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Free Mod How-to?

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I was looking to do the free case breather mods from PlanetKLX, but the site is temporarily down. Does anyone out there have a tutorial with a picture or two?

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If you're familiar with the breather tube and where it's located on the engine (large tube connected to top of the engine case below the carb), all you need to do is remove that tube and push out the rubber restrictor plug that is stuffed inside of it. Blow on it before and after and you will be surprised how much restriction that plug made when in the tube. After removing the restrictor just reinstall the original breather tube onto the engine and the airbox and you've opened it up as much as can be. I did the full blown complete removal of the original tube and replaced it with a length of 5/8 ID heater hose from autozone and routed it from the engine to the top of the airbox and terminated with a small breather filter. This is the method documented on PlanetKLX but really seems like overkill to me. The replacement hose takes up a bit of space to route it up around the carb, through the frame and up into the top of the airbox. Also with this method, you have to plug its original inlet into the airbox with something (I used a 1/2 inch pipe plug and hose clamp) I did it because I already had the materials and lots of time on my hands to mess with it. HTH

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There's more of a chance of water, dirt and grunge (ever look at the bottom of your airbox??) getting into your crank, and therefore piston, tranny, valves, etc. If you cheap out and just punch out the restrictor because crap can come from the bottom of the airbox and into the crankcase. I'd suggest going the full route and put in the heater hose and filter routed up into the airboxx.

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Bill,

Aren't you kind of screwed anyway if you've gotten that much stuff past the filter and the little squeeze drain in the filter compartment? I've not ridden nearly as much as most here but I've had it apart and really think the restrictor may have been there maybe to keep engine oil where it belongs in extreme conditions (in the case, not up into the airbox).

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On a slightly different note, by covering up the breather filter on my system while the motor idles there is definitely some significant airflow coming/going through that puppy. It changes the idle speed even.

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ioneater - not at all. The restrictor is there for emisions reasons. If you open it wide open, you will definately have the possibility of junk going into the crank. If you've ever looked in the airbox. there's lots of junk that ends in there - sticks, small rocks, and of course a lot of dirt. Some KLX's seem more prone to dirty airboxes than others. I'm not sure why. My son's KLX always has a dirty air filter and lots of dust and oily dirt in the airbox - even if he's leading. Even if I'm in the back, my airbox is cleaner. Why? I don't know, but in every airbox (not the filter - the box) I've cleaned that hasn't been cleaned for a while - and that's more than a few - there's always small rocks and debris that ends up in the bottom of them. Now, if there's a clear path down to the crankcase, what do you think will happen??

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Now hold on, isn't the breather on the filtered side of the box? I'll bet you a trials tire against a knobby it is.

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Now hold on, isn't the breather on the filtered side of the box? I'll bet you a trials tire against a knobby it is.

I think Bill P. is aware of the location of the hose, but I'm assuming Bill P. cut out his back fire screen...because their is no way you would be able to get fine dirt or small rocks past the fine back fire screen. If you have removes the screen and have dirt and debris in the box past your filter...most likely new valves will be coming your way!..I removed my screen a few years ago and at most I will get a bit of oil down at the bottom of the box (after the filter). All of us who has removed the air box lid most likely gets tons of dirt and small rocks at the bottom of the box before the filter though.

Sangair

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The hose that goes from your crankcase to the airbox is below the filter. The filter is only for the air that enters your carb and if the hose is below the filter then it would not have a backfire screen. Go take a look at your bike. The hose may be on the filter side but that certainly does not mean that it is protected by the filter.

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The hose that goes from your crankcase to the airbox is below the filter. The filter is only for the air that enters your carb and if the hose is below the filter then it would not have a backfire screen. Go take a look at your bike. The hose may be on the filter side but that certainly does not mean that it is protected by the filter.

I believe the issue was dirt and debris getting into the crankcase through the stock breather hose without the rubber nozzle (bung). If the stock rubber breather hose is connected to the rubber intake duct AFTER the air filter and back fire screen,(which it is) it would be protected from dust, debris and small rocks entering the cranckcase.

