T Vent the Carb


12 replies to this topic
  • crfmatt

Posted March 26, 2006 - 04:14 PM

#1

Can someone explain to me what this is? I have to cross deep water ocasionally so Ive herd it woul dbe a good thing to do.

  • NYMXer

Posted March 26, 2006 - 05:13 PM

#2

This is done by cutting the vent hose, adding a 'tee' and add more hose at the tee to go into the airbox. The idea behind all this is to create a siphon break. :thumbsup:

  • KTMKarl

Posted March 26, 2006 - 07:41 PM

#3

Very good idea and one a lot of folks miss out on. With an FCR carb you shouldn't have to physically add a tee to the hoses, both sides of the carb should have 2 sets of hoses coming out, one horizontal and the other vertical. Just route the vertical hoses up into the airbox and position them with about half the boxes depth of vertical drop. Why the drop? If you don't have the drop in the hose debris from the airbox will enter the hose and drop right into the float bowls (made this mistake). Some aftermarket shops sell little filtered ends to plug the hoses into as this mod was quite the rage in the mid 90's. Also keep in mind that if you loop the bike out and it spends an inordinate amount of time on its back you run the risk of contaminating the airbox/filter with fuel which could be a bad thing. (fire, hot arse! LOL)

Why do it in the first place? I leaned (oops I mean learned) this one the hard way as well. If all the hoses route down there is a higher probability that they will all become plugged resulting in a float bowls that is not vented and a very lean motor. I thought it was BS years ago but it does happen and did have me scratching my head with an old KTM 2 smoke that would spaoradically die and refuse to resart when crossing water. I hadn't had the problem with a FCR equiped bike primarily cuz it is one of the first mods I do to all of my machines and I overlooked it on my 06 450. What do you know second race of the MHSC, series lots of rain, lots of mud, big creeks and a 450 that wants me to shoot myself in the head for neglecting her! Do it! Cheap easy effective what more is there?

  • PMK

Posted March 26, 2006 - 08:18 PM

#4

Don't forget about the engine breather. Some of the bikes if stalled in the water will suck the water into the engine when restarting.

PK

  • One Louder

Posted March 26, 2006 - 09:55 PM

#5

Does anyone have any pics of this mod?

  • 2fastwhitey

Posted March 26, 2006 - 10:27 PM

#6

From what I understand you just run the top two lines off the carb into the airbox or cut the lines, install a T fitting, and run a new line into the airbox(according to cowboyona426). If anyone has got any pics I would like to see them too.

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  • crfmatt

Posted March 26, 2006 - 11:56 PM

#7

I'm having a hard time picturing this in my head..Pics will defintly help. KTMKARL you talked about when its on its back fuel could go to the airbox...Could that happen on a steep wheelie or a big hillclimb? Thanks for the help guys

  • KTMKarl

Posted March 27, 2006 - 10:20 AM

#8

Nah it shouldn't drain unless its all the way over and even then if the hoses are dropped far enough into the box and secured it shouldn't be an issue, personally I throw my bike down continually and have never experienced any issues that way but I can visualize it happening. Of course IF the moons and stars lined up just right you could get fuel in the box no matter how they are routed but I'll leave that issue to the safety nazis out there.

As far as pictures... well may find a way to post some but once you see how simple it is you'll feel foolish! LOL Just take a gander at your carb, you'll notice the breather hoses come out very near one another on each side of the carb FCR's have the "T" essentially cast into the body of the carb. Just take the ones that point up and over the carb out of their looms and route them up and over to the airbox. On my 06 I drilled an oval hole (try to find that bit!) in the side of the box to avoid pinching them under the seat base.

  • One Louder

Posted March 27, 2006 - 11:52 AM

#9

can you take the two top hoses and combine them with a T and run one hose to the airbox?

  • NYMXer

Posted March 27, 2006 - 01:54 PM

#10

can you take the two top hoses and combine them with a T and run one hose to the airbox?



No, run one into the airbox and the other towards the ground. This way, it can't syphon dirt or water into the engine. :thumbsup:

  • cowboyona426

Posted March 27, 2006 - 10:00 PM

#11

I'm still deciding how I want to do this on my 06, the carb vent hoses are set up different than my old 426. On my 00 I just T'ed each of the upper lines and ran a new hose to the airbox, on my new bike it looks like you only need to do one. I'll get some pics when I figure out how I want to do it.

  • 2fastwhitey

Posted March 27, 2006 - 10:54 PM

#12

I'm still deciding how I want to do this on my 06, the carb vent hoses are set up different than my old 426. On my 00 I just T'ed each of the upper lines and ran a new hose to the airbox, on my new bike it looks like you only need to do one. I'll get some pics when I figure out how I want to do it.


Hey Cowoyona did you ever find those pics from when you t-vented your 426. It's been a while but I would appreciate it. The post you emailed me was no longer in the archive.

  • cowboyona426

Posted March 28, 2006 - 08:27 PM

#13

2fast- no the pics are history. Send a PM to IHScoutII, he has my old bike and may be willing to snap some pictures of it for you.





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