Vent Pipes - Keihin PWK38

Davehuge

Davehuge

Member
I have a 2004 EC300, the vent pipes on my Keihin PWK38 carb had gone hard and brown, so I decided to replace them.

I had a hunt around trying to find suitable size pipe that's oil/petrol resistant, but gave up in the end.

I purchased this kit on eBay. The seller is 'Frank MX Parts' based in Holland and I understand he is an official Keihin dealer, so I assume this is a genuine Keihin kit.

Kit also includes the five clips, price was reasonable and delivery was quick.

Vent hose kit Keihin PWK quad vent carburetor / OEM pink breather 35 36 38 39 41
https://ebay.us/FImg8Q

Vents.jpg

He also has a website that you can order from directly and offers worldwide shipping.

Frank! MXParts
https://www.frankmxparts.com/

All the best, Dave.
 
If anyone's interested here's the information from the Vent Pipes...

The 4 vent pipes are marked as PLAS TECH VT3 18B

The smaller diameter pipe for the fuel overflow is marked PLAS TECH VT3 18A

Hose.jpg

:)
 
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I would separate the tubes and run the lower ones down in the stock area by the shock and the upper carb vents go into the air box. This prevents you from sucking garbage into the carb
 
Hi Zman

I would strongly advise against running vent lines into the airbox.

Please correct me if I'm wrong, as I understand it...

The purpose of the vent lines is to keep the float bowl at atmospheric pressure, ensuring that fuel in the float bowl is drawn up through the jets correctly, relieving air as fuel flows into the float bowl. Air or dirt shouldn't flow from the vent lines into the float bowl, no dirt should be sucked in.

With vent lines running into the airbox, if the bike is laid on it's side, when we crash or fall off (about every time I ride!) there is a risk of fuel running into the airbox, obviously not what you want due to the fire hazard.

All the best, Dave.
 
Davehuge said:
Hi Zman

I would strongly advise against running vent lines into the airbox.

Please correct me if I'm wrong, as I understand it...

The purpose of the vent lines is to keep the float bowl at atmospheric pressure, ensuring that fuel in the float bowl is drawn up through the jets correctly, relieving air as fuel flows into the float bowl. Air or dirt shouldn't flow from the vent lines into the float bowl, no dirt should be sucked in.

With vent lines running into the airbox, if the bike is laid on it's side, when we crash or fall off (about every time I ride!) there is a risk of fuel running into the airbox, obviously not what you want due to the fire hazard.

All the best, Dave.
Click to expand...
Warm crankcase + cold water=vacuum. Crankcase breather can suck water into tranny creating a milkshake. Same with carb breathers. Only need to do 1 but I usually do top 2 on carb. Draws water into carb snuffing motor. No breather means all sucking drawing up through carb vents. Mate's 17 TE250 did it last ride. I scolded him about it!

Just run the breathers long enough to loop back downwards(face them downwards). I zip tie mine to subframe rails generally. Just keep them below air filter height so fuel won't leak onto it when bike is sleeping upside down. :)
 
I run them up to the entry at top of airbox Right front. Have done for years now drama. If the bike is upside-down fuel will Piss through the needle jet anyway. Lid is of course open to atmosphere.
Big slot in the bottom for water to run out. Or if the bike is upside-down it will run out the top of the air box.
 
With the lower vent hoses going down and the top vent hoses going up into the air box it provides an air break to prevent sucking in water. Yes these tubes do equalize internal carb air pressure, but to do this air flows in and out. Engines are very dynamic things especially when you toss in the fact that they live inside a very active environment of a dirt bike.

The bike has to be near upside down to leak fuel out of the top vent hoses. As was pointed out it will drain fuel out of the needle jet when this happens so there is not much more of a hazard.

https://slavensracing.com/shop/carburetor-vent-filter-by-7602/
Uptite-Racing had them several years ago too. 111 W Dyer Rd Ste B,
Santa Ana, California 92707 Phone (714) 540-2920
 
john r b said:
I've seen filter systems you run your vent tubes into , cant remember were..
Click to expand...

I've got a PC Racing vent system on my bike. I can't remember exactly how it all goes together but I think that you use the supplied T pieces so that you end up with 2 separate pairs of vent hoses connected together with 2 more vent hoses then running from the T pieces up into the air box and into a plastic piece with a filter. It's supposed to prevent bogging when landing from jumps and also flooding.

http://www.pcracingusa.com/Carb-Vent_p_84.html
 
I just do the F5 method.

Never had any issues with fuel washing the air filter oil off. Have had numerous issues with people who haven't routed the breathers up dropping into a creek and the engine snuffing out.

Have had several issues with water levels higher than the airbox, or the bike 'somehow' going below the surface.. :D

Crankcase drain bolts on the gasser has proven a worth while venture. Not sure why other manufacturers haven't done the same.
 
Yeah Rotax engines had it too.
I first noticed that drain bolt first time I rode my first 200.

It was a Monday, had driven the weekend to go pick it up in crazy weather.

The Monday was beautiful as I sat at work.

Half day sez I . Rode this local track, but being a Monday logging trucks were surveying on the track I was going to take.
Well. River crossing was ok last time I did it. Went for a ride on other side. Came back. Front wheel stopped on hidden rock and over I went.

Cursed myself for riding alone as I managed to get myself from underneath the bike.

Anyhoo. Dragged the bike out and kick kick.

Looked under the bike and saw the drain.

Would have been nice if I'd had some tools. . . :rolleyes:
 
Doing pre first ride new bike sort on Friday night. Was looking for where to run breathers. Bit different with 18+ airbox. Didn't wanna have them anywhere near battery(previous poster spooked me about that!) or electrics for fire danger reasons so ran then up through headstays & over tank mount posts(stick out sideways with rubber wheels that tank slots onto) then ziptied together facing down. Did some swimming yday & no probs. Air filter drain seems rather large & no flap so may silicone that up to 1/3 the current size or seal it completely & drill a 6mm or so hole.
 
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