Sangair

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OK. that makes sense. I didn't look to see exactly where the stock breather tube entered the airbox and it's been a long time since I did the mod. However, it's still MHO that the stock unrestricted hose is not as good as the aftermarket heater hose type breathers. Here's why...

Scenario 1 - not that this has ever happened to me..... :banghead: You flip the bike upside down and oil comes out of the crank into the breather tube and directly in-line so that the carb can suck it in. Not good. I know I've found quite a bit of engine oil in my external air box before. Had I had the stock tube unrestricted, that oil would have been in the airboot ready to suck into the carb.

Scenario 2 - The PowerNow people and their users have a lot to say about the turbulent air flow as it enters the carb. As was noted by ioneater above, the unrestricted breather venting directly into the air flow coming into the carb can't possibly help smooth air flow into the carb. I don't know how big a difference this is, but the people who use the powernow's really have good things to say.

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OK. that makes sense. I didn't look to see exactly where the stock breather tube entered the airbox and it's been a long time since I did the mod. However, it's still MHO that the stock unrestricted hose is not as good as the aftermarket heater hose type breathers. Here's why...

Scenario 1 - not that this has ever happened to me..... :banghead: You flip the bike upside down and oil comes out of the crank into the breather tube and directly in-line so that the carb can suck it in. Not good. I know I've found quite a bit of engine oil in my external air box before. Had I had the stock tube unrestricted, that oil would have been in the airboot ready to suck into the carb.

Scenario 2 - The PowerNow people and their users have a lot to say about the turbulent air flow as it enters the carb. As was noted by ioneater above, the unrestricted breather venting directly into the air flow coming into the carb can't possibly help smooth air flow into the carb. I don't know how big a difference this is, but the people who use the powernow's really have good things to say.

I hear ya Bill and agree with both🤣

I can't say scenario 1 has ever happened to me....but it has happen to my sons klx 110 several times after removing the restrictor, thankfully the breather hose vents out below the bike not into the air box.

I have done the breather mod and honestly can't tell if we actually gain a 1/2 hp increase as mentioned somewhere, but it is definitely a safer application compared to stock without the rubber bung :banghead:

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I didn't know this thread would get such a good discussion going. I'm glad I asked.

I have a TM36 carb installed on the bike. Will I need to adjust the jetting? I would think that ventillating the crank wouldn't require any rejetting.

What do you guys think?

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k, I doubt that you'll need to rejet. It's not affecting the volume of air leaving or entering the engine. What it does is relieve the back pressure on the piston as it comes down in it's stroke - so the engine doesn't have to fight itself as much. Hope that makes sense..... :banghead:

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Bill-

That makes perfect sense. thanks for the quick response time. You either live in the east, or you're goofing off at work, like me. :banghead:

Kimo

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OOOPS sorry guys please disregard my earlier post i wen tout and looked at my bike and realized i got the drain on the airbox mixed up with the crankcase breather. It does get filtered air. Sorry for the misinformation.

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Bill-

That makes perfect sense. thanks for the quick response time. You either live in the east, or you're goofing off at work, like me. :banghead:

Kimo

:banghead:🤣

OK......I admit it.......goofing off.

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Bill, normally I wouldn't contradict you on klx anatomy but I was pretty sure on this one. All I've been able to do is work on this thing the last couple of months due to transportation issues. Still only has 49 miles on the odo. Should change this coming week as we'll be in wide open Eastern Colorado and can finally put some time on the machines on family land! Definitely glad I did the full blown free mod after all this good discussion. Thanks for making me smarter. :banghead:

Greg

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Bill, normally I wouldn't contradict you on klx anatomy but I was pretty sure on this one. Greg

That is one of the great things about this forum, it's OK to question what we read here. Much better than having incorrect information being spread around.

Ride on

Brewster

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