Jump to content
Sign in to follow this  

Routing of carb vent hoses

Recommended Posts

I have a 2016 KTM 250XCW 2 stroker and want to reroute my vent tubes for the carb. I was thinking all 4 under the seat or the tank, but some guys on KTM Talk said 2 vents up and 2 vents down along with the overflow. What do you guys think? I just don't like the idea of the vent tubes hanging on the bottom of the bike getting gunked up all the time. Thinking there must be a better way.

Little Jeff

Edited by Littlejeff
misspell

Share this post


Link to post
Share on other sites

two up, two down.  That way if you're doing water crossings you're not gonna submerge all 4.

Share this post


Link to post
Share on other sites
15 hours ago, zibbit u2 said:

two up, two down.  That way if you're doing water crossings you're not gonna submerge all 4.

I'm probably going to do it that way, but why not all 4 up?

Share this post


Link to post
Share on other sites
17 hours ago, Littlejeff said:

I'm probably going to do it that way, but why not all 4 up?

At least one of the lines (maybe two) is a carb overflow line, which is effectively a drain for when the carb is over-filled. That drain tube needs to be below the level of the carb to work by gravity.  

Back in the day, we used to put T's in the vent hoses to split each line. We would run one set down to the usual spot behind the engine, and the other set, we would route into the airbox, into a canister. 

Search PC racing carb vents to see what I mean. 

Splitting the lines would help reduce bogging for wide open throttle when landing. Also, if the lower vents were submerged in water or blocked by grit, they could breath through the canister. 

If you ride in a lot of silt/dust, consider putting a filter on the vent lines. As a vent line, they are sometimes under a slight pressure and sometimes under a slight vacuum. When under vacuum, or if you bomb through silt, it can work its way into the float bowl and eventually into the engine. 

  • Like 1

Share this post


Link to post
Share on other sites

Yes, Jeff.....2 upper hoses up into the air box and the lower 2 down. Take the actual carb drain low hose and put a loop in it also like JD jetting shows so you don't dribble out fuel needlessly ( getting better mileage).

 

Joe

  • Like 1
  • Helpful 2

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...