The snorkel is to keep out water. So if you drill holes in the airbox lid BELOW the intake of the snorkel but retain the snorkel...whats the point?

See what I mean? Running a high flow snorkel is the lesser mod, the more common is just simply remove it. Then the next in line would be taking the lid off completely (judging by feedback of users on here that I've seen).
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Subaru brat

 

If you plan on any water crossings get the KDX snorkel, if not just throw the whole lid with snorkel on the shelf. While you're at it fit a "proper" air filter.

 

Props on the new sound! I'll also echo what Jason said earlier. Tape-off those holes in your air lid until you get the jetting right. I'd say at least a 128 main, clip at 4th notch from the top of the needle and 2.5 turns CCW from fully closed on the fuel screw to start with at your altitude (always safer to start on the rich end).

Good luck

 

yep, no doubt. you could've just pulled the rubber snorkel out and gotten the same effect as the holes you drilled plus you could've put it back to stock if you ever needed. Removing the lid totally is the best alternative though, but only after you have an exhaust. You really won't feel all that much performance until you exhaust the bike in some way- full or slip-on. The stock system sucks and is such a hindrance. Mod it til the cows come home, it's till the oem system. The 300 system otoh, works well with the buttplug removed.